Hydrochemical characteristics and quality assessment of deep groundwater from the coal-bearing aquifer of the Linhuan coal-mining district, Northern Anhui Province, China.

There is little information available about the hydrochemical characteristics of deep groundwater in the Linhuan coal-mining district, Northern Anhui Province, China. In this study, we report information about the physicochemical parameters, major ions, and heavy metals of 17 groundwater samples that were collected from the coal-bearing aquifer. The results show that the concentrations of total dissolved solids, electrical conductivity, and potassium and sodium (K(+) + Na(+)) in most of the groundwater samples exceeded the guidelines of the World Health Organization (WHO) and the Chinese National Standards for Drinking Water Quality (GB 5749-2006). The groundwater from the coal-bearing aquifer was dominated by the HCO3·Cl-K + Na and HCO3·SO4-K + Na types. Analysis with a Gibbs plot suggested that the major ion chemistry of the groundwater was primarily controlled by weathering of rocks and that the coal-bearing aquifer in the Linhuan coal-mining district was a relatively closed system. K(+) and Na(+) originated from halite and silicate weathering reactions, while Ca(2+) and Mg(2+) originated from the dissolution of calcite, dolomite, and gypsum or anhydrite. Ion exchange reactions also had an influence on the formation of major ions in groundwater. The concentrations of selected heavy metals decreased in the order Mn > Zn > Cr > Cu > Ni > Pb. In general, the heavy metal concentrations were low; however, the Cr, Mn, and Ni concentrations in some of the groundwater samples exceeded the standards outlined by the WHO, the GB 5749-2006, and the Chinese National Standards for Groundwater (GB/T 14848-93). Analysis by various indices (% Na, SAR, and EC), a USSL diagram, and a Wilcox diagram showed that both the salinity and alkalinity of the groundwater were high, such that the groundwater could not be used for irrigating agricultural land without treatment. These results will be significant for water resource exploiting and utilization in coal mine area.

Monitoring of flow field based on stable isotope geochemical characteristics in deep groundwater.

The water circulation in deep aquifers controls not only chemical composition of the groundwater, but also stable isotope composition. In order to analyze the flow field in the process of the deep groundwater circulation in different aquifers, specimens belonging to the fourth aquifer in the Quaternary (the fourth aquifer for short), the coal and sandstone cranny aquifer in the Permian, and Carboniferous (the coal catena aquifer for short), the Taiyuan group limestone aquifer in the Carboniferous (the Taiyuan limestone aquifer for short), and the limestone aquifer in the Ordovician (the Ordovician limestone aquifer for short) were gained from the top down in Renlou colliery and local Linhuan coalmine district, northern Anhui, China, in the study. δD, δ(18)O, and the content of tall dissolve solids (TDS for short) of these specimens were tested. The experimental results had revealed that the groundwater in the fourth aquifer and the Taiyuan limestone aquifer takes on (18)O excursion and the coal catena aquifer takes on D excursion in Linhuan coalmine district, while excursion characteristic in the Ordovician limestone aquifer is not evident in the coalmine district. By analysis, δ(18)O and the content of TDS are in negative relationship in the groundwater of the fourth aquifer and the Taiyuan limestone aquifer in Linhuan coalmine district, yet δD and the content of TDS are in positive relationship in the coal catena aquifer. Mining greatly influences the fourth aquifer and the coal catena aquifer so the groundwater in the fourth aquifer flows from northwest and southeast to mining areas and the groundwater in the coal catena aquifer flows from around to mining areas. However, mining does not influence the Taiyuan limestone aquifer evidently so the groundwater flows from east to west still.

Four trace elements contents of water environment of mining subsidence in the Huainan diggings, China.

Mining subsidence pool is the special waters formed by coal mining, located near the mine. We understand the impact on these waters of the surrounding coal production activities and the electricity plant through research the content and characteristics of harmful trace elements in coal contained in these waters. Pb, Hg, Se and Cr these four trace elements increase 0.52, 0.78, 0.70 and 0.28% respectively in Datong mining subsidence pool from November 2004 to November 2006; the four elements increase 1.52, 1.23, 1.08 and 1.08% respectively in Xie'er mining subsidence pool; the four elements increase 1.01, 1.06, 1.02 and 0.83% respectively in Pansan mining subsidence pool. The absolute value of Pb, Hg, Se and Cr in mining subsidence pool is related with their background value, while the increase in their concentration and their environment of mine and electricity plant surrounded are closely linked.