Arsenic, Fluoride and Iodine in Groundwater of China

Arsenicosis and fluorosis, two endemic diseases known to result from exposure to their elevated concentrations in groundwater of north China used by many rural households for drinking, have been major public health concerns for several decades. Over the last decade, a large number of investigations have been carried out to delineate the spatial distribution and to characterize the chemical compositions of high As and F groundwaters with a focus on several inland basins in north China. Findings from these studies, including improved understanding of the hydrogeological and geochemical factors resulting in their enrichments, have been applied to guide development of clean and safe groundwater in these endemic disease areas. Survey efforts have led to the recognition of iodine in groundwater as an emerging public health concern. This paper reviews the new understandings gained through these studies, including those published in this special issue, and points out the direction for future research that will shed light on safe guarding a long-term supply of low As and F groundwater in these water scarce semi-arid and arid inland basins of north China

River Ecological Restoration and Groundwater Artificial Recharge

Three of the eleven papers focused on groundwater recharge and its impacts on the groundwater regime, in which recharge was caused by riverbed leakage from river ecological restoration (artificial water replenishment). The issues of the hydrogeological parameters involved (such as the influence radius) were also reconsidered. Six papers focused on the impact of river ecological replenishment and other human activities on river and watershed ecology, and on groundwater quality and use function. The issues of ecological security at the watershed scale and deterioration of groundwater quality were of particular concern. Two papers focused on water resources carrying capacity and water resources reallocation at the regional scale, in the context of the fact that ecological water demand has been a significant topic of concern. The use of unconventional water resources such as brackish water has been emphasized in the research in this issue

Determining water allocation scheme to attain nutrient management objective for a large lake receiving irrigation discharge

Irrigation discharge is a relevant water resource for lake ecosystems in arid and semi-arid regions. However, high concentrations of nitrogen and phosphorus in the irrigation discharge raise concerns over potential lake eutrophication in these regions. A Delft3D hydrodynamic-water quality model was used to explore the effects of multiple water sources on water quality of a large shollow lake in the semi-arid west of Northeast China, which is surrounded by irrigated rice paddies. Eighteen scenarios in a combination of different precipitation rates, irrigation discharge operations, and flow conditions were simulated to analyze time and water allocation required in order to achieve nutrient standards of total nitrogen (TN) ≤ 1.5 mg/L and total phosphorus (TP) ≤ 0.1 mg/L. The results showed that time required for the optimal combination to achieve nutrient management objectives displayed an increasing trend from the east to west. In the best control scenario where the irrigation discharge was regulated into the lake, TN and TP concentrations could be reduced by 60% and 70%, respectively. Water diversion from a freshwater reservoir can effectively improve lake water quality even though sediment nutrient resuspension could occur in the eastern region of lake. The findings suggest that using multi-source water supplies can attain nutrient management objectives in order to reduce eutrophication risk for a lake that receives nutrient-rich irrigation discharge. The study also demonstrates the great usefulness of hydrodynamic-water quality modeling for assessing water resource allocation and science-based decision making in intensive agriculture practices

The Amur River border : once a symbol of conflict, could it turn into a water resource stake?

Abstract : the relations between Russia and China have become much warmer since the beginning of the 1990s ; they put an end to severe tensions between the two countries. Now trade is expanding, and investment from China in the border area is stimulating growth along the Amur River. But with growth also come water withdrawals : sortages have already appeared in the basin. Prospects are all the more problematic as northern China is facing severe water shortages that could partly be solved, in the medium term, by a derivation from the Amur/Heilongjiang Basin. Would such a project be considered given the still volatile state of relations between Moscow and Beijing ?Les relations entre la Chine et la Russie se sont considérablement détendues depuis une dizaine d’années. Ce réchauffement diplomatique met un terme à la forte tension qui régnait entre les deux pays. Le commerce croît, et les investissements chinois dans la zone frontière stimulent la croissance le long du fleuve Amour. Mais avec la croissance viennent les prélèvements en eau : des cas de manque d’eau sont déjà apparus dans le bassin. Les perspectives sont d’autant plus problématiques que la plaine de Chine du Nord est confrontée à de graves pénuries d’eau, lesquelles pourraient être en partie résolues, à moyen terme, par un canal en provenance du bassin de l’Amour/Heilongjiang. Une telle perspective pourrait-elle être envisageable, compte tenu de la volatilité des relations entre Moscou et Beijing

Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

This work was funded by National Basic Research Program of China (2014CB953800), Young Talents Projects of the Institute of Urban Environment, Chinese Academy of Sciences (IUEMS201402), National Natural Science Foundation of China (41471190, 41301237, 71704171), China Postdoctoral Science Foundation (2014T70144) and Discovery Early Career Researcher Award of the Australian Research Council (DE170100423). The work contributes to the UK-China Virtual Joint Centres on Nitrogen “N-Circle” and “CINAg” funded by the Newton Fund via UK BBSRC/NERC (grants BB/N013484/1 and BB/N013468/1, respectively).Peer reviewedPostprintPostprin

松花江流域の汚染源分布及び典型的な汚染物除去に関する研究

Songhua River Basin located in Northeast China, owning a total area of 55.68 square kilometers. The Songhua River Basin is the third largest basin in China, after the Yangtze River and the Yellow River. The water quality of Songhua River seriously affects the ecological environment of the basin. It is urgent to scientifically plan pollution sources, improve water quality and ensure residents’ water safety according to the economic development of Songhua River Basin. Based on studying typical pollutant removal methods in Songhua River Basin, this paper studies the pollution source planning in Songhua River Basin. Finally, some suggestions are put forward to solve the pollution sources in Songhua River Basin. Two efficient removal methods of main pollutants are found in this paper, which are not limited to the Songhua River Basin, but also applicable to the pollution control of other waters.北九州市立大

Study on the characteristics and mechanism of antibiotic pollution in different aquifers

The risk posed by antibiotics in various aquifers has attracted wide attention. This study investigated the pollution characteristics and controlling factors of antibiotics in different types of aquifers, and identified the indicator factors of antibiotic pollution in aquifers based on a total of 309 sets of samples from Songnen Plain, North China Plain, and Southwest Karst area. The concentrations of 35 antibiotics were analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results show that: (1) all 35 antibiotics were detected, with karst aquifers (34 types) and North China porous aquifers (32 types) mainly containing quinolones and macrolide antibiotics, while only 6 types of antibiotics, mainly erythromycin, were detected in Northeast porous aquifers. In porous aquifers, the overall pollution in Northeast China is characterized by low concentrations (median = 2.07 ng/L, detection rate = 100%), while the pollution in North China is relatively heavy (11.76 ng/L), accounting for 49% of the spatial distribution. In the karst aquifers, the antibiotic pollution is characterized by high concentrations (37.5 ng/L) and a large spatial extent (87%). (2) The characteristic differences in antibiotic pollution between karst and porous aquifers are attributed to the hydrogeological conditions (openness and permeability), while the emission intensity of antibiotics is the primary reason for the differences between porous aquifers in different regions. (3) Cluster analysis based on correlation coefficients identified the indicator factors of antibiotics in different types of aquifers. Total organic carbon (TOC) can effectively indicate the antibiotic pollution in porous aquifers, while \begin{document}${\mathrm{NH}}_4^+$\end{document} and \begin{document}${\mathrm{SO}}_4^{2-}$\end{document} reveal a positive correlation between human activities and antibiotics. Groundwater property parameters are reliable indicators of antibiotic pollution in karst aquifers, with lower antibiotic concentrations observed in alkaline and oxidizing karst water. The research results can provide scientific basis for regional prevention and control of emerging organic contaminants in groundwater

Temporal-Spatial Variabilities and Influencing Factors of Terrestrial Wet-Dry States and Vegetation Development: A Case Study in Northeast China

The number of hydroclimate disasters has increased dramatically since the late 20th century with profound changes in the environment. The Meteorological Drought Index facilitates long-term monitoring of wet-dry trends and soil moisture (SM) is critical for regulating eco-hydrological and meteorological processes. Evaluating the spatiotemporal variation of terrestrial dry-wet states and its influencing factors from different perspectives was expected to provide a scientific basis for land and water resource management and drought mitigation, yet such comprehensive assessments are lacking. Northeast China (NEC) is a typically sensitive area toward climate change. It has been regarded as a major ecological barrier for northern China and even Northeast Asia, which is important in regulating the regional climate. Therefore, this thesis used NEC as a case study to explore reliable long-term spatiotemporal variation characteristics and the influencing factors of wet-dry states from meteorological (Chapter 2) and SM perspectives (Chapter 3), respectively. Vegetation controls water exchange between the soil and the atmosphere and has faced dual challenges posed by hydroclimate and human activities. On one hand, vegetation growth is expected to become more water-constrained in the context of global warming. Understanding how vegetation responds to water availability results in larger concerns. On the other hand, large demands for food and economic development have led to the degradation of natural vegetation in NEC. Recognizing the importance of sustainable forest utilization, the Chinese central and local governments have implemented a series of ecological conservation projects since 1998. An in-depth understanding of how climate change and human activities affect vegetation at various spatial and temporal scales is essential for managing human activities and restoring vegetation. However, the factors dominating vegetation development and their contribution remain unclear and require quantitative assessment (Chapter 4). Here, the Standardized Precipitation Evapotranspiration Index (SPEI)-aggregated multi-time scales were calculated to comprehensively assess wet-dry states and trends in NEC from 1990 to 2018. The analysis revealed a general drying tendency, with 86.3% of the area exhibiting a drying trend. The percentage of annual drought-affected areas increased by 0.7%/a. Seasonal analysis showed that spring and winter exhibited wet trends in 71% and 84% of NEC, respectively. In contrast, 92–93% of NEC displayed dry tendencies in summer and autumn. The highest interannual drought severity occurred in May and June. The most significant drought impacts and trends were observed in shrub and grassland, sparsely vegetated land, and middle-temperate semiarid regions (M-semiarid). The findings indicate that the warmer the temperature zone, the more sensitive it is towards drought under the same hydrological conditions, resulting in higher drought-affected areas. Similarly, the drier the land, the higher the drought-affected area within the same temperature zone, with pronounced drought trends in spring and summer. Future projections indicate that 86% of NEC will experience wetting trends, while 17% will continue to dry. The ordinary least squares model was employed to investigate the factors (i.e., precipitation, land surface temperature (LST), wind speed, vegetation greenness, elevation, slope, and clay content) influencing the spatiotemporal variability of SM. Results indicate that environmental factors differentially influence SM across various terrains (plains, tablelands, hills, and mountains), ecosystems (croplands, forests, and grasslands), and soil water status (wet and dry). The correlations between SM and land surface temperature (LST), elevation, as well as vegetation greenness were most terrain- and ecosystem-dependent, while precipitation was the least. A significantly different effect of each environmental factor on SM was observed between plains and mountains. Transitioned from wet to dry status, the dependence of SM on precipitation increased in forests but decreased in grasslands, while the opposite held for wind speed. The transit increased the contribution of LST, elevation, and slope to SM while decreasing the contribution of vegetation greenness. Furthermore, the effect of clay content on SM shifted from positive to negative in mountains and forests as soil transitioned from wet to dry. From 2013 to 2017, SM experienced a sharp drop across all terrains and ecosystems. A partial correlation analysis was conducted to identify the drivers of soil drying. The analysis identified several key factors: reduced precipitation in all spatial domains except mountains, elevated LST in grasslands, increased wind speeds in plains, croplands, and grasslands, and a rise in vegetation greenness in plains, tablelands, and croplands. The spatiotemporal variability in vegetation response to water availability, across different land cover types, climate regions, and time scales, was evaluated based on the relationship between Normalized Difference Vegetation Index (NDVI) and SPEI. The effects of human activities and climate change on vegetation development were then quantitatively assessed using the residual analysis method. Our findings indicate that NDVI of grasslands, sparse vegetation, rain-fed crops, and built-up lands, as well as sub-humid and semi-arid areas (drylands), positively correlated with SPEI, and the correlations increased with time scales. Conversely, negative correlations were concentrated in humid areas or areas covered by forests and shrubs. In humid areas, vegetation water surplus weakens with warming, while in drylands, vegetation water constraints intensify. Furthermore, potential evapotranspiration had an overall negative effect on vegetation, and precipitation was a controlling factor for vegetation development in semi-arid areas. From 1990 to 2018, 53% of the total area in NEC showed a trend of improvement, primarily attributed to human activities (93%), especially through the implementation of ecological restoration projects since 1998. In areas of vegetation degradation, the relative contributions of human activities and climate change were 56% and 44%, respectively. In summary, our study deepens the understanding of terrestrial wet-dry states and trends, providing valuable perspectives for land and hydrological management across diverse terrains and ecosystems amidst global shifts toward wetter or drier patterns. The government should develop targeted drought mitigation strategies in accordance with the spatiotemporal variation characteristics of drought, with a particular focus on droughts in M-semiarid regions occurring in summer, especially in May and June. Measures to monitor and mitigate the adverse effects of elevated LST and wind speed on SM in plains, croplands, and grasslands under dry soil conditions should be strengthened. Attention should be paid to addressing land cracks in grasslands and soil aggregation issues in mountainous and forested areas during water replenishment efforts. We also recommend regulating tree and crop planting densities in plains, tablelands, and croplands to mitigate trends of soil drying. Additionally, we mapped the relative contributions and roles of climate change versus human activities in areas experiencing vegetation change, offering crucial insights for developing more detailed vegetation restoration and management strategies to cope with future climate changes.2024-12-1