What controls selenium release during shale weathering?

This study demonstrates that only a combination of a chromous chloride reduction with dual sequential extraction schemes can clearly separate the proportions of Se present in the sulphide versus the organic pools in shales. The data reveals that even small amounts of pyrite outcompete the organic matter for the available Se and pyrite oxidation will control the release of selenium during shale weathering.     

Votalization of selenium in selenium-rich black rock series in Yutangba

Votalization of selenium in selenium-rich black rock series in Yutangba is discussed at 400, 500, 600, 700, 800 and 900℃.Votalization of selenium tends to increase when the temperature is high. So environmental influence of selenium-rich black rock series combustion needs to be considered.     

Study of contents of selenium and arsenic in soil—A long-term field experiment

The potentially dangerous chemical compounds and elements, e.g. selenium and arsenic in relatively high concentrations can cause harmful influence on the environment (irreversible changes). The fate of selenium and arsenic must be followed in the soil-pla…     

Characteristics of selenium migration in soil–plant system of East Meshchera and Transbaikalia

Herein some results of comparative researches to determine the parameters of selenium migration in meadow biogeocenoses of East Meshchera and East Transbaikalia are presented. The parameters of selenium mobility in soils (i.e., the element total content, plant-accumulation coefficient (Kb) and/or mobile form ratio) in Urov biogeochemical provinces of the East Transbaikalia are quite comparable to the element migration parameters found in selenium-deficient landscapes of the same area. Selenium mobility indices and ecological status are significantly higher for meadow biogeocenoses of the East Meshchera (Moscow Region) and also for limestone soils.     

A review of sulfur to selenium ratios in magmatic nickel–copper and platinum-group element deposits

Deviations in the sulfur to selenium ratios (S/Se) from mantle values in magmatic Ni–Cu–Platinum Group Elements (PGE) sulfide deposits have been widely used to constrain the ore forming processes. Basically, S/Se ratios greater than mantle values are interpreted to be the result of contamination of the mantle derived magma by S-rich sedimentary rocks, whereas S/Se ratios lower than mantle values are thought to be the result of S loss during post-crystallization. However, there are many other processes involved in producing a deposit and it is possible that these may be also important in controlling S/Se ratios. In order to investigate the relative importance of these processes, we have compiled a data base of S, Se, δ³⁴S and metal values from Ni–Cu–PGE sulfide deposits. This compilation shows that processes affecting S/Se ratios can be divided into two main classes: the magmatic processes and the late- to post-magmatic processes.

• 1)Magmatic processes include the well-known addition of S from sedimentary rocks, variations in the sulfide to silicate liquid ratio (R-factor), depletion of the silicate magma in Se by early segregation of the sulfide liquid, and the moderate incompatibility of Se into the first sulfide minerals to crystallize from a sulfide liquid, the monosulfide-solid-solution (MSS). This incompatibility results in a change in S/Se ratio between the Fe-rich and Cu-rich zones of magmatic sulfide ores. The fractionation of Se during crystallization of sulfide liquids has not previously been appreciated.
• 2)Late- to post-magmatic processes include: hydrothermal alteration, high-grade metamorphism, serpentinization and supergene weathering. Some metamorphosed Cu-deposits have low S/Se ratios suggesting S-loss by breakdown of sulfide minerals during a high-grade metamorphic event. However, the effectiveness of this process remains unclear and alternative models exist. The preferential remobilization of S relative to Se during hydrothermal alteration, serpentinization and supergene weathering leads to a moderate decrease of S/Se ratios values and can mask the initial S/Se ratio.

     

土壤电化学

土壤电化学是研究土壤中带电粒子之间的相互作用及其化学表现的科学。这些带电粒子包括胶粒、离子、质子和电子。土壤电化学是土壤科学中的一个学科分支。它可以揭示土壤中的化学现象的本质,为土壤的合理利用和改良以及环境保护等提供科学依据。     

污水土壤处理试验研究

污水土壤处理试验,主要是利用透水性较强的土壤层的生物化学作用,其次是淋滤吸附。通过离子交换等作用去除污染质,这一研究在我国属于新的领域,本文通过对污水土壤处理的工作原理,运行效果及环境保护作用等进行了综合论述。     

土壤地理研究的发展

作者围绕14届国际土壤科学大会,介绍了国际土壤分类、土壤调查制图、世界土壤和土地数字化数据库、东亚土壤地理和土壤全球变化等方面研究的最新进展,指出我国应把土壤地理研究置于全球变化的总目标下,加强中国土壤系统分类的研究,开展1∶100万土壤—土地数字化数据库的工作、建立土壤地理信息系统以及防治土壤退化保证农业的持续发展。     

缅怀马溶之教授——纪念马溶之诞辰100周年

马溶之先生是我国著名土壤学家,首任中国科学院土壤研究所所长。由于他的广泛实践、深入探索和勇于创新,对中国土壤地理,包括土壤制图、土壤区划和土壤分布规律做出了杰出的贡献。他是中国土壤分类的革新者,推动了不同时期中国土壤分类的发展,其中,对干旱土、紫色土和水稻土有创新性研究。由于马先生对古土壤发生演化的研究,提供了古环境变化和黄土的生成信息,丰富了第四纪研究的内容,并从农业土壤研究的实践出发,深刻认识人为作用对土壤的影响,马先生有远见地意识到"人类世"的来临。作为全国土壤科学的组织者和领导者,马先生在为土壤资源开发、土壤改良和粮食安全以及为国民经济的建设呕心沥血而受到广泛的赞扬和尊敬。     

The dynamics of organic matter in soil size and density fractions traced by stable carbon isotopes

1IntroductionSoilorganicmatter (SOM)isakeysourceofnutrientsforplantgrowth ,itisessentialforthemaintenanceofsoilstructureanditcontributestotheabilityofsoiltoretainnutrientsandwater.AnimprovedunderstandingofSOMdynamicsiscentraltothedevelopmentofmoreenvironmentallysoundandsustainablepracticesofagriculturalmanagement (Collinsetal.,2 0 0 0 ) .Avarietyofcon ceptualmethodshavebeenusedtodescribetheprocessesofSOMaccumulationandturnover (Jen kinsonandRayner,1 977;Duxburyetal.1 989;Partonetal.,1 99…     

土壤添加物对土-水曲线和土体收缩的影响

为探索不同添加物(小麦秸秆、麦壳和植物油渣)对土壤持水性能和土壤收缩特性的影响,定量掺混3种粉末,采用离心机法测定土-水曲线,并对土壤持水能力和土壤收缩特征进行评价。结果发现:各处理土-水曲线形态无差异,van Genuchten模型可用于此条件土-水曲线拟合;3种添加物均可提高土壤容重和土壤含水率并利于保水,且土壤持水能力表现为油渣 >麦秆 >麦壳 >纯土;随着土壤脱水,土体以轴向收缩为主,三直线模型可用于土壤收缩曲线拟合,土体线缩率与吸力和含水率分别满足对数和Logistic函数关系;土体几何收缩量表现为麦壳 <油渣 <麦秆 <纯土,土壤开裂程度表现为油渣 <麦秆 <麦壳 <纯土。     

土壤中氡浓度检测及其影响因素

综合相关文献研究,通过工程实例介绍土壤中氡气浓度的检测方法,对检测结果进行统计学分析,根据分析结果探讨不同土壤中氡浓度差异及其影响因素。结果显示:土壤孔隙度是影响土壤中氡气浓度的关键因素。不同类型的表层土壤,孔隙度不同,所含氡气浓度也不同。当表层土壤为房渣土、填土时,土质夯实,孔隙率低,氡浓度含量较低;表层土壤为粉土、粉质粘土时,土质较均匀,土层较疏松,孔隙度略大,土壤氡浓度大于前者;表层土壤为粉砂、细砂时,土层更为疏松,土壤中孔隙度再次增大,氡在土壤中有大量的存储空间,所含的氡浓度最大。因此,土壤的孔隙度大小影响氡从地下向地表渗透析出的难易程度,孔隙度越大氡越容易渗透其中,浓度就越高。     

田间非饱和土壤水分运动的数值模拟：Ⅱ数学模型及数值模拟

经过对条件的概化，建立了带有作物根系吸水项的垂向一维土壤水分运动的数学模型，并推导了该数值离散方程，编制了用于该模型数值模拟的计算程序。通过模拟对模型的验证，计算值与实测值拟合较好，这表明，该模型是可靠的，数值方法是可行的，可以用来模拟作物生长条件下田间土壤水分的运动。     

Enrichment of arsenic, antimony, thallium and selenium in high-arsenic coal from Xingren County, Guizhou Province

Since 1976 high arsenic coal in Xingren County, Guizhou Province, has attracted more and more attention because of coal-burning-type arsenic poisoning, There are many studies on enrichment of arsenic in high-arsenic coal and they come from difference materials： organic matter, authigenic pyrite, epigenetic pyrite, authigenic clay mineral and epigenetic clay mineral. In this paper, fourteen samples were examined by proximate analysis. Inductively coupled plasma mass spectrometry （ICP-MS） was used to determine the trace element contents of thirty-six samples in high-arsenic coal, As was determined by instrumental neutron activation analysis （INAA） and atomic fluorescence spectrometry （AFS）. SEM-EDX was used to analyze the contents of As, Sb, Tl and Se in sample XR-8 from Xingren, Guizhou, and we analyzed the petrographic compositions of the same sample.     

岩溶土壤系统对空气CO2的吸收及其对陆地碳汇的意义——以桂林丫吉村岩溶试

以桂林丫吉村岩溶实验场为例 ,对湿润亚热带岩溶土壤系统进行了土壤植被系统CO2 浓度变化、土壤有机质分解的CO2 产生等野外观测以及实验室土壤灰岩土柱系统模拟实验。实验表明在土壤地球化学条件的控制下 ,岩溶土壤系统存在着对空气CO2 的显著吸收效应 ,其值可达 2 2～ 130 g/ (m2 ·a) ,并以此为依据估算了中国岩溶土壤系统对大气的碳汇约为 4× 10 13g/a。因而揭示了岩溶土壤系统可能是十分重要的陆地碳汇 ,在讨论全球碳汇饱和问题中必须重视这一碳汇的变化。     

气温急变带工程创面植生层土壤及微生物群落特征研究

青藏高原地处高寒缺氧的环境条件下，对人类扰动及气候变化非常敏感。人类活动如公路修建形成众多工程创面，对高原生态环境影响较大。创面生态修复的开展促进高原生态的恢复，但关于环境因子对生态修复过程中土壤及生物恢复的影响尚未探明。本研究选取青藏高原派墨公路中不同海拔的工程创面重构植生层，探究海拔变化下植生层土壤养分、酶活性及微生物群落的特征。研究结果表明：随着海拔变化，土壤氮磷养分含量总体随海拔升高先增加后减小，其中海拔3 100 m左右的修复样地土壤养分整体优于其他海拔，其速效磷含量最高，同时全氮、氨态氮和全磷含量较高。此外，随着海拔的升高，土壤酸性蛋白酶和淀粉酶含量整体上略有升高的趋势。海拔变化对土壤酸性磷酸酶、纤维素酶、葡萄糖苷酶活性没有显著影响。海拔变化显著改变了土壤养分及土壤微生物的相对丰度(P<0.05),其中变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)为优势种群，分别占土壤群落的35.81%～53.82%,8.49%～40.74%、5.98%～24.61%、3....