Hydrogeochemistry of Sand Pit Lakes at Sepetiba Basin, Rio de Janeiro, Southeastern Brazil

Four sand pit lakes, at the Rio de Janeiro Sand Mining District, were monitored from November 2003 to November 2005, in order to characterize their hydrogeochemistry aiming to provide information to their possible use as fishponds at the end of mining activities. The results show diluted waters (low electrical conductivity) with low pH (<4) and relatively high sulfate and aluminum concentrations. The major water components (in particular Fe, Mn, SiO₂, Al and SO₄) are related to water acidity, since it controls solubility of aluminum silicate minerals and Mn and Fe oxides. Fe, Mn and Al availability in these waters are probably associated to organic colloids formation. On the other hand, the SiO₂ content, as well as the decrease of sand mining in rainy season, may partially control Al availability by the formation of hydroxi-aluminum silicates. These geochemical processes together with the interruption of sand mining in the rainy season and the dilution of sand pit lakes water by rainwater can support the use of these pit lakes as fishpond for aquaculture.     

Evolution of Mercury Contamination in Brazil

This paper reviews the history of Hg contamination in Brazil by characterizing and quantifying two major sources of Hg emissions to the environment: industrial sources and gold mining, industry was responsible for nearly 100% of total Hg emissions from the late 1940's to the early 1970's, when efficient control policies were enforced, leading to a decrease in emissions. Gold mining, on the other hand was nearly insignificant as a Hg source up to the late 1970's, but is presently responsible for over 80% of total emissions. Presently, over 210 t of Hg are released into the environment in Brazil annually. Nearly 170 t come from gold mining operations. 17 t come from chlor-alkali industry and 10 t come from all other industrial uses. Emissions to the atmosphere are the major pathway of Hg releases to the environment and reach over 160 t.yr-1 with approximately 136 t.yr-1 from gold mining.     

Arsenic Contamination in Rice, Wheat, Pulses, and Vegetables: A Study in an Arsenic Affected Area of West Bengal, India

Water retention and transport in soils is dependent upon the surface tension of the aqueous phase. Surfactants present in aqueous solution reduce the surface tension of aqueous phase. In soil–water systems, this can result in water drainage and reductions in field capacity and hydraulic conductivity. In this investigation, the surface tension of surfactant solutions mixed with soil—in a constant fixed ratio—was measured as a function of surfactant concentration. Two anionic surfactants were used: sodium dodecyl sulphate and sodium bis (2-ethylhexyl) sulfosuccinate. Two soils were also used—a clay soil and a sandy soil. The key observation made by this investigation was that the addition of soil to the surfactant solution provided a further component of surface tension reduction. Neither soil sample reduced the surface tension of water when surfactant was absent from the aqueous phase, though both soils released soil organic matter at low surfactant concentrations as shown by measurement of the chemical oxygen demand of the supernatant solutions. Furthermore, both surfactants were shown to be weakly adsorbed by soil as shown by the use of a methylene blue assay. It is therefore proposed that the additional reduction in surface tension arises from synergistic interactions between the surfactants and dissolved soil organic matter.     

Silicate Minerals as a Source of Arsenic Contamination in Groundwater

The dynamic behavior of water quality and quantity in the Egyptian drains is often viewed as a disruption to the normal operation and performance of the process of water reuse in irrigation. The control of such behavior has been challenging and often elusive in practice. Therefore, this paper presents a framework to advance the understanding and opportunities for improving the reuse process by developing a multivariate process control model. The model starts with preliminary analysis for water quality data that are collected at the reuse site on the examined drain. This phase comprises investigating data distribution and dependency. Then, univariate control charts are used to investigate the state of control for the independent and normally distributed variables. For dependent variables, principal components analysis is used as a method of synthesizing the variables information. In this case, principal component scores are displayed using multivariate control charts. If in-control case existed, process capability index is used to provide a numerical measure of whether or not the reuse process is capable of producing water that satisfies the irrigation quality standards. Since the model will only detect assignable causes if out-of-control or in-capable case existed, management, operational, and/or engineering action will usually be necessary to sustain the reuse process. In these cases, an action plan in response to the model signals will be vital. The main function of the proposed model is to safely manage the reuse practice using statistical quality control techniques. The model was demonstrated using water quality data collected during the period from January 2006 to July 2011 from Hanut (EH02) and El-Salam 3 (ESL03) pump stations along Hadus drain, Eastern Nile Delta-Egypt. The recommended model is automatic, algorithmic, self-tuning, and computerizable.     

Mercury Accumulation in Sediments of a Mangrove Ecosystem in SE Brazil

The Hg accumulation in sedimentary environments of a mangrove ecosystem in Sepetiba Bay, SE Brazil, was investigated. These environments include sediments of a mangrove forest, the main tidal creek that drains the forest, and the bare seaward-edge mud flat adjacent to forest and tidal creek. Maximum Hg concentration peaks in sediments from the mud flat (184 ng g^-1), tidal creek (98 ng g^-1), and mangrove forest (60 ng g^-1) correspond to enrichment factors of 6.1, 3.3, and 2.0 above the estimated average background level, respectively. Average inventories of Hg excess (background-corrected) concentrations were substantiallydifferent between environments, decreasing from mud flat sediments (5.2 mg m^-2) to creek sediments (3.3 mg m^-2)to mangrove forest sediments (0.9 mg m^-2). Mercury concentration profiles indicated a consistently higher accumulation of Hg in surface layers of mud flat and tidal creeksediments, whereas mangrove forest sediments showed a higher Hgaccumulation in root-rich subsurface layers, in agreement with an enrichment of Fe and organic matter contents. While Hg distribution in mud flat and tidal creek sediments appears to belargely affected by contamination, its distribution in mangrove forest substrate appears to be greatly affected by root-sedimentinteractions. Mercury levels in the study site were comparable tothose observed in coastal sediments under moderate Hg contamination at local and regional scales. Results indicate thatsedimentary environments surrounding the mangrove forest retain most of the anthropogenic Hg reaching the ecosystem. Since tidal waters have been previously demonstrated as the main source of metals to the site, it is suggested that the Hg retention in mudflat sediments precede and may avoid a higher Hg accumulation inlandward environments.     

Contamination of highly weathered urban soils in Uberlândia,Brazil

We determined heavy metal, polycyclic aromatic hydrocarbon (PAH), and polychlorinated biphenyl (PCB) concentrations in 18 topsoils of Uberlândia (420,000 inhabitants, Brazil) and in 3 rural topsoils. Concentrations of Al (11—124 g kg^—1) and Fe (13—109 g kg^—1) are large because of desilification. Concentrations of Cd (0.1—0.5 mg kg^—1), Cr (13—72), Cu (6—154), Mn (28—974), Ni (4—29), Pb (3—26), Zn (4—107), the sum of 20 PAHs (=Σ20PAHs:7—390 μg kg^—1), and the sum of 14 PCBs (=Σ14PCBs:0.05—1.25) are comparable to or below background concentrations in temperate soils except for Cu at two sites. More than 67% of the metals are strongly bound in Fe oxides and silicates; metals are more bioavailable in the urban than in the rural soils. The most abundant PAHs in the urban soils, on average, are naphthalene (19.0 ± 13.4% of Σ20PAHs) and the benzo(b+j+k)fluoranthenes (11.4 ± 6.7%); the most abundant PCBs are nos. 138 (23.3 ± 11.0% of Σ14PCBs) and 153 (14.3 ± 6.4%). The rural soils contain larger percentages of low molecular PAHs and up to tetra‒chlorinated PCBs than the urban soils. The different pollutant concentrations and patterns in the studied tropical compared with many temperate soils indicate different sources and fate.     

Heavy Metals Contamination in Century-Old Manmade Technosols of Hope Bay, Antarctic Peninsula

Technosols are anthropogenic soils that may be strongly impacted by heavy metal deposition, which have not yet been described in Antarctica. In this paper, we present a chemical study of what is supposedly the oldest manmade soil from Antarctic Peninsula, developed in the vicinity of Trinity House and Nordenskjold Hut at Hope Bay. Chemical and morphological soil attributes indicate that a former ornithogenic site (penguin rookery) was further subjected to human disturbance, following local exploration since 1903. We detected very high amounts of heavy metals such as Cd, Cu, Pb, and Zn. For the most impacted site, pseudototal concentrations of these elements reach 47, 2,082, 19,381, and 5,225 mg kg^?1, respectively. Enrichment factors were calculated using Zr as reference element, and high values were found for these contaminated sites, qualifying some of them as extremely polluted. Also, both the mobilizable and mobile fraction of Cd and Pb indicate the need of intervention in the affected area. These findings are all consistent with the human impacts and strong contamination. Strong positive correlation between the pseudototal concentrations of Cd, Cu, Mn, Ni, Pb, and Zn indicates a similar source of pollution. These soils may represent the oldest Technosols in Antarctic Continent.     

Human and Environmental Contamination by Mercury from Industrial Uses in Brazil

The amount of Hg used for industrial purposes in Brazil has been estimated as 105 t.yr-1, of which, 50% is released into the environment. As the industries that use this Hg are located in the neighborood of highly populated areas, the number of people exposed to the risk of contamination is high. Severe cases of chronically poisoned workers have been reported, most of them presenting neuropsychological disorders. Contamination of air, soil, and water resources are also observed. Analysis of sediments, water and biota of Guanabara Bay, Rio de Janeiro, show contamination of all segments by Hg originating mainly from a chlor-alkali plant located nearby. Higher concentrations of Hg were found in the sediments (0.7 to 20 mg.kg-1) where it is associated with organic matter usually under anoxic conditions. Mercury can became bioavailable by organification or by changes in the actual environmental conditions and is thus an important source of environmental contamination of people who consume its biota.     

Assessment of potentially toxic element contamination in soils from Portman Bay (SE,Spain)

Purpose

The present study deals with the geochemical fractions of Pb, Cd, Zn, Cu and As present on profiles using chemical simple extraction process. This work was conducted on Portman Bay, located in the SE Spain and strongly affected by mining activities.

Materials and methods

Four simple extractions were applied to selected samples in order to evaluate the potential mobility of metals. X-ray diffraction (XRD) was applied to the characterisation of samples and the residues remaining after each extraction, providing additional information about the sediment phases carrying the elements studied.

Results and discussion

The results obtained after the extractions suggested that the highest potentially toxic element (PTE) content was obtained in the oxidising medium. The mineralogical composition is an important factor that should be taken into account in the evaluation of PTE mobility, firstly because the mineral phases react differently in the proposed situations depending on their chemical nature, and secondly, because the presence of a particular phase depends on the degree of weathering.

Conclusions

The evaluation of PTE mobility and mineralogical composition under different environmental conditions may be very important in the execution of restoration projects which could involve dredging and mobilisation of materials.

     

The Effect of Former Mining Activities on Contamination Dynamics in Sediments,Surface Water and Vegetation in El Avenque Stream,SE Spain

This work aims to identify and characterize heavy metal contamination in a fluvial system from Cartagena–La Unión mining district (SE Spain). In order to assess the dynamics of transport and the accumulation of heavy metals, sediments, surface water and vegetation, samples along “El Avenque” stream were collected. The former direct dumps of wastes and the presence of tailing ponds adjacent to the watercourse have contributed to the total contamination of the stream. Total Cd (103 mg kg⁻¹), Cu (259 mg kg⁻¹), Pb (26,786 mg kg⁻¹) and Zn (9,312 mg kg⁻¹) in sediments were above the limits of European legislation, being highest where tailing ponds are located. Bioavailable metals were high (3.55 mg Cd kg⁻¹, 6.45 mg Cu kg⁻¹, 4,200 mg Pb kg⁻¹ and 343 mg Zn kg⁻¹) and followed the same trend than total contents. Metals in water were higher in sampling points close to ponds, exceeding World Health Organization guidelines for water quality. There is a direct effect of solubilisation of sediment metals in water with high contents of SO₄²⁻, product of the oxidation of original sulphides. The mobility of metals varied significantly with shifts in pH. Downstream, available and soluble metals concentrations decreased mainly due to precipitation by increments in pH. As a general pattern, no metal was bioaccumulated by any tested plant. Thus, native vegetation has adopted physiological mechanisms not to accumulate metals. This information allows the understanding of the effect of mining activities on stream contamination, enforcing the immediate intervention to reduce risks related to metals’ mobility.     

Arsenic Contamination in Soils Affected by a Pyrite-mine Spill (Aznalcóllar, SW Spain)

On 1998, a settling pond of a pyrite mine in Aznalcóllar (SW Spain) broke open, spilling some 3.6?×?10⁶ m³ of water and 0.9?×?10⁶ m³ of toxic tailings into the Agrio and Guadiamar river basin 40 km downstream, nearly to Doñana National Park. The soils throughout the basin were studied for arsenic pollution. Almost all the arsenic penetrated the soils in the solid phase (tailings) in variable amounts, mainly as a result of the different soil structure. The chemical oxidation of the tailings was the main cause of the pollution in these soils. A study of the relationships between the main soil characteristics and arsenic extracted with different reagents (water, CaCl₂, acetic acid, oxalic–oxalate and EDTA) indicates a direct relationship with the total arsenic concentration. The highest amount of arsenic was extracted by oxalic–oxalate (24%–36% of the total arsenic), indicating the binding with the iron oxides.     

利用独立变量分析与高光谱植被指数模型监测成熟期水稻中砷污染

水稻中过量砷（As）能够损害叶片中叶绿素和叶片内部结构,进而影响水稻光合作用效率,并改变水稻在光谱上的表现。利用高光谱植被指数（CARI、PRI、SIPI）和独立变量分析（ICA）模型对水稻中As含量进行了研究。结果表明,以上3种高光谱植被指数与水稻中As含量均呈一定的相关关系,其相关系数在0.67以上;而经过独立变量分析（ICA）可知,在蓝光波段（440～540nm）和红光波段（600～700nm）之间各有一个独立变量与水稻中As含量高度相关,相关系数达到0.95以上。将上述植被指数与独立变量和水稻中As含量之间进行回归分析,得到水稻中As含量的线性回归方程。研究表明,重金属As对水稻生长的影响可以通过其在光谱上的特征（如相关植被指数）改变来体现,并可以用独立变量分析（ICA）方法提取光谱中关于As胁迫的隐含弱信息,建立遥感预测模型,为大面积监测农作物As污染提供依据。     

Metal Contamination of River Waters and Sediments from Effluents of Kaolin Processing in Brazil

In order to evaluate the metal contamination from kaolin industry discharges into rivers in the State of Minas Gerais, Brazil, samples of river water and fluvial sediment were collected up- and down-river from the industries and analysed todetect metal inputs. The metal examined included zinc, iron, andaluminium among others, being selected due to their toxicity andoccurence in waste waters. Metal inputs in the samples analysed appeared to be related to effluent discharges into the rivers. The river water showed high concentrations (in μg mL^-1) of Zn (355), Fe (354) and Al (303). Sediment investigations indicated heavy enrichment (SEF = 9.4) for Zn. The Geoaccumulation Index for this element accounted for 3 (moderately to heavy polluted). River water pH of the sample collected near the effluent discharge site reached 3.7, suggesting inadequate treatment.     

Evaluation of Arsenic Availability in Sulfidic Materials from Gold Mining Areas in Brazil

This study is aimed at evaluating the availability and mobility of arsenic in sulfidic materials from gold mining areas in Minas Gerais State, Brazil. Eight extraction media were employed in a sequential extraction scheme, as follows: exchangeable As; strongly adsorbed As; As coprecipitated with acid-volatile sulfide, carbonates, MnO₂, and Al₂O₃; As coprecipitated with amorphous iron; As linked to crystalline iron oxide; As coprecipitated with silicates; As coprecipitated with amorphous FeS₂ and As₂S₃, and residual As, which was determined by GFAAS. Results demonstrated that in spite of differences in arsenic concentrations, the availability of the metalloid was found to be low for all samples. In general, arsenic was found in less available forms. Nevertheless, most of the arsenic in the environment is retained in the fractions 3, 4, and 5 which are susceptible to dissolution in acid medium, which in turn might be due to oxidation of the sulfide present in the samples.     

Environmental Arsenic and Selenium Contamination and Approaches Towards Its Bioremediation Through the Exploration of Microbial Adaptations: A Review

Bioaccumulation of selenium and arsenic resulting from geogenic activities and aggravated by anthropogenic actions has now become a serious environmental issue. Different parts of the world are experiencing issues of selenium and arsenic contamination, especially in soil and groundwater. The present selenium and arsenic contamination scenario has been well represented in contemporary literature, and there are an array of remediation techniques targeting the decontamination of environmental contamination. The use of microbe-mediated remediation of selenium and arsenic contamination is gaining scientific attention for sustainable environmental bioremediation. The present review elucidates the different aspects of selenium and arsenic contamination, bioaccumulation, and bioremediation with implications for successful decontamination of these heavy metals.     

大连湾养殖海域有机氯农药污染研究

采用毛细管GC-ECD法测定了大连湾海域表层沉积物及表层、微表层海水中16种有机氯农药(OCP₁₆)的含量。结果表明,毛细管GC-ECD测定OCPs回收率高、响应因子变异系数小、检出限低,适合于海洋环境样品中OCPs测定。在大连湾海域沉积物和水体中对OCPs均有检出,但污染水平相对较低。表层海水中OCPs平均含量为4.52 ng/L,表层沉积物中OCPs平均含量为6.17 ng/g。大连湾各站位微表层海水OCPs含量显著高于表层水,显示微表层海水对OCPs有较强的富集作用,平均富集系数在5.1～15.4之间。     

Occurrence of pharmaceutical and personal care products (PPCPs) in marine sediments in the Todos os Santos Bay and the north coast of Salvador,Bahia, Brazil

Purpose

The Todos os Santos Bay is the largest bay in Brazil and receives drainage from various watersheds. For more than 450 years, it was the main destination for the domestic and hospital sewage from the city of Salvador, Bahia. With the growing concern regarding the presence of pharmaceutical and personal care products (PPCPs) in the environment, an investigation was undertaken to determine the presence and levels of some commonly used drugs (i.e., atenolol, caffeine, carbamazepine, diazepam, diclofenac, erythromycin, ibuprofen) and personal care products (i.e., galaxolide, tonalide), using sediments as an indicator of their presence in the water column.

Material and methods

Surficial sediment samples from 17 stations located in the intertidal zone of the Todos os Santos Bay and infralittoral zone along the north coast of Salvador were tested for the presence of some PPCPs using LC-MS/MS (for drugs) and GC-MS/MS (for fragrances).

Results and discussion

The PPCPs examined were present in all sediment samples at levels of parts per billion of dry sediment. The highest concentrations were found for the fragrances galaxolide (52.5 ng g^?1) and tonalide (27.9 ng g^?1), followed by caffeine (23.4 ng g^?1) and pharmaceuticals ibuprofen (14.3 ng g^?1), atenolol (9.84 ng g^?1), carbamazepine (4.81 ng g^?1), erythromycin (2.29 ng g^?1), diclofenac (1.06 ng g^?1), and diazepam (0.71 ng g^?1).

Conclusions

Pharmaceuticals were found to be ubiquitous in the sediments of the study areas. The texture of the sediment was an important factor in PPCPs fixation and deposition. The concentrations of all PPCPs had statistically significant positive correlations with the percentage of clay in the sediments.     

Plant Colonization and Arsenic Uptake on High Arsenic Mine Wastes, New Zealand

Substrates associated with two historic gold mining sites in north Westland, New Zealand, have locally very high arsenic concentrations (commonly 10–40 wt% As). The substrates consist of iron oxyhydroxide precipitates, and processing mill residues. Waters associated with some of these substrates have high dissolved arsenic (commonly 10–50 mg/L As). Natural revegetation of these very high arsenic sites has occurred over the past 50 years, although some areas of substrate remain bare. Revegetating species include native and adventive shrubs, adventive grasses, rushes, and mosses, and native ferns. Revegetation by higher plants follows initial colonization by mosses, and some shrubs are growing directly in high-arsenic substrate. Shrubs, especially manuka (Leptospermum scoparium), gorse (Ulex europaeus), tree fuchsia (Fuchsia excorticata) and broadleaf (Griselinia littoralis) largely exclude arsenic from their shoots (<?10 mg/kg dry weight) irrespective of the As content of the substrate. Likewise, most grasses, and reeds (Juncus spp.), have only modest As contents (typically <?100 mg/kg dry weight). However, mosses growing on high-arsenic substrates have strongly elevated arsenic contents (>?0.2% dry weight). In particular, the moss Pohlia wahlenbergii acts as a hyperaccumulator, with up to 3% (dry weight) As. Antimony (Sb) contents of all plants are about one thousandth of that of arsenic, reflecting the As/Sb ratio of the substrates. Plant establishment in the high-As substrates may be locally limited by low nutrient status, rather than arsenic toxicity. The shrubs, grasses, and reeds identified in this study are arsenic tolerant and largely exclude arsenic from their shoots so that revegetation with these species, can help to isolate the high-arsenic substrates from the surface environment. These species could be used as phytostabilisation agents on high-arsenic sites that are remote from human habitation. In contrast, the mosses, despite their high arsenic tolerance, are a less desirable component of revegetation of high-arsenic substrates because they actively transfer arsenic from the substrate to the biosphere.     

Landslides in the Serra do Mar,Brazil

This paper discusses the environmental and the soil mechanical conditions for the massive planar slides which ravaged the area of Caraguatatuba, Serra do Mar, in 1967. Special attention is given to the hydrology of slopes on weathered gneiss during days of heavy rainfall. It is proposed that, under these circumstances, the forest vegetation indirectly triggers landslides. Both the plasticity index I_p and the sci-fraction (silt + clay + iron oxides) seem to be negatively correlated to the shear strengths of the regoliths. These indices, therefore, may have a value in prediction.