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Nitrate is a ubiquitous drinking water contaminant with potential adverse effects on human health. However, little is known about nitrate toxicity at the cellular and molecular level. The purpose of this study was to examine the effects of environmentally relevant concentrations of nitrate on cytotoxicity and protein expression in human cell lines. To determine if tissue-specific responses occurred, a human hepatoma cell line (HepG2) and a human embryonic kidney cell line (HEK293) were used. Both potassium and ammonium salts of nitrate were used to determine salt-specific toxicity. Test concentrations of nitrate varied from 1 μg/L to 5000 mg/L. Cells were exposed to a nitrate salt for 24, 48, or 72 hours and then examined for effects on viability (using the Neutral Red assay) or proliferation (using the BrdU ELISA assay). To determine the effects of nitrate on protein expression, levels of PCNA, Hsp70, Hsc70, and VEGF protein were monitored using Western blotting in HepG2 and HEK293 cells exposed to KNO3 or NH4NO3 for 24 hours.<p>Nitrate was cytotoxic to both cell types at high concentrations, with EC50 values between 1557 mg/L (approximately) 5852mg/L for viability, and ~2.5 mg/L 3631 mg/L for proliferation. Several EC50 values were not calculable based on the available data, but appeared to be far greater than 5000 mg/L. Ammonium nitrate was generally more toxic than potassium nitrate, and increasing exposure time generally resulted in greater toxicity. The HepG2 and HEK293 cells displayed similar responses for most assays, except the 24 hour KNO3 Neutral Red assay. Here, HEK293 viability increased with increasing KNO3 concentrations, while HepG2 viability decreased. The reason for this finding is unknown, but may involve cell-specific homeostatic mechanisms. A hormetic-like effect was observed in both cell types in several of the proliferation assays; the biological significance of this effect remains unknown.<p>No significant changes in protein expression were observed under these experimental conditions. Some subtle trends were present, such as a slight increase in Hsp70 expression with increasing nitrate concentration in both cell types. In HepG2 cells, PCNA expression increased slightly with increasing nitrate concentrations; however, the opposite effect was observed in HEK293 cells. This may be due to transcriptional or translational regulation.<p>In summary, environmentally relevant concentrations of nitrate did not appear to evoke significant cytotoxicity or changes in protein expression. Cell viability and proliferation effects were observed at higher concentrations of nitrate. Private water supplies may contain nitrate concentrations above the EC50 values in these experiments. More research is required to determine if this poses a direct threat to human health.

Thesis (Ph. D.)--School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 2004. Directed by L. Gregory Huey. / Includes bibliographical references (leaves 74-89).

No description available.

The use of agricultural chemicals often results in water pollution. This research, comprising three parts, was designed to investigate the role of soil and grass strips and water table management in reducing pesticide and nitrate residues in drainage waters. / The first part of the research was made on lysimeters to investigate the effects of soil and grass cover under two water table management regimes. Four treatments were involved: subsurface drainage, controlled drainage, grass cover, and bare soil. Each treatment consisted of three replicates. Contaminated water containing atrazine, metolachlor, and metribuzin residues was applied to the lysimeters and samples of drain effluent were collected. Significant reductions in pesticide concentrations were found in all treatments. / In the first year (1993), herbicide levels were reduced significantly, from an average of 250 mug/L to less than 10 mug/L. In the second year (1995), water polluted at a concentration of 50 mug/L, was applied to the lysimeters, and herbicide residues were reduced significantly to less than 1 mug/L. Subsurface drainage and grass cover lysimeters (SDG treatment) reduced herbicide concentration levels to a greater extent than the other treatments and the controlled drainage lysimeters reduced nitrate concentration levels to a greater extent than the free drainage lysimeters. / The second part of the research was a field study that reports the development and testing of an on-farm pollution control system using soil as a biological filter for trapping herbicide residues. A field site with four shallow surface ditches, underlain with four perforated drain pipes, was used to carry-out field measurements. Polluted water with concentration levels of 30 mg/L of nitrate and 100 mug/L of three commonly-used herbicides was applied to the ditches for 10 days continuously; and no water was applied for the following ten days. This cycle was repeated three times. Water samples were collected both before application and after the water came out of the drains. Herbicide levels were reduced significantly in drainage waters. The average concentration level of nitrate in drainage water was found to be 17 mg/L in comparison to 30 mg/L in applied water. Also, the bio-degradation of herbicide residues in the soil was found to occur between water applications. Thus, it appears that the system would be self-sustainable in the long term. / The third part of the research utilizes a water table model, DRAINMOD, for simulating drainage waters from agricultural land and a solute transport model, PRZM2, for simulating pesticide concentrations in the drain effluent coming out of the grass filter area. DRAINMOD was used to estimate the daily drain outflows that would occur in a 100 ha subsurface drained field in the for a 1-in-20 year annual rainfall period. It was found that 6% of the farm area could be used to bring down the concentrations in drainage water from 50 mug/L to less than 1 mug/L for the three herbicides. (Abstract shortened by UMI.)

No description available.

Ir nitritai ir nitratai tarnauja kaip svarbūs vandens kokybės indikatoriai. Augantis nitratų kiekis vandenyje yra daugiausia žemės ūkio trąšų naudojimo taip pat ir pramoninių procesų pasekmė. Nitratai vandenyje yra mažai nuodingi, tačiau antriniai mikrobakteriniai arba jų sumažėjimas gyvojoje sistemoje sukelia virsmą į nitritus, kurie jungiasi su hemoglobinu ir sukelia methemoglobinemiją Šiame darbe siekėme išsiaiškinti galimą vandens taršą fermų aplinkoje ir ar pasitaiko Linkuvos apylinkėse šulinių naudotojų gyvulių susirgimų atvejų, kurie būtų galimai sukelti girdant užterštu vandeniu. Tyrėme šachtinių šulinių vandenį, kuriame ieškojome nitratų, nitritų, fosfatų, amonio jonų, chloridų, sulfatų ir geležies kiekių nukrypimų. Rezultatai parodė, kad šachtinių šulinių vanduo nėra geros kokybės (n=16), visų tirtų mėginių (n=30) vanduo buvo labai kietas (100%). Ligos paprastai nėra registruojamos, dėl ekonominės situacijos Lietuvoje, todėl jai neskiriama pakankamai dėmesio. Darbo tikslas: Išsiaiškinti galimą vandens taršą fermų aplinkoje ir ar pasitaiko Linkuvos apylinkėse šulinių naudotojų gyvulių susirgimų atvejų, kurie galimai būtų sukelti girdant užterštu vandeniu. Darbo uždaviniai: 1. Išsiaiškinti surinktų šulinių vandens neatitikimus įstatymo (HN 24:2003) nuorodoms. 2. Nustatyti ar šachtinių šulinių vanduo yra kietas ir geros kokybės. 3. Išsiaiškinti ar gyventojai gerai įrengia šulinius, ar prižiūri jų aplinką. 4. Išaiškinti gyvulių ligų atvejus susijusius su girdomu... [toliau žr. visą tekstą] / Both nitrites and nitrates work as an important indicators of water quality. Rising nitrate levels in the water are mainly agricultural fertilizers as well as industrial processes result. Nitrates in water are low toxic, but secondary mikrobacterial or their decrease in the living system leads the conversion to nitrite, which binds to hemoglobin and causes methaemoglobinaemia. In this paper, we tried to find out the possible pollution of the environment of farms and if it occurs animal disease cases in the area of Linkuva, that would potentially lead to oral administration of contaminated water. We analyzed the mine wells, which were looking for nitrates, nitrites, phosphates, ammonium, chloride, sulphate and iron levels of variation. The results showed that the mine water is not of good quality (n = 16), all samples tested (n = 30) and showed that water was very solid (100%). Diseases are generally not recorded, due to the economic situation in Lithuania so it gets not enough attention.

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references. / Electronic reproduction. / Also available by subscription via World Wide Web / xxvi, 257 leaves, bound ill. 29 cm

Copies of author's previously published works inserted. / Bibliography: leaves 219-244. / xv, 244 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines the mechanisms of induction of nitrate tolerance utilizing an in vitro model (isolated bovine coronary artery rings) and an in vivo haemodynamic model (systemic haemodynamics in patients undergoing cardiac catheterization). / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1996

Bibliography: leaves 142-164 / xxi, 165 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1985