Ahuja Monitoring Water Quality

Pollution Assessment, Analysis, and Remediation
1. Auflage 2013
ISBN: 978-0-444-59404-4
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 400 Seiten

Monitoring Water Quality is a practical assessment of one of the most pressing growth and sustainability issues in the developed and developing worlds: water quality. Over the last 10 years, improved laboratory techniques have led to the discovery of microbial and viral contaminants, pharmaceuticals, and endocrine disruptors in our fresh water supplies that were not monitored previously. This book offers in-depth coverage of water quality issues (natural and human-related), monitoring of contaminants,  and remediation of water contamination. In particular, readers will learn about arsenic removal techniques, real-time monitoring, and risk assessment. Monitoring Water Quality is a vital text for students and professionals in environmental science, civil engineering, chemistry - anyone concerned with issues of water analysis and sustainability assessment. - Covers in depth the scope of sustainable water problems on a worldwide scale - Provides a rich source of sophisticated methods for analyzing water to assure its safety - Describes the monitoring of contaminants, including pharmaceutical and endocrine disruptors - Helps to quickly identify the sources and fates of contaminants and sources of pollutants and their loading

Autoren/Hrsg.

Ahuja, Satinder

Leseproben

2 Water Quality Status and Trends in the United States Matthew C. Larsen*, Pixie A. Hamilton and William H. Werkheiser, U.S. GEOLOGICAL SURVEY, RESTON, VA, USA*CORRESPONDING AUTHOR Chapter Outline 2.1 Introduction 2.2 Monitoring and Assessments of Complex Water Quality Problems 2.2.1 Nutrients 2.2.2 Pesticides 2.2.3 Mixtures of Organic Wastewater Compounds 2.2.4 Trends in Selected Sediment-Bound Compounds in Lakes and Reservoirs 2.2.5 Mercury 2.3 USGS Strategies to Assess Status and Trends 2.3.1 Water Quality and the Natural Landscape 2.3.2 Water Quality in Urban Areas 2.3.3 Water Quality in Agricultural Settings 2.3.4 Water Quality as Related to Land- and Water-Management Practices 2.3.5 Water Quality and Seasonal Variation 2.3.6 Water Quality Over the Long Term 2.3.7 The Value of Water Quality Modeling 2.3.8 Water Quality and Climate Change 2.4 Conclusions Acknowledgments References 2.1 Introduction
National interest in water quality issues culminated in the 1972 enactment of the Clean Water Act (CWA) [1]. This law was passed in response to public concerns about burning rivers and dead lakes and a national consensus built over the previous 60 years that pollution of our rivers and lakes was unacceptable. Control of point-source contamination, traced to specific “end of pipe” points of discharge, or outfalls, such as factories and combined sewers, was the primary focus of the CWA. Significant progress toward cleaner water resulted through actions, such as implementing changes in manufacturing processes and wastewater treatment. Water-quality challenges are now increasingly complex. The majority of water-quality problems are caused by diffuse nonpoint sources from agricultural land, urban development, forest harvesting, and the atmosphere (Table 2-1). These nonpoint-source contaminants are more difficult to effectively monitor, evaluate, and control than those from point sources (for example, discharges of sewage and industrial waste). We need improved quantification and understanding of human activities associated with nonpoint sources and how those human activities take place on the landscape—primarily information on how we use and dispose of chemicals, how we convert land over time, our use of water, and our land-management practices. Table 2-1 The Changing National Focus on Water-Quality Challenges Past Focus Present and Future Focus Point sources Nonpoint sources End-of-pipe approach Watershed approach (landscape, human activities) One-time, periodic reporting Seasonal, hydrologic events, continuous, real time Nutrients, dissolved oxygen, bacteria Organic compounds Single pollutants Mixtures Surface water Total resource Chemistry Chemistry, biology, habitat, hydrology, landscape Short-term monitoring Long-term monitoring Monitoring Monitoring and prediction Several factors add to this complexity. First, the amount of pollution from nonpoint sources varies over short periods—hourly to seasonally—making it difficult to monitor and quantify the sources over time. Single or periodic measurements are not adequate to characterize water-quality conditions. Measurements are needed over seasons, hydrologic and meteorological events, and in real time. We face large water-quality challenges because of the increasingly complex and emerging diversity of issues. When the CWA was passed, the dominant concern was the sanitary quality of rivers and streams. The focus was on temperature, salinity, bacteria counts, oxygen levels, and suspended solids, in large part, collected for day-to-day evaluations of compliance or permitting decisions. While these remain important, there are now hundreds of synthetic organic compounds (such as pesticides and volatile organic compounds in solvents and gasoline) that are introduced into the environment every day. Improved laboratory techniques have led to the identification of microbial and viral contaminants, pharmaceutical compounds, and endocrine disruptors in our waters that were not previously measured. We are also finding that many contaminants, such as arsenic and radon, can originate from a wide range of natural sources and are of potential concern with respect to human health, even in relatively undeveloped settings that are perceived as less vulnerable to contamination. This is a critical concern with respect to the quality and safety of water from domestic or “private” wells, which are a source of drinking water for about 40 million people or 15% of the U.S. population, many of whom are based in rural and less-developed settings [2]. Domestic wells are not regulated under the federal Safe Drinking Water Act (SDWA) and are the responsibility of the homeowner. Natural and organic contaminants often end up in our waters as complex mixtures of organic compounds; many of these can, even at very low concentrations, potentially affect the health of humans and/or the reproductive success of aquatic organisms in our waters. Our understanding of water-quality challenges has expanded with our understanding of the importance of the hydrologic cycle for water-quality conditions. Whereas our concerns were focused mainly on streams and rivers, we now recognize water-quality issues as part of an integrated hydrologic system. For example, groundwater and surface water are highly inter-related; reduced base flow from groundwater pumping often results in increased stream temperatures, drying wetlands, and habitats unsuitable for fish and other aquatic species [3]. The historic approach was to look at quality mostly in terms of concentrations independent of hydrology; however, concentrations and types of contaminants and their potential effects on ecosystems and drinking water supplies vary over time and depend largely on the amount of water flowing in streams and the amounts and directions of groundwater flow. Other natural processes, including geology and geomorphology, also control the timing and amount of surface and groundwater flow and the transport of waterborne constituents and contaminants. Furthermore, natural complexity is increasing because of changes in climate, resulting in new patterns of seasonal precipitation, runoff, and the spatial and temporal distribution of snow versus rain [3–6]. Unfortunately, there is a continuing high degree of uncertainty in climate model predictions [7,8]. This set of challenges will continue and probably intensify as both nonclimatic and climatic factors, such as predicted rising temperature and associated changes in runoff, continue to develop [9–12]. Water-quality challenges extend beyond chemistry. We now realize that water quality, habitat disturbances, streamflow alterations, biological systems, and ultimately, ecosystem health are all closely interconnected. Meaningful water-quality assessments must therefore integrate biological monitoring and ecosystem health, such as inclusion of benthic invertebrates and other biological indicators as critical tools to understanding water quality [13–15]. Given our improved understanding of the spatial and temporal complexities in water quality and its numerous natural and human causes, the importance of long-term monitoring is increasingly clear. Comparable data must be collected over time if long-term trends are to be distinguished from short-term fluctuations and if natural fluctuations are to be distinguished from the effects of human activities. Long-term tracking is particularly critical for groundwater and sediment because slow flow paths and long residence times may not allow water quality issues to appear for years or even decades. Monitoring alone does not provide understanding of the causes of water-quality conditions, given the complex interrelations among water quality, natural changes, and human actions over time and space. Furthermore, federal and state resources are increasingly limited, so we cannot expect to monitor water resources in all places and at all times. The value of data collected at individual sites is enhanced by applying assessment tools, including models that use monitoring data in conjunction with our understanding of the hydrologic and aquatic systems, the natural landscape, and human activities to develop more generalized knowledge of the status, trends and causes of these conditions for broader areas, including entire stream reaches and aquifers, large river basins, ecoregions, the states, and the nation as a whole. The integration of monitoring and assessment with modeling and predictive tools is the strategy needed to provide comprehensive statewide, regional, and national water-quality assessments. This strategy also will provide the needed national “water census” of water-quality status and...