Evaluation of an approach for the characterization of reactive and available pools of 20 potentially toxic elements in soils: part II--solid-solution partition relationships and ion activity in soil solutions

To assess environmental risks related to contaminants in soil it is essential to predict the available pool of inorganic contaminants at regional scales, accounting for differences between soils from variable geologic and climatic origins. An approach composed of a well-accepted soil extraction procedure (0.01 M CaCl(2)) and empirical Freundlich-type models in combination with mechanistically based models which to date have been used only in temperate regions was applied to 136 soils from a South European area and evaluated for its possible general use in risk assessment. Empirical models based on reactive element pools and soil properties (pH, organic carbon, clay, total Al, Fe and Mn) provided good estimations of available concentrations for a broad range of contaminants including As, Ba, Cd, Co, Cu, Hg, Mo, Ni, Pb, Sb, Se and Zn (r(2): 0.46-0.89). The variation of the pools of total Al in soils expressed the sorptive capacity of aluminosilicates and Al oxides at the surfaces and edges of clay minerals better than the actual variability of clay contents. The approach has led to recommendations for further research with particular emphasis on the impact of clay on the solubility of As and Sb, on the mechanisms controlling Cr and U availability and on differences in binding properties of soil organic matter from different climatic regions. This study showed that such approach may be included with a good degree of certainty for first step risk assessment procedures to identify potential risk areas for leaching and uptake of inorganic contaminants in different environmental settings.     

Inferring episodic atmospheric iron fluxes in the Western South Atlantic

Iron (Fe) and other trace elements such as Zn, Mn, Ni and Cu are known as key-factors in marine biogeochemical cycles. It is believed that ocean primary productivity blooms in iron deficient regions can be triggered by iron in aeolian dust. Up to now, scarce aerosol elemental composition, based on measurements over sea at the Western South Atlantic (WSA), exist. An association between the Patagonian semi-desert dust/Fe and chlorophyll-a variability at the Argentinean continental shelf is essentially inferred from models. We present here experimental data of Fe enriched aerosols over the WSA between latitudes 22°S–62°S, during 4 oceanographic campaigns between 2002 and 2005. These data allowed inferring the atmospheric Fe flux onto different latitudinal bands which varied from 30.4 to 1688 nmolFe m^?2 day^?1 (October 29th–November 15th, 2003); 5.83–1586 nmolFe m^?2 day^?1 (February 15th–March 6th, 2004) and 4.73–586 nmolFe m^?2 day^?1(October 21st–November 5th, 2005).     

Visual diagnosis of solid waste contamination of a tourist beach: Pernambuco, Brazil

The solid waste accumulation patterns on Tamandaré beach, Pernambuco State (Brazil), was assessed from February 2001 to July 2002. This beach is easily accessible, frequently used, and there is a public cleaning service. The beach is under the influence of three small coastal drainage basins. The study visually divided the beach into 15 segments according to the level of solid waste contamination into absent (A), trace (B), unacceptable (C) and objectionable (D). The lowest levels of contamination were found at the middle part of the study area, the most vulnerable in respect to coastal erosion presenting numerous interventions on the beach, absence of native vegetation and lesser width. The highest levels of contamination were at the northern and southern ends of the area, where there are no developments, the beach morphology favours deposition of sediments, there is native vegetation and the beach is wider. The D level did not occur within the area.     

Exposure to sublethal concentrations of Zn(II) and Cu(II) changes biochemical parameters in Leporinus obtusidens

The aim of the present study was to assess the effect of the exposure of Leporinus obtusidens (Piava) to zinc and copper on catalase activity in the liver, delta-aminolevulinate dehidratase (delta-ALA-D) activity in liver, muscle, brain and kidney, and thiobarbituric reactive species (TBARS) in brain, muscle and liver. In addition, hematological parameters were measured in blood. The fish were exposed to 10% and 20% of the derived LC(50) values, 2.3 and 4.6 mg Zn l(-1) and 0.02 and 0.04 mg Cu l(-1), and sampled on days 30 and 45. Exposure to Zn(II) and Cu(II) decreased hematological parameters and also delta-ALA-D activity mainly in liver and kidney at all concentrations tested. Liver catalase activity increased after zinc or copper exposure at all concentrations and exposure times tested. Thiobarbituric reactive substances (TBARS) increased in the brain and liver of the fish exposed to zinc(II) for 45 days at both metal concentrations. In muscle, zinc(II) increased TBARS production at both exposure times and concentrations tested. Copper(II) exposure reduced the TBARS levels in liver at both concentrations and times tested. In brain, there was a decrease in TBARS levels only after 45 days of exposure. In muscle, this decrease was observed after 30 days of exposure at both concentrations. Although zinc and copper are required as microelements in the cells, our results showed that the sublethal concentrations of these metals can change biochemical parameters which may alter normal cellular function. These results pointed out the differential sensitivity of fish tissues to essential, but also toxic and environmentally relevant metals. The alterations of distinct biochemical parameters in fish tissues certainly contribute to the toxicity of Zn and Cu, and are of importance for an area that has been growing and has still been poorly explored in the literature.     

浙江“99630”特大洪水中水利工程的防洪减灾作用

1999年梅雨期间,浙北的杭嘉湖地区和新安江流域发生了百年未遇的洪灾-“99630”特大洪水。这次洪水的降雨、水位都超过历史记录。在特大灾害面前,各级防汛部门精心调度,正确指挥,各地发扬风格,团结抗洪,各类水利工程充分发挥了防洪减灾作用。     

Heavy metal removal from synthetic wastewaters in an anaerobic bioreactor using stillage from ethanol distilleries as a carbon source

This work was conducted to investigate the possibility of using stillage from ethanol distilleries as substrate for sulfate reducing bacteria (SRB) growth and to evaluate the removal efficiency of heavy metals present in wastewaters containing sulfates. The experiments were carried out in a continuous bench-scale Upflow Anaerobic Sludge Blanket reactor (13 l) operated with a hydraulic retention time of 18 h. The bioreactor was inoculated with 7 l of anaerobic sludge. Afterwards, an enrichment procedure to increase SRB numbers was started. After this, cadmium and zinc were added to the synthetic wastewater, and their removal as metal sulfide was evaluated. The synthetic wastewater used represented the drainage from a dam of a metallurgical industry to which a carbon source (stillage) was added. The results showed that high percentages of removal (>99%) of Cd and Zn were attained in the bioreactor, and that the removal as sulfide precipitates was not the only form of metal removal occurring in the bioreactor environment.     

The influence of suburban land use on habitat and biotic integrity of coastal Rhode Island streams

Watershed land use in suburban areas can affect stream biota through degradation of instream habitat, water quality, and riparian vegetation. By monitoring stream biotic communities in various geographic regions, we can better understand and conserve our watershed ecosystems. The objective of this study was to examine the relationship between watershed land use and the integrity of benthic invertebrate communities in eight streams that were assessed over a 3-year period (2001-2003). Sites were selected from coastal Rhode Island watersheds along a residential land-use gradient (4-59%). Using the rapid bioassessment protocol, we collected biological, physicochemical, habitat, and nutrient data from wadeable stream reaches and compared metrics of structure and integrity. Principal component analyses showed significant negative correlation of indicators for stream physicochemical, habitat, and instream biodiversity with increasing residential land use (RLU) in the watershed. The physicochemical variables that were most responsive to percent RLU were conductivity, instream habitat, nitrate, and dissolved inorganic nitrogen (DIN). The positive correlation of DIN with percent RLU indicated an anthropogenic source of pollution affecting the streams. The biotic composition of the streams shifted from sensitive to insensitive taxa as percent RLU increased; the most responsive biological variables were percent Ephemeroptera, percent Scrapers, percent Insects, and the Hilsenhoff biotic index. These data show the importance of land management and conservation at the watershed scale to sustaining the biotic integrity of coastal stream ecosystems.     

Chemical monitoring of river water bodies in an EU outermost region: examples from the Azores archipelago (Portugal)

Chemical monitoring of water quality on a total of 16 rivers in the Azores archipelago (Portugal), since 2003, made it possible to identify the major pressures and spatial geochemical variations along main course of the rivers. River water pollution is to a large extent associated to point sources, namely domestic wastewater discharges, especially in urban areas, and diffuse sources, associated with pasture land, and explain the high values on BOD(5) and nutrients (P and N). Heavy metals and metalloids, as well as hydrocarbons and pesticides, are generally under the detection limits of the analytical methods. Generally, river water reflects pollution loads according to a simple model, derived from land use in the watershed: in the upper part conditions are pristine, in the intermediate portion of the basin pasture land dominates and near the coast urban discharges are increasingly important. Results stress the role that an approach based on the watershed scale, coupled with land use management measures, are crucial to water management procedures and a successful WFD implementation in small river basin districts like the Azores. The paper also shows the need for full compliance regarding EU directives on urban wastewater and nitrate pollution due to agriculture.     

Water quality of the Ribeirão Preto Stream, a watercourse under anthropogenic influence in the southeast of Brazil

It is known that Brazil still has a privileged position of water quantity and quality, but water use has not proceeded in a responsible manner and often results in impairment of quality. This study aims to evaluate limnological parameters, parasites and bacteria, and concentrations of heavy metals (Cd, Pb, Cu, Cr, Mn, Hg, and Zn) in surface water of Ribeirão Preto Stream. The Ribeirão Preto Stream is located in urban areas under anthropogenic influence. The results showed that the levels of dissolved oxygen values were lower than those established by the National Environmental Council (CONAMA Resolution No 357/2005). The reading of electrical conductivity showed values typical of impacted environments. The parasitological analysis revealed the presence of nematode larvae. The bacteriological analysis showed higher values for total coliform and Escherichia coli than those set by the Brazilian National Environment Council (CONAMA). The heavy metals Cd, Pb, Cu, Cr, Mn, Hg, and Zn showed concentrations in accordance with the guidelines established by CONAMA. The results provide data on the quality of these waters and showed the necessity to protect the watercourse from point sources of contamination, recommending their continued monitoring.