Suchergebnisse

AbstractThe objectives of this study were to investigate the effects of rainfall and underlying surface conditions on nonpoint source (NPS) pollution loads and to identify the uncertainty in NPS pollution loads at different spatial scales in the Fuxi River basin, China. Data on monitored daily flow rates and concentrations of ammonium nitrogen, total nitrogen, total phosphorus and permanganate index at the sub‐basin and basin scales were collected for a period from 2013 to 2015. Dynamic time warping distance and information measures were used to characterize pollution loads and determine the uncertainties. The results indicate that, at both sub‐basin and basin scales, NPS pollution loads increased nonlinearly with rainfall until it reached 38.4 mm, and subsequently, the NPS pollution loads stabilized. The underlying surface conditions affected the NPS pollution loads more profoundly than rainfall. Additionally, the uncertainty in NPS pollution loads increased with the spatial scales.

AbstractBest management practices (BMPs) are the tools which are adopted to run any activity while inflicting least negative impacts on the surrounding environment. Since, water pollution is one of the most important issues in today's world; it is indispensable to discuss the activities which are deteriorating its quality. Although, a number of treatment technologies and methods are in place for treating the point sources of pollution, there is a need to address nonpoint sources of pollution. There are many successful practices which are capable of curtailing the impacts of nonpoint source pollution, if adopted. In this paper an attempt has been made to evaluate the performance and trade‐offs of various management practices to address the issues of agricultural nonpoint source pollution. Nevertheless, there is a dearth of guiding principles which can pave a way for adoption of these practices. Therefore, an attempt has also been made to explore the aspects of policy formulations along with emphasizing the factors which can lead to adoption/ non‐adoption of such practices.

Much of modern-day agriculture relies heavily on fertilizers and pesticides to increase yields, yet when applied in excess or without proper control mechanisms these inputs can wreak havoc on local waterways. This dissertation analyzes policy approaches implemented in Europe, the U.S. and California to abate discharges from farms. The research utilizes a mixed methods approach, integrating qualitative, quantitative and spatial analyses, to investigate regulatory tools, governance structures, policy outcomes, and stakeholder opinions relating to water pollution from agriculture. The dissertation is comprised of four interrelated parts. The first part assesses the range of regulatory approaches employed to control agricultural nonpoint source pollution in the United States and the European Union. Findings suggest that transitioning from the voluntary control mechanisms to more effective instruments based on measurable water quality performance relies predominantly on three factors: (1) more robust quality monitoring data and models; (2) local participation; and (3) political will. Identifying obstacles to and successes of national and international agricultural water pollution policies set the context for delving deeper into this regulatory problem on a regional level. The second, third, and fourth parts of this doctoral research focus on the primary regulatory mechanism for agricultural discharges in California's Central Coast Region: The Conditional Agricultural Waiver. One of these parts uses the policy tool framework to assess the overall effectiveness of the Conditional Agricultural Waiver and its associated monitoring programs. Research results show that while the regional policy represented a small step forward in implementing appropriate control mechanisms for agricultural pollution, the significance of monitoring programs greatly limited the policy's success. Another part of this dissertation surveyed 1,000 growers and their opinions on water quality practices and regulations. Results corroborate with prior research—growers' trust in the majority of regional agricultural groups was closely correlated with communication. However, trust in the Regional Board did not correspond to the relatively high contact frequency with the regulatory agency, most likely due to a divergence of interests and institutional distance. This study also confirms anecdotes of declining trust between farmers and the Regional Board over the course of the two Ag Waivers. A final part of the dissertation focuses on specific provisions aimed at controlling two pesticides in the region. Results from this chapter indicate that the 2012 Central Coast Conditional Agricultural Waiver was a contributing factor in successfully reducing the use of diazinon and chlorpyrifos, but several unintended consequences, such as continued presence of the pollutants in waterways, remain unsettled.

AbstractWater quality regulations in the United States apply almost exclusively to point sources. In impaired watersheds where both point and nonpoint sources contribute to pollution, the U.S. Environmental Protection Agency (EPA) is encouraging the use of point‐nonpoint trading to reduce the cost of point sources to meet their permit requirement, and to encourage nonpoint sources to voluntarily contribute more towards meeting overall water quality goals. The EPA guidance encourages trading programs to set a nonpoint source eligibility baseline that extracts some "extra" abatement from nonpoint sources. Research has shown that setting an eligibility baseline that is substantially more stringent than current management could discourage nonpoint source participation and significantly hinder trading. In this paper we examine how choosing the eligibility baseline for agricultural sources affects the efficiency goal of trading (reducing costs to point sources), as well as how it affects the EPA goal of encouraging nonpoint abatement. Using data from the Chesapeake Bay Watershed we find that eligibility baselines set to encourage additional nonpoint source abatement reduce the supply of credits in a market; the more stringent the baseline, the fewer the trades and the smaller the overall abatement from nonpoint sources. A subsidy to farmers for reducing the cost of meeting a baseline encourages greater nonpoint source abatement, but may not benefit the trading market.

Chances are that today you have already unwittingly advanced the slow but steady demise of America's freshwater supply. The sausage and egg biscuit you ate for breakfast, the half-empty bottle of Drano you dumped into your backyard, and the quick trip to the grocery store-these seemingly innocent actions each significantly degrade American watersheds.' In response to this systemic and persistent assault on water quality, Congress enacted the Federal Water Pollution Control Act of 1972. More commonly known as the Clean Water Act ("CWA"), this legislation attempted to take an aggressive and comprehensive approach to improving water quality. To achieve its sweeping goal of "restoring [ing] and maintain[ing] the chemical, physical, and biological integrity of the Nation's waters," the CWA established a bifurcated regulatory scheme. The first prong of the this scheme prohibits "the discharge of any pollutant" into "navigable waters from any point source." Like the drain-cleaning chemical you dumped into your backyard, a point source is "any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged." This program is complicated but effective.