Agricultural Surface Water Research Articles

Impact of agricultural development on variation in surface runoff in arid regions: a case of the Aksu River Basin

Located in the south of Xinjiang Uygur autonomous region, the Tarim River is the longest inland river in China. Agricultural development, excessive exploitation and low surface water use efficiency in the headstream regions have led to a marked decrease in the water supply to the mainstream. This, in turn, has resulted in the drying-up of the watercourse in the lower reaches of the Tarim River and serious deterioration of the eco-environment. The Aksu River Basin, the most important headstream of the Tarim River, was selected as the research area in this study. Taking elastic coefficient, water demand coefficient and water utilization intensity as the indices, we studied the impact of agricultural development on decreasing surface runoff since the 1950s. The re- sults indicated that (1) the increasing rate of consumption of surface runoff outstripped the rate of increase meas- ured in the natural catchment discharge, resulting in ever diminishing stream discharge into the Tarim River. Agri- cultural irrigation and seepage loss in irrigation canal systems were the major sources for runoff consumption, tak- ing 63.72% of the overall runoff consumption. What's more, agricultural water consumption took up more than 97% of the water used for long-term production; (2) the expansion of cultivated land, change of planting structure and comparatively low agricultural irrigation efficiency all contributed to the decrease in surface runoff of the Aksu River. The elasticity coefficient of surface runoff reduction corresponding to the increase in planted area was 0.34 in the 1950s, while in the 2000s it had increased to 7.87. This reflected a more sensitive response of runoff decrease to cultivated land expansion. The increase in cotton and fruit production, without widely-used scientific irrigation methods and water-saving technology, led to considerable waste of the water resources. Meanwhile, the irrigation efficiency was still quite low, characterized by the waste of water resources, and the decrease of surface runoff; (3) in different stages, cultivated land area, planting structure and agricultural water use efficiency exerted different effects on runoff decrease. In the early stage, agricultural development showed no obvious effect on runoff de- crease. Since the 1960s, the expansion in cultivated land resulted in large consumption of surface runoff; since the 1990s, not only expansion in cultivated land expansion, but also planting structure exerted significant impact on the consumption of surface runoff. Recently, though agricultural water use efficiency has improved in some regions to reduce the consumption of runoff to a certain extent, overall agricultural water use efficiency is still quite low; (4) during the investigation period, water consumption by agricultural development reflected the unbalanced relation- ship between human activities and water resources.

Thiacloprid affects trophic interaction between gammarids and mayflies

Neonicotinoid insecticides like thiacloprid enter agricultural surface waters, where they may affect predator–prey-interactions, which are of central importance for ecosystems as well as the functions these systems provide. The effects of field relevant thiacloprid concentrations on the leaf consumption of Gammarus fossarum (Amphipoda) were assessed over 96 h (n = 13–17) in conjunction with its predation on Baetis rhodani (Ephemeroptera) nymphs. The predation by Gammarus increased significantly at 0.50–1.00 μg/L. Simultaneously, its leaf consumption decreased with increasing thiacloprid concentration. As a consequence of the increased predation at 1.00 μg/L, gammarids' dry weight rose significantly by 15% compared to the control. At 4.00 μg/L, the reduced leaf consumption was not compensated by an increase in predation causing a significantly reduced dry weight of Gammarus (∼20%). These results may finally suggest that thiacloprid adversely affects trophic interactions, potentially translating into alterations in ecosystem functions, like leaf litter breakdown and aquatic-terrestrial subsidies.

Qualitative Risk Assessment of Surface Water Contamination with Cryptosporidium Sp. Oocysts: A Case Study of Three Agricultural Catchments

ABSTRACT In recent years there have been a number of waterborne outbreaks of cryptosporidiosis in some major urban centers in Ireland. The Irish Environmental Protection Agency has adapted and modified the qualitative “Scottish Water Directions” to help prevent such outbreaks. When this risk assessment method was applied to three small agricultural river catchments in Ireland, the results suggested an equal risk of water contamination for each catchment. A survey was conducted in each catchment focusing on agricultural activity and surface waters. Fecal samples were collected from 1–8-week-old calves along with associated slurry and dung from beef and dairy farms and water samples were collected monthly at the outlet of the three catchments. Two of the catchments had much higher infection rates among neonatal calves as well as higher oocyst contamination of surface waters than the remaining one. It was concluded that the qualitative risk assessment could be more robust if cognizance was taken of the temporal and epidemiological aspects of cryptosporidiosis in beef and dairy herds.

Pesticide Risk Mitigation by Vegetated Treatment Systems: A Meta-Analysis

Pesticides entering agricultural surface waters threaten water quality and aquatic communities. Recently, vegetated treatment systems (VTSs) (e.g., constructed wetlands and vegetated ditches) have been proposed as pesticide risk mitigation measures. However, little is known about the effectiveness of VTSs in controlling nonpoint source pesticide pollution and factors relevant for pesticide retention within these systems. Here, we conducted a meta-analysis on pesticide mitigation by VTSs using data from the scientific literature and the European LIFE ArtWET project. Overall, VTSs effectively reduced pesticide exposure levels (i.e., the majority of pesticide retention performances was >70%). A multiple linear regression analysis of 188 retention performance cases identified the two pesticide properties, organic carbon sorption coefficient value and water-phase 50% dissipation time, as well as the VTS characteristics overall plant coverage and hydraulic retention time for targeting high efficacy of pesticide retention. The application of a Tier I risk assessment (EU Uniform Principle) revealed a higher toxicity reduction for hydrophobic and nonpersistent insecticides compared with less sorptive and not readily degradable herbicides and fungicides. Overall, nearly half (48.5%) of all pesticide field concentrations ( = 130) failed Tier I standard risk assessment at the inlet of VTSs, and 29.2% of all outlet concentrations exceeded conservative acute threshold levels. We conclude that VTSs are a suitable and effective risk mitigation strategy for agricultural nonpoint source pesticide pollution of surface waters. Further research is needed to improve their overall efficacy in retaining pesticides.

Assessment of the impact of various mitigation options on nitrous oxide emissions caused by the agricultural sector in Europe

A European Union (EU-27) wide N2O emission estimate for the agricultural sector is presented, using the INTEGRATOR model, combined with detailed GIS-based environmental data and farming data. INTEGRATOR links various modules, calculating NH3, NOx, N2O, CO2, and CH4 emissions from housing and manure storage systems, agricultural and non-agricultural soils and surface waters, while accounting for the interaction between agricultural and non-agricultural systems through an emission-deposition model for NH3 and NOx. This study is limited to N2O emissions from housing and manure storage systems and agricultural soils. All emissions are based on N2O emission factors which depend on environment (weather and soil conditions), land use (grassland, arable land, crop residues), and management (type of manure and fertilizer, etc). We assessed the plausibility by a comparison of calculated present nitrous oxide emissions at country level with those derived by more simple emission factor approaches and detailed ecosystem models. The model was used to assess the impact of various farming practice packages to mitigate N2O emissions. For the agricultural sector of the EU-27, a total N2O emission of 347 kton N2O‒N is calculated for the year 2000, which is comparable to other estimates. The overall achievable reduction in N2O emissions with the evaluated mitigation measures is about 25%. For the EU-27, the most effective measures are balanced fertilization and maximum manure application, but this is highly variable per country.

Groundwater Rights in Mexican Agriculture: Spatial Distribution and Demographic Determinants*

Groundwater use intensity and aquifer depletion increase from south to north with decreasing rainfall and increasing economic activity in Mexico. To heighten scholarly understanding and offer new insights that strengthen policy responses to aquifer depletion, we analyze the spatial distribution of agricultural groundwater use from irrigation well titles in 2,429 municipalities and its relation to agricultural surface water and population employed in agriculture. Exploratory spatial data analysis reveals spatial dependence among all three variables implying that policy initiatives to address intensive groundwater use must be targeted at clusters of aquifers and municipalities.

Phylogenetic Analysis Implicates Birds as a Source ofCryptosporidiumspp. Oocysts in Agricultural Watersheds

Cryptosporidium parvum and C. hominis are protozoan parasites responsible for cryptosporidiosis, an acute gastrointestinal illness that can be life-threatening for immunocompromised persons. Sources and genotypes of Cryptosporidium oocysts were investigated in two agricultural areas within the Wachusett Reservoir watershed, a drinking water source for Boston, Massachusetts. Two brooks (denoted Brook SF and Brook JF, respectively), each downgradient from a dairy farm, were chosen as sample sites. For one year, Brooks SF and JF were sampled monthly; oocysts were detected in 6 (50%) out of 12 samples from Brook JF, and no oocysts were detected in Brook SF. Oocyst genotypes from agricultural surface waters were compared to oocyst genotypes from Genbank, as well as fecal samples of cattle and birds, using phylogenetic analysis of a hypervariable region of the 18S rRNA gene by both neighbor-joining and parsimony methods. Results show extensive heterogeneity among Cryptosporidium spp. 18S rRNA sequences, and also suggest that birds are an oocyst source in this watershed. Principal components analysis showed oocyst presence correlating strongly with seasonal factors, and oocysts in surface waters were only detected in the summer through late fall, co-incident with the presence of migratory birds in this watershed. If birds are confirmed to be an important source of oocysts infectious to humans, the data suggest that protection of raw drinking water supplies in some agricultural areas may depend upon management and control of resident and migratory bird populations.

Discharge of Escherichia Coli from Agricultural Surface and Subsurface Drainage Water: Tillage Effects

Drainage water from agricultural fields with applied manure can degrade the bacterial quality of surface and groundwater. The impact of conventional tillage (CT) and zero tillage (ZT) practices on Escherichia coli (E.coli) discharge through artificially drained soils is not well understood. Consequently, two field trials were conducted during 2002–2004. The first trial involved fall applications of beef manure while the second involved spring applications of dairy manure. Both surface and subsurface drainage water were monitored in the first trial while only subsurface drainage water was monitored in the second. Under fall applied beef manure (trial 1), no differences (p > 0.05) were observed in E.coli concentrations (cfu/100 ml) in combined drainage water under both tillage systems. However, during 2003–2004, subsurface drainage water under ZT had higher E.coli concentrations and loads than drainage water under CT. When the combined (surface + subsurface) annual E.coli loads were considered, CT loads were greater than ZT during 2002–2003 with an opposite situation during 2003–2004. Overall, annual E.coli loads were similar under ZT (4.7 × 1010 cfu/ha) and CT (4.8 × 1010 cfu/ha). Spring dairy manure application (trial 2) produced significant (p > 0.03) tillage effect on E.coli loads in subsurface drainage water only during the second year. During the study period, ZT plots (1.55 × 1010 cfu/ha) discharged 5× more E.coli than CT (0.23 × 1010 cfu/ha). A longer duration of ZT practices resulted in higher subsurface flow volumes and subsequently greater loads of E.coli discharge in both trials.

Pesticide interception by emergent aquatic macrophytes: Potential to mitigate spray-drift input in agricultural streams

An increasing amount of research has focused on alternate methods to mitigate pesticide exposure in agricultural surface waters. The interception of spray-drift-derived azinphos-methyl (AZP) by emergent aquatic macrophytes was investigated in a tributary of the Lourens River, South Africa. The stream was dominated (80% coverage) by three species of emergent aquatic macrophytes; Juncus capensis , Fuirena hirsuta and Pycreus sp. During an application of AZP, drift deposition was determined on the surface of the vegetation, on the surface of the exposed channel of the stream and beneath J. capensis and F. hirsuta by means of drift collectors ( n = 6). Drift deposition on the surface of the vegetation (1.5 ± 0.3 mg/m 2 ) was well predicted by 90th percentile basic drift values (1.3 mg/m 2 ), indicating that the sampling devices resulted in an accurate measurement of drift deposition. Drift deposition on the surface of the exposed channel (1.0 ± 0.3 mg/m 2 ) was lower than measured on the vegetation surface indicating a positive shielding effect by the emergent plants. Drift deposition beneath J. capensis was significantly lower ( p = 0.005) than on the vegetation surface and the exposed channel ( p = 0.048), indicating highly effective interception of AZP. A simple formula was generated to make predictions of drift deposition reductions based on different percentage macrophyte coverage. Predictions showed that 50% macrophyte coverage in combination with a 5 m buffer strip resulted in as large a reduction in drift deposition as the combination of a 10 m buffer strip with 0% macrophyte coverage. Results thus indicate that emergent aquatic vegetation may be as effective a mitigation strategy for reducing spray-drift induced pesticide input as increasing the width of the no spraying buffer zone.

Microbiological impact of atrazine pollution in river sediment and soil

Atrazine is a frequently detected pollutant in agricultural soils, groundwater and surface waters. Microbial degradation was confirmed in soils, and recently several atrazine-degrading bacteria have been isolated. Degradation in aquifers, however, is not well understood, and to date, atrazine degraders have not been isolated from water. In the present study, the impact of atrazine was assessed in agricultural soil and river sediment and the composition of the atrazine-degrading bacterial community in the soil and sediment was compared. Atrazine pollution increased the number and diversity of the endogenous atrazine degraders in both environments. Proteobacteria were predominant atrazine degraders in soils, whereas the community of atrazine-degrading bacteria in sediment consisted mostly of coryneforms.

Occurrence of Cryptosporidium in agricultural surface waters during an annual farming cycle in lowland UK

A 17-month survey based on weekly testing for Cryptosporidium oocysts in surface waters draining a livestock farm on a Warwickshire (UK) estate has shown that the parasite is present throughout the year, with the highest frequency of occurrence and maximum concentrations during the autumn and winter. The 190 ha farm is managed as an exemplar for a teaching institution. There were up to 800 livestock present at peak times of year in the catchment of the stream draining the estate. Oocysts were concentrated from grab samples by a flocculation procedure, stained with monoclonal antibody and detected by fluorescence microscopy. Overall, 274/418 (66%) of samples were positive for Cryptosporidium. Where the stream passed from the estate, the occurrence was 79%, with mean and median oocysts/l of 0.48 and 0.2, respectively. Highest oocyst levels coincided with calving and increased wild animal numbers following breeding. There was no correlation of oocyst levels with rainfall or slurry spreading. Cryptosporidium was also frequently found in a pond on arable land (no livestock) indicating that wild animals alone contributed oocysts to surface waters. These results from a well managed livestock farm may represent a typical natural baseline for levels of occurrence and concentration of Cryptosporidium oocysts in surface waters of the lowland agricultural environment of the UK.

Toxicity of aqueous‐phase and suspended particle‐associated fenvalerate: Chronic effects after pulse‐dosed exposure of Limnephilus lunatus (Trichoptera)

AbstractNon‐point source pollution of agricultural surface waters via spraydrift and runoff can lead to different short‐term exposure scenarios: contamination with water‐dissolved or particle‐associated pesticide. To compare water‐dissolved and particle‐associated exposure, fenvalerate (FV) was tested in a 1‐h exposure setup with suspended silt particles (5 g dry wt/L; total organic carbon = 3.2%). Chronic effects on the test organism Limnephilus lunatus Curtis (Trichoptera), second and third instar, were observed more than 240 d after transfer of larvae into an outdoor‐stream microcosm with pesticide‐free water. Significant‐effect concentrations were 0.001 μg/L in water and 0.2 μ.g/kg in suspended sediments. Toxicity is lower in the presence of suspended particles by factors between 100 (using mortality and production of biomass as endpoints) and 10 (using emergence pattern and dry wt of adults as endpoints). Effect levels were generally lower than those in previous studies using older larval stages. The reduction of adult dry weight may diminish reproductive success. Aqueous‐phase contamination caused lethal and sublethal effects at concentrations of FV that can be measured in the field. In contrast, levels of particle‐associated FV that are relevant to the field situation elicited only sublethal responses in the present experiment. Results from this study suggest that short‐term FV contamination at expected, field‐relevant levels may lead to long‐term effects even if the chemical is associated with suspended particles.

Toxicity of aqueous-phase and suspended particle-associated fenvalerate: chronic effects after pulse-dosed exposure of Limnephilus lunatus (Trichoptera).

Non-point source pollution of agricultural surface waters via spray drift and runoff can lead to different short-term exposure scenarios: contamination with water-dissolved or particle-associated pesticide. To compare water-dissolved and particle-associated exposure, fenvalerate (FV) was tested in a 1-h exposure setup with suspended silt particles (5 g dry wt/L; total organic carbon = 3.2%). Chronic effects on the test organism Limnephilus lunatus Curtis (Trichoptera), second and third instar, were observed more than 240 d after transfer of larvae into an outdoor-stream microcosm with pesticide-free water. Significant-effect concentrations were 0.001 microgram/L in water and 0.2 microgram/kg in suspended sediments. Toxicity is lower in the presence of suspended particles by factors between 100 (using mortality and production of biomass as endpoints) and 10 (using emergence pattern and dry wt of adults as endpoints). Effect levels were generally lower than those in previous studies using older larval stages. The reduction of adult dry weight may diminish reproductive success. Aqueous-phase contamination caused lethal and sublethal effects at concentrations of FV that can be measured in the field. In contrast, levels of particle-associated FV that are relevant to the field situation elicited only sublethal responses in the present experiment. Results from this study suggest that short-term FV contamination at expected, field-relevant levels may lead to long-term effects even if the chemical is associated with suspended particles.

Denitrification in an Estuarine Headwater Creek within an Agricultural Watershed

AbstractNonpoint agricultural surface water runoff has been identified as a significant contributor to watershed nitrogen (N) loading. Denitrification is thought to be a substantial sink for N inputs to estuaries. Denitrification rates and inorganic N concentrations were measured in Culvert Creek, NC for a 3‐yr period with an adaptation of the acetylene block technique using saturation kinetic incubations that provided estimated in situ and potential rates. Estimated in situ denitrification and inorganic N concentrations were elevated in portions of Culvert Creek, NC following fertilizer application at adjacent Open Grounds Farm. Statistical correlations indicated that denitrification in Culvert Creek was regulated by inorganic N, paticularly at headwater sites. Regulation was complex at estuarine sites, where dynamic hydrological conditions affected microbial processing of N through coupled nitrification‐denitrification. Potential denitrification rates were often an order of magnitude higher than estimated in situ rates. Potential denitrification showed a similar seasonal‐spatial pattern to that of nitrification at the most estuarine site, with lower rates at the mid‐creek sites where nitrification was inhibited during periods of anoxia. Annual N removal in Culvert Creek was estimated at 1.27% (in situ) or 68.70% (potential rates) of inputs. An estimated 11% of N inputs were removed via the nitrification‐denitrification pathway in Culvert Creek assuming that rates were closely coupled. Mean annual (1995–1997) creek denitrification rates of 2.17 kg N ha−1 yr−1 (in situ) and 90.52 kg N ha−1 yr−1 (potential) were within the range of rates measured in various freshwater wetland systems receiving agricultural drainage. In Culvert Creek, denitrification was a significant mediator of estuarine headwater N cycling.

Agricultural best management practices and surface water improvement and management

Restoration and enhancement of Lake Okeechobee and the Florida Everglades requires a comprehensive approach to manage agricultural runoff. The Florida Surface Water Improvement and Management (SWIM) Act of 1987 was promulgated to develop and implement plans for protecting Florida waters. The South Florida Water Management District was directed by Florida legislature to develop management plans for Lake Okeechobee (SWIM) and the Everglades ecosystem (Marjory Stoneman Douglas Everglades Protection Act of 1991). These plans require agriculture to implement best management practices (BMPs) to reduce runoff phosphorus (P) loads. The Lake Okeechobee SWIM plan established a P load reduction target for Lake Okeechobee and set P concentration limitations for runoff from non-point source agricultural sources. Agricultural water users in the Everglades Agricultural Area (EAA) are required to develop farm management plans to reduce P loads from the basin by 25%. The Everglades Forever Act of 1994 additionally emphasized linkage of these landscapes and consequent protection and restoration of the Everglades. Agricultural BMPs are being developed and implemented to comply with water management, environmental, and regulatory standards. Although BMPs are improving runoff water quality, additional research is necessary to obtain the best combination of BMPs for individual farms. This paper summarizes the development of comprehensive water management in south Florida and the agricultural BMPs carried out to meet regulatory requirements for Lake Okeechobee and the Everglades.

Agricultural best management practices and surface water improvement and management

Restoration and enhancement of Lake Okeechobee and the Florida Everglades requires a comprehensive approach to manage agricultural runoff. The Florida Surface Water Improvement and Management (SWIM) Act of 1987 was promulgated to develop and implement plans for protecting Florida waters. The South Florida Water Management District was directed by Florida legislature to develop management plans for Lake Okeechobee (SWIM) and the Everglades ecosystem (Marjory Stoneman Douglas Everglades Protection Act of 1991). These plans require agriculture to implement best management practices (BMPs) to reduce runoff phosphorus (P) loads. The Lake Okeechobee SWIM plan established a P load reduction target for Lake Okeechobee and set P concentration limitations for runoff from non-point source agricultural sources. Agricultural water users in the Everglades Agricultural Area (EAA) are required to develop farm management plans to reduce P loads from the basin by 25%. The Everglades Forever Act of 1994 additionally emphasized linkage of these landscapes and consequent protection and restoration of the Everglades. Agricultural BMPs are being developed and implemented to comply with water management, environmental, and regulatory standards. Although BMPs are improving runoff water quality, additional research is necessary to obtain the best combination of BMPs for individual farms. This paper summarizes the development of comprehensive water management in south Florida and the agricultural BMPs carried out to meet regulatory requirements for Lake Okeechobee and the Everglades.

Nonpoint sources

Nonpoint sources

Survival and injury of Escherichia coli, Campylobacter jejuni, and Yersinia enterocolitica in stream water

Experiments were done to describe the survival and injury of three strains each of enteropathogenic Escherichia coli, Yersinia enterocolitica, and Campylobacter jejuni in agricultural surface water. Bacterial suspensions within membrane diffusion chambers were immersed in two large vessels of stream water that were held at 6 and 16 degrees C and changed daily. The results of daily plate counts, using selective and nonselective media, revealed some variation among strains and genera. Injury increased rapidly in all of the bacteria examined during an initial 4-day period of population stability. Bacterial persistence was generally prolonged at 6 degrees C, while the occurrence of injury was directly related to temperature. However, both survival and injury in C. jejuni were less dependent on temperature, while Y. enterocolitica displayed the greatest survival at both 6 and 16 degrees C. These results suggest that surface water in the temperate zone might serve as a persistent vehicle for the transmission of these enteropathogenic bacteria between animals and humans.

Potential of the Conservation Reserve Program to control agricultural surface water pollution

The Conservation Reserve Program (CRP), initiated by the Conservation Title of the Food Security Act of 1985, is the primary federal program to control nonpointsource pollution in agricultural watersheds of the United States. However, the program is designed primarily to reduce soil erosion rather than to retire croplands in a manner optimal for controlling runoff of sediment and associated pollutants. This study estimates potential enrollment of streamside and floodplain croplands in this ten-year retirement program in order to gauge the potential of the CRP as a water-quality improvement policy. A contingent choice survey design was employed in Fayette County, Illinois, to demonstrate that there is substantial potential for retirement of streamside and floodplain croplands in the CRP. Enrollments in each program climb from less than 6% to over 83% of eligible croplands as the annual rental rate is increased from $20 to $200/acre. Potential retirement of streamside and floodplain croplands declines, however, if tree planting, drainage removal, or a 20-year contract are required. The potential of a CRP-based water-quality program to improve water quality and aquatic ecosystems in agricultural watersheds is thus substantial but constrained by the economic trade-offs that farmers make between crop production and conservation incentives in determining the use of their riparian lands.

Pseudomonas fluorescens survival and plasmid RP4 transfer in agricultural water

Transfer of plasmid RP4 via conjugation between introduced Pseudomonas fluorescens donor and recipient cells was studied in agricultural surface water samples at 22°C over a 10 day period. Transconjugants were recovered when the water was sampled after 3 and 10 days incubation, from non-sterile (unfiltered) surface water that was amended with dilute tryptone-yeast extract (TY) broth and 0.1% (v/v) bentonite clay slurry. RP4 plasmid transfer was not observed in unamended filtered water samples inoculated with donor and recipient cells. However, viable donor and recipient cells were usually present in reduced numbers in most water samples after 10 days.