Deep challenges for China's war on water pollution Han, Dongmei; Currell, Matthew J.; Cao, Guoliang
Environmental pollution (1987),
November 2016, 2016-Nov, 2016-11-00, 20161101, Letnik:
218
Journal Article
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Odprti dostop
China's Central government has released an ambitious plan to tackle the nation's water pollution crisis. However, this is inhibited by a lack of data, particularly for groundwater. We compiled and ...analyzed water quality classification data from publicly available government sources, further revealing the scale and extent of the crisis. We also compiled nitrate data in shallow and deep groundwater from a range of literature sources, covering 52 of China's groundwater systems; the most comprehensive national-scale assessment yet. Nitrate pollution at levels exceeding the US EPA's maximum contaminant level (10 mg/L NO3N) occurs at the 90th percentile in 25 of 36 shallow aquifers and 10 out of 37 deep or karst aquifers. Isotopic compositions of groundwater nitrate (δ15N and δ18ONO3 values ranging from −14.9‰ to 35.5‰ and −8.1‰ to 51.0‰, respectively) indicate many nitrate sources including soil nitrogen, agricultural fertilizers, untreated wastewater and/or manure, and locally show evidence of de-nitrification. From these data, it is clear that contaminated groundwater is ubiquitous in deep aquifers as well as shallow groundwater (and surface water). Deep aquifers contain water recharged tens of thousands of years before present, long before widespread anthropogenic nitrate contamination. This groundwater has therefore likely been contaminated due to rapid bypass flow along wells or other conduits. Addressing the issue of well condition is urgently needed to stop further pollution of China's deep aquifers, which are some of China's most important drinking water sources. China's new 10-point Water Pollution Plan addresses previous shortcomings, however, control and remediation of deep groundwater pollution will take decades of sustained effort.
•China's official groundwater and surface water quality classification data reviewed.•Compilation of literature groundwater nitrate data reveals endemic pollution.•Deep groundwater pollution widespread, pointing to major well integrity problems.•Ten-point water pollution plan addresses previous barriers, but not all mechanisms.
With rapid socio-economic development, China's coastal areas are among the fastest growing and most economically dynamic regions in the world. Under the influence of climate change and human ...activities, protecting the quality of coastal groundwater has emerged as one of the key environmental and resource management issues for these areas. This paper reviews (for the first time) groundwater quality data for the coastal basins of China, where over 600 million people live, focussing on key inorganic indicators/pollutants; groundwater salinity, nitrate, fluoride, and arsenic. These pollutants present major water quality issues and are also valuable as indicators of wider processes and influences impacting coastal groundwater quality – e.g. saltwater intrusion, agricultural pollution and release of geo-genic contaminants. We discuss the major drivers causing water quality problems in different regions and assess future trajectories and challenges for controlling changes in coastal groundwater quality in China. Multiple processes, including modern and palaeo seawater/brine migration, groundwater pumping for agricultural irrigation, pollution from agrochemical application, rapid development of aquaculture, urban growth, and water transfer projects, may all be responsible (to different degrees) for changes observed in coastal groundwater quality, and associated long-term health and ecological effects. We discuss implications for sustainable coastal aquifer management in China, arguing that groundwater monitoring and contamination control measures require urgent improvement. The evolution and treatment of coastal groundwater quality problems in China will serve as an important warning and example for other countries facing similar pressures, due to climate change, coastal development, and intensification of anthropogenic activity in coming decades.
Processes affecting the quality of coastal groundwater in China Display omitted
•First review of groundwater quality issues and their extent in coastal China•Analysis of data reveals primary causes of China’s coastal groundwater quality issues.•High nitrate, salinity, fluoride, and arsenic groundwater are all major challenges.•Implications and learnings for improving coastal groundwater quality management
Following recent rapid industrialization, China is now one of the largest producers and consumers of organic chemicals in the world. This is compounded by variable regulatory oversight with respect ...to storage, use and waste management of these chemicals and their byproducts. This review synthesizes the data on the distribution of selected persistent organic pollutants (POPs) in waters in China. Surface water heavily polluted with POPs is distributed in the Yangtze River Estuary, Pearl River Delta, Minjiang River Estuary, Jiulongjiang Estuary, Daya Bay, Taihu Lake, and the waterways of Zhejiang Province, where concentrations of Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) frequently exceed both international and Chinese guideline values. These areas are mainly distributed along the southeast coast of China, within or downstream of major manufacturing districts, intensive agricultural basins, and other industrial centers. A comparison of the levels of OCPs in the aquatic environment of China with other indicative regions worldwide shows comparable levels of pollution (overall range from below detection limit (BDL) to 5104.8ng/L and regional means from 2.9–929.6ng/L). PAHs and PCBs pollution appear to be particularly serious in China (PAHs overall ranging from BDL to 474,000ng/L with regional means from 15.1–72,400ng/L; PCBs from BDL to 3161ng/L with regional means ranging from 0.2–985.2ng/L). There is as yet limited evidence of serious perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) pollution. We discuss major sources and processes responsible for high POP occurrence using a range of measures (including diagnostic ratios of different compounds), regulatory oversight and policy gaps in the control of POPs in China, and potential long-term health and ecological effects. We argue that water quality guidelines, pollution control measures and cleanup strategies for POPs in China should be urgently improved.
Schematic figure showing sources and transport processes for persistent organic pollutants, and their interaction with the hydrological cycle. Numbers indicate classes of POPs reviewed in this study; 1=Polycyclic aromatic hydrocarbons (PAHs); 2=Organochlorine pesticides (OCPs); 3=Polycholorinated Biphenyls (PCBs); 4=Perfluorinated compounds (PFCs). Display omitted
•Pollution of China's waterways by persistent organic pollutants reviewed•PAHs and PCBs pollution appears more serious in China than other countries.•Serious POPs-polluted areas mainly distributed along the southeast coast of China.•Likely POPs sources revealed by ratios of isomers and different weight compounds
•Groundwater recharge mapped in an urbanising catchment using multiple techniques.•Recharge restricted to specific geographic areas where volcanic clays are absent.•Approximately half of recharge ...occurs over 15% of the land area.•Future land use planning must prioritize protection of high recharge areas.
Understanding how land-use change influences the water cycle is of critical importance to land and water management. Determining the timing, location and rates of groundwater recharge and their relationship to land-use is often challenging, leading to significant uncertainties in water budgets and water cycle planning. In this study, a combination of physical and hydrochemical/isotope techniques were used to estimate and map groundwater recharge rates and identify its key controlling factors in a rapidly urbanising catchment in southeast Australia. The primary objective was to provide qualitative and quantitative information regarding recharge, allowing comparison and monitoring of changes as future urbanisation takes place. The presence of significant tritium in shallow groundwater (>1.0 TU), along with radiocarbon activities > 85 pMC and low salinity (e.g. EC < 600 µs/cm) allowed identification of areas where significant recharge has taken place in recent years. These were strongly associated with elevated topography on the basin margin, and the absence of volcanic clay - the dominant lithology underlying most of the region. This interpretation is supported by time-series analysis of soil moisture profiles, which indicate minimal vertical propagation of precipitation below 1.5 m depth in volcanic clay soils. Estimation of recharge rates was conducted using chloride mass balance and water table fluctuation analysis in water table aquifer monitoring bores. Rates mostly ranged between 1.5 and 50 mm/yr; however, recharge exceeding 100 mm/year was identified in a spatially restricted zone at the edge of the basin. Here, the volcanic lithology is absent and Quaternary sand directly overlies the lower Cainozoic sand aquifer. This area comprises a small percentage of land in the study area (approximately 15%) but is estimated to contribute a large proportion (nearly half) of recharge. The findings underscore the importance of characterising recharge locations and processes to support the protection of groundwater quality and quantity, for example, through careful land-use planning.
Identification of different nitrate sources in groundwater is challenging in areas with diverse land use and multiple potential inputs. An area with mixed land-uses, typical of the piedmont-plain ...recharge area of the North China Plain, was selected to investigate different nitrate sources and the impact of land use on nitrate distribution in groundwater. Multiple environmental tracers were examined, including major ions, stable isotopes of water (δ2H-H2O, δ18O-H2O) and nitrate (δ15N-NO3− and δ18O-NO3−). Groundwater was sampled from four land-use types; natural vegetation (NV), farmland (FL), economic forestland (EF) and residential areas (RA). A mixing model using δ18O and Cl− concentrations showed that groundwater recharge predominantly comprises precipitation and lateral groundwater flow from areas of natural vegetation in the upper catchment, while irrigation return water and wastewater from septic tanks were major inputs in farmland and residential areas, respectively. Land use variation is the major contributing factor to different nitrate concentrations. In total, 80%, 49% and 86% of samples from RA, FL and EF, respectively exceeded the WHO standard (50mg/L NO3−), compared to 6.9% of samples from NV. Isotopes of δ15N-NO3− and δ18O-NO3− verified that nitrate in groundwater of the NV (with δ15N ranging from 1.7‰ to 4.7‰) was sourced from soil and precipitation. Examination of δ15N-NO3− vs δ18O-NO3− values along with multivariate statistical analysis (principle component and cluster analysis) helped identify sources with overlapping isotopic values in other land-use areas (where δ15N values range from 2.5‰ to 10.2‰). Manure and septic waste were dominant sources for most groundwater with high NO3− and Cl− concentrations in both farmland and residential areas. The lack of de-nitrification and fact that the area is a recharge zone for the North China Plain highlight the importance of controlling nitrate sources through careful application of manure and fertilizers, and control of septic leakage.
“(δ15N:1.7~4.7‰)” means range of nitrate isotopes;
“(NO3−:6~26mg/L, 6.9%)” means “(Range of NO3− Concentration: 6~26mg/L, Percent of samples with nitrate concentration above WHO standard (50mg/L NO3−) to all samples)”. Display omitted
•We investigated the impacts of diverse land use on nitrate in groundwater.•Multivariate statistics methods were combined to identify source of nitrate.•Manure and septic waste were dominant sources for groundwater with high nitrate.•Lack of de-nitrification highlights the importance of controlling nitrate sources.
This essay explores the international dimensions of China's water pollution crisis, examining the following questions: 1. What role has international trade and the evolution of the globalized economy ...played in China's pollution crisis? 2. Who have been the major actors in this evolution, and who has been most affected? 3. What are the future implications and prospects for improvement in China's water pollution situation? In terms of future global implications of China's water pollution crisis, there is strong evidence that the "pollution haven" model that was predicted by some scholars to accompany trade globalization indeed materialized in China, with profound environmental, health, and social effects. There are opportunities to learn from China's pollution crisis, and set new standards for international trade relationships based on equitable sharing of economic and environmental benefits and costs.
•We examine hydrodynamics of groundwater in a multi-layer aquifer affected by saltwater intrusion.•Hydrochemical-isotopic data aid understanding of groundwater flow system and recharge ...sources.•Geochemical indicators show that palaeo-seawater intrusion is important salinity sources.•Implications are for groundwater exploitation management in complex, layered coastal aquifers.
A hydrochemical-isotopic investigation of the Laizhou Bay Quaternary aquifer in north China provides new insights into the hydrodynamic and geochemical relationships between freshwater, seawater and brine at different depths in coastal sediments. Saltwater intrusion mainly occurs due to two cones of depression caused by concentrated exploitation of fresh groundwater in the south, and brine water for salt production in the north. Groundwater is characterized by hydrochemical zonation of water types (ranging from Ca–HCO3 to Na–Cl) from south to north, controlled by migration and mixing of saline water bodies with the regional groundwater. The strong adherence of the majority of ion/Cl ratios to mixing lines between freshwater and saline water end-members (brine or seawater) indicates the importance of mixing under natural and/or anthropogenic influences. Examination of the groundwater stable isotope δ18O and δ2H values (between −9.5‰ and −3.0‰ and −75‰ and −40‰, respectively) and chloride contents (∼2 to 1000meq/L) of the groundwater indicate that the saline end-member is brine rather than seawater, and most groundwater samples plot on mixing trajectories between fresh groundwater (δ18O of between −6.0‰ and −9.0‰; Cl<5meq/L) and sampled brines (δ18O of approximately −3.0‰ and Cl>1000meq/L). Locally elevated Na/Cl ratios likely result from ion exchange in areas of long-term freshening. The brines, with radiocarbon activities of ∼30 to 60 pMC likely formed during the Holocene as a result of the sequence of transgression-regression and evaporation; while deep, fresh groundwater with depleted stable isotopic values (δ18O=−9.7‰ and δ2H=−71‰) and low radiocarbon activity (<20 pMC) was probably recharged during a cooler period in the late Pleistocene, as is common throughout northern China. An increase in the salinity and tritium concentration in some shallow groundwater sampled in the 1990s and re-sampled here indicates that intensive brine extraction has locally resulted in rapid mixing of young, fresh groundwater and saline brine. The δ18O and δ2H values of brines (∼−3.0‰ and −35‰) are much lower than that of modern seawater, which could be explained by 1) mixing of original (δ18O enriched) brine that was more saline than presently observed, with fresh groundwater recharged by precipitation and/or 2) dilution of the palaeo-seawater with continental runoff prior to and/or during brine formation. The first mechanism is supported by relatively high Br/Cl molar ratios (1.7×10−3–2.5×10−3) in brine water compared with ∼1.5×10−3 in seawater, which could indicate that the brines originally reached halite saturation and were subsequently diluted with fresher groundwater over the long-term. Decreasing 14C activities with increasing sampling depth and increasing proximity to the coastline indicate that the south coastal aquifer in Laizhou Bay is dominated by regional lateral flow, on millennial timescales.
Chemical analysis of groundwater and sediments was carried out to investigate causes of elevated F
− (1.5–6.6
mg/L) and As concentrations (10–27
μg/L; one sample affected by local contamination with ...4870
μg/L As), in groundwater from the Yuncheng Basin, northern China. Groundwater from 9 out of 73 wells contains both F and As concentrations above World Health Organisation safe drinking guidelines (>1.5
mg/L and >10
μg/L, respectively); F
− concentrations above safe levels are more widespread than As (27 vs. 12 wells). The elevated As and F concentrations represent a significant health risk, as groundwater is widely used to supply agricultural and domestic water in the region. High F and As concentrations occur in shallow groundwater affected by agriculture and deep groundwater with long residence times (>13
ka) that shows little sign of anthropogenic influence. The strong positive correlation between groundwater F/Cl and As/Cl ratios (
r
2
=
0.98 and 0.77 in shallow and deep groundwater, respectively) indicates that these elements are mobilized and enriched by common processes. Positive correlations between F and As concentrations and Na/Ca ratios (
r
2
=
0.67 and 0.46, respectively) indicate that groundwater major ion chemistry plays a significant role in mobilizing F and As. Mobilization likely occurs via de-sorption of As and F anions (e.g.
HAsO
4
2
-
and F
−) from hydrous metal oxides. Moderate positive correlations between pH and As and F concentrations (
r
2
=
0.36 and 0.17, respectively) indicate that high pH may favour de-sorption, while HCO
3 may act as a sorption competitor. High groundwater Na/Ca ratios likely result from cation exchange, while pH and HCO
3 contents are predominantly controlled by carbonate weathering reactions. Sediments from the area were reacted with various water solutions, producing F concentrations between 0.49 and 2.7
mg/L and As concentrations between 0.51 and 16.7
μg/L. Up to 45% more F and 35% more As were released when sediments were reacted with a Na-rich, Ca-poor solution compared to a Ca-rich solution; this is consistent with increased mobilization of F
− and
HAsO
4
2
-
by Na-rich, Ca-poor groundwater. Increasing F and As concentrations across a wide area caused by high levels of pumping is a potential future health concern.
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