Long-term coal mining activities have led to severe heavy metal pollution in the soil environment of coal mining areas, posing significant threats to both ecological environments and human health. In this study, surface soil samples were collected from the overlying soil of coal gangue and the surrounding areas of the Panyi coal mine in Huainan. The concentrations of Cd, Zn, Cu, Ni, and Pb elements were determined. A self-organizing map (SOM) and an absolute principal component score multiple linear regression (APCS-MLR) receptor model were employed for the quantitative analysis of the soil’s heavy metal pollution sources and contributions. Additionally, this study focused on the analysis of the pathways of the relatively serious pollution of Cd. The results revealed that the average concentrations of heavy metals (Cd, Pb, Zn, Cu, Cr, and Ni) in the study area were 4.55, 0.59, 1.54, 0.69, 0.59, and 0.71 times the local soil background values, respectively. The concentrations of Cd and Zn exceeded the risk screening values at some sampling points, with exceedance rates of 44% and 8%, respectively, indicating a relatively serious Cd contamination. The sources of heavy metals in the soil in the study area were classified into four categories: mining activities, agricultural activities, weathering of natural matrices, and other unknown sources, with average contributions of 55.48 percent, 24.44 percent, 8.91 percent and 11.86 percent, respectively. Based on the spatial distribution of Cd, it was inferred that atmospheric deposition is one of the important pollution pathways of Cd in the study area. Cd profile distribution patterns and a surface water pollution survey showed that the farmland areas were affected by the irrigation water pathway to some extent. The vertical distribution of heavy metal content in the forest area showed a strong disorder, which was related to the absorption function of plant roots. The results of this study can help to improve the environmental management of heavy metal pollution so as to protect the ecological environment and human health.

In China, fence net aquaculture practices have been established in some subsidence waters that have been formed in coal mining subsidence areas. Within this dynamic ecological context, diverse fish species grow continuously until being harvested at the culmination of their production cycle. The purpose of this study was to investigate diverse factors influencing the bioavailability and distribution of mercury (Hg) and methylmercury (MeHg), which have high physiological toxicity in fish, in the Guqiao coal mining subsidence area in Huainan, China. Mercury and MeHg were analyzed in 38 fish samples of eight species using direct mercury analysis (DMA-80) and gas chromatography-cold vapor atomic fluorescence spectrometry (GC-CVAFAS). The analysis results show that the ranges of Hg and MeHg content and methylation rate in the fish were 7.84-85.18 ng/g, 0.52-3.52 ng/g, and 0.81-42.68 %, respectively. Meanwhile, conclusions are also summarized as following: (1) Monophagous herbivorous fish that were fed continuously in fence net aquaculture areas had higher MeHg levels and mercury methylation rates than carnivorous fish. Hg and MeHg contents were affected by different feeding habits of fish. (2) Bottom-dwelling fish show higher MeHg levels, and habitat selection in terms of water depth also partially affected the MeHg content of fish. (3) The effect of fence net aquaculture on methylation of fish in subsidence water is mainly from feed and mercury-containing bottom sediments. However, a time-lag is observed in the physiological response of benthic fishes to the release of Hg from sediments. Our findings provides baseline reference data for the ecological impact of fence net aquaculture in waters affected by soil subsidence induced by coal mining in China. Prevalent environmental contaminants within coal mining locales, notably Hg, may infiltrate rain-induced subsidence waters through various pathways.

The Hg released from coal mining activities can endanger soil ecosystems and pose a risk to human health. Understanding the accumulation characteristics of mercury (Hg) in coal mining soil is important for effectively controlling Hg emissions and developing measures for the prevention and control of Hg contamination. To identify the potential sources of Hg in soils, the Hg concentration and isotopic composition characteristics of raw coal and different topsoil types from the areas surrounding a coal mine were determined in this study. The results showed that Hg in coal mainly exists mainly in the form of inorganic Hg, and Hg has experienced Hg2+ photoreduction prior to incorporating into coal. In addition, the composition of Hg isotopes differed significantly among different topsoil types, and the δ202Hg value of the farmland soil exhibited large negative excursions compared to the coal mining soil. The ternary mixed model further revealed the presence of substantial differences in potential Hg sources among the two regions, with the coal mining soil being greatly disturbed by anthropogenic activity, and the relative contributions of Hg from raw coal, coal gangue, and background soil to coal mining soil being 33.42%, 34.4%, and 32.19%, respectively. However, Hg from raw coal, coal gangue and background soil contributed 17.04%, 21.46%, and 61.51% of the Hg in the farmland soil, indicating that the accumulation of Hg in farmland soil was derived primarily from the background soil. Our study demonstrated that secondary pollution in soil caused by immense accumulation of solid waste (gangue) by mining activities offers a significant challenge to ecological security. These findings provide new insights into controlling soil Hg in mining areas and further highlight the urgency of strict protective measures for contaminated sites.

This study prepared and characterized bamboo-derived biochar loaded with different ratios of iron and manganese; evaluated its remediation performance in arsenic-contaminated soil by studying the changes in various environmental factors, arsenic speciation, and arsenic leaching amount in the soil after adding different materials; proposed the optimal ratio and mechanism of iron-manganese removal of arsenic; and explained the multivariate relationship between enzyme activity and soil environmental factors based on biological information. Treatment with Fe-Mn-modified biochar increased the organic matter, cation exchange capacity, and N, P, K, and other nutrient contents. During the remediation process, O-containing functional groups such as Mn-O/As and Fe-O/As were formed on the surface of the biochar, promoting the transformation of As from the mobile fraction to the residual fraction and reducing the phytotoxicity of As, and the remediation ability for As was superior to that of Fe-modified biochar. Mn is indispensable in the FeMn-BC synergistic remediation of As, as it can increase the adsorption sites and the number of functional groups for trace metals on the surface of biochar. In addition to electrostatic attraction, the synergistic mechanism of ferromanganese-modified biochar for arsenic mainly involves redox and complexation. Mn oxidizes As(Ⅲ) to more inert As(V). In this reaction process, Mn(Ⅳ) is reduced to Mn(Ⅲ) and Mn(II), promoting the formation of Fe(Ⅲ) and the conversion of As into Fe-As complexes, while As is fixed due to the formation of ternary surface complexes. Moreover, the effect of adding Fe-Mn-modified biochar on soil enzyme activity was correlated with changes in soil environmental factors; catalase was correlated with soil pH; neutral phosphatase was correlated with soil organic matter; urease was correlated with ammonia nitrogen, and sucrase activity was not significant. This study highlights the potential value of FM1:3-BC as a remediation agent in arsenic-contaminated neutral soils.

Mercury in coals might emit into the environment from coal combination, and finally cause environmental pollution. In this paper, 26 coal samples were selected from No. 1 which is coal in the Shanxi Formation of Zhangji and Xinjier mines in the Huainan coalfield. The mineralogical and geochemical components of coal samples were determined by DMA-80 mercury-measuring instrument, XRF, XRD, ICP-MS, and the relationship between the depositional environment of the coal seam and mercury enrichment was analyzed. The results show that the mercury content of coal in the study area ranged from 0.03 to 0.93 μg/g, with an arithmetic means of 0.21 μg/g, higher than the background values of coal in China and the world. The mercury content of Shanxi Formation coal varied among different mines, the arithmetic mean value of mercury in Zhangji coal mine and Xinjier mine coal is 0.35 μg/g and 0.12 μg/g respectively. Due to the complex depositional environment and depositional facies, the distribution of mercury content in the coal seam is quite different. XRD, Microscopic observation and the ratio of (CaO + MgO + Fe2O3)/(SiO2+ Al2O3) and Al2O3/TiO2 show that the main mineral in the depositional environment of this study area is kaolinite, quartz and pyrite, and the depositional facies are intercontinental and sea-land, so the parent rock type belongs to acid bedrock. The Ni/Co, Sr/Ba, and Sr/Cu ratios were used to indicate a weak oxidation-reduction, Marine salt water, and an arid and hot environment. The vertical distribution of mercury in coal and the characteristics of the depositional environment are combined to show that mercury in coal is easily affected by redox conditions, paleosalinity and paleoclimate in the depositional environment. At the same time, mercury accumulation is more easily in the depositional environment dominated by seawater intrusion than in the terrigenous input.

Abstract In some coal mining areas, the soil will gradually sink and collapse due to underground gouging and form water areas with rainfall, and the mercury and methylmercury accumulated in the soil will enter the water environment and become potential mercury pollutants source. Therefore, in order to understand the temporal and spatial distribution characteristics of mercury in soil under the influence of coal mining activities, total mercury and methylmercury in the soil of subsidence areas located in Huainan, China with different subsidence years were collected and tested. The results show that longer the subsidence years in the soils of different mining areas, lower the methylmercury and mercury methylation rate. In the same mining area, the methylmercury and mercury methylation in the soil will slowly increase with the subsidence time. The total mercury and methylmercury in cultivated soil around the mining area are only close to half of the uncultivated topsoil. The total mercury in farmland soil is mainly concentrated in the topsoil. At the same time, the total mercury continues to decrease with the increase of soil depth. The methylmercury in different farmland soils has a similar trend of methylmercury with the increase of depth, and all peak at the same depth. We find that the main reason is that soil subsidence affects the distribution of soil particle size in depth and then affects the internal structure of soil. This research can provide reference materials for future research on the methylation reaction of mercury in the bottom sediments of subsidence waters.

为了解淮南迪沟采煤沉陷区水体水质状况,将该沉陷积水区水域划分为3个单元(济河、沉陷积水区、对照区),采集不同单元样品,测试分析其水质特征,并利用单因子和综合水质标识指数法进行评价.结果表明:济河和沉陷积水区均为弱碱性水体,水质比较澄清,透明度好.氮磷营养盐指标总体含量表现为济河最高,这与济河周边的农业面源污染有关;重金属Cu、Zn、Pb和As在沉陷积水区均出现一定程度的富集,与沉陷区周边充填煤矸石中重金属淋溶释放、汽车尾气的排放以及地表扬尘有关;通过对沉陷积水区距离济河由近及远每隔15 m采集水样的纵向采样点C1、C2、C3分析得出,其TN和NH4+分布表现出距离济河越近,则含量越低,而TP、Cu、Zn、Pb和As表现出相反的规律性;单因子水质标识指数结果显示,Hg和CODMn在济河和沉陷积水区污染相对严重;综合水质标识指数法显示,3个单元综合水质指标Pi均符合III级标准.在交汇水域,济河采样点J3、J4与沉陷积水区采样点C1、C2的水质状况表现为J3(2.320)

The increase in NO3- content in surface water caused by intensive mining activities in Huainan City, China, has attracted considerable attention owing to the deterioration of water quality and the degradation of ecosystems in recent years. The Huainan mining area, which is highly disturbed by anthropogenic activities, was selected as a typical observation area, and the surface water was classified as open subsidence water (OSW), closed subsidence water (CSW), and river water (RW). Moreover, the hydrochemical parameters and the 815N and 818O values of nitrate were employed to quantitatively trace the sources and biochemical transformation of NO3- and the contribution ratios of different NO3- sources were estimated using the stable isotope analysis in R based on the Bayesian model. There was evident nitrification in the study area, but no significant denitrification has occurred. A substantial portion of 815N-NO3- demonstrated complex sources of NO3- . Compared with those of CSW, the NO3-; compositions of the OSW approached to those of the RW due to river recharge and discharge, and were greatly affected by anthropogenic activities. The proportional contribution of manure and sewage in the OSW was found to be the highest with a mean value of 39.5 % +/- 12.3 %, which was followed by that of mine drainage (mean: 22.1 % +/- 13.1 %), chemical fertilizer (mean: 17.5 % +/- 10.6 %), and soil organic nitrogen (mean: 17.5 % +/- 11.6 %). In the RW, the highest mean contribution of manure sewage was 35.2 % +/- 9.7 %, which was followed by that of chemical fertilizer (mean: 29.3 % +/- 7.2 %), mine drainage (mean: 23.4 % +/- 13.0 %), and soil organic nitrogen (mean: 10.9 % +/- 8.3 %). In contrast, the contribution of chemical fertilizer to the CSW was the highest with a mean value of 33.9 % +/- 13.6 %, which was followed by that of soil organic nitrogen (mean: 26.5 % +/- 13.8 %), mine drainage (mean: 18.1 % +/- 11.6 %). Therefore, NO3-; in the surface water of the mining area primarily originates from chemical fertilizers and manure sewage. In addition, the contribution of mine drainage to nitrate in the study area indicates the potential impact of mining activities on surface water. These findings highlight the value of classifying different types of surface water in tracing NO3- contamination sources, and provide relevant theoretical basis for tracing nitrate sources in other areas.

我国东部矿区是重要的煤粮生产复合区,由于境内地势平坦,地下潜水位高,采空区形成的沉陷大多常年积水或季节性积水,所引起的土地、生态、环境问题尤为严重.植被作为矿区生态环境的重要组成部分,因外界干扰和环境要素的变化而具有动态特征.归一化差值植被指数(NDVI)是植被生长状况遥感监测的常用指示因子,基于NDVI时间序列数据的分析可以有效揭示植被的扰动效应.以安徽淮南顾桥矿为研究对象,基于2007-2018年Landsat NDVI时间序列数据的分级统计,以及热点分析、聚类与异常值分析和剖面线分析,研究NDVI值的时空变化特征,探讨煤矿开采沉陷对周围植被的扰动效应.研究表明:2007-2018年间顾桥矿植被生长状况整体良好,但植被覆盖离散程度在增大;NDVI分布具有明显的空间聚集特征,均为"高-高"聚类和"低-低"聚类,无异常出现;受煤炭开采影响,热点区减少,冷点区增加,热点向冷点的转化主要发生在沉陷积水区、德上高速和永幸河附近;沉陷积水区周围一定范围内存在明显的植被扰动,开采初期扰动较小,随着积水区范围的增长和时间的推移,扰动范围逐渐增大,最后趋于稳定,具有时序滞后性和时空累积性.研究成果为采煤沉陷区生态影响范围的确定及生态环境的恢复治理提供了参考.

为了解采煤沉陷区水体沉积物中汞的分布特征及影响因素,该文采集淮南煤田顾桥采煤沉陷区水体沉积物样品,测定了样品理化特征及总汞、甲基汞含量,分析探讨样品中总汞和甲基汞分布特征及影响因素.结果表明:(1)顾桥采煤沉陷区水体沉积物中总汞含量范围为16.20～67.10 ng/g,甲基汞含量范围为0.37～1.12 ng/g,甲基化率(MeHg％)范围为1.44％～2.30％.(2)水体沉积物总汞分布具有较大空间差异性,总汞含量高值区主要分布在北部及西部靠近矸石充填道路样点,甲基汞分布与总汞类似,北部与西南样点含量较高;MeHg％高值主要集中在养殖鱼箱附近样点,渔业养殖活动是导致甲基化率较高的主要原因.(3)相关性分析结果显示,水体沉积物中有机质、黏粒含量与总汞、甲基汞均呈正相关关系,细颗粒中有机质是水体沉积物汞的主要载体,减少研究区无机汞和有机质的输入可降低甲基汞产生带来的环境危害;MeHg％与pH呈正相关关系,与黏粒含量呈负相关关系,主要与水体沉积物汞的存在形态及有机质类型有关,MeHg％与有机质和总汞含量的相关性不明显,有机质与总汞的共沉积可能是影响MeHg％的主要作用方式.研究结果可为研究区水体环境汞污染防治提供科学依据.

以淮南煤田深部A组煤为研究对象,全层刻槽采集了煤、夹矸和顶底板岩石样品,采用电感耦合等离子质谱仪(ICP-MS)测试分析了样品中13种有害微量元素的含量,对比研究了其分布特征,结合Tessier五步形态提取法和相关性分析探讨了煤中有害微量元素的赋存形态.结果表明:(1)与中国上陆壳中各种微量元素含量均值相比,淮南深部A组煤中B,As,Se,Mo,Cd,Pb,Hg的富集系数均大于1,在A组煤中表现为富集;A组煤中B,As,Se,Cd的含量均高于淮南煤田上部B组煤、华北煤以及中国煤中的含量均值;(2)相关性分析和逐级提取实验结果表明,A组煤中微量元素主要以残渣态和铁锰氧化物结合态存在,两者质量分数之和达到55％～98％,其中Ni,Mo,Cd,Hg,Cu,Pb和Zn主要赋存于硫化物矿物中,Mn主要赋存于碳酸盐矿物中,V,Cr,Se,B和As主要赋存于硅铝酸盐等黏土矿物中.(3)B元素示踪物源及沉积环境结果显示,淮南煤田深部A组煤成煤环境为海相咸水沉积环境,稳定的咸水沉积环境以及受海水影响等因素导致A组煤中微量元素出现不同程度的富集.

In order to explore the distribution and migration characteristics of trace elements among overlying water, sediment and pore water, overlying water (n=10) and surface sediment (n=10) samples were collected in the Guqiao coal mining subsidence water body. The surface sediments were centrifuged to obtain the corresponding pore water samples (n=10). The heavy metals(As, Cd, Cr, Cu, Mn, Ni, Sb and Zn)in these samples were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Atomic Fluorescence Spectrometry (AFS), with an aim of evaluating the associated pollution degree of heavy metals by methods of heavy metal pollution index and geo-accumulation index. The following results were obtained. (1) The water quality of Guqiao coal mining subsidence area was acceptable, satisfying the water quality standard of fish culture. The mass concentrations of Cr, Cd and Zn in the pore water were 193.11, 2.14 and 176.18 μg·L-1, respectively, which were potentially toxic to the biota. Compared with the China sediment and the Huainan soil background values, As, Cd, Cu, Cr, Ni were enriched in the studied sediment samples. It was noted that the average content of Cd was as high as 1.114 mg·kg-1. (2) The distribution of heavy metals obeyed the following order:sediment>pore water>overlying water. (3) The distribution coefficients of Cd, Zn, Sb indicated that they easily migrated from sediments to the overlying water, posing potential environmental hazards. Correlation analysis showed that As and Mn, and Cu and Cd might have the same pollution source in overlying water. The heavy metals in the pore water were well correlated, indicating that these heavy metals might have the same sources. It appears that Ni in sediments has the same sources as Zn and Mn. (4) Geo-accumulation index revealed that Cd in sediments was in heavy pollution and Cr was in slight pollution. The order of heavy metal pollution degree was as following: Cd>Cr>Sb>Cu>As>Ni=Mn>Zn. Cd and Cr pollution should be paid attention to.

以淮南采煤沉陷区土壤为研究对象,测试分析了样品中汞的含量,结合土壤pH值、有机质含量特征,探讨了采煤沉陷区土壤中汞的时空分布特征.结果表明:与未沉陷区土壤相比,沉陷区土壤有机质破坏严重,最高下降了46％;采煤沉陷区土壤中汞的含量为0.013～0.050 mg/kg,平均值为0.027 mg/kg,69.7％的采样点超过了淮南市土壤背景值;沉陷8a后土壤汞含量最高,为0.033 mg/kg,是未沉陷土壤汞含量的1.74倍,且随着沉陷时间的增加,土壤中汞存在富集趋势;水稻土壤汞富集能力最高,高于玉米和大豆土壤;在垂直剖面上,汞含量由表层向下依次降低;且汞与pH值表现出显著负相关,有机质与汞显著正相关.