June 2011 Issue - Volume 7, Number 3

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Global Water Sustainability

Janet G. Hering, Chen Zhu, and Eric H. Oelkers – Guest Editors

Overview

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2011 Topics

Overview

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2011 Topics

Thematic Articles

Water: Is There a Global Crisis?

By Eric H. Oelkers, Janet G. Hering, Chen Zhu

Providing safe drinking water to the world’s 6.9 billion and growing population is one of the greatest challenges of the century. Consideration of the global water cycle, however, shows that the available renewable freshwater resources exceed the current human demand by roughly a factor of 10. Scarcity results from the uneven spatial and temporal distribution of water. Over-withdrawal of surface water and groundwater has led to depletion of water resources and environmental damage in some regions. In many developing countries, inadequate sanitation is a major cause of disease. These problems can be solved through the improved management of water infrastructure and water resources, advances in technology, and a valuation of water that reflects its importance to society. The role of Earth scientists in addressing the global water crisis is crucial. Indeed, resource monitoring, development of novel waste-water treatment technologies, and determination of the quantities of water that can be withdrawn without causing adverse effects on the environment will be essential for the efficient management of global water resources in the future.

Water and Sanitation in Developing Countries: Geochemical Aspects of Quality and Treatment

By Richard B. Johnston, Michael Berg, C. Annette Johnson, Elizabeth Tilley, Janet G. Hering

Safe drinking water and basic sanitation are key elements of the Millennium Development Goals, a United Nations initiative. The microbial quality of drinking water is inherently linked to sanitation practices because fecal pathogens are the most common source of drinking water contamination in developing countries. Filtration of water through soil and aquifer sediments can provide natural protection against pathogens, and this makes groundwater an attractive option for safe drinking water supply. Groundwater quality may, however, be compromised by the leaching of natural chemical constituents from geologic materials. Conversely, geochemical processes provide the basis both for the removal of such contaminants and for the recovery of nutrients from wastewater through physicochemical treatment.

Hydrogeochemical Processes and Controls on Water Quality and Water Management

By Chen Zhu, Franklin W. Schwartz

The chemical constituents in water determine its potability, usability for agriculture and recreation, and interactions with biological systems. Anthropogenic processes have significantly influenced the geochemistry of water in many regions. Physical, chemical, and biological processes control the chemistry and chemical evolution of water in natural and contaminated systems. Advances in our ability to quantify these processes will improve our ability to manage our water resources, help us identify potential sources of contamination, and illuminate potential solutions to water-quality problems. Particularly impressive are the applications of chemical and isotopic tracers, which can track water movement and quantify water fluxes on the surface and in the subsurface. To better address societal needs, future advances will require a holistic approach to interpreting geochemical data.

Groundwater: A Resource in Decline

By Franklin W. Schwartz, Motomu Ibaraki

Around the world, groundwater sources are in decline due to overpumping and pollution. History informs us that as water supplies are lost so are civilizations. Such was the case with the Garamantian civilization, which thrived in the western Libya desert from 500 BCE to 400 CE, then disappeared when the groundwater ran out. Present-day mining of groundwater from large aquifers in the United States, North Africa, and China illustrates this problem. In less than a century, pressures from food production and population growth are leading to declines in supplies that appeared to many as inexhaustible. In many countries, there can be no replacement for declining water resources. Food scarcity and health epidemics, leading to societal decline, are likely outcomes as people chase dwindling water supplies.

Water Management Challenges Associated with the Production of Shale Gas by Hydraulic Fracturing

By Kelvin B. Gregory, Radisav D. Vidic, David A. Dzombak

Development of unconventional, onshore natural gas resources in deep shales is rapidly expanding to meet global energy needs. Water management has emerged as a critical issue in the development of these inland gas reservoirs, where hydraulic fracturing is used to liberate the gas. Following hydraulic fracturing, large volumes of water containing very high concentrations of total dissolved solids (TDS) return to the surface. The TDS concentration in this wastewater, also known as “flowback,” can reach 5 times that of sea water. Wastewaters that contain high TDS levels are challenging and costly to treat. Economical production of shale gas resources will require creative management of flowback to ensure protection of groundwater and surface water resources. Currently, deep-well injection is the primary means of management. However, in many areas where shale gas production will be abundant, deep-well injection sites are not available. With global concerns over the quality and quantity of fresh water, novel water management strategies and treatment technologies that will enable environmentally sustainable and economically feasible natural gas extraction will be critical for the development of this vast energy source.

Water Conservation, Efficiency, and Reuse

By Henry Vaux Jr.

Global water scarcity is intensifying. Economizing on water use will be an important aspect of any effective response. Water recycling and reuse technologies offer possibilities for more extensive use of water, depending on cost. Institutional responses, such as the use of rational pricing and the creation of water markets or exchanges, promise to improve wateruse efficiency. Consumer education is a simple and inexpensive means of economizing on water in the urban and agricultural sectors. Rationing is effective in managing short-term interruptions such as drought. Point-of-use technology will also offer opportunities for economizing on many water uses.