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

Characteristics of karst groundwater flow systems of typical faulted basins in Yimeng Mountain area: A case study of Laiwu Basin

China Geological Survey has organized and implemented 1:50 000 standard map hydrogeological survey with an area of more than 40000 square kilometers in Yimeng Mountain area. And it carried out a large amount of water prospecting and well drilling demonstration work in villages and towns with serious water shortage, obtained rich geological data and gained a new understanding of groundwater flow systems. Under the influence of Mesozoic and Cenozoic structures, the faults and folds, extensional detachment and magmatic intrusion occurred in Yimeng Mountain area, formed a series of graben-semi graben basins characterized by overlapping in the south and faulting in the north, and finally formed today's typical "basin-mountain" karst hydrogeological structure and the relatively independent karst groundwater system, which taking basin as unit. In order to study the development characteristics of groundwater flow system in Yimeng Mountain area, Laiwu Basin was selected as a typical study area. On the basis of the field geological survey, through comprehensively analyze the geomorphic units, the three-dimensional spatial distribution of water bearing rock groups, groundwater level, hydrochemistry, and water isotope results on the north and south sides of the basin, this paper comprehensively discusses the characteristics of multistage karst groundwater flow systems with typical "basin-mountain" structure in Yimeng Mountain area. The results show that, the karst groundwater in Laiwu Basin presents a "centripetal" runoff from the outer periphery to the center of the basin. Affected by human activities, controlled by geological structure and aquifer distribution, the characteristics of groundwater flow systems between the north and south sides of the basin are different. There are mainly intermediate and local groundwater flow systems in the south of the basin, while a single local groundwater flow system is developed in the north of the basin, however, it occupies nearly 1/2 of the groundwater sources that have been explored and demonstrated. In addition, it is found that at the lowest erosion base level of Dawen River, the voids separated by regional detachment structure and hydrothermal mixing, together with rock layer, interlayer fissures and bedding dissolution voids, form a three-dimensional karst groundwater network, which influence the circulation path and depth of karst water. Guided by this understanding, the completion rate of exploration production combined wells has reached 86%, which strengthens the combination of theory and practice of groundwater flow system theory in hydrogeological work in bedrock mountainous areas in North China

Progress and prospect of hot dry rock exploration and development

The exploitation and utilization of clean energy is a resource and environmental issue of common concern for global sustainable development. As a vital strategic and sustainable future energy, hot dry rock (HDR) has attracted more and more attention. In this paper some thoughts on the future research direction of HDR resources in China are provided based on a worldwide experience summary, hoping to provide a useful reference for the future exploration and engineering development of HDR. Since the concept of HDR was put forward in the 1970s, the number of worldwide HDR construction has been increasingly growing. Although a lot of theoretical and technical breakthroughs have been made, only a small fraction of projects still in operation due to the lack of sustained financial support, induced microearthquakes and other issues. At present, the global development of HDR is gradually entering a new stage of exploration, and the basic theories of HDR to tackle the key problems are strengthening around the world. Since 2012, the China Geological Survey has organized and implemented the nationwide terrestrial HDR resources survey, evaluation, exploration and development, and significant stage progress has been achieved. A series of fundamental maps have been compiled, such as terrestrial heat flow value, curie surface depth, distribution of acidic rock, and heat-controlling structure in China. The resource potential of terrestrial HDR in China has been preliminarily estimated and a sounding basis for the target site selection is provided. HDR exploration and evaluation have been carried out in typical areas of Qinghai, Shandong, Hebei, Shanxi and Jiangsu provinces, and a breakthrough has been achieved in the Gonghe Basin of Qinghai. The first HDR resources exploration and production demonstration project in China was carried out in 2019, which made a series of meaningful outcomes in deep HDR exploration, high-temperature hard rock drilling, large-scale reservoir stimulation, reservoir connectivity and flow circulation, organic Rankine cycle (ORC) power generation, etc. The large-scale reservoir stimulation was carried out in 2020, and the first power generation test was completed in 2021. In general, the global exploration and development of HDR has made great progress. Practice has proved that HDR resources are a promising green energy and are expected to become an inexhaustible energy support for the world in the future. However, there is still a large gap between the existing path of HDR development and utilization and the economics of its supporting technologies compared with commercial development expectations at present. Although the development of HDR resources in China has achieved a breakthrough from “0” to “1”, there is still a long way to go from the international level. In order to solve the problems of large-scale and economic development, it is still needed to promote disruptive technological innovation in high temperature hard rock drilling and completion, fine characterization of deep reservoirs, safe large-scale reservoir construction, efficient heat transfer and heat recovery and other aspects