Non-point Source Nutrient Pollution Research Articles

Applying water environment capacity to assess the non-point source pollution risks in watersheds

Comprehension of the spatial and temporal characteristics of non-point source (NPS) pollution risk in watersheds is essential for NPS pollution research and scientific management. Although the concept of water functional zones (WFZ) has been considered in the NPS pollution risk assessment process. However, no comprehensive study of the NPS pollution risk has been conducted to effectively protect water quality in watersheds with different water environment capacity. Therefore, this study proposes a new NPS pollution risk assessment method that integrates water functional zoning, receiving water body environmental capacity, and space-time distribution of pollution load for quantifying the impact of pollution discharge from sub-catchment on nearby water body quality. Based on the NPS nutrient loss process modeled by the Soil and Water Assessment Tool (SWAT), this method was used to assess the NPS pollution risk in the Le 'an River Watershed at annual and monthly scales. The results showed that the NPS pollution risk is characterized by seasonal and spatial variability and is influenced clearly by the water environment capacity. High NPS pollution loads are not necessarily high pollution risks. Conversely, a low NPS nutrient pollution load does not represent a low regional risk sensitivity. In addition, NPS risk assessment based on the water environment capacity could also distinguish the differences in risk levels that were masked by similar NPS pollutant loss and the same water function zoning to achieve accurate control of NPS pollution management in watersheds.

Tile Drainage Increases Total Runoff and Phosphorus Export During Wet Years in the Western Lake Erie Basin

Artificial subsurface (tile) drainage is used in many agricultural areas where soils have naturally poor drainage to increase crop yield and field trafficability. Studies at the field scale indicate that tile drains disproportionately export large soluble reactive phosphorus (SRP) and nitrate loads to downstream waterbodies relative to other surface and subsurface runoff pathways, but knowledge gaps remain understanding the impact of tile drainage to nutrient export at watershed scales. The Western Lake Erie Basin is susceptible to summertime eutrophic conditions driven by non-point source nutrient pollution due to a shallow mean water depth and land use dominated by agriculture. The purpose of this study is to analyze the impact of tile drainage on downstream discharge, nutrient concentrations, and nutrient loads for 16 watersheds that drain to the Western Lake Erie Basin. Daily discharge and nutrient concentrations were summarized annually and during the main nutrient loading period (March–July) for 2 years representing normal nutrient loading period precipitation (2018) and above normal precipitation (2019). Results indicate positive correlations between watershed tile drainage percentage and runoff metrics during 2019, but no relationship during 2018. Additionally, SRP concentration and load were positively correlated to watershed tile drainage percentage in 2019, but not in 2018. Watershed tile drainage percentage was correlated with nitrate concentration and load for both years. The SRP concentration-discharge relationships suggested relatively weak, chemodynamic behavior, implying a slight enriching effect where SRP concentrations were greater at higher stream discharge conditions during both years. In contrast, nitrate concentration-discharge relationships suggested strong, enriching chemodynamic behavior during 2018, but chemostatic behavior during 2019. The difference in SRP and nitrate export patterns in the 2 years analyzed highlights the importance of implementing appropriate best management practices that target specific nutrients and treat primary delivery pathways to effectively improve downstream aquatic health conditions.

An evaluation of corn production within a Wetlaculture™ system at Buckeye Lake, Ohio

Harmful algal blooms (HABs) are increasing in frequency and severity worldwide due to nonpoint source nutrient pollution, mainly a product of agricultural runoff. This issue is compounded by the steady, global loss of wetlands and their water quality services. Wetlaculture, an integrated system of wetlands and agriculture, has been proposed as a solution to HABs in which farmland located on former wetlands is flipped to serve as a nutrient-sequestering treatment wetland for a period of years, then flipped back to farmland which consumes the stored nutrients for crop production without the need for fertilizers. A wetlaculture mesocosm experiment was initiated at Buckeye Lake, Ohio in 2016, where all of the site's mesocosms had been functioning as treatment wetlands fed with water from an adjacent, nutrient-impaired stream prior to the 2020 season. This study serves as both a continuation of the treatment wetland experiment, and a first attempt at the cultivation of an agricultural crop in wetlaculture mesocosms. Eight of the twenty-eight mesocosms were drained and planted with corn (Zea mays), while the remaining twenty continued to function as treatment wetlands. Inflow and outflow concentrations of five nutrient species were monitored in the wetland mesocosms, while suitability for corn was evaluated via preplant soil tests and ultimate grain yield, which was compared to that of a nearby commercial farm. End-of-season soil analyses from both the corn and wetland mesocosms were taken to determine the impact of these disparate management regimes on total soil N, P, K, and C. Results indicate that the treatment wetlands continued to improve water quality and that the mesocosms planted with corn produced a grain crop without fertilization. Mesocosm yields (58 ± 9.5 bu./ac) fell significantly below those of the reference farm (160 ± 15.3 bu./ac)(p = 0.004). Some of that difference may be due to the frequent herbivory that occurred during this study, in addition to the limited soil volume in the 0.285 m3 mesocosm tubs versus the open agricultural field.

Characteristics of Pollutant Dynamics Under Rainfall-Runoff Events in the Chaohe River Watershed

In semi-arid and semi-humid areas, the occurrence of non-point source nutrient pollution is mainly driven by rainfall-runoff events, and nutrient loss under rainfall events determines annual total pollution load. Therefore, research on riverine nutrient dynamics under rainfall-runoff events in flood seasons is critical for simulating and controlling pollution load in semi-arid and semi-humid areas. The Chaohe River watershed, upstream watershed of Miyun Reservoir in Beijing was considered as study area, water quantity and quality of rainfall-runoff process at Gubeikou and Xiahui stations were monitored synchronously in flood seasons in 2018 and 2019. The results indicated the following:① Among the three rainfall events (E1, E2, and E3), E1 had the highest precipitation and rainfall intensity, and the corresponding discharge and pollutant concentrations were the highest. ② Under different rainfall events, the pollutant concentrations and their variations were different. The variations of concentrations of total nitrogen (TN), ammonia (NH4+-N), nitrate (NO3--N), total phosphorus (TP), and total suspended solids (TSS) were similar to the discharge process under the heavy rainstorm event (E1) and the rainstorm event (E3). The concentrations of total nitrogen (TN), ammonia (NH4+-N), total phosphorus (TP), and total suspended solids (TSS) were similar to the discharge process under the heavy rain events (E2), but the variations of nitrate (NO3--N) concentrations were opposite to those in the discharge process. ③ The concentrations and variations of different forms of pollutants were different under different rainfall events. Under the event of strong rainfall erosion (E1 and E2), the concentrations of particulate pollutants varied significantly, being positively correlated with that of total suspended solids (TSS). For the rainfall event that did not cause soil erosion (E3), the forms of nitrogen and phosphorus were dominated by total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) respectively, whose variations were mainly related to discharge. ④ The discharge and pollutant concentrations at each station varied under different rainfall events. Heavy rainfall erosion was more obvious at Gubeikou station, causing significant variations in discharge, TP, and TSS. Therefore, these results can be used to determine migration patterns of non-point source pollutants caused by rainfall-runoff events and provide references for water quality prediction and control in flood seasons.

Considerations when using nutrient inventories to prioritize water quality improvement efforts across the US

Ongoing water quality degradation tied to nitrogen and phosphorus pollution results in significant economic damages by diminishing the recreational value of surface water and compromising fisheries. Progress in decreasing nitrogen and phosphorus pollution to surface water over the past two decades has been slow. Limited resources need to be leveraged efficiently and effectively to prioritize watersheds for restoration. Leveraging recent nitrogen and phosphorus inventories for the years 2002, 2007, and 2012, we extracted relevant flux and demand terms to help identify US subbasins that are likely contributing a disproportionate amount of point and non-point source nutrient pollution to surface water by exploring the mean spatial distribution of terrestrial anthropogenic surplus, agricultural surplus, agricultural nutrient use efficiency, and point source loads. A small proportion of the landscape, <25% of subbasin area of the United States, contains 50% of anthropogenic and agriculture nitrogen and phosphorus surplus while only 2% of landscape contributes >50% of point source loads into surface water. Point source loads are mainly concentrated in urban areas across the country with point source loading rates often exceeding >10.0 kg N ha−1 yr−1 and >1.0 kg P ha−1 yr−1. However, the ability for future upgrades to wastewater treatment plant infrastructure alone is unlikely to drive further improvement in water quality, outside of local water ways, since point source loads only account for ~4% of anthropogenic N and P surplus. As such, further progress in boosting nutrient use efficiency in agricultural production, usually lowest in areas of intensive livestock production, would likely contribute to the biggest gains to water quality restoration goals. This analysis and the corresponding database integrate multiple streams of information to highlight areas where N and P are being managed inefficiently to give decision makers a succinct platform to identify likely areas and sources of water quality degradation.

Spatial ecology of common carp (Cyprinus carpio) in Lake Winnipeg and its potential for management actions

Common carp feeding and spawning behaviours negatively impact the functioning of marsh ecosystems. In the Netley-Libau Marsh, situated on the southern end of Lake Winnipeg, water level regulations, nonpoint source nutrient pollution, and the non-native common carp are thought to be the main contributors to the degradation of the marsh habitat. Using acoustic telemetry, we analysed the movement rate, frequency and timing of suspected spawning migrations, spatial ecology, and aggregation of common carp in the Lake Winnipeg drainage over a three year time period. Common carp moved the farthest during the open water period when water temperature was >5 °C. Their annual migration into Netley-Libau Marsh was correlated to ordinal date. Common carp left the marsh in late spring/early summer, presumably feeding in Lake Winnipeg, before moving to overwintering sites situated in Traverse Bay and Lake Winnipeg, where they arrived typically by October and formed aggregations. These findings will inform habitat and fisheries managers in the effort to undertake evidence-based management actions. The predictability of the movements and the tendency for common carp to aggregate indicates that exclusion techniques and commercial fishing may represent viable management solutions.

Seasonal changes predominant over manure application in driving dissolved organic matter shifts in agricultural runoff

Non-point source nutrient pollution can cause eutrophication, hypoxic events, and harmful algal blooms in surface waters. Surface water eutrophication is frequently attributed to agricultural runoff, a known source of inorganic and organic nutrients to surface and subsurface waters. Analysis of dissolved organic matter (DOM) using ultrahigh resolution mass spectrometry is an effective tool for characterizing diverse organic nitrogen and phosphorus components of DOM that may be mineralized and/or assimilated and ultimately contribute to eutrophication. An anion exchange resin was applied to extract DOM from surface and subsurface tile runoff from agricultural plots located within the Maumee River watershed (Ohio, USA) that received raw liquid manure, polymer-treated dewatered manure, or no manure (control). DOM extracts were analyzed using Fourier transform ion cyclotron resonance mass spectrometry prior to manure application and during three runoff events after manure application. Organic nitrogen compounds were predominant, making up 38–48% of the total assigned formulas. Principle coordinates analysis indicated clustering predominately by sample month and secondarily by treatment. These findings show that a large amount of variability in DOM in runoff was observed regardless of manure application, indicating the important role played by natural processes in driving transformation of the DOM pool during the growing season. Molecular ions unique to runoff from manure-applied plots were also identified that may be useful in source-tracking of non-point source nutrient pollution in waters draining to Lake Erie.

Using Spatially Targeted Conservation to Evaluate Nitrogen Reduction and Economic Opportunities for Best Management Practice Placement in Agricultural Landscapes.

The US Cornbelt leads North American production of intensively managed, row-crop corn and soybeans. While highly productive, agricultural management in the region is often linked with nonpoint source nutrient pollution that negatively impacts water quality. Presently, conservation programs designed to install best management practices (BMPs) to mitigate agricultural nonpoint source pollution have not been targeted to those areas of the landscape that contribute disproportionately to surface water quality concerns. We used an innovative spatially targeted conservation protocol coupled with a GIS-based landscape planning tool to evaluate the cost and effect on water quality from nitrate-nitrogen loss under alternative landscape scenarios in an Iowa watershed. Outputs indicate large reductions in watershed-level nitrate-nitrogen loss could be achieved through coordinated placement of BMPs on high-contributing parcels with limited reduction of cultivated land, resulting in improved surface water quality at relatively low economic costs. For example, one scenario, which added wetlands, cover crops, and saturated buffers in the watershed, required the removal of <5% of cultivated area to reduce nitrate-nitrogen loss by an estimated 49%, exceeding the Iowa Nutrient Reduction Strategy goal for enhancing water quality. Annualized establishment and management costs of landscape scenarios that met the nonpoint source nitrogen reduction goal varied from $3.16 to $3.19 million (2017 US dollars). These results support our hypothesis that water quality can be improved by targeting high-contributing parcels, and highlights the potential to minimize tradeoffs by coupling targeted conservation and planning tools to help stakeholders achieve water quality outcomes within agricultural landscapes.

A novel method to rapidly assess the suitability of water treatment residual and crushed concrete for the mitigation of point and nonpoint source nutrient pollution

Freshwater ecosystems worldwide are at risk of becoming degraded as a result of excessive inputs of phosphorus (P) associated with terrestrial activities. This study describes a novel methodology to rapidly assess the potential of low-cost adsorbents which might be used to combat this issue. The ability of aluminum drinking water treatment residual (Al-WTR) and crushed concrete (CC) to remove P from dairy wastewater (DW) and forestry runoff (wastewaters representative of point and nonpoint P pollution sources, respectively) was assessed. In addition to predicting the longevity of these media in large-scale filters, potential risks associated with their use were also examined. The results indicate that both CC and Al-WTR show promise for use in removing P from forestry runoff, however the raised pH of effluent from CC filters may pose an environmental concern. Al-WTR showed greater promise than CC for the treatment of DW due to its higher adsorption capacity at high concentrations. Small releases of aluminum (13.63-96.17 μg g−1) and copper (5.25-31.9 μg g−1) were observed from both media when treating forestry runoff, and Al-WTR also released a small amount of nickel (0.16 μg g−1). Approximately 50% of total metal loss occurred during the first 25% of total filter loading, indicating that pre-washing of the media would help prevent metal release. These results indicate that field-scale tests are warranted for the treatment of both wastewaters with Al-WTR; CC is likely to be unsuitable for either forestry runoff or DW due to its effects on pH and its short lifespan.

Landscape patterns regulate non-point source nutrient pollution in an agricultural watershed

Landscape pattern critically affects hydrological cycling and the processes of non-point source nutrients pollution. However, little is known about the quantitative relationship between landscape characteristics and the river water quality, and very few studies have addressed the abrupt changes in river water quality with the gradient of landscape metrics. The present study was conducted in a typically intensive agriculture watershed of eastern China including 13 sub-watersheds with different landscape pattern metrics. We adopted redundancy analysis, nonparametric deviance reduction approach, bootstrap sampling and other statistical methods to reveal the quantitative relationship between landscape pattern metrics and water quality variables; then, the phenomenon of an abrupt change in river water quality was explored with different landscape pattern gradients. The results show that landscape pattern significantly affects river water quality, and this effect was quite different in dry and rainy seasons. In the studied watershed, landscape pattern metrics could respectively explain 71.1% and 55.3% of the total variance in the river water quality in dry and rainy seasons. The configuration metrics of landscape pattern had a stronger ability than their composition metrics to explain the variance in water quality. In the dry season, largest patch index of forestland (LPIfor), the most important landscape index, explained 37.9% of the total variance in water quality. While, in the rainy season, the most important landscape index was the largest patch index of farmland (LPIfar), and it could explain 32.4% of that variance. In the studied watershed, when the LPIfor was <35% or LPIfar was over than 50%, water quality would typically change abruptly, at which the probability of a change in river water would suddenly rise substantially.

Influences of agricultural land use composition and distribution on nitrogen export from a subtropical watershed in China

Despite the significant impacts of agricultural land on nonpoint source (NPS) nitrogen (N) pollution, little is known about the influence of the distribution and composition of different agricultural land uses on N export at the watershed scale. We used the Soil and Water Assessment Tool (SWAT) to quantify how agricultural distribution (i.e., the spatial distributions of agricultural land uses) and composition (i.e., the relative percentages of different types of agricultural land uses) influenced N export from a Chinese subtropical watershed, accounting for aquatic N retention by river networks. Nitrogen sources displayed high spatial variability, with 40.7% of the total N (TN) export from the watershed as a whole derived from several subwatersheds that accounted for only 18% of the watershed area. These subwatersheds were all located close to the watershed mouth. Agricultural composition strongly affected inputs to the river network. The percentages of dry agricultural land and rice paddy fields, and the number of cattle together explained 70.5% of the variability of the TN input to the river network among different subwatersheds. Total N loading to the river network was positively correlated with the percentage of dry land in total land areas and the number of cattle within subwatersheds, but negatively with the proportion of paddy fields. Distribution of agricultural land uses also affected N export at the mouth of the watershed. Moreover, N retention in the river network increased with increasing N transport distance from source subwatershed to the watershed mouth. Results provide important information to support improved planning of agricultural land uses at the watershed scale that reduces NPS nutrient pollution.

Newly-established free water-surface constructed wetland to treat agricultural waters in the low-lying Venetian plain: Performance on nitrogen and phosphorus removal

Constructed wetlands offer promising solutions for controlling nutrient pollution in agricultural systems with relatively low costs and energy inputs. In mainly central and northern Italy, semi-natural and reconstructed Free-Water Surface Constructed Wetlands (FWS CWs) are designed to treat nonpoint-source pollution from agricultural catchments. However, their performance depends on system design and time of establishment. This paper evaluates the efficiency of a recently established FWS CW to remove nonpoint-source nutrient pollution due to agricultural drainage in the low-lying Venetian plain (NE Italy). The system was established in 2014 by creating five consecutive sub-basins vegetated with macrophytes to restore a semi-natural wetland, and later monitored in terms of water quality parameters and nutrients removal over three consecutive agricultural seasons (2014–2016). Total (TN) and nitrate (N-NO3) nitrogen concentrations showed peaks (16.37 and 15.31 mg l−1 for TN and N-NO3, respectively) in the various sub-basins during spring 2015, associated with fertilisation of surrounding croplands and intense rain events. Performance improved over the three years, with increasing median removals of TN (33.3–49.0%) and N-NO3 (32.2–80.5%), corresponding to average mass of 1355 kg y−1 and 1011 kg y−1 for TN and N-NO3. Concentrations of ammonium (N-NH4) and orthophosphate (P-PO4) were generally low (<1 and <0.3 mg l−1 for N-NH4 and P-PO4, respectively), with average yearly mass removals of 50 kg for N-NH4 and 9 kg for P-PO4. According to the overall treatment performance, the FWS CW could treat a total area of about 30 ha with a wetland/catchment ratio of 7%. However, we expect that treatment efficiency will increase as a result of bank stabilisation and improvement of the aquatic environment, together with increases in surface vegetation.

Sensitivity to climate change of land use and management patterns optimized for efficient mitigation of nutrient pollution

Beginning in the mid-1990s, re-eutrophication has reemerged as severe problems in Lake Erie. Controlling non-point source (NPS) nutrient pollution from cropland, especially dissolved reactive phosphorus (DRP), is the key to restore water quality in Lake Erie. To address NPS pollution, previous studies have analyzed the effectiveness of alternative spatially optimal land use and management strategies (represented as agricultural conservation practices (CPs)). However, few studies considered both strategies and have analyzed and compared their sensitivity to expected changes in temperature and precipitation due to climate change and increased greenhouse gas concentrations. In this study, we evaluated impacts of climatic change on the economic efficiency of these strategies for DRP abatement, using an integrated modeling approach that includes a watershed model, an economic valuation component, and a spatial optimization model. A series of climate projections representing relatively high greenhouse gas emission scenarios was developed for the western Lake Erie basin to drive the watershed model. We found that performance of solutions optimized for current climate was degraded significantly under projected future climate conditions. In terms of robustness of individual strategies, CPs alone were more robust to climate change than land use change alone or together with CPs, but relying on CPs alone fails to achieve a high (> 71%) DRP reduction target. A combination of CPs and land use changes was required to achieve policy goals for DRP reductions (targeted at ~ 78%). Our results point to the need for future spatial optimization studies and planning to consider adaptive capacity of conservation actions under a changing climate.

Soil Erosion and Nutrient Runoff in Corn Silage Production with Kura Clover Living Mulch and Winter Rye

Corn (Zea mays L.) silage is a productive and popular forage crop that can exacerbate soil loss, surface water runoff, and nonpoint source nutrient pollution from agricultural fields. The objective of this research was to compare soil loss, nutrient runoff, and soil physical properties in conventional monocrop corn silage production to production in Kura clover (Trifolium ambiguum M. Bieb.) living mulch or with a winter rye (Secale cereale L.) cover crop. Five runoff events from simulated rainfall were conducted over a 1‐yr period on loess soils with 8 to 15% slope. Based on weighted averages across all simulations, Kura clover living mulch reduced runoff by 50%, soil loss by 77%, and P and N losses by 80% relative to monocrop corn. Rye planted after corn silage harvest reduced runoff by 67%, soil loss by 81%, P loss by 94%, and N loss by 83%. When rye was planted following corn silage in Kura clover living mulch, runoff was reduced by 68%, soil loss by 77%, P loss by 94%, and N loss by 84% relative to monocrop corn. Greater groundcover in the Kura clover and rye treatments was the primary factor in reducing soil and nutrient losses, but soil aggregate stability and soil disturbance from rye planting were also associated with improved infiltration and reduced runnoff. When grown in Kura clover living mulch, both corn and rye had lower forage yields, a trade‐off with the environmental benefits; but that economic loss would be partially offset by lower fertilizer requirements.Core Ideas Corn silage intercropped with Kura clover reduces soil erosion Winter rye cover crop reduces soil erosion Kura clover increases soil aggregate stability

Agricultural Diffuse Nutrient Pollution Transport in a Mountain Wetland Complex

Wetlands in mountain environments provide critical ecosystem services but are increasingly threatened by agricultural land use intensification. This study evaluates agricultural nonpoint source nutrient pollution transport in a wetland–stream–lake complex in a mountain, tussock grassland catchment in the South Island, New Zealand. Flow and water-quality monitoring in the Lake Clearwater catchment during three flow events from May to August 2010 (autumn high flow, winter low flow, and winter high flow) showed high concentrations and exceedances of water quality guidelines for total nitrogen (TN) and total phosphorus (TP) in small ephemeral streams draining agricultural land during high flows. Concentrations were attenuated through the wetlands to below guidelines, with the exception of TN which still remained slightly higher. Most TN was in the organic form above and below the wetland, suggesting N sources from animal waste/agricultural land and organic material and vegetation within the wetland. Most TP was particulate associated with suspended solids during high flows. Dissolved forms of N and P generally were below guidelines. Flows and loads (instantaneous and daily) increased at the lake outlet during winter high flow, indicating unaccounted sources to the lake from groundwater, the wetlands, or the lake sediments, and seasonal N saturation. Infiltration losses to shallow groundwater along the main perennial tributary likely re-appear as discharge to the wetlands and lake downstream. Surface–groundwater interactions play a dominant role in N transport to the wetland complex due to highly permeable soils and glacial alluvial deposits. Loads and unit loads of TN and TP were also elevated in the ephemeral streams. Results show that TN and TP concentrations and unit loads during high flows in ephemeral streams in this mountain grassland catchment are similar to, or higher than, values for impacted lowland pasture catchments. Although impacts to the wetland ecosystem have not been observed to date, the lake is shifting toward a mesotrophic state, and further research is needed to elucidate impacts of nutrient loads and help meet conservation and restoration goals.

Stimulation of fecal bacteria in ambient waters by experimental inputs of organic and inorganic phosphorus

Fecal microbial pollution of recreational and shellfishing waters is a major human health and economic issue. Microbial pollution sourced from stormwater runoff is especially widespread, and strongly associated with urbanization. However, non-point source nutrient pollution is also problematic, and may come from sources different from fecal-derived pollution (i.e. fertilization of farm fields, lawns and gardens, and ornamental urban areas). Fecal bacteria require nutrients; thus the impact of such nutrient loading on survival and abundance of fecal coliform bacteria in ambient waters was experimentally investigated in a constructed wetland in coastal North Carolina, USA. A series of nutrient-addition bioassays testing impacts of inorganic and organic nitrogen and phosphorus demonstrated that additions of neither organic nor inorganic nitrogen stimulated fecal coliform bacteria. However, phosphorus additions provided significant stimulation of fecal coliform growth at times; on other occasions such additions did not. Dilution bioassays combined with nutrient additions were subsequently devised to assess potential impacts of microzooplankton grazing on the target fecal bacteria populations. Results demonstrated grazing to be a significant bacterial reduction factor in 63% of tests, potentially obscuring nutrient effects. Thus, combining dilution experiments with nutrient addition bioassays yielded simultaneous information on microzooplankton grazing rates on fecal bacteria, fecal bacterial growth rates, and nutrient limitation. Overall, when tested against a non-amended control, additions of either organic or inorganic phosphorus significantly stimulated fecal coliform bacterial growth on 50% of occasions tested, with organic phosphorus generally providing greater stimulation. The finding of significant phosphorus stimulation of fecal bacteria indicates that extraneous nutrient loading can, at times, augment the impacts of fecal microbial pollution of shellfishing and human contact waters.

Factors determining the distributions of total phosphorus, total nitrogen, and chlorophyll a in Florida lakes

Using data from 1387 lakes collected over 3 decades, we found a wide range in the concentrations of total phosphorus (TP), total nitrogen (TN) and chlorophyll (Chl-a) in Florida lakes, and that edaphic factors as outlined by the United States Environmental Protection Agency's Florida Lake Regions were dominant in determining the concentrations of plant nutrients in the state's lakes. The hypothesis that the majority of the eutrophic lakes in Florida without known point source pollution are the result of nonpoint source nutrient pollution was tested in several ways and rejected. There was no correlation between the Landscape Development Intensity index and the concentrations of TP, TN, and Chl-a examined in Florida lakes. Several of Florida's 30 benchmark lakes (lakes with minimal human impact and meeting designated uses) were eutrophic, and there was no significant difference between the mean concentrations of TP and TN in these lakes versus all remaining Florida lakes. Paleolimnological studies also showed that several lakes were eutrophic to hypereutrophic prior to 1900, a time before significant population growth in the State of Florida. To help develop numeric nutrient criteria for Florida lakes that take regional differences into account, we grouped similar lakes into 6 TP zones and 5 TN zones. [Supplemental materials are available for this article. Go to the publisher's online edition of Lake and Reservoir Management to view the supplemental file.]

Effects of Environmental Variation and Non-point Source (NPS) Nutrient Pollution on Aquatic Plant Communities in Weeks Bay National Estuarine Research Reserve (WBNERR), AL

This study was designed to investigate non-point source nutrient pollution and its influences on submerged aquatic plant community structure and biological invasion in the Weeks Bay National Estuarine Research Reserve (WBNERR). A monthly vegetation survey was conducted to document plant abundance and changes in community structure; physicochemical data and water samples were collected on a bi-monthly basis to monitor environmental conditions (i.e., pH, salinity, dissolved oxygen, light intensity, and attenuation) and water column nutrient (NO2−/NO3− and NH4+) and chlorophyll a concentrations. A total of seven submerged aquatic species were identified at the WBNERR with the occurrence of only one non-native species (Hydrilla verticillata). Statistical analyses suggest that water column nitrogen concentrations along with variations in dissolved oxygen (0.6–11.5 mg L−1), light attenuation, pH (5.6–8.6), and temperature (11–33°C) play key roles in determining the aquatic plant abundance and distribution in the WBNERR.

Employing River Corridor Protection and Restoration Strategies to Attenuate Non-point Source Nutrient Pollution

Employing River Corridor Protection and Restoration Strategies to Attenuate Non-point Source Nutrient PollutionThroughout Vermont, rivers and streams have been effectively isolated from large floodplain areas through channel alteration. Of the nearly 1,400 river miles in Vermont that have been assessed to date, nearly three-quarters (74%) have become confined to deeper, straighter channels and no longer have access to historic floodplains. These manipulations of the stream corridor are suspected of causing...Author(s)Julia S. MooreSourceProceedings of the Water Environment FederationSubjectSession 16: Focused Discussion: Natural Systems for Nutrient RemovalDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:1L.1106;1-DOI10.2175/193864711802867298Volume / Issue2011 / 1Content sourceNutrient Removal and Recovery SymposiumFirst / last page(s)1106 - 1106Copyright2011Word count253

Long-term vegetation landscape pattern with non-point source nutrient pollution in upper stream of Yellow River basin

Grassland, forest, and farmland are the dominant land covers in upper catchments of the Yellow River and their landscape status has direct connection with dynamics of non-point source (NPS) pollution. Understanding the correlations between landscape variables and different formats of NPS nutrients pollutants is a priority in order to assess pollutants loading and predicting the impact on surface water quality. The regional vegetative cover in 1977, 1996, 2000 and 2006 was determined by classifying historical multi-temporal Landsat imagery and clipping data from the National Landcover Database. The landscape pattern is expressed means of metrics such as patch density, edge density, fractal distribution index, all of which were calculated by FRAGSTATS. The soil and water assessment tool (SWAT) was used to analyze and visualize the fate of NPS nitrogen and phosphorus loads in diverse formats from different land cover types in different years. Statistical analysis indicated that the grassland landscapes played a major role in NPS nutrient pollution dynamics and grassland patch edges benefited pollution control. However, the presence of more forest and farmland lead to more NPS nitrogen emissions. It was found that grassland areas reduced nitrogen loss and had a multi-function role in the nutrient pollution process. Farmland was the direct source of organic nutrients, but did not have great impacts on sediment P and soluble N loadings. Forest areas contributed NPS nutrients pollution loading. The statistical models derived in this study can be used to estimate watershed NPS nutrient pollution losses. These equations can help identify pollution sources and suggest appropriate and effective solutions for planing basin management practices.