Differences In Nitrate Levels Research Articles

Sample stacking – Capillary electrophoretic determination of nitrate and nitrite contents as nitric oxide metabolites in honey varieties originated from Anatolia

Abstract Nitrate and nitrite ions taken from food are the sources of bioavailable nitric oxide (NO) in the nitrogen cycle. Some beneficial effects of honey on health are attributed to the ability of honey to increase NO production. The variation of nitrate and nitrite levels of honey samples collected from different Anatolia regions were clarified using capillary electrophoresis technique. The sensitivities of both anions were improved with the application of the sample stacking method. Separation buffer consisted of 30 mmol L−1 formic acid and 30 mmol L−1 sodium sulfate at a pH of 4.0. The CE technique revealed that 18 honey samples contained nitrate anion ranged between 2.53 and 31.8 mg kg−1. Nitrite amounts were found in lower amounts in the honey samples as between non-detected and 0.533 mg kg−1. The observed differences in nitrate levels between honey varieties may be a way to determine honey's origin.

Chemical quality of tap water in Madrid: multicase control cancer study in Spain (MCC-Spain).

Chronic consumption of water, which contains contaminants, may give rise to adverse health effects. The Madrid region, covered by the population-based multicase-control (MCC-Spain) study, includes two drinking water supply areas. The different sources of the water, coupled together with the possible differences in water management, mean that there may be differences in drinking water quality. In the context of the MCC study, our aims were to describe contaminant concentrations in tap water drawn from various sampling points distributed around the region, assess these concentrations by reference to guideline values and study possible differences between the two supply areas. Tap water samples were collected from 34 sampling points in 7 towns in the Madrid region (19-29 April 2010), and 23 contaminants (metals, nitrates, disinfection by-product and Mutagen X levels) were quantified. We undertook a descriptive analysis of the contaminant concentrations in the water and compared them between the two water supply areas (Wilcoxon test). We created maps representing the distribution of the concentrations observed at water sampling points and assessed the correlations (Spearman's coefficient) between the different parameters measured. The concentrations of the contaminants were below guideline values. There were differences between the two supply areas in concentration of nitrates (p value=0.0051) and certain disinfection by-products. While there were positive correlations (rho >0.70) among some disinfection by-products, no correlations were found in metals or nitrates. The differences in nitrate levels could be linked to differences in farming/industrial activities in the catchment areas and in disinfection by-products might be related to the existence of different treatment systems or bromine content in source waters.

CONTENIDO DE NITRATOS Y PROTEÍNA EN LECHUGA CRESPA Y AMARANTO HORTÍCOLA PRODUCIDOS CON ENMIENDA Y UREA

In Argentina, lettuce (Lactuca sativa L.) is the most common vegetable used in salads, while amaranth (Amaranthus mantegazzianus Pass.) is characterized by its high production of green matter, with high protein and mineral levels; both species are considered accumulators of nitrate, so in order to avoid health problems for the consumer, the European Commission regulates the levels of nitrate in lettuce. In order to assess the accumulation of nitrates in both species and evaluate the protein levels and dry matter content, a trial was conducted at the Faculty of Agronomy, UNLPam, Santa Rosa, La Pampa, Argentina. On December 28, 2009, crisp lettuce was transplanted and amaranth was sown. Four levels of fertilization were added for both species: 1) Compost base: 10 dm 3 ·m -2 moderately composted manure, 2) Double Compost: 20 dm3·m-2 moderately composted manure, 3) Compost base + 30 kg·ha-1 urea and 4) Compost base + 60 kg·ha-1 urea. An experimental design of randomized complete blocks with five replications was employed; significant differences in nitrate levels between species and levels of fertilization were obtained. The values in lettuce were 2.9 % dry basis and 2,634 mg·kg-1 fresh-1 and in ama

Comparison of Nitrate Levels in Raw Water and Finished Water from Historical Monitoring Data on Iowa Municipal Drinking Water Supplies

Nitrate contamination of water sources is a concern where large amounts of nitrogen fertilizers are regularly applied to soils. Ingested nitrate from dietary sources and drinking water can be converted to nitrite and ultimately to N-nitroso compounds, many of which are known carcinogens. Epidemiologic studies of drinking water nitrate and cancer report mixed findings; a criticism is the use of nitrate concentrations from retrospective drinking water data to assign exposure levels. Residential point-of-use nitrate data are scarce; gaps in historical data for municipal supply finished water hamper exposure classification efforts. We used generalized linear regression models to estimate and compare historical raw water and finished water nitrate levels (1960s-1990s) in single source Iowa municipal supplies to determine whether raw water monitoring data could supplement finished water data to improve exposure assessment. Comparison of raw water and finished water samples (same sampling date) showed a significant difference in nitrate levels in municipalities using rivers; municipalities using other surface water or alluvial groundwater had no difference in nitrate levels. A regional aggregation of alluvial groundwater municipalities was constructed based on results from a previous study showing regional differences in nitrate contamination of private wells; results from this analysis were mixed, dependent upon region and decade. These analyses demonstrate using historical raw water nitrate monitoring data to supplement finished water data for exposure assessment is appropriate for individual Iowa municipal supplies using alluvial groundwater, lakes or reservoirs. Using alluvial raw water data on a regional basis is dependent on region and decade.

A univariate model of river water nitrate time series

Four time series were taken from three catchments in the North and South of England. The sites chosen included two in predominantly agricultural catchments, one at the tidal limit and one downstream of a sewage treatment works. A time series model was constructed for each of these series as a means of decomposing the elements controlling river water nitrate concentrations and to assess whether this approach could provide a simple management tool for protecting water abstractions. Autoregressive (AR) modelling of the detrended and deseasoned time series showed a “memory effect”. This memory effect expressed itself as an increase in the winter–summer difference in nitrate levels that was dependent upon the nitrate concentration 12 or 6 months previously. Autoregressive moving average (ARMA) modelling showed that one of the series contained seasonal, non-stationary elements that appeared as an increasing trend in the winter–summer difference. The ARMA model was used to predict nitrate levels and predictions were tested against data held back from the model construction process – predictions gave average percentage errors of less than 10%. Empirical modelling can therefore provide a simple, efficient method for constructing management models for downstream water abstraction.

Crop-weed interference as influenced by a leguminous or synthetic fertilizer nitrogen source: I. Doublecropping experiments with crimson clover, sweet corn, and lambsquarters

Field experiments were undertaken to assess the effect of N source (incorporated legume residue vs. synthetic fertilizer) on crop-weed interference. In a 2 year study, a doublecropping system was used in which a crimson clover ( Trifolium incarnatum L.) green manure was followed by a crop of sweet corn ( Zea mays L.) grown alone or with lambsquarters ( Chenopodium album L.). Inclusion of several rates of ammonium nitrate fertilizer in the experiment allowed determination of the clover's N equivalency value (55 kg N ha −1) and contrast of the clover treatment with a comparable rate of N fertilizer addition (45 kg N ha −1). Soil NO 3-N concentration in the experiment at one week after corn and lambsquarters planting was 52% lower in the clover than the fertilizer treatment. Differences in nitrate levels between the two treatments tended to decrease at subsequent sampling dates. At two weeks after emergence, drymatter accumulation of lambsquarters was 72% lower in the clover than the fertilizer treatment and remained 39% lower at final harvest. In contrast, sweet corn biomass accumulation in the clover treatment was 31% lower than in the fertilizer treatment at 2 weeks after emergence but recovered to levels attained in the fertilizer treatment as the growing season progressed. As a result of reduced lambsquarters growth, loss of corn drymatter accumulation to weed interference was 8% in the clover treatment as compared to 28% in the fertilizer treatment. Results of a second experiment in which crimson clover was followed by lambsquarters grown alone also showed a weed suppressive effect of the legume N source in comparison to use of fertilizer N. These experiments demonstrate that use of legume green manure has the potential to reduce the need for herbicide as well as synthetic fertilizer applications in subsequent crops.

Variability of Nitrate Levels in Sweetclover Seedlings

Nitrate concentrations in cotyledons of 8-10-day-old field-grown seedlings of yellow sweetclover (Melilotus officinalis cv. Norgold) were determined by HPLC ion chromatography over a 3-day period. No diurnal variation in nitrate values was observed. Nitrate concentrations were also measured in cotyledons and unifoliate leaves of 18-21-day-old seedlings of Melilotus infesta Guss., an annual sweetclover resistant to sweetclover weevil feeding damage, and cv. Norgold grown in a controlled environment chamber. Nitrate levels in each species fluctuated widely but did not follow a rhythmic or diurnal pattern. There was a significant difference in nitrate levels between the species, with M. infesta having significantly higher levels both in cotyledons and in unifoliate leaves (1.65 and 1.58 mg/g, respectively) than Norgold (0.91 and 0.51 mg/g, respectively), and this interspecific difference was more consistent in the early morning.