Geochemical and mineralogical characteristics of elephant geophagic soils in Udawalawe National Park,Sri Lanka

Geophagy or deliberate ingestion of soils was observed among Asian elephants (Elephas maximus) in the Udawalwe National Park, Sri Lanka, for several years. The geochemical and mineralogical composition of the clayey soil layers which are purposefully selected and eaten by elephants in the park were studied, in order to identify the possible reasons for elephant geophagy. The concentrations of major and trace elements were determined by means of X-ray fluorescence spectrometry in 21 soil samples from eight geophagic sites and six soil samples collected from four non-geophagic sites. The mineralogical composition of selected soil samples was investigated using X-ray diffractometry (XRD). These geochemical analyses revealed that geophagic soils in the study areas are deeply weathered and that most of the elements are leached from the soil layers under extreme weathering conditions. The XRD data showed that the soils of the area consisted mainly quartz, feldspar, and the clay minerals kaolinite, Fe-rich illite, and smectite. Although no significant geochemical differences were identified between geophagic and non-geophagic soils, a clear difference was observed in their clay mineralogical content. Soils eaten by elephants are richer in kaolinite and illite than non-geophagic soils, which contain a higher amount of smectite. It is suggested that elephants in Udawalawe National Park ingest soils mainly not to supplement the mineral contents of their forage but to detoxify unpalatable compounds in their diet.     

基于不同能源底物和营养水平的酸性矿山废水产生机制研究

硫化矿物在氧气、水和铁氧化细菌的共同作用下会形成pH值极低、富含可溶性Fe、SO₄^2-和重金属离子等的酸性矿山废水.本研究选取黄铁矿、磁黄铁矿和黄铜矿作为能源底物,以及0×9K、1/4×9K、1/2×9K、1×9K培养基作为营养水平,在氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans）的参与下,从能源底物和营养水平角度探索不同硫化矿物酸性废水的产生特点和机制.结果表明,3种硫化矿物的生物产酸能力依次为黄铁矿>磁黄铁矿≈黄铜矿.经过38 d的生化反应后,黄铁矿体系的pH值达到1.41,总Fe （TFe）和SO₄^2-浓度分别达到771.82 mg·L^-1和357.25 mg·L^-1.水体营养水平在黄铁矿的生物产酸过程中起着至关重要的作用.经过16 d的生化反应后,0×9K、1/4×9K、1/2×9K、1×9K培养基处理的终点pH值分别为1.68、1.44、1.30、1.29.根据各营养体系中Fe²⁺和TFe浓度的变化趋势,以及反应终点收集矿物的X射线衍射（XRD）和扫描电镜（SEM）,分析认为充足的营养会提高Acidithiobacillus ferrooxidans的活性或密度,加快Fe²⁺生物氧化形成Fe³⁺并通过水解产酸作用合成黄钾铁矾等次生铁矿物,从而导致溶液的pH值更低.本研究所得结果对明晰酸性矿山废水形成规律具有一定的指导意义.     

AHP法在区域矿产资源综合经济评价中的应用

本文运用AHP法对某省20种主要矿产进行了综台经侪评价,确定了该省经济优势矿产、潜在优势矿产和劣势矿产,为制定该省矿产资源开发战略提供了科学依据。     

The minerals sector, sectoral analysis, and economic development

Sectoral analysis, a new branch of political science, alleges that mineral extraction creates a socio-political climate that promotes inflexible statism, which in turn leads to substandard development performance. The theory, that mineral economies underperform bureaucratically and economically, is said not only to hold in a post-dictive sense for the mature mineral economies, such as Zambia, but also in a predictive sense for the newer mineral economies, such as Ecuador. This essay reviews and assesses this hypothesis in the light of the empirical evidence comparing mineral production, state capacity, and economic performance. It finds that the sectoralist view is supportable only in selected cases, and is not a general result.     

从化学加工工艺谈磷矿物的分类及其意义

作者认为磷矿物是以固溶体形式出现的一组含氟磷酸钙盐,多种矿物盐的组合常以其最为稳定的形式,即能量最低的状态存在。因此,作者对磷矿物的分类不是从矿物类型而是以能量方程式所具有的特征系数进行分类。根据矿物类型建立P_2O_5枸溶率、晶胞参数a_0轴的模拟方程。分类结果:自然界的磷矿物共分高氟磷灰石、富氟磷灰石、低碳氟磷灰石,氟磷灰石和低氟磷灰石五类。由于磷矿物中的氟含量直接影响了磷矿物的各种性质,而磷矿煅烧(包括脱氟磷肥生产)过程实质上是模拟磷矿在自然界的变质过程,使P_2O_5枸溶率和化学反应性下降。因而可根据本文分类对磷矿物的应用进行直接评价。     

次生石英岩型非金属矿床蚀变建造的矿物学研究

本文总结了火山成因的次生石英岩型非金属矿床中蚀变矿物的共生组合类型及在空间上的分带,主要蚀变矿物的矿物学特征(包括标型特征)及其形成与转变;指出这些特征和转变在不同方面指示成矿原岩性质,矿床形成温度,成矿溶液物化条件的变化过程。     

矿物材料预处理对餐厨垃圾高温厌氧消化过程的影响

选用4种矿物材料对400g餐厨垃圾在35℃下进行4h好氧预处理,比较了预处理前后餐厨垃圾水解率的变化,并且详细研究了预处理对餐厨垃圾高温厌氧消化过程及产沼气效果的影响.结果表明:在同等条件下,添加矿物材料可以有效促进餐厨垃圾的水解,其中添加1.25%(质量分数,以餐厨垃圾湿基计)膨润土和添加2.5%轻烧MgO的处理水解率分别达到了96.79%和96.51%.轻烧MgO有效地缓解了餐厨垃圾由于酸化引起的pH值下降,使产气高峰期较早来到;而在总产气量上添加白云石粉的促进作用显著.膨润土次之,其中添加2.5%白云石粉的总产气量最高,为10925mL.添加矿物材料降低了消化液中钠离子的浓度,可减轻对产甲烷细菌的抑制作用.     

海洋沉积物的环境磁学研究简述

环境磁学是一门介于地球科学、环境科学和磁学之间的边缘学科,可提供大量有关区域或全球环境变化及人类活动对环境影响等的重要信息.海洋沉积物是当前环境磁学研究的主要领域之一.根据最近20多a的研究成果,本文简述了海洋沉积物中的磁性矿物和磁学性质及其古环境意义等方面所取得的进展.     

Potential for microbially mediated redox transformations and mobilization of arsenic in uncontaminated soils

Surface soil samples, which had no significant As contamination, were examined for As(V) reduction, As(III) oxidation and As mobilization capability. All five soil samples tested exhibited microbial As(V)-reducing activities both in aerobic and anaerobic conditions. Under aerobic conditions when As(V) reduction had almost ceased, oxidation of As(III) to As(V) occurred, whereas only As(V) reduction was observed under anaerobic conditions. In cultures incubated with As(III), As(III) was oxidized by indigenous soil microbes only under aerobic conditions. These results indicate that microbial redox transformations of As are ubiquitous in the natural environment regardless of background As levels. Mobilization through microbially mediated As(V) and Fe(III) reduction occurred both in the presence and absence of oxygen. Significant variation in dissolved As occurred depending on the Fe contents of soils, and re-immobilization of As arose in the presence of oxygen, presumably as a consequence of dissolved As(III) and Fe(II) oxidation. There was no apparent correlation between dissolved Fe(II) and As, suggesting that reductive dissolution of Fe(III) minerals does not necessarily determine the extent of As release from soils.     

Sorption and desorption of diuron on Typic Argiudoll,Oxic Argiudoll and on their clay fractions: environmental aspects

Abstract

The sorption and desorption of diuron by soil samples from Horizons A and B (HA and HB) and by their different clay fractions were investigated, using two soil samples, classified as Typic Argiudoll and Oxic Argiudoll. The sorption and desorption curves were adjusted to the Freundlich model and evaluated by parameters K_f, K_d and K_oc. Based on the data of groundwater ubiquity score (GUS), leachability index (LIX) and hysteresis index (HI), the risk of groundwater pollution was evaluated. The K_d values obtained for soil samples were between 4.5?mL g^?1 (Oxic Argiudoll – HB) and 15.9?mL g^?1 (Typic Argiudoll – HA) and between 1.13 and 14.0?mL g^?1 for the different mineral fractions, whereas the K_oc values varied between 276 (Oxic Argiudoll – HB) and 462 (Typic Argiudoll – HA). According to the parameter GUS, only Oxic Argiudoll – HB presented leaching potential, and based on the LIX index this same soil presented the highest leaching potential. Some samples presented low LIX and GUS values, indicating no leaching potential, but none presented HI results indicative of hysteresis, suggesting weak bonds between diuron and the soil samples and, hence, the risk of groundwater pollution by diuron.