Enrichment of heavy metals in coal gangue by puff balls and mechanism research

Coal gangue with/without wild puff balls growing on or covering up were analyzed by means of inductively coupled plasma atomic emission spectrometry （ICP-AES） and atomic fluorescence spectrometry （AFS） to detect the contents of heavy metal elements in the plants. Seven heavy metals were chosen to do the experiments, which showed that the puffballs have strong enrichment capacity for heavy metals （As, Pb, Mn and Ni）. The highest enrichment level was Mn, 220.3 mg/kg （dry weight） for puffball fruiting bodies, and the highest As, Cr and Pb enrichment levels for puffball mycelium were 111,265.3 and 86 mg/kg, respectively. Cd, Mn and Ni could transfer from puffball mycelium to its fruiting bodies, while As, Cr, Pb and Co mainly accumulated in the mycelium. The contents of five organic acids （tartaric acid, glycolic acid, lactic acid, citric acid and malic acid） in puffballs were determined with high performance liquid chromatography. With water, ethanol and ethyl acetate as solvents, the puffball extracts performed dissolution reactions with coal gangue, in which the water extract （containing a large amount of organic acids） was most effective in releasing heavy metals, especially As, Pb, Cr, Mn, Co and Ni from coal gangue. As a pioneer species, puff balls absorbed the hazardous trace elements in coal gangue matrix to reduce its eco-toxicity, on the other hand, it raised the pH value of coal gangue, improving the vegetation growing conditions for coal gangue matrix to a certain extent and laying the foundation for ecological restoration of coal gangue dumps.     

Organic geochemical characterization of the New Albany Shale group in the Illinois Basin

Benzene extractable aliphatic hydrocarbons from the New Albany Shale in the Illinois Basin were characterized by gas chromatography and mass spectrometry, and the total organic matter of the shale was characterized by solid state carbon-13 cross polarization magic angle spinning nuclear magnetic resonance. Core samples from a northwest-trending cross-section of the Illinois Basin were studied. Gas chromatography (GC) and gas chromatography-mass spectrometric analysis (GC/MS) data indicate a regional variation of the aliphatic composition of the shale extracts. A positive, linear relationship between the two ratios, pristane/n-C₁₇ and phytane/n-C₁₈, is indicated. The NMR results indicated that organic matter deposited in northwestern Illinois shale is relatively high in aliphatic hydrocarbon content while, in contrast, organic matter found in southeastern Illinois shale is relatively low in aliphatic hydrocarbon content. Our findings suggest that the organic variation of the shale is mainly due to the differences in thermal maturity of the shale organic matter and the use of pristane/n-C₁₇ ratio as a thermal parameter in the study of oil may be extended to the study of the ancient sediments.     

Petrologic and geochemical characteristics of Seam 9-3 and Seam 2, Xingtai Coalfield, Northern China

Six samples of Carboniferous (Mississippian–Pennsylvanian) coal (Seam 9-3) and 11 samples of Permian coal (Seam 2) from the Xingtai Coalfield were studied by petrological and organic geochemical methods. Both seams show different petrological and geochemical compositions. In Seam 9-3 of the Carboniferous age, the predominant maceral is vitrinite (83%) whereas in Seam 2 of Permian age, inertinite predominates (45%). “Barkinite” was found with an average content 1% only in Seam 2. Sixty-four different aromatic compounds were identified by gas chromatography (GC)/mass spectrometry (MS) analysis of solvent extracts (Extr) of both seams. Abundant polyaromatic sulfur hydrocarbons (PASH) were determined in coal samples from Seam 9-3, while they are very low in samples from Seam 2. 1,2,5-Trimethylnaphthalene and 1,2,5,6-tetramethylnaphthalene contents are much higher in Seam 2, while 2-methylfluorene contents are higher in Seam 9-3. Cadalene was found in Seam 2 with a high content of 94 mg/kg coal but was not detected in samples from Seam 9-3. This might indicate a different floral contribution to the sedimentary organic matter. All petrologic and geochemical results indicate that Seam 2 formed in a more oxidized environment compared with Seam 9-3.     

Biomarkers and compound-specific stable carbon isotope of n-alkanes in crude oils from Eastern Llanos Basin,Colombia

Representative samples of crude oils from Cusiana, Cupiagua, Apiay, Castilla and Chichimene fields in the Eastern Llanos Basin of Colombia were analyzed to determine its compound-specific stable carbon isotope composition (CSIA) using gas chromatography–isotopic ratio–mass spectrometry (GC–IRMS). GC–IRMS analyses of n-alkanes allowed differentiating between Cretaceous and Cretaceous/Tertiary oil samples. Cretaceous sourced samples have δ¹³C-enriched values than Cretaceous/Tertiary sourced samples; the heavier isotope composition of these samples is due to their major terrigenous organic matter input. Their isotope distribution patterns suggest significant algal and/or bacterial contribution (marine origin). The analysis of the n-alkane fractions by GC–IRMS confirms that the organic matter has marine origin in those samples from Cusiana, Cupiagua and Apiay while Castilla and Chichimene have marine origin with terrestrial inputs. The results were confirmed by gas chromatography/FID and gas chromatography/mass spectrometry (GC/MS). Basic geochemical composition show that samples from Cupiagua/Cusiana fields and Apiay/Castilla/Chichimene fields in the Llanos basin, Colombia present different characteristics reflecting a specific for each depositional environment.     

不同地质年代煤矸石中有机质的溶出特征对比

分别以神东矿区补连塔矿侏罗纪煤矸石和保德矿二叠纪煤矸石为研究对象,通过浸泡实验,结合三维荧光光谱测试技术及平行因子分析法,对比研究2种煤矸石中有机质的溶出特征,这对于开展煤矿区地下水库水处理机理研究具有重要意义。研究结果表明:由于煤矸石自身矿物组成不同,补连塔矿煤矸石浸泡液中总离子质量浓度高于保德矿,且2种煤矸石浸泡液均呈弱碱性;其中补连塔矿煤矸石溶解性有机质（DOM）中含有较多的共轭双键或苯环类简单芳香族化合物,以富里酸和分子量较大的陆源类腐殖质为主,且含量普遍高于保德矿,而保德矿煤矸石中富里酸和酪氨酸类有机质较多。根据DOM样品荧光指数（FI）、生物源指数（BIX）、腐殖化指数（HIX）的计算结果,2种煤矸石中DOM主要为内源有机质,并具有较强的自生源特征,且煤矸石形成地质年代越早,煤矸石DOM样品的"微生物源"特征越明显。      

Organic components in thermally altered coal waste: Preliminary petrographic and geochemical investigations

The petrographic and geochemical composition of coal wastes exposed to fire in the minestone dump of Piekary Ślą¹skie town (Upper Silesia, Poland) was investigated using samples collected at various distances from a recent fire site. The question as to whether geochemical biomarker maturity parameters could be applied to assess thermal changes in organic matter caused by waste dump fires, was examined using the data obtained. Geochemical parameters were correlated with observed petrographic changes in the organic matter caused by oxidation and heating. Petrographic analyses included the determination of maceral group contents (vitrinite, liptinite and inertinite), mineral matter and coke contents, and reflectance measurements on organic matter. All results were supported by proximate and ultimate analyses. Geochemical analysis included ultrasonic solvent extraction of bitumen followed by gas chromatography–mass spectrometry (GC–MS) of the extracts. In petrographic terms, the influence of heating was seen in reflectance variations and as oxidation rims, cracks, pores and coke development. Some zoned oxidation rims may be interpreted as re-heating episodes. In terms of chemical fingerprints, less thermally-stable compounds such as lighter n-alkanes, cyclic isoprenoids, methyl- and dimethylnaphthalenes, methyphenanthrenes and five-ring polycyclic aromatic hydrocarbons were destroyed or evaporated in the most fire-affected material. The presence/absence of particular compound groups was used to assess heating temperatures. Biomarker parameters of thermal maturity were used to assess alterations in organic matter around the waste dump fires, especially those indices and ratios with higher maturity ranges, e.g. (3-methylbiphenyl + 4-methylbiphenyl)/dibenzofurane and Σdimethylbiphenyls/Σmethyldibenzofuranes.     

煤矸石堆积区土壤重金属形态组成与生物有效性的空间变化特征

煤矸石地表堆积是我国东部煤矿区生态环境破坏的典型形式,造成堆积区土壤重金属污染的防控已成为当前研究热点。以河北峰峰矿区某在用煤矸石山周边(方圆300 m以内)浅层土壤(垂直深度40 cm以浅)为研究对象,采用Tessier连续提取法和电感耦合等离子体发射光谱仪,测定Cu、Cr、As、Pb这4种土壤重金属的有效态、铁(锰)氧化物结合态、有机结合态和残渣态含量,基于生物活性系数(MF)和生态风险评价编码法(RAC)计算与评价4种土壤重金属生物有效性及生态风险,剖析4种土壤重金属形态组成与生物有效性的空间变化特征。结果表明:(1) 煤矸石的堆存具有提高周围土壤中Cu、Cr、As、Pb有效态质量分数和降低残渣态质量分数的效应,且与距煤矸石山的水平距离成反比,当水平距离达到或接近300 m时,该效应基本消失。(2) 土壤总有机碳(TOC)质量分数与4种重金属有效态质量分数的相关系数均超过0.6,达到显著正相关水平(p<0.05),是影响研究区土壤重金属有效态含量空间变化特征的主要因素。(3) 4种土壤重金属生物有效性的空间变化特征可分为2个类型,Ⅰ类为“MF值一般大于3,且具有显著的空间异质性”;如 Cu、Cr,Ⅱ类为“MF值一般小于3,且具有显著的空间同质性” ,如As、Pb。(4) 当距煤矸石山水平距离分别小于80和40 m时,土壤重金属Cu、Cr的 MF平均值超过中等风险水平阈值的60%,应予以重视。建议综合考虑煤矸石山存续状态、土壤重金属累积效应及生物有效性空间变化特征等因素,制定煤矸石堆积区土壤重金属污染精准防控及安全利用策略。      

Organic Geochemistry Characteristics in Ores and Host Rocks from Qixiashan Lead-Zinc Deposit, Nanjing, China

Organic matter, associated with ores, host rocks, ore source rocks and present in fluid inclusions in the Qixiashan lead-zinc polymetailic deposit hosted in Upper Carboniferous dolomites and limestones in East China, was systematically analyzed using Fourier transform infrared spectroscopy, gas chromatography (GC), GC/mass spectrometry and proton-induced X-ray emission. The biomarker ratios of nC21^--/n22^ -alkanes, C23-tricydic/C30-hopane and the tricyclic terpane parameters induding C21/C23, C19-10/C21-29 and C19-25/C26-29 can effectively discriminate ores from host rocks. Extractable organic matter present in fluid inclusions displays similariUes to those enclosed in the ore source rocks in the biomarker ratios, suggesting that a proportion of orphic matter was introduced into the deposit from the ore source strata. The presence of copper and zinc in stage Ⅱ pyrobitumen indicates that some metals may have been transported by an organic fluid or removed from an aqueous fluid by organic matter.     

Characteristics of biomarkers in source rocks of the Ganquan Formation in the Dahulishan region, Ejina Banner

Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors examined biomarker characteristics of the Ganquan Formation source rocks in the area of Dahulishan, Ejina, and analyzed the information and petroleum geological significance that were indicated by the source of organic matter, sedimentary environment and maturity and so on. Gas chromatography peak of saturated hydrocarbons from the Ganquan Formation source rocks showed "the former peak" of the single peak distribution, the main peak of carbon being C18 , indicating the main sources of organic matter with marine organic matter. Pr/Ph ranges from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Biomarker assemblages of the Ganquan Formation source rocks are abundant in tricyclic terpane with long side chains, with a high level of gammacerane, showing dominant distribution of C27 sterane. High contents of gammacerane in organic matter show organic facies of source rocks in the saltwater sedimentary environment. That average hopane/sterane ratio is 0.59, showing that algae have made more contributions to organic matter than bacteria. And the high level of C27 steranes shows that algae are the main source of hydrocarbon precursors. The Ganquan Formation’s methylphenanthrene index, which is an effective molecular parameter index to measure thermal evolution of organic matter, ranges from 0.35 to 0.50, and the conversion of vitrinite reflectance Rc from it is within the range of 2.00-2.09, indicating that the Ganquan Formation source rocks are in the over-mature stage of thermal evolution.     

褐煤高温水萃物生物产气及化学组成变化

微生物与煤的相互作用过程复杂，为了深入分析煤中有机物在生物产气过程中的作用及变化规律，选取义马褐煤和实验室保存的产甲烷菌群作为研究对象，研究褐煤水溶性有机物产气特征及其产气前后化学组成变化。利用去离子水在70℃下萃取褐煤得到水溶性有机物、水萃余煤，分别以其作为底物开展生物产气实验，并利用甲醇对产气后的残煤进行有机萃取，采用GC、HPLC-MS和GC-MS方法分析产气量变化及发酵液和煤甲醇萃取物的化学组成。结果表明，褐煤原煤、水溶性有机物和水萃余煤的产气量分别为0.46、0.45和0.15 mmol/g。产气初期水溶性有机物化学组成复杂，分子量主要集中在200~300 Da，生物产气后化合物种类减少，分子量降至150~200 Da，并且产气后发酵液中检测到一些分子中具有苯环结构的含氮和氧杂原子的化合物。水萃余煤生物产气后的甲醇萃取物中出现少量水溶性化合物如甲酰胺、乙酰胺、亚硫酸二甲酯等。70℃萃取得到的义马褐煤水溶性有机质能被产甲烷微生物利用产气，经过生物产气后煤中非水溶性有机物会转变成水溶性有机物。本研究探索了褐煤中水溶性有机物在生物产气过程中的潜在作用，为阐明煤生物产气的物质基础提供了实验依据。      

Sourcing sedimentary cherts with archaeological use through the combination of chromatographic and spectroscopic techniques

The nature and distribution of organic matter in geological cherts of archaeological use can serve to estimate the sources and origins of some remains of lithic industry. For example, organic and biomarker analysis can provide information to allow a deeper insight into source catchment areas, artefact displacement or the way in which the artefacts were employed. In this work, soluble (bitumen) and insoluble (kerogen) organic matter were isolated from several chert samples with different depositional history and analysed by means of gas chromatography–mass spectrometry (GC–MS) and spectroscopic techniques such as infrared and Raman spectroscopy. Chemometric treatment of the results allowed observation of differences between organic matter content on the basis of the depositional setting of the cherts. Samples with a continental deposition seemed to preserve more organic matter with little alteration. The hydrocarbon profiles of these samples were dominated by high molecular weight n-alkanes, alkylcyclohexanes and isoprenoid groups which allowed distinguishing them from the rest of the analysed samples.     

陕北侏罗纪富油煤有机地球化学特征

富油煤的有机地球化学特征对研究其形成时期的古沉积环境和演化过程具有重要意义。以陕北地区侏罗纪延安组6个主采煤层为研究对象,运用煤质分析和气相色谱–质谱联用方法分析其有机地球化学特征。结果表明:陕北地区延安组主采煤的氯仿沥青“A”含量较高,饱芳比较低;正构烷烃呈单峰型分布,中链饱和烃占优势,Pr/nC₁₇、Ph/nC₁₈、Pr/Ph的值较高;C₂₈和C₂₉的规则甾烷和重排甾烷占主导地位。分析表明:陕北地区延安组主采煤层处于低热–成熟阶段,为富氢基质镜质体和壳质组生油的有利阶段;有机质来源以陆生高等植物为主并有部分水生生物混入,形成于贫氧的泥炭沼泽环境,且经历了较强的生物降解作用,为富氢组分的形成提供了有利的条件。      

近代盐湖沉积物中的生物标志化合物

    生物标志化合物是在沉积有机质地质演化过程中可保留其原碳骨架的生物分子，具记录沉积环境和沉积有机质热演化历史的功能。用有机地球化学方法（气相色谱、气相色谱/质谱、热解色谱和同位素质谱）对采自我国西部盐湖的近代沉积物进行了大量研究，而且对盐湖沉积环境地球化学特征、有机质组成与早期成岩作用的关系和各种生物标志化合物指标进行了更加深入细致的探索。研究结果表明干酪根碳同位素组成（δ¹³C PDB）和盐湖类型有关系，例如，硫酸盐型湖的干酪根δ¹³C 值较重，而碳酸盐型盐湖的δ¹³C值则较轻。姥鲛烷/植烷比（Pr/Ph）、总三环萜烷/总萜烷（%）、孕甾烷/甾烷比（%）、伽玛蜡烷/αβ—藿烷和三芴系列化合物组成三角图等生物标志化合物指标可以用来判识沉积环境的盐度。通常，在盐湖或咸水沉积环境中，除额吉卓尔盐湖样品因采自边缘，Pr/Ph比值较大而外，其余各盐湖样品的Pr/Ph比值一般≤1.0，而其余各比值均明显大于在淡水湖中的比值；三芴系列化合物三角图中，各盐湖样品均集中分布在硫芴含量高的区域。与我国各典型沉积环境中的原油及古代岩样的分析结果作了对比，发现同样表现出上述规律，故认为是良好的识别标志。正构烷烃分布、甾烷相对含量及某些特殊生物标志化合物的含量如三环二萜烷可以用来划分可溶有机质类型。察汉卓和查干诺尔盐湖可溶有机质中，正烷烃以低碳数占优势，显示其组成主要来源于低等水生生物；额吉卓尔盐湖则以高碳数为主，显然与边缘相陆生高等植物的输入有关；而小柴旦盐湖正烷烃高低碳数分布均衡，说明高等植物与低等水生生物同时输入。C₂₇～C₂₉正常甾烷及三环二萜烷的组成与分布也显示了相似特征。
    另外，还发现了多种非常规生物标志化合物，报导了其 m/z 217、m/z 231、m/z 245、m/z 259离子色谱特征。这些特征离子大多由三芳甾烷产生。三芳甾烷是由生物分子（甾体）在地质条件下演化而成的。盐湖沉积物中大量该类化合物的发现意味着含盐沉积环境及其继后的早期成岩作用在甾体的这种芳化过程中起着积极作用。     

淮南塌陷塘重金属空间分布特征研究

长期地下煤炭开采在地表产生了大面积的塌陷塘,并造成了不同程度的水域污染。为研究塌陷塘重金属的分布特征及成因,选择了8种对环境影响较大的重金属元素（Fe,Mn,Zn,Cu,Cr,Cd,Pb,Ni）为研究对象,以淮南潘集一矿塌陷塘为研究区域,利用ArcGIS地统计模块中的协同克里格算法,通过水体实测光谱反射率作为协变量来估算水体中的重金属含量空间分布特征。结果表明:水体实测光谱与重金属含量有较好的关系,以水体光谱为协变量的协同克里格插值与单变量的普通克里格插值相比,8种重金属元素的预测值与实际值之间的均方根误差明显减少,证明水体实测光谱适合作为协变量来估计水体重金属的空间分布情况。综合分析发现,水体中的Cd,Pb,Cu,Ni主要来自水域西北部的煤矸石堆山,且Cd,Cu,Pb含量均超过了当地的背景值,对环境影响较大;Cr主要来自农业肥料、成土母质和周边道路旁的煤泥灰厂及煤矸石堆;Zn的来源主要是煤矸石、上游生活污水、农业肥料、土壤母质,由于其含量较低,对水环境质量的影响不大。      

Paleocene-Eocene potential source rocks in the Avengco Basin,Tibet: Organic geochemical characteristics and their implication for the paleoenvironment

The Avengco Basin is located in the western part of the Tibetan Plateau and is similar to the Nima Basin in the central part of the plateau and the Lunpola Basin in the eastern part in terms of sedimentary characteristics and tectonic settings, which are well known to provide a good source rock potential. However, the organic geochemical characteristics of the Paleocene-Eocene potential source rocks in the Avengco Basin have been under debate. Thirty-four marl and mudstone outcrop samples of the Niubao Formation in the Avengco Basin were collected and subjected to the following analyses: total organic carbon (TOC), Rock–Eval pyrolysis, stable carbon isotopes of kerogen, gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). Here, we present the results indicating the organic matter of the upper Niubao Formation is mainly composed of Type II kerogen with a mixed source, which is dominated by algae. However, the lower Niubao Formation has the less oil-prone Type II–III kerogen, and the sources of the organic matter are mainly terrestrial plants with less plankton. In addition, the samples are thermally immature to marginally mature. The Niubao Formation was deposited in an anoxic–oxic environment which was brackish with an imperceptible stratified water column. The upper Niubao Formation has a medium to good hydrocarbon-generating potential. However, the lower Niubao Formation has a zero to poor hydrocarbon-generating potential.     

Influences of the basin brines on extractable bitumen of Kupferschiefer from southwestern Poland

A study of the influences of the basin brines on hydrocarbon generation of the Kupferschiefer in southwestern Poland has been carried out.The samples from the Konrad and Polkowics mines were analyzed by orgainc geochemical,microscopic and FTIR methods.The results indicate that organic matter of Kupferschiefer tends to decrease with the ascending,oxidizing brines,In the Konrad profile,the Kupferschiefer was strongly oxidized.The extract yields were depleted up to 50mg Ext/g Corg.Gas chromatography(GC) and gas chromatography-mass spctrometry(GC/MS) data indicate that the depletion occureed predominantly in saturated hydrocarbon compounds.The identified n-alkanes in smpale KD1 were depleted at least to 5000μg/g Corg.The aromatic compounds show a fidderent trend of variation.The concentrations of phenanthrene alkylphenanthrenes(Ph-PAH) and naphthalene alkylnaphthalenes(Na-PAH) show a decrease,whereas sulfur polyaromatic hydrocarbons(S-PAH)and oxygen polyaromatic hydrocarbons(O-PAH) show an incrase under the influences of oxidizing brines,In the Polkowice profile,organic matter under the influences of oxidizing fluids shows a simlar trend of varation as in the Konrad mine.Analyses of polar compounds shed light on the oxidation processes at the molecule level.The dominant products of oxidation are aliphatic acid.alcohol and ester.FTIR results indicate that the oxidation of organic matter led to a decrease in aliphatic CH3 and an increase in C-O,C=O bands.     

Hydrocarbon source potential and depositional environment of the Surma Group shales of Bengal basin,Bangladesh

Surma Group is the most important geological unit of Bengal basin, Bangladesh, because petroleum resources occur within this group. It is mainly composed of alternation of shale and sandstone and the shale fraction has long been considered as source rocks and the sandstone fraction as reservoir. These source and reservoir rocks have been studied by different authors by different approach but none of them adopted organic geochemistry and organic petrology as a means of study of source rock and their possible depositional environment. A total of thirty shale core samples have been collected from eight different gas fields to fulfill the short coming. The collected samples have been subjected to Source Rock Analysis (SRA) and/or Rock-Eval (RE) followed by pyrolysis gas chromatography (PyGC), gas chromatography mass spectrometry (GCMS), elemental analysis (EA) and organic petrological study such as vitrinite reflectance measurement and maceral analysis. The analyzed organic matter extracted from the shales of Surma Group consists mainly of Type III along with some Type II kerogen. The studied shales are mostly organically lean (TOC ±1%) and the extracted organic matter is fair to moderate. Based on these results, the analyzed shales have been ranked as poor (mostly) to fair quality source rock. The organic matter of the analyzed shale samples is thermally immature to early mature for hydrocarbon generation considering their T_max and measured mean vitrinite reflectance values. The hopane 22S/(22S + 22R), moretane/hopane ratio and sterane parameters are also in good agreement with these thermal maturity assessments. The predominance of odd carbons over even carbons (most common) and/or even carbons over odd carbon numbered n-alkanes, moderate Pr/Ph ratio, low to high Tm/Ts ratio, comparative abundance of sterane C₂₉ (i.e., C₂₉ >C₂₇>C₂₈), Pr/nC₁₇ — Ph/nC₁₈ values, C/S ratio and dominance of vitrinite macerals group with the presence of liptinite macerals demonstrate that the organic matter has derived mainly from terrestrial inputs with an insignificant contribution from the marine sources. The condition of deposition alternates from oxic to anoxic.     

Pollution of a water course impacted by acid mine drainage in the Imgok creek of the Gangreung coal field,Korea

The purposes of this study are to (i) determine the geochemical characteristics of Imgok creek impacted by acid mine drainage (AMD) generated from abandoned coal mines, (ii) to assess the pollution of heavy metals in the stream sediments and soils, and (iii) to identify the chemical form of Fe precipitates collected in the study area where there are 4 abandoned coal mines, which belong to the Grangreung coal field at the eastern part of Korea. AMD generated from mine adits and coal refuse piles shows low pH, and high concentrations of Fe, Al and SO₄, especially in the Youngdong coal mine. In Imgok creek, pH values increased, and total dissolved solids (TDS) values decreased with distance. The concentrations of toxic heavy metals and major cations except Fe decreased by dilution, but the concentration of Fe decreased rapidly due to the formation of precipitates. The quality of groundwater samples did not exceed the Korean drinking-water standard. In the stream sediments, the concentrations of Fe are relatively high in the Youngdong tributary and Imgok creek, but the concentrations of heavy metals are similar to those of unpolluted sediments. Pollution indices of agricultural soils range from 0.28 to 0.47. Yellowish red Fe precipitates collected in the study area turned out to be amorphous or poorly crystallized minerals (determined by X-ray diffraction patterns and Fe_ox/Fe_tot ratios) and to contain chemically bonded SO₄ and OH [determined by infra-red (IR) spectral analysis]. With these, the mol ratios of Fe/S ranging from 4.6 to 6.1 determined by electron probe micro-analysis (EPMA) in precipitates strongly support the existence of schwertmannite.     

Organic geochemical evaluation of Cretaceous shale samples from the Orange Basin,South Africa

Organic geochemical evaluation of thirty-two Aptian to Campanian shale samples from seven wells drilled on the shelf of the Orange Basin (southwestern Atlantic margin) was carried out in order to determine their origin, depositional environment, thermal maturity and hydrocarbon potential. The shale samples, selected to represent highstand, lowstand and transgressive systems tracts, were analysed by Rock–Eval pyrolysis for total organic C characteristics and by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) for n-alkanes, aliphatic isoprenoid hydrocarbons and biomarkers (steranes, hopanes and tricylic terpanes). For most of the shale samples Rock–Eval data, hydrogen (HI) and oxygen index (OI) point to mainly Type III terrigenous organic matter. Only a few samples of Turonian age reveal a higher proportion of marine organic matter being classified as Type II/III or Type II. Biomarker parameters suggest that the samples are deposited under suboxic to oxic environmental conditions. Rock–Eval data and biomarker maturity parameters assign for most of the samples a maturity level at the beginning of the oil window with some more mature samples of Aptian, Albian and Cenomanian age. The hydrocarbon generation potential is low for most of the shelf shales as indicated by the S2/S3 ratio and HI values. Exceptions are some samples of Turonian and Aptian age.     

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine,Middle Benue Trough,Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leavescassava tuberspeelings. In the same plant species, metal levels decreased in the order of ZnFeMnCuPbCrCd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.