Добірка наукової літератури з теми "Nitrate"
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Статті в журналах з теми "Nitrate"
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Mawaddah, Aida, Roto Roto, and Adhitasari Suratman. "PENGARUH PENAMBAHAN UREA TERHADAP PENINGKATAN PENCEMARAN NITRIT DAN NITRAT DALAM TANAH (Influence of Addition of Urea to Increased Pollution of Nitrite and Nitrate in The Soil)." Jurnal Manusia dan Lingkungan 23, no. 3 (February 27, 2017): 360. http://dx.doi.org/10.22146/jml.22473.
Повний текст джерелаАнотація:
ABSTRAKNitrat dan nitrit merupakan sumber nitrogen bagi tanaman. Nitrogen sangat diperlukan tanaman untuk pertumbuhan dan perkembangan. Bentuk-bentuk nitrogen di lingkungan mengalami transformasi sebagai bagian dari siklus nitrogen seperti nitrifikasi dan denitrifikasi. Apabila kadar nitrogen dalam tanah rendah, maka urea digunakan sebagai sumber nitrogen. Perubahan urea menjadi nitrit atau nitrat pada beberapa sampel tanah perlu diketahui. Kadar nitrit dan nitrat yang tinggi dapat meningkatkan pencemaran di dalam tanah. Sampel tanah yang digunakan dalam penelitian ini adalah tanah pasir, tanah sawah, tanah pupuk kompos dan tanah pupuk kandang. Analisis nitrit dan nitrat dilakukan dengan menggunakan pereaksi asam p-amino benzoat (PABA) yang dikopling dengan N-naftiletilendiamin (NEDA) dan reduktor spongy cadmium. Sebelum digunakan untuk analisis nitrit dan nitrat, metode divalidasi terlebih dahulu. Hasil validasi metode analisis nitrit dan nitrat dengan pereaksi PABA/NEDA menunjukkan persentase perolehan kembali masing-masing antara 87,15–100,8% untuk nitrit dan 88,16–105,7% untuk nitrat. Setelah ditambah urea sebesar 0,66 g.kg-1 ke dalam tanah, konsentrasi nitrit dan nitrat pada semua sampel tanah mengalami peningkatan. Dari penelitian ini diketahui bahwa peningkatan kadar nitrit dan nitrat setelah ditambahkan urea sangat dipengaruhi oleh kondisi tanah. ABSTRACTNitrate and nitrite were sources of nitrogen for plants. Nitrogen is indispensable for the growth and development of plants. The forms of nitrogen in the environment undergoes a transformation as part of the nitrogen cycle like nitrification and denitrification. If nitrogen level in the soil is low, urea is used as a source of nitrogen. Changes of urea into nitrite or nitrate in some of soil samples need to be known. The levels of nitrite and nitrate are high can increase pollution in the soil. Some of soil samples which is used in this research were sandy soil, paddy soil, compost soil and manure soil. Analysis of nitrite and nitrate were conducted by using a reagent p-amino benzoic acid (PABA) / N-napthylethylenediamine (NEDA) and spongy cadmium as reductor. Before being used for the analysis of nitrite and nitrate, this method was validated first. The results of validation of nitrite and nitrate analysis method by using a reagents PABA / NEDA showed the percent recovery were respectively 87.15-100.8% for nitrite and 88.16-105.7% for nitrate. After the addition of 0.66 g.kg-1 urea into the soil, nitrite and nitrate concentration in all soil sample has increased. Based on this research was known that the increased levels of nitrite and nitrate after the addition of urea was influenced by soil condition.
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Bernardo, Patrícia, Luís Patarata, Jose M. Lorenzo, and Maria João Fraqueza. "Nitrate Is Nitrate: The Status Quo of Using Nitrate through Vegetable Extracts in Meat Products." Foods 10, no. 12 (December 5, 2021): 3019. http://dx.doi.org/10.3390/foods10123019.
Повний текст джерелаАнотація:
Nitrate and nitrites are used to give the characteristic color to cured meat products and to preserve them. According to the scientific knowledge available at the moment, these compounds are approved as food additives based on a detailed ponderation between the potential risks and benefits. The controversy over nitrites has increased with the release of an IARC Monograph suggesting an association between colorectal cancer and dietary nitrite in processed meats. The trend in “clean label” products reinforced the concern of consumers about nitrates and nitrites in meat products. This review aims to explain the role of nitrates and nitrites used in meat products. The potential chemical hazards and health risks linked to the consumption of cured meat products are described. Different strategies aiming to replace synthetic nitrate and nitrite and obtain green-label meat products are summarized, discussing their impact on various potential hazards. In the light of the present knowledge, the use or not of nitrite is highly dependent on the ponderation of two main risks—the eventual formation of nitrosamines or the eventual out-growth of severe pathogens. It is evident that synthetic nitrite and nitrate alternatives must be researched, but always considering the equilibrium that is the safety of a meat product.
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Mastanjević, Krešimir, Dragan Kovačević, Martina Dančić, and Kristina Habschied. "Levels of nitrite and nitrate content in traditional dry sausage “homemade kulen”." Meso 26, no. 5 (2024): 619–427. http://dx.doi.org/10.31727/m.26.5.3.
Повний текст джерелаАнотація:
When it comes to sausages production, the meat industry relies on the effectiveness of antimicrobial agents such as nitrite (NO2 − ), nitrate (NO3 − ) and their potassium and sodium salts. These additives are important as curing agents, antioxidants, and they enhance the color, flavor, aroma and inhibit the growth and reproduction of bacteria Staphylococcus aureus and Clostridium botulinum. However, nitrites and nitrates are known to react in such a way to form N-nitrosamines which are, according to the IARC (International Agency for Research on Cancer), claimed as probably or possibly carcinogen. This stimulated the establishment of The European Regulation (EC) No 1333/2008 which regulates the maximum permitted levels of nitrate and nitrate additives in meat products. Commercially available meat products are designated to 150 mgkg− 1 and for traditional meat products this limit was set each product type (50 to 180 mg kg−1 and from 10 to 300 mg kg−1 for nitrite and nitrate). On the other hand, the European Regulation (EC) No 2108/2023 prescribes (from the 9th of October 2025.) the reduction of nitrite and nitrate in dry sausages to 80 and 90 mgkg− 1. The aim of this investigation was to screen the nitrate and nitrite levels in commercially available dry sausage “Homemade kulen”. The investigation was conducted consecutively for four years and 158 samples of “Homemeade kulen” have been analyzed. The results show that mean value for nitrites was 4.42 mgkg−1 and for nitrates 16.22 mgkg−1 in the first year. In year two, mean values were a bit higher, amounting to 5.68 mgkg−1 for nitrites and 17.86 mgkg−1 for nitrates. In the third year samples showed a drop in nitrite and nitrate mean values (2.92 and 9.80 mgkg−1) while in the fourth year nitrites showed and increase to 4.95 mgkg−1 and nitrates to 19.32 mgkg−1. Maximal values ranged 7.82−19.67 mgkg−1. Minimal values for years three and four were 2.65 mgkg−1 and 1.45 mgkg−1. Maximal value for nitrates was reached in year four amounting above 90 mgkg−1. This shows that this kind of traditional products contain nitrates and nitrites and the amounts of this additive must be monitored
4
Fogarasi, Erzsébet, Ibolya Fülöp, Emanuela Marcu, and Mircea Dumitru Croitoru. "Presence of Nitrate and Nitrite in Well Water in Mureș County." Acta Medica Marisiensis 62, no. 1 (March 1, 2016): 78–81. http://dx.doi.org/10.1515/amma-2015-0063.
Повний текст джерелаАнотація:
AbstractObjective: One of the most important sources of nitrite and nitrate anions, besides vegetables and meat products, is the drinking water. Presence of nitrite and nitrate in the water in higher concentrations than those set by EFSA (0.5 mg/l nitrite, 50 mg/l nitrate), may have toxicological significance. A quantitative determination of these ions in samples collected from several pleases from Mureș County was made. Methods: Ninety-seven well water samples were tested from 12 different places from Mureș County. We used a simple HPLC-UV ion pair method for the determination of nitrite and nitrate concentrations. Sensitivity of the method enables the quantification for concentrations far below the MCL value. Results: The highest amounts of nitrate and nitrite were measured in Sangeorgiu de Mureș and Cristești. Concentrations of nitrite and nitrate were exceeded in 4.12% and respectively 44.32% of the samples. Conclusions: The high amounts of nitrites and nitrates existing in well water go beyond the expected extent. This pollution can become a health risk since this water is used in human nutrition especially in child nourishment.
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KATSOULOS (Π. Δ. ΚΑΤΣΟΥΛΟΣ), P. D., N. PANOUSIS (Ν. ΠΑΝΟΥΣΗΣ), and H. KARATZIAS (Χ. ΚΑΡΑΤΖΙΑΣ). "Nitrate poisoning in ruminants." Journal of the Hellenic Veterinary Medical Society 55, no. 3 (December 6, 2017): 226. http://dx.doi.org/10.12681/jhvms.15098.
Повний текст джерелаАнотація:
This paper describes the nitrate - nitrite poisoning of ruminants. This disease is caused by the ingestion of large amount of nitrate salts, which are reduced in the rumen to nitrite ions. Nitrites, after their absorption, cause the formation of methemoglobin and, in turn, respiratory and circulatory distress. The aim of the treatment is to reduce the percentage of methemoglobin in blood and to stop the continuing production of nitrite ions in the rumen. For the prevention of the disease, avoidance of feedstuff rich in nitrates and improvement of the water quality, are suggested.
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Al_Nawaiseh, FY, and RH Mashal. "Nitrate in raw and cooked vegetables: content, variation and influence of cooking methods." African Journal of Food, Agriculture, Nutrition and Development 25, no. 1 (January 29, 2025): 25596–618. https://doi.org/10.18697/ajfand.138.25335.
Повний текст джерелаАнотація:
Nitrate concentrations in vegetables are pivotal in dietary nitrate benefit-risk assessments. This study examined nitrate and nitrite levels in vegetables commonly consumed in Jordan, highlighting the impact of different cooking methods (boiling, steaming, baking, stir-frying, and deep frying) on nitrate content. The study examined the nitrate and nitrite levels in 270 raw vegetables and vegetable-based dishes purchased from retail markets and restaurants in Amman, Jordan, during the winter months of 2022 and 2023. Furthermore, 91 experimentally -cooked vegetables were tested for their nitrate and nitrite contents before and after cooking to determine the effect of cooking methods on nitrate levels. The nitrate and nitrite concentrations were measured using an in-house validated molecular absorption spectrometric method. Nitrate levels varied considerably within and between vegetable groups and species. Celery had the highest mean nitrate content (1700 mg/kg), and radish (1300 mg/kg) and beetroot (900 mg/kg) were next. Approximately 32% of vegetables contained moderate amounts of nitrate (200–1000 mg/kg). Leafy greens such as spinach, tossa jute, and lettuce contain nitrates in averages exceeding 500 mg/kg. Among fruit vegetables, zucchini and eggplant have the highest mean nitrate levels (311.6 and 221.6 mg/kg, respectively). Flower, root (excluding radishes and beetroot), and legume (excluding green beans) vegetables have nitrate levels below 200 mg/kg. On average, the mean nitrite level in raw and cooked vegetables was less than 1 mg/kg. Different cooking methods influence vegetable nitrate content differently. Boiling reduced nitrate by 22-40%. Steaming had no significant impact. Although deep-frying, stir-frying, and baking increased nitrate by 130%, 66.7%, and 57.6%, respectively, the overall effect was not statistically significant for deep-frying and baking. These findings are essential for public health and food safety authorities in evaluating nitrate exposure and assessing the risk and benefit of dietary nitrate intake. The data may support the development of evidence-based guidelines for safe nitrate intake. Key words: Nitrate, nitrite, raw vegetables, cooked vegetables, cooking methods
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Yulianti, Wina, Ima Kusumanti, and Nurul Jannah. "Determination of Nitrite and Nitrate Level in Wastewater Discharge from Smoked Fish Industry." JURNAL SAINS NATURAL 12, no. 1 (January 27, 2022): 17. http://dx.doi.org/10.31938/jsn.v12i1.323.
Повний текст джерелаАнотація:
This research aimed to determine nitrite and nitrate contamination in wastewater discharge from the smoked fish industry around the fishpond area in Penatarsewu village, Sidoarjo East Java. Samples were taken from ten locations along The Alo River from September to November 2020. Nitrate and nitrite levels were determined by the Standard Method for Examination of Water and Wastewater 4500-NO2-B dan 4500-NO3-B. Nitrite formed a reddishpurple azo dye produced by coupling diazotized sulfanilamide with N-(1-naphthyl)-ethylene-diamine dihydrochloride after a visible spectrophotometer measured the complexes nitrite at wavelength 543 nm. Meanwhile, the Nitrate level was determined by ultraviolet spectrophotometer at a wavelength of 220 nm. The standard nitrite calibration curve was shown by the line equation y= 3,30361x-0,0028 and a determination coefficient of 0.9999. Whereas the standard nitrate was showed by the line equation y=0,2507x + 0,0067 and a determination coefficient 0,9996. The level of nitrate and nitrite in the sample ranged from 0.05-0.93mg / L 1,2-1,6 mg / L. According to a quality standard threshold value for nitrite and nitrate-based on the Government Regulation of the Republic of Indonesia (PPRI) No.82 2001 is 0,06mg/L and 10 mg/L, therefore it can be concluded that some samples are above the threshold value for nitrite level.Keywords: Alo River, nitate, nitrite, smoked fish, spectrophotometerPenentuan Kadar Nitrit dan Nitrat Pembuangan Limbah Cair Industri Ikan AsapABSTRAKPenelitian bertujuan untuk menentukan tingkat kontaminasi nitrat dan nitrit pada limbah industri ikan asap di sekitar kawasan tambak ikan asap di Desa Penatarsewu, Sidoardjo, Jawa Timur. Sampel diambil dari 10 titik di areal sekitar tambak sepanjang badan Sungai Alo pada bulan September sampai November 2020. Penentuan kadar nitrat dan nitrit mengacu pada Standard Methods for the Examination Water and Wastewater 4500-NO2-B dan 4500-NO3-B. Nitrit membentuk kompleks ungu kemerahan yang dihasilkan dari kopling sulfanilamida dengan N-(1-naptil)-etilena-diamina dihidroklorida kemudian kadarnya ditentukan dengan spektrofotometer sinar tampak pada panjang gelombang 543 nm. Kadar nitrat ditentukan menggunakan spektrofotometer ultraviolet pada panjang gelombang 220 nm. Hasil pengukuran standar nitrit menghasilkan persamaan garis y=3,30361x-0,0028 dengan koefesien determinasi 0,999 dan standar nitrat menghasilkan persamaan garis y=0,2507x+0,0067 dengan koefesien determinasi 0,9996. Kadar nitrit dan nitrat secara berturut-turut berkisar antara 0,05-0,93 mg/L dan 1,2-1,6 mg/L. Berdasarkan nilai ambang batas baku mutu nitrit dan nitrat berdasarkan Peraturan Pemerintah Republik Indonesia (PPRI) No.82 tahun 2001 adalah 0,06 mg/L dan 10 mg/L, maka dapat disimpulkan bahwa beberapa sampel mengandung kadar nitrit di atas ambang batas.Kata kunci : ikan asap, nitrat, nitrit, Sungai Alo, spektrofotometer
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R, Stanek, and Zabranska J*. "Inhibition of Biological Denitrification by Nitric Oxide, Its Early Detection and Prevention of Negative Impact on the Denitrification of Industrial Wastewater." Journal of Biomedical Research & Environmental Sciences 6, no. 1 (January 2025): 001–11. https://doi.org/10.37871/jbres2050.
Повний текст джерелаАнотація:
Biological denitrification is used to treat industrial wastewater containing high concentrations of nitrate and sulfate from nitrocellulose production, which contains high concentrations of nitrates and sulfates. The reactor emits brown nitrogen dioxide gas suggesting significant Nitric Oxide (NO) formation and reaction with air. NO may significantly inhibit the denitrification process, reduce treatment efficiency and cause potentially serious issues in nitrocellulose production. An NO-sensitive oxygen luminescence probe demonstrated an accumulation of exceptionally high NO levels. The presence of excess NO under conditions that replicate the industrial denitrification process have further revealed that NO formation is triggered by an oversupply of ethanol, as the reducing substrate, under high nitrate loading. This overdosing is ultimately caused by the failure of an automatic ethanol dosage control, which relies on the signal from a nitrate- and nitrite-sensitive Nitratax probe. When the reduction rate of nitrate and nitrites appears to slows, nitrites continue to accumulates. Thus, the Nitratax probe signals for additional ethanol delivery even when it is unnecessary. Nitrite accumulation and nitrite reduction increase NO concentrations. Excess NO, or nitrite, apparently disrupts the next step in microbial denitrification, the reduction of NO by NO-reductases, and the denitrification pathway that ultimately yields N2. An NO or nitrite-specific probe may better serve as an early warning system by providing the timely feedback required to prevent inhibitory conditions. Additionally, a correlation was observed between inhibition events and lower pH levels in the denitrification reactor, particularly within the range of 6.1-6.3. However, no connection was found between NO evolution and temperature within the range of 16-35°C. Elevated industrial reactor NO may significantly inhibit the denitrification process, reduce treatment efficiency and cause potentially serious issues in nitrocellulose production.
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McMullen, Sarah E., John A. Casanova, Lois K. Gross, and Frank J. Schenck. "Ion Chromatographic Determination of Nitrate and Nitrite in Vegetable and Fruit Baby Foods." Journal of AOAC INTERNATIONAL 88, no. 6 (September 1, 2005): 1793–96. http://dx.doi.org/10.1093/jaoac/88.6.1793.
Повний текст джерелаАнотація:
Abstract An ion chromatographic method was developed for the determination of nitrate and nitrite in vegetable and fruit baby foods. The introduction of nitrate or nitrite to food may be natural or artificial as a preservative. Because of the higher pH found in babies' stomachs, nitrate can act as a reservoir for the production of nitrite by nitrate-reducing bacteria that can be harbored in the intestinal tract. This problem does not exist in adults because of the lower pH of the adult stomach. Exposure to nitrite by infants can result in methemoglobinemia (blue baby syndrome). There are also indications that carcinogenic nitrosamines can be formed from nitrates at the higher pH. These gastric conditions disappear at approximately 6 months of age. In this method, nitrate and nitrite were separated on a hydroxide-selective anion exchange column using online electrolytically generated high-purity hydroxide eluant and detected using suppressed conductivity detection. Average recoveries of spiked nitrite residue ranged from 91 to 104% and spiked nitrate residue ranged from 87 to 104%. This method and the AOAC Official Method yield comparable results for samples containing incurred nitrate residue. In addition, this method eliminates the hazardous waste associated with the use of cadmium found in the AOAC Official Method.
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Drysdale, G. D., H. C. Kasan, and F. Bux. "Assessment of denitrification by the ordinary heterotrophic organisms in an NDBEPR activated sludge sytem." Water Science and Technology 43, no. 1 (January 1, 2001): 147–54. http://dx.doi.org/10.2166/wst.2001.0036.
Повний текст джерелаАнотація:
The purpose of this study was to isolate and characterise the ordinary heterotrophic organisms (OHOs) present in a NDBEPR system in order to gain a better understanding of the organisms involved in denitrification as well as a more holistic and accurate evaluation of the OHO fraction attributable to denitrification in such a system. Heterotrophic bacteria were isolated from the pre- and secondary anoxic zones of the Darvill NDBEPR process and characterised according to their ability to reduce nitrates and/or nitrites under anoxic conditions. Results showed that the OHO fraction is more complex than currently accepted and, with respect to denitrification, can be more accurately subdivided into five functional groups, four of which interactively contribute to denitrification occurring in the system and one group that are non-denitrifying. These groups were defined as true denitrifiers (bacteria capable of both nitrate and nitrite reduction), incomplete denitrifiers (bacteria that reduced nitrates to nitrites with no further reduction of the nitrites produced), incomplete-nitrite reducers (bacteria capable of both nitrate and nitrite reduction, however, exhibiting severe inhibition of nitrite reduction by nitrates), exclusive nitrite reducers (bacteria only capable of reducing nitrites) and non-denitrifiers (bacteria not capable of nitrate or nitrite reduction).
Дисертації з теми "Nitrate"
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Machado, Genikelly Cavalcanti. "Determinação sequencial de nitrato e nitrito por voltametria de pulso diferencial empregando um ultramicroeletrodo de ouro." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-20092010-144502/.
Повний текст джерелаАнотація:
Este trabalho descreve o desenvolvimento de um método eletroanalítico para determinação sequencial de nitrito (NO2-) e nitrato (NO3-), utilizando como técnica, a voltametria de pulso diferencial. O método se baseia na redução eletroquímica dos íons nitrato sobre um ultramicroeletrodo de ouro modificado in situ com cádmio depositado em regime de subtensão, e na seqüência, a remoção da monocamada de cádmio e a oxidação eletroquímica dos íons nitritos sobre o ultramicroeletrodo não modificado. Os ensaios voltamétricos para determinação quantitativa de nitrato e nitrito foram realizados em solução de NaClO4 0,1 molL-1 + HClO4 1,0x 10-3 molL-1 (pH = 3,3) preparada com água ultrapura. Utilizando as condições experimentais e os parâmetros voltamétricos otimizados, foram construídas curvas analíticas para determinação de nitrito e nitrato separadamente e também para determinação sequencial dos dois analitos. Para a determinação do NO2-, foi observado uma relação linear entre a corrente de pico e a concentração desse íon dentro do intervalo de concentração de 1,0 x 10-5 molL-1 a 1,1 x 10-4 molL-1, com um limite de detecção igual a 1,151 ± 0,091 µmolL-1 e limite de quantificação igual a 3,838 ± 0,091 µmolL-1. Para a determinação do NO3-, também foi observado uma relação linear entre corrente de pico e concentração desse analito dentro do intervalo estudado, que foi de 2,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1. O limite de detecção encontrado foi 4,839 ± 0,275 µmolL-1 e o limite de quantificação 16,131 ± 0,275 µmolL-1. A determinação sequencial de nitrito e nitrato foi avaliada dentro do intervalo de concentração de 5,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1 para NO3- e 1,00 x 10-5 molL-1 a 4,50 x 10-5 para NO2-. Para ambos os casos, a relação entre corrente de pico versus concentração do analito foi linear. Para a determinação sequencial os limites de detecção são 16,177 ± 0,794 µmolL-1 para NO3- e 2,243 ± 0,179 µmolL-1 para NO2- e os limites de quantificação são 53,922 ± 0,794 µmolL-1 para o NO3- e 7,476 ± 0,179 µmolL-1 para o NO2-. Os limites de detecção, os limites de quantificação e demais parâmetros estatísticos apresentados nesse trabalho, foram obtidos a partir de cálculos baseados em procedimentos descritos em Miller e Miller68 e Silva69.<br>This work describes the development of an electroanalytical method for sequential determination of nitrite (NO2-) and nitrate (NO3-), using as a technique, differential pulse voltammetry. The method is based on the electrochemical reduction of nitrate ions on a gold ultramicroelectrode modified in situ by underpotential deposition of cadmium, and subsequently, the removal of cadmium monolayer and the electrochemical oxidation of nitrite on ultramicroelectrode unmodified. The voltammetric analysis for quantitative determination of nitrate and nitrite were carried out in NaClO4 0.1 molL-1 + HClO4 1.0 x 10-3 molL-1 (pH = 3.3) prepared with ultrapure water. Using the optimized experimental conditions and voltammetric parameters, analytical curves were constructed for determination of nitrite and nitrate separately and for sequential determination of the two analytes. The relationship between peak current and concentration of NO2- were found to be linear in the concentration range between 1.0 x 10-5 molL-1 and 1.1 x 10-4 molL-1, with a detection limit of 1.151 ± 0.091 µmolL-1 and quantification limit of 3.838 ± 0.091 µmolL-1. For determination of NO3- was also observed a linear relationship between peak current and concentration of analyte within the concentration range studied, which was from 2.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1. The detection limit was 4.839 ± 0.275 µmolL-1 and the quantification limit was 16.131 ± 0.275 µmolL-1. The sequential determination of nitrite and nitrate was assessed within concentration range from 5.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1 for NO3- and from 1.00 x 10-5 molL-1 to 4.50 x 10-5 for NO2-. In both cases, the relationship between peak current versus analyte concentration were found to be linear. The detection limits for sequential determination are 16.177 ± 0.794 µmolL-1 for NO3- and 2.243 ± 0.179 µmolL-1 for NO2- and the quantification limits are 53.922 ± 0.794 µmolL-1 for NO3- and 7.476 ± 0.179 µmolL-1 for NO2-. The detection and quantification limits and other statistical parameters presented in this work were obtained from calculations based on procedures described in Miller and Miller68 and Silva69.
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Jiquiriçá, Paulo Ricardo Ilha. "Efeitos letais e subletais da poluição por nitrogênio em larvas de anuros." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-13122010-144109/.
Повний текст джерелаАнотація:
As atividades humanas vêm aumentando dramaticamente a quantidade de nitrogênio inorgânico liberado nos ecossistemas, seja através da aplicação de fertilizantes na agricultura, da descarga de dejetos humanos e de seus rebanhos, ou da queima de combustíveis fósseis. Os excessos de nitrogênio são eventualmente transportados para corpos d´água, onde podem, na forma de nitrato, nitrito e amônio, atingir concentrações tóxicas para organismos aquáticos. Nesta pesquisa tive dois objetivos principais. O primeiro foi testar em laboratório a toxicidade relativa dos íons nitrato, nitrito e amônio, e a variação interespecífica na sensibilidade a esses íons, em larvas de cinco espécies de anuros (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri e Physalaemus olfersii ). Para isso utilizei bioensaios seguindo protocolos internacionalmente padronizados para testes de ecotoxicidade com organismos aquáticos, e que portanto permitem máximas reprodutibilidade e comparabilidade de resultados entre compostos, espécies, e laboratórios. No entanto, estes bioensaios carecem de realismo uma vez que simulam um cenário de exposição aguda a altas concentrações de contaminantes quando na natureza o cenário de exposição tende a ser crônico e prolongado a baixas concentrações. Além disso, bioensaios usam mortalidade como principal variável de resposta, quando também efeitos subletais podem influenciar a persistência de populações ao modular o sucesso dos indivíduos. Por isso, meu segundo objetivo foi testar em laboratório se concentrações relativamente baixas e ecologicamente relevantes de nitrato, nitrito e amônio podem afetar a sobrevivência, o crescimento, o desenvolvimento e o comportamento das larvas de R. ornata, P. cuvieri e H. faber. Demonstrei através dos bioensaios de exposição aguda que nitrato, a forma mais abundante na natureza, é de baixa toxicidade quando comparada a nitrito e amônio. Demonstrei também que há significativa variação interespecífica na sensibilidade ao nitrogênio inorgânico, e que o ranqueamento de sensibilidade das espécies ao nitrato e ao nitrito foram similares, possivelmente por conta de mecanismos comuns de ação tóxica. Através de experimentos de exposição crônica demonstrei que concentrações relativamente baixas de nitrogênio inorgânico podem causar efeitos letais e subletais às larvas de anuros se houver exposição prolongada. O nitrato causou redução no desenvolvimento larval de P. cuvieri e o amônio na sobrevivência e nas taxas de atividade nos girinos de H. faber. A exposição crônica ao nitrito também reduziu significativamente a sobrevivência das três espécies testadas, o crescimento de H. faber e as taxas de atividade de R. ornata. Contudo, é improvável que as concentrações de nitrito que manipulei em laboratório sejam comuns na natureza, especialmente em condições aeróbicas. Esta pesquisa, além de fornecer importantes informações sobre os possíveis efeitos da poluição por nitrogênio em larvas de anuros, contribui para o avanço da ecotoxicologia no Brasil ao estabelecer as bases para o emprego de espécies nativas de anfíbios como sistema-modelo experimental. Estudos futuros que almejem avaliar o risco ambiental da contaminação por nitrogênio deverão por um lado monitorar concentrações em hábitats naturais e por outro avaliar as consequências das interações sinérgicas entre nitrogênio inorgânico e outros estressores físicos, químicos ou biológicos para larvas de anfíbios.<br>Human activities dramatically increased the amount of inorganic nitrogen released in ecosystems through the application of fertilizers in agriculture, the generation of human and livestock waste, and the combustion of fossil fuels. This nitrogen eventually reaches water bodies where it can, in the form of nitrate, nitrite and ammonium, be toxic to aquatic organisms. In this study I had two main objectives. The first was to test the relative toxicity of nitrate, nitrite and ammonium, and the interspecific variation in sensitivity to these ions, in tadpoles of five anuran species (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri and Physalaemus olfersii ). This objective was accomplished by laboratory bioassays following internationally standardized protocols for ecotoxicity tests with aquatic organisms, therefore allowing maximum reproducibility and comparability of results among compounds, species and laboratories. However, these bioassays lack realism for simulating a scenario of acute exposure to high concentrations of contaminants, while exposure in nature tends to be chronic and prolonged at low concentrations. Furthermore, bioassays use mortality as the main response variable, whereas sublethal effects may also influence the persistence of populations by modulating individual success. My second objective was therefore to test in the laboratory if low and environmentally relevant concentrations of nitrate, nitrite and ammonium affect survival, growth, development and behavior of R. ornata, P. cuvieri and H. faber larvae. Through acute exposure bioassays I demonstrated that nitrate, the most abundant N form in nature, has low toxicity when compared to nitrite and ammonium. I also demonstrated that there is significant interspecific variation in the sensitivity to inorganic nitrogen, and that the ranking of species sensitivity to nitrate and nitrite were similar, possibly due to common mechanisms of toxic action. Through chronic exposure I demonstrated that relatively low concentrations of inorganic nitrogen can cause lethal and sublethal effects on anuran larvae if there is extended exposure. Nitrate decreased developmental rate in P. cuvieri and ammonia decreased survival and activity rates in H. faber tadpoles. Chronic exposure to nitrite also significantly reduced survival of all three species tested, growth of H. faber and activity rates of R. ornata. However, it is unlikely that the concentrations of nitrite manipulated in the laboratory are common in nature, especially in aerobic conditions. This is the first study to document deleterious effects of nitrogen pollution to Brazilian amphibian species, and contributes to the development of ecotoxicology in Brazil by establishing the basis for the employment of native amphibians as model experimental system. Future studies that aim to assess the environmental risk of nitrogen contamination should monitor concentrations in natural habitats and evaluate the effects of synergistic interactions between inorganic nitrogen and other physical, chemical or biological stressors to amphibian larvae.
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Pinheiro, Lucas Cézar. "Estudo de mecanismos anti-hipertensivos do nitrito de sódio na hipertensão renovascular experimental." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/17/17133/tde-18032015-230532/.
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O NO regula diversos sistemas orgânicos. No sistema cardiovascular participa ativamente na regulação do tônus vascular entre outras funções. Disfunções na produção ou disponibilidade de NO podem comprometer sua atuação fisiológica. No âmbito vascular isto pode participar da hipertensão. Além da produção de NO pelas óxido nítrico sintases, outras vias paralela de produção fisiológica de NO a partir do nitrito tem sido descritas. O nitrito é o produto inicial da oxidação do NO, sendo posteriormente oxidado a nitrato. Sabe-se que estas três moléculas formam um ciclo dentro do organismo, onde o nitrato é excretado na saliva e convertido a nitrito pelas bactérias bucais.Este nitrito é deglutido com a saliva e exerce seus efeitos, através da conversão a NO. A conversão de nitrito a NO pode ocorrer de forma enzimática ou não enzimática. Como forma não enzimática, o nitrito é convertido a NO pela reação com H+. Esta redução ocorre principalmente no estômago. Esta tese visa elucidar possíveis mecanismos responsáveis pelos efeitos anti-hipertensivos do nitrito de sódio. Avaliamos ratos 2 rins 1 clipe (2R1C) tratados com nitrito e nitrato e verificamos os efeitos anti-hipertensivo destes. De forma Interessante, o aumento do pH gástrico com omeprazol impediu o efeito anti-hipertensivo tanto do nitrito quanto do nitrato. O omeprazol não gerou qualquer diferença na concentração plasmática de nitrito e nitrato. Foi verificado que o tratamento com nitrito e nitrato resultou em aumento das espécies nitrosiladas no plasma e este aumento foi impedido pelo omeprazol. Também testamos a influência do ciclo entero-salivar no efeito do nitrito e nitrato. Verificamos que o tratamento com enxaguante bucal levou ao bloqueio do efeito anti-hipertensivo do nitrato, mas não alterou este efeito nos animais tratados com nitrito. Em todas as abordagens experimentais o efeito anti-hipertensivo do nitrito apenas ocorreu quando houve aumento da concentração plasmática de espécies nitrosiladas.<br>Nitric Oxide plays many functional roles in physiological systems. In the cardiovascular system it participates in a unique way in the regulation of vascular tone among other functions. Dysfunctions in the production or availability of NO may compromise their physiological activity and participate in hypertension. Besides the production of NO by the nitric oxide synthase, other physiological pathways of NO production from nitrite have been described. The nitrite and nitrate are oxidation products of NO. Further nitrite is oxidized to nitrate. These three molecules are known to forma cycle in the body. Nitrate is excreted in saliva and reduced to nitrite by oral bacteria. Nitrite then is swallowed with the saliva and exerts its effects through conversion to NO. The conversion of nitrite to NO may occur by enzymatic or non-enzymatic manner. As a non-enzymatic way nitrite is reduced to NO by reaction with H+.This reaction occurs mainly in the stomach. This thesis aims to elucidate possible mechanisms responsible for the antihypertensive effects of sodium nitrite. We studied 2K1C rats treated with nitrite and nitrate and checked anti-hypertensive effects of these molecules. The increased gastric pH by omeprazole prevented the anti-hypertensive effect of nitrite and nitrate. Omeprazole did not cause any differences in plasma nitrite and nitrate. It was found that treatment with nitrite and nitrate resulted inincreased nitrosylated species in the plasma, and this increase was blocked by omeprazole. We also tested the influence of the entero-salivarycycle effect of nitrite and nitrate. We found that treatment with mouthwash blunted the antihypertensive effect of nitrate but this effect did not change in animals treated with nitrite. Interestingly in all experimental approaches the anti-hypertensive effect of nitrite only occurred when there was an increase in the plasma concentration of nitrosylated species
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Lanza, Luciana Nunes Menolli 1981. "Tolerância ao estresse por hipóxia em soja = os efeitos do nitrato." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315219.
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Previous issue date: 2011<br>Resumo: A soja é a leguminosa de maior importância econômica no Brasil com produção de 72,23 milhões de toneladas na safra de 2010/2011. O cultivo de soja em regiões que sofrem alagamento é uma das principais causas de perda de produtividade no Brasil. Nestas condições, ocorre redução na taxa de oxigênio do solo, e o sistema radicular da planta entra em hipoxia prejudicando o desenvolvimento e a produtividade das plantas. Existem evidências de que a adição de nitrato em condições de alagamento do sistema radicular (hipoxia) promove tolerância ao estresse, entretanto os mecanismos bioquímicos que envolvem essa tolerância ainda não estão totalmente elucidados. Analisando as alterações no metabolismo de nitrogênio em hipoxia, em plantas submetidas a diferentes condições experimentais, observou-se redução do conteúdo de nitrato dentro da planta, aumento no teor de aminoácidos solúveis totais, aumento na composição dos aminoácidos livres: Ala e Gaba, e redução de Asn, em plantas não noduladas e noduladas, além de redução no conteúdo de ureídeos totais em plantas noduladas. A adição de nitrato promoveu maior conteúdo de nitrato nas raízes, seiva do xilema e nódulos, maior teor de aminoácidos solúveis totais, maior conteúdo de proteínas solúveis totais nas raízes e menor nas folhas. A atividade da enzima redutase do nitrato in vivo em condições de hipoxia reduziu nas raízes das plantas não noduladas e nas raízes e folhas das plantas noduladas. A inclusão de K15NO3 no meio demonstrou que o nitrato é, de fato, absorvido em condições de hipoxia, pois as raízes, folhas e nódulos todos incorporaram o 15N. Entretanto, absorção do nitrato sob hipoxia foi bem menor do que sob normoxia. Tanto em normoxia como hipoxia as raízes apresentaram o maior grau de enriquecimento com 15N enquanto que a incorporação nos nódulos foi menor. Houve incorporação de 15N em aminoácidos em todos os tecidos, o que permite concluir que o nitrato não é apenas absorvido pelas raízes sob hipoxia mas também assimilado e transportado para a parte aérea. Os aminoácidos mais próximos ao processo de assimilação de nitrato, Asp, Glu, Ala e Asn, foram os que mais incorporaram o 15N. No entanto, em geral um grau menor de incorporação foi encontrado sob hipoxia. A adição de nitrato, no dia 7, na solução do vaso de cinco cultivares de soja cujo sistema radicular estava alagado promoveu, na cultivar IAC Foscarin-31, maior crescimento da planta quando comparada às plantas com nitrato desde o início do experimento; na cultivar IAC-23, maior massa seca do sistema radicular; nas cultivares IAC-17 e IAC-18 foi evidenciado o mesmo crescimento da planta que as demais com nitrato; e na cultivar IAC-24, houve menor crescimento da planta. A adição também promoveu maior formação de aerênquima no caule, na raiz principal e adventícia, além de estimular a maior formação de raízes adventícias. Os dados sugerem que em condições de hipoxia, embora em quantidades bastante reduzidas e num processo mais lento, o nitrato é absorvido pelas raízes, sendo parte, convertida a aminoácidos e menos de 40% convertidos a nitrito, o qual é eliminado para o meio. A redução do nitrato via redutase do nitrato, passo inicial de sua metabolização, não é um passo limitante, uma vez que há produção de nitrito, produto da atividade da enzima. Com a adição de nitrato na solução do vaso de cinco cultivares de soja foram observadas tendências para suprir a ausência de nitrogênio e manter o desenvolvimento da plantas em condições de alagamento. A cultivar IAC Foscarin-31 e IAC-24 apresentaram crescimento geral da planta, sendo maior o crescimento observado na cultivar IAC Foscarin-31. Na cultivar IAC-23 houve maior crescimento do sistema radicular; na cultivar IAC-17, da parte aérea, assim como na IAC-18<br>Abstract: Soybean is a legume of great economic importance in Brazil with a production of some 72.23 million tons (2010/2011 harvest). One of the main causes of diminished yields of the cultivars produced in Brazil is their cultivation in regions subject to flooding. Under such conditions reduced availability of oxygen in the soil leads to hypoxia of the root system which impairs plant development and yield. There is evidence that the presence of nitrate during flooding can improve tolerance to hypoxic stress. However, the biochemical mechanisms underlying this phenomenon have not been fully elucidated. After analysis of the changes in nitrogen metabolism that occur under hypoxia, in plants subjected to a variety of experimental conditions, it was observed that there was a reduction in plant nitrate content, an increase in total soluble amino acids, an increase in the relative abundance of free Ala, Gaba, and a reduction in Asn, in both nodulated and non-nodulated plants, as well as a reduction of ureides in nodulated plants. The addition of nitrate during flooding resulted in a higher nitrate content of the root, nodule and xylem sap. Total soluble amino acids and soluble proteins also increased in the root under these conditions but decreased in the leaf. Under hypoxia the in vivo nitrate reductase activity declined in the roots of non-nodulated plants and in both the roots and leaves of nodulated plants. The inclusion of K15NO3 in the nutrient solution confirmed the uptake of nitrate under hypoxia, since roots, leaves and nodules became labelled. However, uptake under hypoxia was much lower than that observed under normoxia. Under both normoxia and hypoxia the roots showed the highest degree of 15N enrichment while the nodules showed the weakest. Incorporation of 15N in amino acids of all tissues shows that 15NO3 was not only taken up by the roots under hypoxia but that it was assimilated and transported to the shoot. The amino acids considered closest to N assimilation, Asp, Glu, Ala and Asn, were the most highly labelled. Nevertheless, lower levels of incorporation were generally found under hypoxia. The addition of nitrate to the hydroponic nutrient solution of five soybean cultivars, 7 days after flooding the root system, stimulated greater growth of the cultivar IAC Foscarin-31 as compared to plants with nitrate from the beginning of the experiment. It also stimulated greater root dry mass of the cultivar IAC-23, produced a similar growth increase of cultivars IAC-17 and IAC-18 compared to those with nitrate from the beginning, but resulted in less growth for the cultivar IAC-24. The addition of nitrate also stimulated formation of adventitious roots as well as aerenchyma which formed on both the stem and the main and adventitious roots. The data show that under conditions of hypoxia, nitrate is taken up by the roots although at a much lower rate than under normoxia, and in part is assimilated into amino acids while nearly 40% is reduced to nitrite which is excreted to the surrounding medium. The reduction of nitrate by the enzyme NR, the first step of nitrate metabolism, does not appear to be limiting since large quantities of the reaction product, nitrite, accumulate. With the addition of nitrate to the flooding medium of five soybean cultivars there was a tendency to overcome the absence of nitrogen and maintain plant development under flooded conditions. Of the five cultivars studied, IAC Foscarin-31 and IAC-24 responded positively through overall plant growth, with Foscarin-31 showing the greatest growth. Cultivar IAC-23 responded with greater root growth while IAC-17 and IAC-18 presented greater shoot growth<br>Doutorado<br>Biologia Vegetal<br>Doutor em Biologia Vegetal
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Castro, Leonidia Maria de. "Interferência dos metais zinco, chumbo e cobre, no processo de nitrificação no tratamento de efluentes de uma indústria química: estudo de caso." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-27012017-162144/.
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Durante o estudo de um sistema de tratamento de efluentes de uma indústria química, contendo em suas águas residuárias vários metais pesados foi observada a ineficiência no processo de nitrificação do efluente tratado. Diante dessa constatação, desenvolveu-se este trabalho visando estudar as interferências dos metais pesados, Pb2+, Zn2+ e Cu2+ no desempenho do processo de nitrificação em um sistema similar de tratamento. Para observação dos efeitos dos metais Zn2+, Pb2+ e Cu2+ isoladamente, foram montados 3 reatores e simuladas as concentrações afluentes do tanque de aeração da indústria. Outros três reatores alimentados com soluções contendo Zn+Cu, Zn+Pb e Pb+Cu utilizados para observação de possíveis efeitos de sinergismo e antagonismo. Um outro reator foi alimentado com a solução dos três metais (Zn2+, Cu2+ e Pb2+). Todos os reatores, recebendo adição de metal ou não, apresentaram concentrações muito elevadas de nitrito. Na realização do ensaio de NMP ficou evidente a inibição dos organismos oxidantes de nitrito, que pode ter ocorrido pela alta concentração do próprio nitrito, ácido nitroso ou amônia livre. Efeitos dos metais Zn2+ e Cu2+ não foram evidentes, o Pb2+ foi o único metal que apresentou efeito de inibição no processo de nitrificação. Os reatores que receberam combinação de íons metálicos não evidenciaram efeitos de sinergismo nem antagonismo, sendo que o reator que recebeu adição dos três íons apresentou menor eficiência.<br>During the study of the chemical industry effluent treatment system containing, several heavy metals, was observed an inefficiency in the nitrification process in final effluent. Therefore, this work was deve!oped to find out ofthe study of the interference of the heavy metals, Pb2+, Zn2+ and Cu2+ on the performance of nitrification process in a similar system of treatment. For observation of the effects of metals Zn2+, Pb2+ and Cu2+ separately, were established three reactors and simulate the influent concentration in the aeration tank of the industry. Other three reactors were fed with solution containing Zn+Cu, Zn+Pb and Pb+Cu for observation of possible synergism or antagonism effects. The other reactor was fed with a solution of the three metals (Zn2+, Cu2+ and Pb2+). All the reactors, receiving the addition of metaIs or not, presented very high concentrations of nitrite. In the realization of the test of NMP, the inhibition of the nitrite oxidizers organisms was evident, that might have happened due to high concentration of nitrous acid, free ammonia and nitrite. The effects of the metals Zn2+ and Cu2+ were not evident; but the Pb2+ was the only metal that presented inhibition effect in the nitrification process. The reactors that received the metallic ion combination didn\'t evidence neither synergism nor antagonism effects, however the reactor that received the addition of the three ions presented smaller efficiency.
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Melane, Pumeza. "Kinetics reactions of Ammonium Nitrate-Sodium Nitrite Reaction and Ammonium Nitrate Emulsion Explosives." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/6333.
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The aim of this study was to understand and control the gasification rates in ammonium nitrate emulsion explosive using ammonium nitrate-sodium nitrite reaction. This reaction produces N2 gas which is the sensitizer in emulsion explosives. The NH4NO3-NaNO2 gassing reaction produces N2 gas and so the reaction could be followed by the pressure increase in a closed reaction vessel. The reaction is pH sensitive, so the role of pH was investigated in the pH range 2 to 5. Gasification reactions for unbuffered NH4NO3-NaNO2 reaction were found to be rapid below pH = 3 and maximum pressure was attained within 2 hours of starting the reaction. At pH = 4.5 and 5 the reaction failed to attain maximum pressure. Initial rate of reaction showed sensitivity to pH, the rate of reaction decreasing with increasing pH. The reaction was found to be second order with respect to nitrite species. The effects of three different buffers (potassium hydrogen phthalate, sodium formate and sodium citrate) were also investigated. At pH = 3 pressure traces for the buffered reactions had attained maximum pressure while at pH = 3.5 only sodium citrate buffer had reached a pressure stable state. The presence of the buffers resulted in a lower overall pressure change and absolute pH change and higher rate constants and initial rate of reaction than in their absence. iv A Lewis acid (Zinc Nitrate) was added to the buffered and unbuffered NH4NO3-NaNO2 reactions to investigate a patent claim that addition of a Lewis acid would increase the rate of reaction. The presence of zinc nitrate in the buffered reactions resulted in rapid pressure increase; higher initial rate of reactions than the unbuffered with zinc nitrate. Ammonium nitrate solution was emulsified resulting in an ammonium nitrate emulsion explosive and kinetics of gasification was investigated. The gasification reactions were found to be rapid at pH 3.2, slowing significantly with increased pH as indicated by initial rates of reaction and as predicted by the gasification reaction rate law. Maximum pressure increase was attained within three hours at pH 3.2, whereas reactions conducted at pH 4.0 and 4.5 failed to reach maximum pressure even after 24 hours as evidenced by plots of pressure versus time. The effect of buffers in the ammonium nitrate emulsions was also investigated.
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Fletgen, Marie Christine. "Le devenir des nitrates et des nitrites dans l'organisme humain et leur danger potentiel : problème des nitrosamines." Paris 5, 1992. http://www.theses.fr/1992PA05P241.
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Hüsler, Bruno R. "Nitrite/nitrate status in veal calves: effects of feeding nitrite, nitrate, arginine, and iron and of endotoxin administration /." [S.l.] : [s.n.], 1999. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.
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Melchert, Wanessa Roberto. "Desenvolvimento de procedimentos analíticos limpos em sistemas de análises em fluxo para determinação de espécies de interesse ambiental." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-20102006-084230/.
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A química limpa tem como principal objetivo o desenvolvimento e a implementação de processos e produtos químicos para reduzir ou eliminar o uso ou a geração de substâncias nocivas à saúde humana e ao meio ambiente. Neste trabalho, foram desenvolvidos procedimentos analíticos limpos para a determinação de nitrato e nitrito em águas naturais e para o tratamento dos resíduos gerados na determinação espectrofotométrica de nitrito e fenóis. Para tanto, foram exploradas as principais estratégias empregadas em química limpa: substituição dos reagentes tóxicos, minimização do consumo dos reagentes e dos resíduos gerados e tratamento desses resíduos. O procedimento analítico limpo para a determinação de nitrato em águas naturais foi baseado em medidas diretas no ultravioleta, após separação de nitrato dos interferentes utilizando um sistema de análises em fluxo com coluna de resina aniônica. O método desenvolvido emprega um único reagente (HClO4) em quantidades mínimas (18 µL/determinação) e permite a determinação de nitrato entre 0,50 e 25,0 mg L-1, sem interferência de ácido húmico, NO2-, PO43-, Cl-, SO42- e ferro(III) nas quantidades usuais em águas naturais. A freqüência de amostragem e o coeficiente de variação (n = 20) foram estimados em 17 determinações h-1 e 0,7%, respectivamente. Os resultados obtidos para amostras de águas de diferentes procedências foram concordantes com o método de referência (redução a nitrito por limalhas de cádmio cobreado seguida por reação de diazo-acoplamento) a nível de confiança de 95%. O tratamento do resíduo gerado na determinação de nitrito, empregando irradiação (UV) na presença do reagente de Fenton (80 mmol/L H2O2 e 1 mmol/L Fe2+), promoveu completa descoloração do resíduo com diminuição de ca. 87% na concentração de carbono orgânico total. A fotodegradação também foi aplicada no tratamento do resíduo gerado na determinação de fenóis totais com 4-aminoantipirina. A degradação ocorreu na presença de H2O2 e irradiação (UV). A completa supressão da absorção de radiação pela 4-aminoantipirina foi observada após 30 min de recirculação da solução no foto-reator, à vazão de 4 mL/min. O procedimento analítico para a determinação de nitrito foi baseado em sistema de análises em fluxo com multicomutação empregando mini-bombas solenóides para o gerenciamento das soluções. O sistema foi acoplado a um foto-reator para a degradação em linha dos resíduos gerados. O método desenvolvido minimiza as quantidades de reagentes (0,6 mg sulfanilamida e 0,03 mg N-naftil-etilenodiamina por determinação) e permite a determinação de nitrito entre 0,10 e 1,00 mg L-1 (r = 0,998) com sensibilidade comparável à alcançada no procedimento com adição contínua de reagentes. O limite de detecção (99,7% de confiança), coeficiente de variação (n = 20) e freqüência de amostragem foram estimados em 17 µg L-1, 2,6% e 80 determinações h-1, respectivamente.<br>Green chemistry has as principal objective the development and implementation of chemical processes and products to minimize or eliminate the use or generation of harmful substances to the human health and the environment. In this work, clean analytical procedures for determination of nitrate and nitrite in natural waters and for the treatment of wastes generated in the spectrophotometric determination of nitrite and phenol were developed. The principal strategies employed in green chemistry were explored to achieve these goals: replacement of the toxic reagents, minimization of reagent consumption and waste generation and waste treatment. The clean analytical procedure for nitrate determination in natural waters was based on the direct spectrophotometric measurement in the ultraviolet, after separation of nitrate from interfering species in a flow-injection system with an anion-exchange resin. The developed method employ only one reagent (HClO4) in minimum amount (18 µL/determination) and can be applied for nitrate determination within 0.50 and 25.0 mg L-1, without interference of humic acid, NO2-, PO43-, Cl-, SO42- and iron(III) in concentrations typically found in natural waters. The sampling rate and the coefficient of variation (n = 20) were estimated as 17 determinations per hour and 0.7%, respectively. Results obtained for natural water samples of different origin were in agreement with the reference method (reduction to nitrite by copperized cadmium filings followed by a diazo-coupling reaction) at the 95% confidence level. The treatment of the waste generated in nitrite determination employing UV irradiation in the presence of Fenton reagent (80 mmol/L H2O2 and 1 mmol/L Fe2+) caused the complete discoloration of the waste and reduced the total organic carbon concentration in 87%. The photodegradation was also applied for the treatment of the waste generated in the determination of total phenols with 4-aminoantipyrine. The degradation occurred in the presence of H2O2 and UV irradiation. Radiation absorption by 4-aminoantipyrine was completely suppressed after 30 min of treatment of solution in the recirculation mode at 4mL/min. The analytical procedure for nitrite determination was based on a flow system with multicommutation employing solenoid micro-pumps for the solution handling. The developed method minimizes the reagent amounts (0.6 mg sulfanilamide and 0.03 mg N-(1-Naphthyl)-ethylene-diamine per determination) and can be applied for nitrite determination within 0.10 and 1.00 mg L-1 (r = 0.998) with sensitivity comparable to the achieved in the procedure with continuous reagent addition. The detection limit (99.7% of confidence), coefficient of variation (n = 20) and sampling rate were estimated as 17 µg L-1, 2.6% and 80 determinations per hour, respectively.
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Ferreira, Paulo Eduardo Gomes. "Efeito de um programa pré-operatório de fortalecimento supervisionado da musculatura inspiratória na evolução hospitalar de pacientes submetidos a operações cardíacas." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/17/17137/tde-05042013-230022/.
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Introdução: A disfunção respiratória é uma das complicações mais frequentes após operações cardíacas. Vários fatores contribuem para que as disfunções respiratórias ocorram, dentre eles está a disfunção da musculatura inspiratória que, por sua vez, pode ser multifatorial. Objetivo: O condicionamento da musculatura inspiratória no período pré-operatório poderia ajudar a reduzir a incidência de complicações respiratórias no pós-operatório de operações cardíacas. Métodos: No presente trabalho 21 pacientes voluntários, de ambos os sexos, com idade mínima de 50 anos, com fraqueza de musculatura inspiratória e candidatos à operação de revascularização cirúrgica do miocárdio e/ou operação valvar cardíaca no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto-USP foram distribuídos aleatoriamente em 2 grupos. Em um grupo, 10 pacientes foram submetidos a um período mínimo de 9 dias de treinamento da musculatura inspiratória utilizando um incentivador respiratório marca Threshold® IMT (Respironics, Cedar Grove, NJ, EUA), com carga de 40, 60 e 80% da pressão inspiratória máxima. Os outros 11 pacientes receberam apenas orientações gerais, sem treinamento objetivo da musculatura respiratória. Comparamos os valores espirométricos antes e após o treinamento dentro de cada grupo. A evolução da pressão inspiratória máxima, da pressão expiratória máxima e da gasometria arterial de ambos os grupos, antes e após o treinamento, bem como a sua evolução temporal no pós-operatório, além dos valores de nitrito/nitrato no condensado do exalado pulmonar. Comparamos também a evolução clínica de ambos os grupos. Resultados: Observamos que o treinamento causou elevação significativa do pico de fluxo expiratório (p=0,028) e diminuição nos valores de nitrito/nitrato no condensado do exalado pulmonar (p=0,05) e redução das complicações pós operatórias (p=0,057), sendo as duas últimas não significativas. Todavia, não houve diferença na evolução gasométrica e nem da pressão inspiratória máxima ou da pressão expiratória máxima entre ambos os grupos. Conclusão: O treinamento da musculatura respiratória inspiratória em pacientes internados, além de factível e seguro, resulta em maior fortalecimento dessa musculatura, reduz a morbidade pós-operatória e os níveis de nitrito/nitrato no condensado do exalado pulmonar<br>Introduction: Respiratory dysfunction is one of the most common complications after cardiac operations. Several factors contribute to respiratory dysfunctions that occur among them is inspiratory muscle dysfunction that, in turn, may be multifactorial. Objective: The conditioning of inspiratory muscles on preoperative could help reduce the incidence of respiratory complications in the postoperative period of cardiac operations. Methods: In this study 21 patients volunteers of both sexes, aged 50 years, with weakness of inspiratory muscles and candidate operation of CABG and / or heart valve surgery at the Hospital of the Medical College of Ribeirão Preto-USP were randomized into 2 groups. In one group, 10 patients underwent a minimum of 9 days of inspiratory muscle training using an incentive spirometry \"Threshold® IMT\" (Respironics, Cedar Grove, NJ, USA) with a load of 40, 60 and 80% of maximal inspiratory pressure. The other 11 patients received only general guidelines without respiratory muscle training goal. We compared spirometric values before and after training within each group. The evolution of maximal inspiratory pressure, maximal expiratory pressure and arterial blood gas analysis of both groups before and after training, as well as its temporal evolution postoperatively, and the values of nitrite / nitrate in exhaled breath condensate. We also compared the clinical outcomes in both groups. Results: We observed that the training caused significant peak expiratory flow (p=0,028) and decrease in nitrite/nitrate in exhaled breath condensate (p=0,05) and reduction of postoperative complications (p=0,057), the last two being non-significant. However, there was no difference in blood gas evolution nor maximal inspiratory pressure and maximal expiratory pressure between both groups. Conclusion: The inspiratory muscle training in patients hospitalized, and feasible and safe, results in further strengthening these muscles, reduces postoperative morbidity and levels of nitrite / nitrate in exhaled breath condensate
Книги з теми "Nitrate"
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Bryan, Nathan S., and Joseph Loscalzo, eds. Nitrite and Nitrate in Human Health and Disease. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-60761-616-0.
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Bryan, Nathan S., and Joseph Loscalzo, eds. Nitrite and Nitrate in Human Health and Disease. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2.
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Loscalzo, Joseph, and Nathan S. Bryan. Nitrite and nitrate in human health and disease. New York: Humana Press, 2011.
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4
Imperial Cancer Research Fund (Great Britain). Nitrate, nitrite and nitroso compounds in human cancer. Edited by Forman David, Shuker David, and Shuker David E. G. Oxford, U.K: Published for the Imperial Cancer Research Fund by Oxford University Press, 1989.
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5
International Agency for Research on Cancer and World Health Organization, eds. Ingested nitrate and nitrite, and cyanobacterial peptide toxins. Lyon, France: International Agency for Research on Cancer, 2010.
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6
Tsadilas, Christos. Nitrate Handbook. New York: CRC Press, 2021. http://dx.doi.org/10.1201/9780429326806.
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Bogárdi, Istvan, Robert D. Kuzelka, and Wilma G. Ennenga, eds. Nitrate Contamination. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76040-2.
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E, Rezaković Dženana, and Alpert Joseph S, eds. Nitrate therapy & nitrate tolerance: Current concepts and controversies. Basel: Karger, 1993.
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9
Edmundson, William. The Nitrate King. New York: Palgrave Macmillan US, 2011. http://dx.doi.org/10.1057/9780230118799.
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Alahi, Md Eshrat E., and Subhas Chandra Mukhopadhyay. Smart Nitrate Sensor. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20095-4.
Повний текст джерелаЧастини книг з теми "Nitrate"
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Makkar, Harinder P. S., P. Siddhuraju, and Klaus Becker. "Nitrate and Nitrite." In Plant Secondary Metabolites, 33–39. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-425-4_7.
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Ware, George W. "Nitrate and Nitrite." In Reviews of Environmental Contamination and Toxicology, 117–30. New York, NY: Springer New York, 1988. http://dx.doi.org/10.1007/978-1-4684-7083-3_10.
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Bellucci, Elisa Rafaela Bonadio, Camila Vespúcio Bis Souza, José Manuel Lorenzo, Gonzalo Aleu, Alfredo Teixeira, Rubén Domínguez, and Andrea Carla da Silva-Barretto. "Nitrate and Nitrite." In Methods to Assess the Quality of Meat Products, 85–95. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2002-1_8.
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Bryan, Nathan S. "Inorganic Nitrate and Nitrite." In Nitrate Handbook, 357–73. New York: CRC Press, 2021. http://dx.doi.org/10.1201/9780429326806-21.
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Klurfeld, David M. "Nitrite and Nitrate in Cancer." In Nitrite and Nitrate in Human Health and Disease, 263–78. Totowa, NJ: Humana Press, 2011. http://dx.doi.org/10.1007/978-1-60761-616-0_16.
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Klurfield, David M. "Nitrite and Nitrate in Cancer." In Nitrite and Nitrate in Human Health and Disease, 311–23. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2_21.
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Hotchkiss, Joseph H., Michael A. Helser, Chris M. Maragos, and Yin-Ming Weng. "Nitrate, Nitrite, andN-Nitroso Compounds." In ACS Symposium Series, 400–418. Washington, DC: American Chemical Society, 1992. http://dx.doi.org/10.1021/bk-1992-0484.ch033.
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Lück, Erich, and Martin Jager. "Nitrate." In Chemische Lebensmittelkonservierung, 90–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-57868-7_9.
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Lück, Erich. "Nitrate." In Chemische Lebensmittelkonservierung, 78–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-96924-9_11.
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Bailey, Stephen J., Anni Vanhatalo, and Andrew M. Jones. "Nitrate and Exercise Performance." In Nitrite and Nitrate in Human Health and Disease, 293–310. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46189-2_20.
Повний текст джерелаТези доповідей конференцій з теми "Nitrate"
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Mickalonis, J. I. "Corrosion of Steel in Simulated Nuclear Waste Solutions." In CORROSION 1994, 1–20. NACE International, 1994. https://doi.org/10.5006/c1994-94117.
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Abstract Processing of inhibited nuclear waste to forms for long-term storage will cause waste tank environments to have dynamic conditions. During processing compositional changes in the waste may produce a corrosive environment for the plain carbon steel tanks. Large concentrations of nitrates which corrode steel are contained in the waste. Nitrite and hydroxides are added to inhibit any corrosion. Concentration changes of nitrate and nitrite were investigated to identify corrosion regimes that may occur during processing. Corrosion testing was performed with cyclic potentiodynamic polarization and linear polarization resistance. Test samples were plain carbon steel which was similar to the material of construction of the waste tanks. The corrosion morphology of test samples was investigated by visual evaluation and scanning electron microscopy. Qualitative chemical analysis was also performed using energy dispersive spectroscopy. The corrosion mechanism changed as a function of the nitrate concentration. As the nitrate concentration was increased the steel transitioned from a passive state to general attack, and finally pitting and crevice corrosion. The nitrate anion appeared to destabilize the surface oxide. Nitrite countered the oxide breakdown, although the exact mechanism was not determined.
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Hubert, C., G. Voordouw, M. Nemati, and G. E. Jenneman. "Is Souring and Corrosion by Sulfate-Reducing Bacteria in Oil Fields Reduced More Efficiently by Nitrate or by Nitrite?" In CORROSION 2004, 1–8. NACE International, 2004. https://doi.org/10.5006/c2004-04762.
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Abstract Successful application of both nitrate and nitrite to combat souring in oil fields has been reported. The effect of these treatments on corrosion is not well documented. Using up-flow, packed-bed bioreactors simulating an oil field we have found that both nitrate and nitrite are effective sulfide removers. The required dose depended on the concentration of oil organics used as the energy source by the microbial community. Because of its higher oxidative power, nitrate can remove more oxidizable oil organics than nitrite. However, nitrite is a strong SRB inhibitor. Nitrate gives less SRB inhibition, because it is only partially converted to nitrite. Because iron corrosion is either not affected or increased by the presence of nitrate, but strongly inhibited by nitrite under our experimental conditions we conclude that use of nitrite is on balance more favorable than use of nitrate.
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Voordouw, G., M. Nemati, and G. E. Jenneman. "Use of Nitrate-Reducing, Sulfide-Oxidizing Bacteria to Reduce Souring in Oil Fields: Interactions with SRB and Effects on Corrosion." In CORROSION 2002, 1–6. NACE International, 2002. https://doi.org/10.5006/c2002-02034.
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Abstract Injection of nitrate or nitrite into oil reservoirs can reduce the sulfide concentration through the activity of nitrate-reducing, sulfide-oxidizing bacteria. These inhibit sulfate-reducing bacteria (SRB), but appear to contribute also to increased corrosion risk. Combinations of nitrate or nitrite with other inhibitors can work synergistically in inhibiting SRB activity.
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Zapp, Philip E., and John W. Van Zee. "Electrochemical Studies of Nitrate-Induced Pitting in Carbon Steel." In CORROSION 1999, 1–13. NACE International, 1999. https://doi.org/10.5006/c1999-99471.
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Abstract The phenomenon of pitting in carbon steel exposed to alkaline solutions of nitrate and chloride was studied with the cyclic potentiodynamic polarization technique. Open-circuit and pitting potentials were measured on specimens of ASTM A537 carbon steel in pH 9.73 salt solutions at 40°C, with and without the inhibiting nitrite ion present. Nitrate is not so aggressive a pitting agent as is chloride. Both nitrate and chloride did induce passivity breakdown and pitting in nitrite-free solutions, but the carbon steel retained passivity in solutions with 0.11-M nitrite even at a nitrate concentration of 2.2 M.
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Folwell, Benjamin, Jan Larsen, Alessandra Allegrucci, and Andrew Price. "Investigation of the Effects of Nitrate and Nitrite on Halfdan Sulfate-Reducing Archaea." In CORROSION 2016, 1–10. NACE International, 2016. https://doi.org/10.5006/c2016-07162.
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Abstract Nitrate injection forms part of the mitigation strategy used in the Halfdan field to control reservoir souring. A review of Halfdan well data suggests that the H2S generated is due to the activity of sulfate-reducing archaea (SRA) in the Halfdan producing wells. The aim of this study was to determine SRA susceptibility to inhibition by nitrite, and determine whether SRA contain known nitrate and nitrite reduction genes. qPCR was used to enumerate total Archaea, narG, nirK and nirS copies (nitrate- and nitrite-reducing genes) in the produced water from five Halfdan producing wells. SRA were detected in four samples; however, nitrate and nitrite reduction genes were not detected. This is evidence that SRA contribute to H2S generation in the Halfdan field. It also suggests the SRA lack the ability to reduce nitrate or nitrite. Minimal inhibitory concentration tests on planktonic samples with field-cultured SRA revealed that the SRA were more susceptible to inhibition by nitrite than sulfate-reducing bacteria (SRB). Sessile toxicity tests determined the concentration of nitrite ion required to produce a significant biocidal effect was at least 5–10 fold greater than for planktonic SRA. These data suggest that when nitrite reaches the Halfdan producing wells, sulfate-reduction by SRA will be inhibited.
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Hubert, C., G. Voordouw, J. Arensdorf, and G. E. Jenneman. "Control of Souring through a Novel Class of Bacteria That Oxidize Sulfide as Well as Oil Organics with Nitrate." In CORROSION 2006, 1–10. NACE International, 2006. https://doi.org/10.5006/c2006-06669.
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Abstract Hydrogen sulfide production by sulfate-reducing bacteria (SRB) in oil fields (souring) can be eliminated through the activity of nitrate-reducing bacteria (NRB). Two distinct classes of NRB have been described. The heterotrophic NRB (hNRB) reduce nitrate using similar oil organics as used by SRB for the reduction of sulfate. These inhibit SRB by competitive exclusion. The nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) directly oxidize sulfide with nitrate. Many of these use only CO2 as the carbon source and do not compete with SRB for oil organics. Both hNRB and NR-SOB produce nitrite as an intermediate in nitrate reduction, which strongly inhibits SRB. The NR-SOB Thiomicrospira sp. strain CVO has previously been shown to be an effective agent for sulfide removal in situ and in laboratory studies. A continuous up-flow packed-bed bioreactor was inoculated with a microbial consortium obtained from the same oil field. Although SRB-generated sulfide was removed by nitrate addition, community analysis indicated that strain CVO did not become a major component under these conditions. Also, strain CVO could not be established in the bioreactor by bioaugmentation. Two related microorganisms Sulfurospirillum sp. strains NO2B and KW became major community members during nitrate treatment. These were found to have both hNRB and NR-SOB activity and be capable of producing large amounts of nitrite, make them ideal agents for souring control.
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Locke, Carl E., and Oladis Rincon. "A Study of Corrosion Electrochemistry of Steel in Chloride Contaminated Concrete Using a Rapid Scan Polarization Technique." In CORROSION 1987, 1–18. NACE International, 1987. https://doi.org/10.5006/c1987-87128.
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Abstract Corrosion of steel in portland cement concrete has been found to be very damaging and costly to many countries in the world. It is possible to control this corrosion damage in several ways and one of these is the use of inhibitors. Several electrochemical techniques have been used and this paper illustrates rapid scan polarization as one applied to the study of inhibitors in concrete. Work conducted at the University of Oklahoma studied the effect of oxygen and salt on the behavior of steel in concrete. Investigators at the University of Zulia studied several compounds as possible inhibitors for steel in salt contaminated concrete. Calcium nitrite, calcium nitrate, lead nitrate, zinc oxide, a mixture of calcium nitrite and calcium nitrate, a mixture of calcium nitrate and lead nitrate, and a mixture of lead oxide and calcium nitrate were evaluated as inhibitors for steel in concrete containing 0.5% salt. Slow scan (0.278 mV/sec) polarization curves and rapid scan polarization (14 mV/sec) curves were obtained for all samples. These data indicated it was possible to determine the presence and stability of the passive film from the rapid scan technique. The rapid scan technique was applied to steel in the inhibitor containing cylinders and indicated all but the ZnO had a passivating type behavior. The rapid scan technique should be helpful to investigators in studying inhibition of steel in concrete.
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Yin, Bei, and Kenneth Wunch. "Combined Effects of Microbes and Nitrate on SRB Growth, Souring and Corrosion." In CORROSION 2017, 1–11. NACE International, 2017. https://doi.org/10.5006/c2017-09425.
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Abstract Controlling reservoir souring is critical to successful production and asset protection in hydrocarbon recovery. Nitrate injection has been used in water flooding for controlling biogenic sulfide in oil reservoirs. Souring control via nitrate implementation is based on the interactions between nitrate-reducing bacteria (NRB) and sulfate-reducing bacteria (SRB). As a result, it is important to understand how the NRB and SRB population profile controls the effectiveness of nitrate on SRB growth, sulfide levels, and corrosion. In laboratory studies, the impact of NRB (including denitrifiers (N2NRB) and nitrite-producing NRB (NO2NRB)) and SRB (including SRB with and without nitrate-reducing ability) composition on nitrate effectiveness was evaluated. A stationary testing method and a porous media flow reactor method were used for these studies. The effect of different NRB, including NO2NRB and sulfide-oxidizing NRB (SONRB) on corrosion of carbon steel beads in the presence and absence of nitrate was also investigated using porous media flow reactors. It was found that the effectiveness of nitrate on sulfide level, SRB growth, and metal corrosion can be dynamically affected by the composition of SRB and NRB present in the testing systems.
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Tanji, Yasunori, Kazuhiko Miyanaga, and Kamarisima. "Mpact of Nitrate Addition on the Population Dynamics of Surfate-Reducing and Nitrate-Reducing Bacteria in the Oilfield Water." In CORROSION 2019, 1–7. NACE International, 2019. https://doi.org/10.5006/c2019-12743.
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Abstract Seawater injection into oil reservoirs for secondary oil recovery is frequently accompanied by souring. Souring causes various problems, such as microbiologically influenced corrosion (MIC) and deterioration of crude oil. Sulfate-reducing bacteria (SRB) are considered to be major players in souring. Nitrate injection has been widely used to control the growth of SRB. The aim of this study was to investigate the changes in the bacterial community in response to nitrate addition to control biological souring. We investigated the effect of nitrate addition in an artificial souring experiment, using diluted crude oil as substrate and electron donor. Desulfotignum sp. was the predominant SRB under all conditions tested. Addition of nitrate at the beginning (N0) repressed the growth of SRB, concomitant with significant growth of the nitrate-reducing bacteria (NRB) Thalassospira sp. Nitrate addition after SRB growth (at day 28, N28) successfully remediated the sulfide produced by SRB, but no significant reduction in sulfate was observed subsequently. In the N28 experiment might be the result of the role of Arcobacter sp., which are nitrate-reducing sulfide-oxidizing bacteria, and/or the ability of Desulfotignum sp. to reduce nitrate and/or nitrite as a stress response. Thus, SRB might persist after nitrate addition, potentially causing subsequent SRB outbreaks
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Justnes, H. "Inhibiting Chloride Induced Corrosion of Concrete Rebars by Calcium Nitrate Addition." In CORROSION 2003, 1–17. NACE International, 2003. https://doi.org/10.5006/c2003-03287.
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Abstract Both calcium nitrate and calcium nitrite may act as anodic inhibitors against chloride induced corrosion of rebars in concrete through a similar mechanism, although the kinetics of reaction may be different. Recently an extended test programme was launched for direct comparison of inhibitor performance of calcium nitrate versus nitrite at equimolar dosage, in addition to comparison of the inhibitors against a reference concrete without inhibitor addition. The test program and strategy are described in detail. Specimens are still only 1 years old, so examples of inhibitor performance are taken from earlier simple tests.
Звіти організацій з теми "Nitrate"
1
Hobbs, D. T. Evaluation of nitrate and nitrite destruction/separation technologies. Office of Scientific and Technical Information (OSTI), August 1997. http://dx.doi.org/10.2172/573703.
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Van Rijn, Jaap, Harold Schreier, and Yossi Tal. Anaerobic ammonia oxidation as a novel approach for water treatment in marine and freshwater aquaculture recirculating systems. United States Department of Agriculture, December 2006. http://dx.doi.org/10.32747/2006.7696511.bard.
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Ammonia waste removal in recirculating aquaculture systems is typically accomplished via the action of nitrifying bacteria in specially designed biofilters that oxidize ammonia to produce nitrate. In the majority of these systems nitrate is discharged to the environment through frequent water exchanges. As environmental considerations have made it necessary to eliminate nitrate release, new strategies for nitrate consumption are being developed. In the funding period we showed that ammonia removal from wastewater could take place by an anaerobic ammonia oxidation process carried out by bacterial Planctomycetessp. Referred to as “anammox”, this process occurs in the absence of an organic source and in the presence of nitrite (or nitrate) as an electron acceptor as follows: NH₃ + HNO₂ -> N₂ + 2H₂O. Annamox has been estimated to result in savings of up to 90% of the costs associated with was wastewater treatment plants. Our objective was to study the applicability of the anammox process in a variety of recirculating aquaculture systems to determine optimal conditions necessary for efficient ammonia waste removal. Both seawater and freshwater systems operated with either conventional aerobic treatment of ammonia to nitrate (USA) or, in addition, denitrifying biofilters as well as anaerobic digestion of sludge (Israel) were tested. Molecular tools were used to screen and monitor different treatment compartments for the presence of Planctomycetes. Optimal conditions for the enrichment of the anammox bacteria were tested using laboratory scale biofilters as well as a semi-commercial system. Enrichment studies resulted in the isolation of some unique heterotrophic bacteria capable of plasmid-mediated autotrophic growth in the presence of ammonia and nitrite. Our studies have not only demonstrated the presence and viability of Planctomycetes spp. in recirculating marine and freshwater systems biofilter units but also demonstrated the applicability of the anammox process in these systems. Using our results we have developed treatment schemes that have allowed for optimizing the anammox process and applying it to recirculating systems.
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Congdon, J. W. Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate. Office of Scientific and Technical Information (OSTI), March 2001. http://dx.doi.org/10.2172/781032.
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Asmussen, Robert, Christopher Bagwell, Derek Dixon, Leah Hare, Stephanie Johansen, Christian Johnson, Philip Meyer, et al. Nitrate and Nitrite at Hanford – From Tanks to Natural Attenuation. Office of Scientific and Technical Information (OSTI), February 2024. https://doi.org/10.2172/2483349.
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Szecsody, James, Robert Mackley, and Charles Resch. Characterization of Nitrate, Nitrite, Ammonia, and Tritium in D0220 Cores. Office of Scientific and Technical Information (OSTI), September 2024. http://dx.doi.org/10.2172/2476875.
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Burger, L. L., and R. D. Scheele. The reactivity of cesium nickel ferrocyanide towards nitrate and nitrite salts. Office of Scientific and Technical Information (OSTI), September 1991. http://dx.doi.org/10.2172/5293537.
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Cox, J. L., M. A. Lilga, and R. T. Hallen. Thermochemical nitrate reduction. Office of Scientific and Technical Information (OSTI), September 1992. http://dx.doi.org/10.2172/7077253.
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Upadhyaya, Shrini K., Abraham Shaviv, Abraham Katzir, Itzhak Shmulevich, and David S. Slaughter. Development of A Real-Time, In-Situ Nitrate Sensor. United States Department of Agriculture, March 2002. http://dx.doi.org/10.32747/2002.7586537.bard.
Повний текст джерелаАнотація:
Although nitrate fertilizers are critical for enhancing crop production, excess application of nitrate fertilizer can result in ground water contamination leading to the so called "nitrate problem". Health and environmental problems related to this "nitrate problem" have led to serious concerns in many parts of the world including the United States and Israel. These concerns have resulted in legislation limiting the amount of nitrate N in drinking water to 10mg/g. Development of a fast, reliable, nitrate sensor for in-situ application can be extremely useful in dynamic monitoring of environmentally sensitive locations and applying site-specific amounts of nitrate fertilizer in a precision farming system. The long range objective of this study is to develop a fast, reliable, real-time nitrate sensor. The specific objective of this one year feasibility study was to explore the possible use of nitrate sensor based on mid-IR spectroscopy developed at UCD along with the silver halide fiber ATR (i.e. attenuated total internal reflection) sensor developed at TAU to detect nitrate content in solution and soil paste in the presence of interfering compounds. Experiments conducted at Technion and UCD clearly demonstrate the feasibility of detecting nitrate content in solutions as well as soil pastes using mid-IR spectroscopy and an ATR technique. When interfering compounds such as carbonates, bicarbonates, organic matter etc. are present special data analysis technique such as singular value decomposition (SYD) or cross correlation was necessary to detect nitrate concentrations successfully. Experiments conducted in Israel show that silver halide ATR fiber based FEWS, particularly flat FEWS, resulted in low standard error and high coefficient of determination (i.e. R² values) indicating the potential of the flat Fiberoptic Evanescent Wave Spectroscopy (FEWS) for direct determinations of nitrate. Moreover, they found that it was possible to detect nitrate and other anion concentrations using anion exchange membranes and M1R spectroscopy. The combination of the ion-exchange membranes with fiberoptices offers one more option to direct determination of nitrate in environmental systems.
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Mickalonis, J. I. Corrosion of steel in simulated waste containing different nitrate and nitrite concentrations. Office of Scientific and Technical Information (OSTI), July 1993. http://dx.doi.org/10.2172/10177023.
Повний текст джерела
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ADAS, RSK. Nitrate Surveillance Monitoring Program (Annual Report May 2021 - March 2022). Food Standards Agency, December 2022. http://dx.doi.org/10.46756/sci.fsa.uau489.
Повний текст джерелаАнотація:
Every Member State is required to monitor and report levels of nitrate in specified foodstuffs as part of the European Commission regulation and the UK also requires this information as part of the collection of data to support the review of retained EU law in the UK and inform the setting of policy around maximum nitrate levels. The requirement to carry out monitoring for nitrate in lettuce, spinach and rocket is being met by the UK Nitrate Surveillance Programme. Results are presented for the period between 1st April 2021 and 31st March 2022. A total of 202 samples were collected within the sampling period, comprising of 130 lettuce, 9 rocket, 26 spinach samples. A further 37 samples categorised at “Other Green Leafy Vegetables”, which comprised of samples including mustard, mizuna, celery, Pak Choi and cabbage. The lowest average nitrate concentration was recorded in summer-grown iceberg lettuce (935.2 mg/kg), and no iceberg samples exceeded the maximum nitrate concentration. The highest average nitrate concentration was seen in winter grown non-iceberg lettuce grown under protection within the lettuce group (3242.2 mg/kg), and in winter-grown rocket overall (4271.2 mg/kg). The number of samples exceeding the maximum threshold increased this year to 7 samples – 2 samples of open-air non-iceberg lettuce sampled in the summer, 1 sample of protected non-iceberg lettuce in the summer, and 3 samples of spinach. A further 4 samples were within 10% of the maximum threshold. Consistent with previous years of this project, a strong correlation was found between nitrate concentration and sampling date, with samples collected later in the season showing greater concentrations, indicating potential interactions between nitrate accumulation and climate – particularly light levels and available soil moisture and the accumulation of nitrate in the soil through subsequent fertiliser applications with successive planting. Furthermore, there was significant interaction between nitrate accumulation, product type and cultivation type, which could be further explored to better identify risk factors associated with nitrate accumulation in leafy vegetables grown in the UK.