Nonpoint sources

Line, Daniel E.; McLaughlin, Richard A.; Osmond, Deanna L.; Jennings, Gregory D.; Harman, William A.; Lombardo, Laura A.; Spooner, Jean

doi:10.2175/106143098x134514

Cited by 10 publications

(3 citation statements)

References 132 publications

(136 reference statements)

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“…Non-point source pollution caused by nitrogen from agro-ecosystems is a serious threat to water environments and has received increasing attention regionally and globally [ 12 , 16 – 20 ]. Agricultural activities contributed to approximately 75% of non-point pollution, which accounted for approximately two-thirds of the total pollution, in the US [ 21 ]. Agriculture is a primary source of river and groundwater pollution in rural areas of the UK [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments

Wang

Gao

et al. 2015

PLoS ONE

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To evaluate the process of nitrate accumulation and leaching in surface and ground water, we conducted simulated rainfall experiments. The experiments were performed in areas of 5.3 m2 with bare slopes of 3° that were treated with two nitrogen fertilizer inputs, high (22.5 g/m2 NH4NO3) and control (no fertilizer), and subjected to 2 hours of rainfall, with. From the 1st to the 7th experiments, the same content of fertilizer mixed with soil was uniformly applied to the soil surface at 10 minutes before rainfall, and no fertilizer was applied for the 8th through 12th experiments. Initially, the time-series nitrate concentration in the surface flow quickly increased, and then it rapidly decreased and gradually stabilized at a low level during the fertilizer experiments. The nitrogen loss in the surface flow primarily occurred during the first 18.6 minutes of rainfall. For the continuous fertilizer experiments, the mean nitrate concentrations in the groundwater flow remained at less than 10 mg/L before the 5th experiment, and after the 7th experiment, these nitrate concentrations were greater than 10 mg/L throughout the process. The time-series process of the changing concentration in the groundwater flow exhibited the same parabolic trend for each fertilizer experiment. However, the time at which the nitrate concentration began to change lagged behind the start time of groundwater flow by approximately 0.94 hours on average. The experiments were also performed with no fertilizer. In these experiments, the mean nitrate concentration of groundwater initially increased continuously, and then, the process exhibited the same parabolic trend as the results of the fertilization experiments. The nitrate concentration decreased in the subsequent experiments. Eight days after the 12 rainfall experiments, 50.53% of the total nitrate applied remained in the experimental soil. Nitrate residues mainly existed at the surface and in the bottom soil layers, which represents a potentially more dangerous pollution scenario for surface and ground water. The surface and subsurface flow would enter into and contaminate water bodies, thus threatening the water environment.

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Section: Introductionmentioning

confidence: 99%

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments

Wang

Gao

et al. 2015

PLoS ONE

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“…In the Charleston, South Carolina region, urban land use has increased by 256% between 1973 and 1994 and is predicted to increase by another 200% by 2030 (Jeffery and Lu, ). Numerous studies have linked urbanisation to a significant alteration of the hydrologic processes governing watersheds, changes that ultimately threaten the quality and health of nearby fresh and estuarine water bodies (Farahmand et al , ; Holland et al , ; Line et al , ). The hydrology of urbanised streams can be affected during storm events as these water bodies experience stream channel modification, increased erosion rates, variable base flow, stream flashiness and increased volumes of storm water runoff resulting in flooding (Poff et al , ; Watts and Hawke, ).…”

Section: Introductionmentioning

confidence: 99%

Groundwater–surface water interactions in a lowland watershed: source contribution to stream flow

Garrett

Vulava

Callahan

et al. 2012

Hydrological Processes

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Abstract:The lower coastal plain of the Southeast USA is undergoing rapid urbanisation as a result of population growth. Land use change has been shown to affect watershed hydrology by altering stream flow and, ultimately, impairing water quality and ecologic health. However, because few long-term studies have focused on groundwater-surface water interactions in lowland watersheds, it is difficult to establish what the effect of development might be in the coastal plain region. The objective of this study was to use an innovative improvement to end-member mixing analysis (EMMA) to identify time sequences of hydrologic processes affecting storm flow. Hydrologic and major ion chemical data from groundwater, soil water, precipitation and stream sites were collected over a 2-year period at a watershed located in USDA Forest Service's Santee Experimental Forest near Charleston, South Carolina, USA. Stream flow was ephemeral and highly dependent on evapotranspiration rates and rainfall amount and intensity. Hydrograph separation for a series of storm events using EMMA allowed us to identify precipitation, riparian groundwater and streambed groundwater as main sources to stream flow, although source contribution varied as a function of antecedent soil moisture condition. Precipitation, as runoff, dominated stream flow during all storm events while riparian and streambed groundwater contributions varied and were mainly dependent on antecedent soil moisture condition. Sensitivity analyses examined the influence of 10% and 50% increases in analyte concentration on EMMA calculations and found that contribution estimates were very sensitive to changes in chemistry. This study has implications on the type of methodology used in traditional forms of EMMA research, particularly in the recognition and use of median end-member water chemistry in hydrograph separation techniques. Potential effects of urban development on important hydrologic processes (groundwater recharge, interflow, runoff, etc.) that influence stream flow in these lowland watersheds were qualitatively examined.

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“…G round water is a major drinking source for many citizens, and its contamination by nonionic organic chemicals (NOCs) has become a worldwide concern since some chemicals were discovered in ground water (Jury et al, 1987; Teso et al, 1996). Research about factors affecting the transportation of NOCs in soils is needed to prevent further contamination of ground water (Line et al, 1998; Fava et al, 2000). However, it is costly and tedious to use a conventional lysimeter facility (Suzuki et al, 1998) to measure the leaching potential of a chemical in a soil–water system.…”

mentioning

confidence: 99%

Retention Equations of Nonionic Organic Chemicals in Soil Column Chromatography with Methanol–Water Eluents

Liang

Lin

2002

J of Env Quality

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Research efforts dealing with chemical transportation in soils are needed to prevent damage to ground water. Methanol-containing solvents can increase the translocation of nonionic organic chemicals (NOCs). In this study, a general log-linear retention equation, log k' = log k'w - Sphi (Eq. [1]), was developed to describe the mobilities of NOCs in soil column chromatography (SCC). The term phi denotes the volume fraction of methanol in eluent, k' is the capacity factor of a solute at a certain phi value, and log k'w and -S are the intercept and slope of the log k' vs. phi plot. Two reference soils (GSE 17204 and GSE 17205) were used as packing materials, and were eluted by isocratic methanol-water mixtures. A model of linear solvation energy relationships (LSER) was applied to analyze the k' from molecular interactions. The most important factor determining the transportation was found to be the solute hydrophobic partition in soils, and the second-most important factor was the solute hydrogen-bond basicity (hydrogen-bond accepting ability), while the less important factor was the solute dipolarity-polarizability. The solute hydrogen-bond acidity (hydrogen-bond donating ability) was statistically unimportant and deletable. From the LSER model, one could also obtain Eq. [1]. The experimental k' data of 121 NOCs can be accurately explained by Eq. [1]. The equation is promising to estimate the solute mobility in pure water by extrapolating from lower-capacity factors obtained in methanol-water mixed eluents.

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Nonpoint sources

Cited by 10 publications

References 132 publications

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments

Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments

Groundwater–surface water interactions in a lowland watershed: source contribution to stream flow

Retention Equations of Nonionic Organic Chemicals in Soil Column Chromatography with Methanol–Water Eluents

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