A continuous and mechanistic representation of calcite reaction-controlled kinetics in dilute solutions at 25°C and 1 atm total pressure     

Takeshi Arakaki  Alfonso Mucci 《Aquatic Geochemistry》1995,1(1):105-130

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Effects of heavy metals on the survival ofDiacypris compacta (Herbst) (Ostracoda) from the Coorong,South Australia     

Anna Brooks  Rehema M. White  David C. Paton 《International Journal of Salt Lake Research》1995,4(2):133-163

The hypermarine southern Coorong is threatened by proposals to drain relatively fresh surface water and groundwater from adjacent agricultural areas into the Coorong. These influent waters carry moderate loads of heavy metals. Acute toxicity of heavy metals toDiacypris compacta, an abundant ostracod in the Coorong, was measured in the laboratory at 18°C in a static system using Coorong water (pH 7.8 salinity 50 ppt). At 4 days (96 h) the mean values of LC₅₀ for copper, zinc, lead and, cadmium respectively were 0.8, 2.1, 3.1 and 4.3 mg L^–1, and at 8 days the respective mean LC₅₀ s were 0.4, 0.7, 2.2 and 1.1 mgL^–1. The effect of two or three metals on mortality was additive in some cases and synergistic in other cases, but generally less than additive. However, in all cases mortality was greater in the presence of two or three metals than in the presence of a single metal. According to ANZECC (1992) guidelines, maximum acceptable concentrations of heavy metals should be no higher than 0.01 x the lowest LC₅₀ value. Using the lowest LC₅₀ values forDiacypris compacta obtained at 8 days, maximum acceptable concentrations in the Coorong would be 4, 5, 9 and 22 gL^–1 for copper, zinc, cadmium and lead respectively, the values for zinc and copper failling below those recommended by ANZECC (1992) for marine waters. Reported concentrations of copper and zinc in surface water and groundwater in areas adjacent to the Coorong sometimes exceed these values, hence drainage of these waters into the Coorong represents a significant hazard to the Coorong biota.  相似文献   

北京地区降水量时空分布规律分析   总被引：30，自引：4，他引：30  

徐宗学  张玲  阮本清 《干旱区地理》2006,29(2):186-192

通过运用非参数检验方法(Mann-Kendall法),利用北京地区20个气象站点44年(1961-2004)观测的逐月降水资料,分析了北京地区降水量的时空分布规律。结果表明:在时间上,年平均降水量总趋势以每年1.72 mm的变化率减少,这种减少主要是由夏季、冬季降水量减少所引起的,尤以夏季最为显著,变化率为-3.26 mm/a,而在春、秋两季降水量则呈现出增加的趋势,变化率分别为0.34 mm/a和0.77 mm/a。降水期主要集中于夏季(6~8月),可占全年降水量的72.5%。在空间上,年降水量的高值区位于山前迎风坡一带,大致呈带状自西南伸向东北,高值区的西北、东南两侧雨量逐渐减少。市区形成一个明显的下降中心,其中海淀区年均减少3.7mm,降幅最大。  相似文献   

Retailing local food in the Scottish-English borders: A supply chain perspective     

B. Ilbery  D. Maye 《Geoforum》2006,37(3):352-367

Local food is championed as one alternative response to industrial systems of food production and supply. While advocacy for local food is high, there is a lack of empirical evidence about the actual shape and scale of such food supply chains, especially from a retail perspective. Using supply chain diagrams, this paper presents a summary of ‘new’ agro-food geographies for five different retail types—farm shops, butchers, caterers, specialist shops, supermarkets/department stores—that all source local food from suppliers in the Scottish-English borders. Presented as five separate ‘shopping trips’, the paper examines where, how and why retailers source local food. Results reveal the complex nature of local food systems, especially in terms of intra-sector competitive dynamics (with a notable tension between direct forms of retail and established (independent) retailers), links and overlaps with ‘normal’ food retail systems and elastic notions of the ‘local’. The paper also draws a key distinction between locally produced and locally supplied food products.  相似文献   

Environmental impacts from mining at Taojiang Mn ore deposit, central Hunan, China     

Bo PENG Shurong XIE Meilian XIAO Fucheng WU Zhi SONG 《中国地球化学学报》2006,25(B08):23-24

The Taojiang Mn ore deposit was exploited in the early 1960s, and waste rocks were developed since then. Because the Mn ores were hosted within the metal-enriched black shales （Peng et al., 2004）, the continuous mining has led to the exposure of an immense quality of black shales, which might cause serious impacts on environments. The present study deals with this environmental issue with samples from the waste rocks, and from the surrounding soils and surface water. The mineralogy of the waste rock was studied using EMPA, then a large number of elements in all waste rock, soil, and water samples were analyzed at a wide range of concentrations with high accuracy using an Elan6000 ICP-MS machine at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. The waste rock is composed mostly of black shales, with minor Mn carbonates. Both black shales and Mn carbonates of the waste rock contain many sulfide minerals, mainly pyrite, with minor galena, sphalerite, chalcopyrite, and others. The waste rocks are enriched in many metals including Sc, V, Cr, Co, Ni, Fe, Mn, Cu, Zn, Pb, Th, U, Mo, Sb, Sn, Tl, and others, and the metals are mostly hosted within the sulfides. Weathering of waste rocks might cause emission of the following metals： V, Cd, Ni, Th, U, Mo, Sb, Tl, Sc, Cr, Cu, Zn, Sn, and minor Co, and Pb. The surrounding soils are highly enriched in Cr, Co, Cu, Zn, Mn, Mo, Cd, Tl, and Pb, with the enrichment factors of 2.67.3.8, 7.26, 7.27, 8.2, 5.7, 13, and 5.4, respectively. The element ratios （Rb/Cs, Fe/Mn, Nb/Zr, Hf/Zr, and Ba/Sr） and REE distribution patterns of the soils are similar to those of the waste rocks and bedrocks.  相似文献   

Mobility of heavy metals from tailings to stream waters in local zinc smelting activities contaminated site     

Taoze LIU Yuangen YANG Bangyu LIU Xiangyang BI Feili LI 《中国地球化学学报》2006,25(B08):41-42

It has been found that stream waters were severely contaminated with wastes from a long-time smelting factory in Hezhang, Guizhou, China. The main sources of contamination are the smelting wastes stored in the open air and abandoned in the vicinity of stream. A method of lead isotope was adopted in order to identify relations between tailings and water contamination. Representative samples of tailings and stream sediments were collected. Mineralogical characterizations were conducted using XRD and TEM/SEM, while acid digestion was carried out for determining metal contents. BCR sequential leaching tests were performed in order to assess metal mobility. The tremendous ‘actual＇ and ‘potential＇ mobility of heavy metals indicates that the smelting waste and stream sediments present a considerable threat to the environment. Besides the chemical remobilization of heavy metals from the sediments and the reworking of riverbed sediments act as a secondary source of pollution. Also groundwater and stream water were sampled in specific locations and were measured.  相似文献   

The effects of carbon dioxide leakage on fractures, and water quality of potable aquifers during geological sequestration of CO2     

Wei ZHANG Yilian LI Tianfu XU Wei QIANG Shangping XIAO 《中国地球化学学报》2006,25(B08):58-58

Since industrial revolution, the ＂greenhouse effect＂ is one of the most important global environmental issues. Of all the greenhouse gases, CO2 is responsible for about 64% of the enhanced ＂greenhouse effect＂, making it the target for mitigation, so reducing anthropogenic discharge of carbon dioxide attracts more and more attention. Geological sequestration of CO2 in deep saline aquifers is one of the most promising options. But because unknown fractures and faults may exist in the caprock layers which can prevent the leakage of CO2, CO2 will leak upward into upper potable aquifers, and lead to adverse impacts on the shallow potable aquifers. In order to assess the potential effect of CO2 leakage from underground storage reservoirs on fractures and water quality of potable aquifers, this study used the non-isothermal reactive geochemical transport code TOUGHREACT developed by Xu et al to establish a simplified 2-D model of CO2 underground sequestration system, which includes deep saline aquifers, caprock layers, and shallow potable aquifers, and study and analyze the changes of mineral and aqueous components. The simulation results indicated that the minerals of deep saline aquifers and fractures should be mainly composed of aluminosilicate and silicate minerals, which not only enhance the mass of CO2 sequestrated by mineral trapping, but also decrease the porosity and permeability of caprock layers and fractures to prevent and reduce CO2 leakage. The results from deep saline aquifers showed that the mass of carbon dioxide trapped by minerals and solution phases is limited, the rest remained as a supercritical phase, and so once the caprock aquifers have some unknown fractures, the free carbon dioxide phase may leak from CO2 geologic sequestration reservoirs by buoyancy.  相似文献   

Geochemistry of soils derived from black shale, central Hunan, China     

Bo PENG Shurong XIE Meilian XIAO Zhi SONG 《中国地球化学学报》2006,25(B08):85-86

The black shale formed under anoxic conditions usually contains high concentrations of many metals. Weathering of such black shale might cause the emission of many metals. Moreover, soils derived from black shale （SBS） are believed to be affected by black shale weathering. In recent years, many studies such as Lee et al. （2002）, Woo et al. （2002）, Fang et al. （2002）, Pasava et al. （2003）, and Peng et al. （2004） have approached the heavy metal contaminations of SBS, but systematical geochemical study is rare. Presently, the SBS and its corresponding black shales （CBS） were both sampled from central Hunan （China）, and analyzed for a large number of elements, using an Elan6000 ICP-MS/AES machine at Guangzhou Institute of Geochemistry, CAS. In this paper, some preliminary results are reported. The analytical results show that the SBS in central Hunan contains very high concentrations of heavy metals such as Co, Cu, Hg, Mo, Pb, Zn, U, Th, Sb, T1, Cd, Cr, Sc, V, Sn, As, Se, and Ni.  相似文献   

Heavy metal contamination in the sediment of the Second Songhua River   总被引：1，自引：0，他引：1  

Chunye LIN Mengchang HE Baixing YAN Xiangchun QUAN Yuxiang ZHOU Wei GUO Zhifeng YANG 《中国地球化学学报》2006,25(B08):118-119

The Second Songhua River was subjected to a large amount of untreated effluent from petrochemical industries in Jilin City in the 1960s to the 1970s. The objectives of this study were to investigate the mercury and other heavy metal contamination in the sediment of the river. The river bottom sediment was sampled from the river segment between Jilin City to Haerbin City in 2005. Total concentrations of Hg, Cd, Cu, Cr, Pb, Zn, Ni, As, Sc, and major cations （A1, Fe, Mg, Ca, K, Na） in the sediment were measured by atomic fluorescence spectrometer, ICP-MS, and ICP-OES, respectively, following digestion with various acids. We found the concentrations of most elements in the uncontaminated sediment were significantly correlated to those of Sc.  相似文献   

Ecological risk assessment for heavy metal contamination of a new consideration Agricultural soils     

《中国地球化学学报》2006,25(B08):123-123

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