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"Water pollution"
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Managing nitrogen to restore water quality in China
The nitrogen cycle has been radically changed by human activities
. China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers
and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary'
in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 ± 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 ± 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 ± 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 ± 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.
Journal Article
Physical and chemical processes in the aquatic environment
\"This book has a unique outline in that it follows pollution from sources to impact. Included in the text is the treatment of various tracers, ranging from pathogens to stable isotopes of elements and providing a comprehensive discussion which is lacking in many other books on pollution control of natural waters\"- Provided by publisher.
Book
Review: Safe and sustainable groundwater supply in China
Exploitation of groundwater has greatly increased since the 1970s to meet the increased water demand due to fast economic development in China. Correspondingly, the regional groundwater level has declined substantially in many areas of China. Water sources are scarce in northern and northwestern China, and the anthropogenic pollution of groundwater has worsened the situation. Groundwater containing high concentrations of geogenic arsenic, fluoride, iodine, and salinity is widely distributed across China, which has negatively affected safe supply of water for drinking and other purposes. In addition to anthropogenic contamination, the interactions between surface water and groundwater, including seawater intrusion, have caused deterioration of groundwater quality. The ecosystem and geo-environment have been severely affected by the depletion of groundwater resources. Land subsidence due to excessive groundwater withdrawal has been observed in more than 50 cities in China, with a maximum accumulated subsidence of 2–3 m. Groundwater-dependent ecosystems are being degraded due to changes in the water table or poor groundwater quality. This paper reviews these changes in China, which have occurred under the impact of rapid economic development. The effects of economic growth on groundwater systems should be monitored, understood and predicted to better protect and manage groundwater resources for the future.
Journal Article
The low but uncertain measured benefits of US water quality policy
US investment to decrease pollution in rivers, lakes, and other surface waters has exceeded $1.9 trillion since 1960, and has also exceeded the cost of most other US environmental initiatives. These investments come both from the 1972 Clean Water Act and the largely voluntary efforts to control pollution from agriculture and urban runoff. This paper reviews the methods and conclusions of about 20 recent evaluations of these policies. Surprisingly, most analyses estimate that these policies’ benefits are much smaller than their costs; the benefit–cost ratio from the median study is 0.37. However, existing evidence is limited and undercounts many types of benefits. We conclude that it is unclear whether many of these regulations truly fail a benefit–cost test or whether existing evidence understates their net benefits; we also describe specific questions that when answered would help eliminate this uncertainty.
Journal Article
Evaluation of Shallow Groundwater Contamination and Associated Human Health Risk in an Alluvial Plain Impacted by Agricultural and Industrial Activities, Mid-west China
Intensive human activities have caused contamination to groundwater quality which consequently affects human health. In this study, an evaluation of groundwater quality was carried out for better understanding of the status of groundwater contamination and potential risks to local residents in an alluvial plain (China) where agricultural and industrial activities are intensive. Comprehensive water quality index was used for drinking water-quality assessment and sodium adsorption ratio, Na%, and residual sodium carbonate were applied for irrigation water-quality assessment. The human health risks caused by intake of the contaminated groundwater through the oral and dermal pathways were also assessed. The assessment results reveal that most of the water samples are generally suitable for irrigation purpose, but over 60 % of them are not fit for drinking, and the total hardness, NO
3
−
, NO
2
−
, TDS, SO
4
2−
, and F
−
are the main contaminants affecting its suitability for drinking purpose. Residents in the study area are at high health risk, and NO
3
−
originating mainly from industrial and agricultural pollution is the greatest contributory cause of the health risks. Furthermore, children in this area are at higher health risk than adults, and oral ingestion is the dominate exposure pathway of health risk. Therefore, urgent and efficient measures must be taken to combat groundwater pollution and reduce health risk in the area.
Journal Article
Shedding light on the invisible: addressing the potential for groundwater contamination by plastic microfibers
The processes of microplastic fiber pollution in groundwater are unknown. The recent research on this contaminant threat is generally focused on surface waters (mainly oceans and rivers), while aquifer contamination is only marginally mentioned as an issue needing further investigation. Synthetic microfibers can be introduced into soils in different ways (e.g. wastewater treatment plants or greywater discharge, septic tank outflows, direct injection of contaminated water in cases of managed aquifer recharge, losing streams, etc.), and can thus reach aquifer systems due to leaching or infiltration in soil pores. Microfibers can then adsorb persistent bioaccumulative and toxic chemicals, which include persistent organic pollutants and metals, and become a carrier of harmful substances in the aquifer system, hence contributing to the overall contamination in both urban and rural areas. For this reason, it is of paramount importance, not only to assess the occurrence and fate of microplastic fibers in groundwater, but also to study the role of microplastics as carriers of contaminants within the aquifer and to advance standardization and organization of monitoring campaigns. Only by addressing these key challenges can hydrogeologists contribute to the state of the art on microplastic pollution and ensure that groundwater is not neglected in the environmental assessments tackling this contaminant of emerging concern.
Journal Article