Hydrogeochemical characteristics of acid mine drainage and water pollution at Makum Coalfield,India

Acid mine drainage (AMD) is one of the severe environmental problems that coal mines are facing. Generation of AMD in the northeastern part of India due to the coal mining activities has long been reported. However detailed geochemical characterization of AMD and its impact on water quality of various creeks, river and groundwater in the area has never been reported. Coal and coal measure rocks in the study area show finely disseminated pyrite crystals. Secondary solid phases, resulted due to oxidation of pyrite, occur on the surface of coal, and are mainly consisting of hydrated sulphate complexes of Fe and Mg (copiapite group of minerals). The direct mine discharges are highly acidic (up to pH 2.3) to alkaline (up to pH 7.6) in nature with high concentration of SO₄²⁻. Acidic discharges are highly enriched with Fe, Al, Mn, Ni, Pb and Cd, while Cr, Cu, Zn and Co are below their maximum permissible limit in most mine discharges. Creeks that carrying the direct mine discharges are highly contaminated; whereas major rivers are not much impacted by AMD. Ground water close to the collieries and AMD affected creeks are highly contaminated by Mn, Fe and Pb. Through geochemical modeling, it is inferred that jarosite is stable at pH less than 2.5, schwertmannite at pH less than 4.5, ferrihydrite above 5.8 and goethite is stable over wide range of pH, from highly acidic to alkaline condition.     

基于分形理论的粉砂质泥岩酸雨崩解特征研究

黏土岩的崩解过程易受环境条件(如崩解液特征)影响,酸雨作用对其影响显著,但其酸雨崩解特征有待研究。目前对黏土岩崩解特征的评价多采用耐崩解性指数,仅考虑崩解后大于2mm的残留颗粒质量,未反映崩解后的整体粒径分布特征。本文以典型酸雨区攀枝花机场滑坡为依托,选取滑带粉砂质泥岩,开展不同pH值条件下的岩石崩解试验;引入分形理论,建立分形维数与酸雨历时、降雨酸度间的相关关系,定量刻画粉砂质泥岩酸雨崩解特征及影响因素;采用电感耦合等离子体发射光谱法分析不同酸度崩解溶液的离子成分差异,以探索降雨酸度造成岩石崩解特征差异的本质原因。结果表明:采用分形理论可以较好地反映粉砂质泥岩酸雨崩解特征,分形维数越大,粉砂质泥岩崩解程度越大;分形维数与酸雨历时、降雨酸度之间皆存在明显对数正相关关系;不同降雨酸度粉砂质泥岩崩解特征存在差异的原因在于白云石、方解石溶蚀程度不同。研究成果可为酸雨地区黏土岩的工程性质评价提供参考。     

湖北省2007年酸雨特征及其与气象污染条件的关系

利用湖北省32个气象酸雨监测站的酸雨监测资料及相关气象资料对2007年湖北省酸雨特征及其与气象污染条件的关系进行了分析。结果表明：2007年湖北省年均降水pH值为4．47,年酸雨发生频率为71．5％,各酸雨监测站年均降水K值（电导率）在19．3-106．1μs／cm之间,降水强度、逆温及大气中酸性气体的浓度对酸雨强度及发生频率有明显的影响。此外,根据湖北省大气污染的实际情况提出了酸雨防治的相关对策。     

福州气象条件与酸雨的关系研究

利用1991～2000年福州市的探空、雨量和酸雨资料来探讨不同气象条件对降水酸度、酸雨出现率的影响,结果表明：雨量对降水酸度、酸雨出现率有着显著影响;逆温特征越明显,降水酸度越酸。酸雨出现率越大;1500m上空风对福州酸雨有着明显的影响;在暖平流控制下降水酸度不仅酸且酸雨出现率大;随着K指数增大,酸雨出现率逐渐减小。     

湖北西部城市酸雨特征及其与气象条件的关系

根据对湖北省西部宜昌、襄樊、巴东、十堰等城市自然降水pH值的检测结果,对降水pH值变化、时空分布,降水的化学成分、酸雨出现时的风与气象条件、酸雨与降水云类的关系进行了详细的分析。分析结果表明:酸雨形成与当地的地理条件和气象因子有关。稳定的大气环境对酸雨形成有利,较强的逆温和静风频率,可以为当地降水的二次酸化提供有利条件。各地酸性降水化学成分中阴阳离子SO42-/NO2-比值表明,西部城市酸雨具有典型的硫酸型特征。巴东监测的时间较短,但酸雨年出现频率有上升的趋势,并且酸雾出现的几率比较大。襄樊、十堰酸雨出现频率较低与雨水中有较高浓度的阳离子有关。     

２００８年１月１０—１４日陕西区域暴雪成因分析

本文通过对太原市2007年-2009年酸雨观测资料进行分析,讨论了太原市酸雨的年变化规律,分析了太原市酸雨与降水量、风速、风向等气象要素的关系,指出太原市近三年的酸雨频率较高,酸雨强度较强,酸雨已经成为太原市的环境问题.     

A laboratory study of covers made of low-sulphide tailings to prevent acid mine drainage

Covers with capillary barrier effects (CCBE) are considered to be one of the most effective ways to control acid mine drainage (AMD) production from mine wastes. The use of low-sulphide tailings in CCBE has been proposed recently for cases where other types of material may be unavailable near the mining site. This paper presents leaching column test results showing that CCBEs with a moisture-retaining layer made of slightly reactive tailings, with three different sulphide contents, can effectively limit the production of AMD from the acid-generating tailings placed underneath. With these layered covers, the leachate pH was maintained near neutrality throughout the testing period. When compared to uncovered tailings, the efficiency of the cover systems for reducing the amount of contaminants in the percolated water was determined to be greater than 99% for zinc, copper and iron. This study shows that the use of low-sulphide tailings can improve the ability of a CCBE to limit gas diffusion by consuming a fraction of the migrating oxygen.     

Strontium as a tracer of weathering processes in a silicate catchment polluted by acid atmospheric inputs, Strengbach, France

This paper determines the weathering and atmospheric contributions of Ca in surface water from a small spruce forested silicate catchment (N–E France) receiving acid atmospheric inputs. The bedrock is a granite with K-feldspar and albite as dominant phases. The calcium content in plagioclase is low and the Ca/Na ratio in surface water is high, reflecting other sources of calcium from those expected from the weathering of major mineral phases. The biotite content is low. Only traces of apatite were detected while no calcite was found in spite of a major hydrothermal event having affected the granite. The strontium isotopic ratio ⁸⁷Sr/⁸⁶Sr and Sr content was used as a tracer of weathering and was determined in minerals and bulk bedrock, open field precipitation, throughfall, soil solution, spring and stream water. The Sr isotopic ratio of the reacting weathering end-member was predicted by simulating the alteration of the granite minerals by incorporating strontium into the water–rock interaction kinetic code KINDIS. In the early stages of water–rock interaction, K-feldspar and biotite strongly influence the isotopic composition of the weathering solution whereas, the Na-rich plagioclase appears to be the main long-term reactive weathering end-member. Approximately 50% of dissolved Sr in streamwater are atmospherically derived. The ⁸⁷Sr/⁸⁶Sr ratios of exchangeable Sr in the fine fraction at 1-m depth from a soil profile indicate that the amount of exchangeable Sr seems essentially controlled by atmospheric inputs. The exception is the deep saprolite where weathering processes could supply the Sr (and Ca). Na-Plagioclase weathering obviously control the chemistry and the isotopic composition of surface waters. The weathering of trace mineral plays a secondary role, the exception is for apatite when plagioclase is absent. Our hydrochemical, mineralogical and isotopic investigations show that a major part of the strong Ca losses detected in catchment hydrochemical budgets that result from the neutralization of acid precipitation has an atmospheric origin. Consequently, in the long term, in such areas, the availability of such an exchangeable base cation might be strongly limited and surface waters consequently acidified.     

海拉尔盆地贝尔凹陷原油芳烃化合物组成和分布特征

通过色谱-质谱分析,对海拉尔盆地贝尔凹陷35个原油样品进行聚类分析,将之分成4类.Ⅰ类原油是贝尔凹陷原油主体,占分析样品的77%,特点足菲系列含量高,平均值为64.7%,三芳甾类化合物和三芴类化合物含量次之,分别为11.42%和11.81%.Ⅱ类原油为高三芳甾类原油,三芳甾类化合物占芳烃化合物的53.9%,是该类原油的主要成份,非系列化合物含量较低,为32.5%,萘系列含量和三芴化合物含量最低,分别为0.6%和3.54%.Ⅲ类原油为高菲系列和高萤蒽含量原油,菲系列为64%,萤蒽含量高达11%,是其它原油的16倍以上.Ⅳ类原油具有高萘、高三芴化合物和低菲系列化合物的特点,分别占原油芳烃馏分的30%、32%和26%,三芳甾类化合物含量低,占3.6%.这充分说明海拉尔箍地烃源岩沉积期间有不同的沉积环境,原油有不同的牛烃母质.Ⅱ类原油以藻类为主要生烃母质,Ⅲ类原油以高等植物为主,Ⅰ类原油介于Ⅱ类和Ⅲ类原油之间,为混合型生烃母质.Ⅳ原油沉积环境和前三类原油明显不同,为咸水强还原湖相沉积环境.