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At least 703 records · Page 39Linked to original sources
USGS1995

Ground-water flow and effects of agricultural application of sewage sludge and other fertilizers on the chemical quality of sediments in the unsaturated zone and ground water near Platteville, Colorado, 1985-89

From fall 1985 through 1989, 6,431 dry tons of anaerobic, digested, sewage sludge were applied as a fertilizer on about 1 square mile of sandy farm- land near Platteville, Colorado. Mean nitrite plus nitrate as nitrogen concentrations in the surficial aquifer increased during the period of sewage- sludge application. However, the effects of municipal sewage sludge applied to the soil in section 16 are difficult to ascertain because anhydrous ammonia and cattle and chicken manure were applied to section 16 prior to sewage-sludge application and anhydrous ammonia was applied during the period of sewage-sludge application. Mostly ammonia plus organic nitrogen was detected in the unsaturated zone while nitrite plus nitrate as nitrogen predominated in the surficial aquifer. The areas of largest concentrations of nitrite plus nitrate as nitrogen were in the northeastern and southwestern quarter sections os section 16. Changes in nitrite plus nitrate as nitrogen concentrations with depth and time were detected in water samples from the multilevel ground-water sampling devices in the surficial aquifer. Nitrogen probably entered the saturated zone in the irrigated areas and low temporarily ponded areas and moved to the northeast with water in the surficial aquifer.

Water-Resources Investigations Report↗
USGS1999

Hydrogeologic framework and sampling design for an assessment of agricultural pesticides in ground water in Pennsylvania

State agencies responsible for regulating pesticides are required by the U.S. Environmental Protection Agency to develop state management plans for specific pesticides. A key part of these management plans includes assessing the potential for contamination of ground water by pesticides throughout the state. As an example of how a statewide assessment could be implemented, a plan is presented for the Commonwealth of Pennsylvania to illustrate how a hydrogeologic framework can be used as a basis for sampling areas within a state with the highest likelihood of having elevated pesticide concentrations in ground water. The framework was created by subdividing the state into 20 areas on the basis of physiography and aquifer type. Each of these 20 hydrogeologic settings is relatively homogeneous with respect to aquifer susceptibility and pesticide use—factors that would be likely to affect pesticide concentrations in ground water. Existing data on atrazine occurrence in ground water was analyzed to determine (1) which areas of the state already have sufficient samples collected to make statistical comparisons among hydrogeologic settings, and (2) the effect of factors such as land use and aquifer characteristics on pesticide occurrence. The theoretical vulnerability and the results of the data analysis were used to rank each of the 20 hydrogeologic settings on the basis of vulnerability of ground water to contamination by pesticides. Example sampling plans are presented for nine of the hydrogeologic settings that lack sufficient data to assess vulnerability to contamination. Of the highest priority areas of the state, two out of four have been adequately sampled, one of the three areas of moderate to high priority has been adequately sampled, four of the nine areas of moderate to low priority have been adequately sampled, and none of the three low priority areas have been sampled. Sampling to date has shown that, even in the most vulnerable hydrogeologic settings, pesticide concentrations in ground water rarely exceed U.S. Environmental Protection Agency Drinking Water Standards or Health Advisory Levels. Analyses of samples from 1,159 private water supplies reveal only 3 sites for which samples with concentrations of pesticides exceeded drinking-water standards. In most cases, samples with elevated concentrations could be traced to point sources at pesticide loading or mixing areas. These analyses included data from some of the most vulnerable areas of the state, indicating that it is highly unlikely that pesticide concentrations in water from wells in other areas of the state would exceed the drinking-water standards unless a point source of contamination were present. Analysis of existing data showed that water from wells in areas of the state underlain by carbonate (limestone and dolomite) bedrock, which commonly have a high percentage of corn production, was much more likely to have pesticides detected. Application of pesticides to the land surface generally has not caused concentrations of the five state priority pesticides in ground water to exceed health standards; however, this study has not evaluated the potential human health effects of mixtures of pesticides or pesticide degradation products in drinking water. This study also has not determined whether concentrations in ground water are stable, increasing, or decreasing.

Water-Resources Investigations Report↗
USGS1966

Effects of agricultural conservation practices on the hydrology of Corey Creek basin, Pennsylvania, 1954-60

Analyses of data collected from two small basins in northern Pennsylvania during the period May 1954 to September 1960 indicated that changes in land use and land treatment have affected suspended- sediment discharge from the basins. Extensive land use and land-treatment changes have taken place in the 12.2-square-mile Corey Creek study basin, whereas such changes in the 10.2-square-mile Elk Run basin, which is adjacent to the northeast, have been relatively slight. Elk Run basin, which is topographically and hydrologically similar to Corey Creek basin, was used as an external control for the Corey Creek basin study. Multiple-regression analysis showed that of all the variables, runoff correlated most highly with the sediment yield of each basin. Surveys at selected cross-sections of the two streams indicated that most channel changes were in the banks rather than in the bed. At points where the stream channel slope was greater than 70 feet per mile, the average annual change in cross-sectional area at the measured ranges was less than +--2.5 square feet. Filling of the stream channel occurred where the slope was 70 feet per mile or less, and such filling was greater in Corey Creek than in Elk Run. Trend analyses of data from both basins indicated no persistent changers in quantity of runoff, precipitation, or runoff intensity (peakedness), although similar analyses indicated significant changes in the rate of suspended-sediment discharge from both basins. During the period September 1957 to September 1960, sediment discharge from Corey Creek basin decreased by 11 percent relative to the sediment discharge from Elk Run. All, or most, of this decrease was the result of a decrease in sediment discharge during the May to October growing seasons. No significant trends were detected in data collected d-ring the November to April dormant season. A factor, termed the relative erosion potential, was formulated for evaluating the effects of changes in the hydrologic cover conditions. This factor was adjusted for- the effects of diversion terrace construction in the Corey Creek basin. A rank correlation test of the adjusted relative erosion potential versus the growing season Corey Creek-Elk Run suspended-sediment discharge ratio resulted in a correlation coefficient, r=0.71, significant at the 3 percent level. The least-squares regression equation derived from the .same data. was Y=0.276 X - 6.89. where Y was the Corey Creek-Elk Run sediment-discharge ratio and X was the adjusted relative erosion potential. The correlation coefficient was 0.65. significant at the 12 percent level. Standard error of estimate was 0.44. or about ?20 percent of the observed variation in the sediment-discharge ratio.

Water Supply Paper↗
USGS1995

The occurrence and transport of agricultural pesticides in the Tuttle Creek lake-stream system, Kansas and Nebraska

Median monthly atrazine concentrations detected in surface-water samples from the Big Blue River basin (1977-86) exceeded the U.S. Environmental Protection Agency health-advisory level (3.0 micrograms per liter) during May through September. Herbicide loads transported from the basin in 1986, expressed in tons and in percentage of amount applied, were alachlor (1.2 tons, 0.23 percent), atrazine (19 tons, 2.2 percent), and metolachlor (2.2 tons, 2.7 percent).

Kansas, Nebraska↗
USGS2017

Could changes in the agricultural landscape of northeastern China have influenced the long-distance transmission of highly pathogenic avian influenza H5Nx viruses?

In the last few years, several reassortant subtypes of highly pathogenic avian influenza viruses (HPAI H5Nx) have emerged in East Asia. These new viruses, mostly of subtype H5N1, H5N2, H5N6, and H5N8 belonging to clade 2.3.4.4, have been found in several Asian countries and have caused outbreaks in poultry in China, South Korea, and Vietnam. HPAI H5Nx also have spread over considerable distances with the introduction of viruses belonging to the same 2.3.4.4 clade in the U.S. (2014–2015) and in Europe (2014–2015 and 2016–2017). In this paper, we examine the emergence and spread of these new viruses in Asia in relation to published datasets on HPAI H5Nx distribution, movement of migratory waterfowl, avian influenza risk models, and land-use change analyses. More specifically, we show that between 2000 and 2015, vast areas of northeast China have been newly planted with rice paddy fields (3.21 million ha in Heilongjiang, Jilin, and Liaoning) in areas connected to other parts of Asia through migratory pathways of wild waterfowl. We hypothesize that recent land use changes in northeast China have affected the spatial distribution of wild waterfowl, their stopover areas, and the wild-domestic interface, thereby altering transmission dynamics of avian influenza viruses across flyways. Detailed studies of the habitat use by wild migratory birds, of the extent of the wild–domestic interface, and of the circulation of avian influenza viruses in those new planted areas may help to shed more light on this hypothesis, and on the possible impact of those changes on the long-distance patterns of avian influenza transmission.

Frontiers in Veterinary Science↗