Freshwater macroinvertebrate distribution in two basins with different salinity gradients (Guadalete and Guadaira river basins,south-western Spain)   总被引：1，自引：0，他引：1  

Alfonso Gallardo-Mayenco 《International Journal of Salt Lake Research》1994,3(1):75-91

This work reports the results of one year's sampling of aquatic macroinver-brates in various streams with different salinity gradients. The study area was the headwaters of the rivers Guadaíra and Guadalete, located in the same geographical area in south-western Spain. The most interesting feature of the Guadaíra basin is the natural salinity of its waters due to the abundance of gypsum in its headwaters. Lithologically, the headwaters of the Guadalete basin flow over marls, clay, sandstone and limestone. Salinity values in most streams do not reach 1 mS cm^–1. At least at the levels of salinity found in the Guadaíra basin headwaters, the existence of a well-structured community of macroinvertebrates can be claimed. Of the groups studied, Diptera and Coleoptera showed the highest species richness, being distributed preferentially at the ends of the conductivity spectrum. Groups including taxa inhabiting waters of low salinty and taxa inhabiting waters with high salinity could be reliable indicators of salinity.  相似文献   

柴达木石——一种锌和铁的硫酸盐新矿物   总被引：1，自引：0，他引：1  

李万茂  陈国英  彭志忠 《矿物学报》1986,(2)

柴达木石是一种Zn和Fe~(3+)的硫酸盐新矿物,发现于我国青海省柴达木锡铁山铅锌矿氧化带。矿物属单斜晶系,空间群P2_1/m或P2_1,晶胞参数a=9.759(9)A,b=7.134(9)A,c=7.335(11)A,β=106.2(1)°,Z=2。化学分子式为ZnFe~(3+)(SO_4)_2(OH)·4H_2O。它是四水铜铁矾(guildite)的类似物。  相似文献   

Potential use of organic waste substances as an ecological technique to reduce pesticide ground water contamination     

Hicham El Bakouri  Jos Morillo  Jos Usero  Abdelhamid Ouassini 《Journal of Hydrology》2008,353(3-4):335-342

The heavy use of pesticides in agriculture has meant that the fate due to their movement after their application continue to be a real problem for the environment. In this work, a viable eco-remediation technique based on the use of natural organic substances (NOS) that characterize the Mediterranean region is proposed to demonstrate the efficiency of endosulfan sulphate removal from water. Experimental results showed that the pH of pesticide solutions and temperature negatively affect the adsorption process. According to adsorption kinetic data, 5 h were considered as the equilibrium time for realizing adsorption isotherm. The Freundlich isotherm model describes better the adsorption process of endosulfan sulphate on NOS tested. The Freundlich constant K_f depended mainly on the nature of each adsorbent and ranged from 5.56 for straw to 13.54 for date stones. The adsorption tests gave very satisfying results and point to the possible application of these supports as an ecological remediation technique to reduce pesticide contamination of aquatic ecosystems.  相似文献   

A modelling study of aerosol processing by stratocumulus clouds and its impact on general circulation model parameterisations of cloud and aerosol     

K. N. Bower  A. Jones  T. W. Choularton   《Atmospheric Research》1999,50(3-4)

A model of the aqueous phase processing of an aerosol population undergoing multiple cycling through a stratocumulus (Sc) cloud layer is presented. Results indicate that a significant modification of the aerosol properties is achieved following the first cycle through cloud. In a polluted atmosphere, further modification in subsequent cycles is seen to be hydrogen peroxide limited unless there is a flux of ammonia entering the system through cloud base (CB). The modification of the aerosol population is seen to have little effect on the microphysics (specifically the cloud droplet concentration and effective radius) of the processing cloud. However, it enables processed aerosols to subsequently act as efficient cloud condensation nuclei (CCN) in less vigorous clouds (as a result of reducing the critical supersaturation required to activate them). The effects of variations in the internal mixture of soluble components of aerosols on the microphysics of clouds forming on them are also investigated using the cloud model. A (K2) parameterisation of the effects of variations in internally mixed nitrate loadings on the cloud droplet number concentration is presented. The effects of applying this K2 correction to the droplet number (derived from a parameterisation based on sulphate) for the presence of nitrate in aerosol have been investigated using the HadAM3 version of the Hadley Centre General Circulation Model (GCM). The effect on global annual mean simulations of the indirect forcing and effective radius is small, but more pronounced regionally. Suggestions (based on model results and observations) for parameterising the size distribution and in-cloud growth of aerosols for use in GCMs are presented.  相似文献   

Mass transport modelling for assessement of groundwater contamination around Mathura oil refinery, Mathura, Uttar Pradesh, India     

V. V. S. Gurunadha Rao  R. L. Dhar  T. Jayachand  C. S. Khoker 《Environmental Geology》2000,39(10):1138-1146

Mathura oil refinery was commissioned during 1977 and effluent storage ponds were constructed at the same time. These storage ponds receive wastewater from the refinery at a rate of 10000 m³/day. After treatment, waste water is discharged through a 3-km pipeline to a stream leading to the Yamuna river. The groundwater-monitoring as well as water-quality monitoring was carried at 24 observation wells in the refinery site during 1997. The water quality measurements indicated total dissolved chloride and sulphate concentration of native groundwater as 400 mg/l, whereas elevated levels up to 600 mg/l were found at the wells close to polishing ponds. Thus combined transport of chloride and sulphate was simulated in the mass transport model. A three-dimensional flow, pathlines and mass transport model of the aquifer system were constructed to analyze the impact of seepage from polishing ponds contaminating the groundwater regime. The permeability of aquifer varies between 1.5–2.5 m/day. The porosity of formation was assumed as 0.2. The constant head and constant concentration boundaries were assigned to the nodes representing effluent storage ponds. Longitudinal dispersivity of 100 m, horizontal transverse dispersivity of 10 m and vertical transverse dispersivity of 0.01 m were assumed. The mass transport model was calibrated for 20 years by comparing total dissolved chloride and sulphate concentrations from 1997. The model predictions indicate further migration of contaminants on the east of effluent ponds in future. Received: 4 January 1999 · Accepted: 12 July 1999  相似文献   

白令海和楚科奇海测区沉积物硫酸盐还原菌初步研究   总被引：8，自引：2，他引：6       下载免费PDF全文

陈皓文  高爱国 《极地研究》2000,12(3):211-218

用 MPN法测定了取自白令海和楚科奇海 35个沉积物样品中的硫酸盐还原菌 (SRB)含量。所有样品的 SRB平均含量约 1 .68× 1 0 5个 .g- 1,变幅约为 0～ 2 .2 8× 1 0 6个 .g- 1。分析并比较了 SRB含量在表层、次表层或混合层样中及不同站位、测区间的差异 ,大体看来 ,SRB含量表层少于次表层。若以白令海峡为界 ,在海峡两侧 SRB含量的增加呈相反趋势 :即在白令海呈向南增加、在楚科奇海呈向北增加的趋势 ;经向分布也显示出相反的趋势 :在白令海呈向东增加、在楚科奇海呈向西增加的趋势。结果还表明 SRB在不同培养温度中有各自的出现率 ,反映测区SRB以适冷菌为主。温度是其主要控制因子。相当多的中温菌也有出现  相似文献   

Estuarine behaviour of metal loads leached from coastal lowland acid sulphate soils     

Nordmyr L  Osterholm P  Aström M 《Marine environmental research》2008,66(3):378-393

The estuarine behaviour of the metal load leaching from acid sulphate (AS) soils was studied in a selected river system (the V?r? River), in western Finland. Large amounts of metals were transported with the river and deposited within the estuary, causing highly elevated metal concentrations in both the sediment traps and in the underlying bottom sediments. Among the metals, there was a diverging deposition pattern where Al, Cu, La and U demonstrated a strong association with organic matter and were deposited within approximately 4 km from the river mouth. In contrast, the deposition of Co, Mn, Ni and Zn occurred when pH reached circumneutral conditions further out in the estuary. Yet other metals were not abundantly leached from the AS soils and thus not elevated in the river and estuary (Fe, Ti, Cr, V). Five separate chemical extractions indicated the geochemical speciation of the metals.  相似文献   

Relationships between microbial communities and groundwater chemistry in two pristine confined groundwater aquifers in central China     

Jie Ma  Hui Liu  Lei Tong  Yan Wang  Rong Chen  Shan Liu  Lei Zhao  Zhimin Li  Liegang Cai 《水文研究》2019,33(14):1993-2005

This study explores linkages between the microbial composition and hydrochemical variables of pristine groundwater to identify active redox conditions and processes. Two confined aquifers underlying the city of Qianjiang in the Jianghan Plain in China were selected for this study, having different recharge sources and strong hydrochemical gradients. Typical methods for establishing redox processes according to threshold concentration criteria for geochemical parameters suggest iron or sulphate reduction processes. High‐throughput 16S rRNA sequencing was used to obtain diversity and taxonomic information on microbial communities. Instead of revealing iron‐ and sulphate‐reducing bacteria, salt‐ and alkali‐tolerant bacteria, such as the phylum Firmicutes and the class Gammaproteobacteria, and in particular, the family Bacillaceae, were dominant in the downstream groundwater of the first aquifer that had high ion concentrations caused by the dissolution of calcite and dolomite; meanwhile, the heterotrophic microaerophilic families Comamonadaceae and Rhodocyclaceae prevailed in the upstream groundwater of the first aquifer. Sulphate‐reducing bacteria were extremely abundant in the upstream groundwater of the second aquifer, as the SO₄^2? concentration was especially high. Methanogens and methanotrophs were predominant in the downstream groundwater of the second aquifer even though the concentration of SO₄^2? was much higher than 0.5 mg L^?1. The microbial communities, together with the geochemical parameters, indicated that the upstream region of the first aquifer was suboxic, that Fe(III) and Mn(IV) reductions were not the main redox processes in the downstream groundwater of the first aquifer with high Fe and Mn concentrations, and that the redox processes in the upstream and downstream regions of the second confined aquifer were SO₄^2? reduction and methanogenesis, respectively. This study expands understanding of the linkages between microbial communities and hydrogeochemistry in pristine groundwaters and provides more evidence for identifying active redox conditions and processes.  相似文献   

含钙铝铁水解聚合产物的矿物学研究Ⅰ:形态和物相   总被引：4，自引：3，他引：1  

章兴华  刘世荣  龚国洪  孙传敏  周丽芸  陆洋 《矿物学报》2009,29(2)

用X射线粉晶衍射分析技术结合热重分析、红外光谱及电镜观察对合成的含钙聚合氯化铝铁(PAFCCa)及其合成前体含钙聚合氯化铝(PACCa)、含钙聚合氯化铁(PFCCa)的低温干燥样进行了表征.XRD衍射结果表明,Ca(Ⅱ) 分别与Al(Ⅲ)、Fe(Ⅲ)都能形成结晶化合物,在PACCa中结晶化合物主要是Ca3Al2(OH)12,在PFCCa中结晶化合物主要是Ca4Fe14O25,在PAFCCa中形成Al-Ca-Fe三相结晶化合物铁取代的氯钙矾石结构体,其组成是(Ca6(Al,Fe)2[(OH)4Cl2]3·20H2O).热重分析、红外光谱与电镜观察都支持了XRD的衍射结果.  相似文献   

Thermochemical sulphate reduction in the Upper Devonian Cairn Formation of the Fairholme carbonate complex (South-West Alberta, Canadian Rockies): evidence from fluid inclusions and isotopic data     

VEERLE VANDEGINSTE  RUDY SWENNEN  SARAH A. GLEESON†  ROB M. ELLAM‡  KIRK OSADETZ§  FRANÇOIS ROURE¶ 《Sedimentology》2009,56(2):439-460

The Fairholme carbonate complex is part of the extensively dolomitized Upper Devonian carbonate reefs in west-central Alberta. The studied formations contain moulds (up to 10 cm in diameter), which are filled partially with (saddle) dolomite, quartz and calcite cements. These cements precipitated from a mixture of brines that acquired high salinity by dissolution of halite and brines derived from evaporated sea water. The fluids were warm (homogenization temperature of primary fluid inclusions of 76 to 200 °C) and saline (20 to 25 wt% NaCl equivalent) and testify to thermochemical sulphate reduction processes. The latter is deduced from S in solid inclusions, CO₂ and H₂S in volatile-rich aqueous inclusions and depleted δ¹³C values down to −26‰ Vienna Pee Dee Belemnite. High ⁸⁷Sr/⁸⁶Sr values (0·7094 to 0·7110) of the cements also indicate interaction of the fluids with siliciclastic sequences. The thermochemical sulphate reduction-related cements probably formed during early Laramide burial. Another (younger) calcite phase, characterized by depleted δ¹⁸O values (−23·9‰ to −13·9‰ Vienna Pee Dee Belemnite), low Na (27 to 37 p.p.m.) and Sr (39 to 150 p.p.m.) concentrations and non-saline (∼0 wt% NaCl equivalent) fluid inclusions, is attributed to post-Laramide meteoric water.  相似文献