Removal of Hydrophobic Volatile Organic Compounds in an Integrated Process Coupling Absorption and Biodegradation—Selection of an Organic Liquid Phase

Since usual processes involve water as absorbent, they appear not always really efficient for the treatment of hydrophobic volatile organic compound (VOC). Recently, absorption and biodegradation coupling in a two-phase partitioning bioreactor (TPPB) proved to be a promising technology for hydrophobic compound treatment. The choice of the organic phase, the non-aqueous phase liquid (NAPL) is based on various parameters involved in both steps of the process, hydrophobic VOC absorption in a gas?Cliquid contactor, and biodegradation in the TPPB. VOC solubility and diffusivity in the selected NAPL, as well as NAPL viscosity, seems to be the main parameters during the absorption step, while biocompatibility, namely the absence of toxic effect of the NAPL towards microorganisms, non-biodegradability and VOC partition coefficient between NAPL and water were revealed as the key factors during the biodegradation step. The screening of the various NAPL available in the literature highlighted two families of compounds matching the required conditions for the proposed integrated process, silicone oils and ionic liquids.     

Effect of Organic Matter and Salinity on Ethylenediaminetetraacetic Acid–Extractable and Solution Species of Cadmium and Lead in Three Agricultural Soils

Abstract

A study was conducted to investigate the chemical speciation of added cadmium (Cd) and lead (Pb) and their availability as influenced by fresh organic matter (OM) and sodium chloride (NaCl) in three agricultural soils. The soils were treated with 20 mg Cd/kg as cadmium nitrate [Cd(NO₃)₂ · 4H₂O], 150 mg Pb/kg as lead nitrate [Pb(NO₃)₂], 20 g/kg alfalfa powder, and 50 mmol/kg of NaCl and then incubated for 3 months at 60% water‐holding capacity (WHC) and constant temperature (25 °C). Subsamples were taken after 1, 3, 6, and 12 weeks of incubation, and electrical conductivity (EC), pH, dissolved organic carbon (DOC), and concentrations of cations and anions were determined in the 1:2.5 soil/water extract. Available Cd and Pb were determined in 0.05 M ethylenediaminetetraacetic acid (EDTA) extract. Concentrations of organic and inorganic species of Cd and Pb in soil solution were also predicted using Visual Minteq speciation program. The most prevalent species of dissolved Pb and Cd in the soils were Pb‐DOC and Cd²⁺ species, respectively. Salinity application increased the available and soluble Cd significantly in the acid and calcareous soils. It, however, had little effect on soluble Pb and no effect on available Pb. Organic‐matter application decreased availability of added Pb significantly in all soils. In contrast, it raised soluble Pb in all soils except for the acid one and approximated gradually to the added Pb with time. Impact of OM on available Cd was somewhat similar to that of Pb. Soluble Cd increased by OM application in the calcareous soil, whereas it decreased initially and then increased with time in the other soils.     

Lead Isotopic and Metallic Pollution Record in Tree Rings from the Copperbelt Mining�CSmelting Area, Zambia

The composition of tree rings and soils was studied at several locations affected by smelting and transportation in the vicinity of Kitwe (Copperbelt, Zambia). The contents of cobalt (Co), copper (Cu), manganese (Mn), and lead (Pb) and the ²⁰⁶Pb/²⁰⁷Pb isotope ratios in the tree rings were interpreted in relation to potential sources of contamination such as smelter production, acidification of the environment, soil composition, raw material processing, and atmospheric suspended particulate matter (SPM). The highest Co contents in the tree rings correspond to maximum ore production in the mid-1970s. Acidification through SO₂ emissions is documented in the increased Mn contents from the mid-1980s. The isotopic composition of the tree rings of the studied tree species varies in the interval 1.16?C1.34 and the youngest parts of all the studied trees exhibit a low ²⁰⁶Pb/²⁰⁷Pb ratio (<1.17). The soil isotope composition varies in the range ²⁰⁶Pb/²⁰⁷Pb?=?1.18?C1.35. The Pb isotope composition in the soils and tree rings was formed by a combination of lithogenic Pb (²⁰⁶Pb/²⁰⁷Pb????1.3), Pb in processed ores (²⁰⁶Pb/²⁰⁷Pb????1.2), and SPM (automobile) Pb (²⁰⁶Pb/²⁰⁷Pb??1.1). As the soils in the distant region have high ²⁰⁶Pb/²⁰⁷Pb ratios (>1.3) in the whole profile and simultaneously the youngest parts of the tree rings of tree species growing in this soil have a low ²⁰⁶Pb/²⁰⁷Pb ratio (<1.17), it can be assumed that the Pb in the youngest parts of the tree species is derived from absorption of SPM Pb through the bark rather than root uptake. The absence of Pb with a low ²⁰⁶Pb/²⁰⁷Pb ratio in soils in the distant area is probably affected by fires in the herbaceous and bush undergrowth and plant litter, which prevents Pb from biomass from entering the soil and mobilize it back into the atmosphere.     

Geochemical and Mineralogical Features of Overbank and Stream Sediments of the Beal Wadi (Cartagena-La Union Mining District, SE Spain): Relation to Former Lead�CZinc Mining Activities and Its Environmental Risk

Heavy metals and some major element concentrations were investigated in overbank sediments and stream bed sediments of the ephemeral Beal wadi creek in the Cartagena-La Union mining district (SE Spain). Two vertical sediment profiles were extracted and the chemical and mineralogical compositions were both investigated by X-ray fluorescence and X-ray diffraction. Geochemical variations in vertical profiles of these two kinds of sediments allow observing noticeable heavy metals pollution (especially Fe, Pb, and Zn) in both kind of sediments but especially in the overbank sediments (reaching values of approximately 13% Fe, 6% Pb, and 6% Zn). A single extraction (DIN 38414-S4 leaching test) was made to observe the transfer of metals from solids to liquid phase. Pb, Zn, Cu, and Cd contents surpass the leaching values established by the DIN 38414-S4 limits established by Spanish legislation to consider these wastes as hazardous wastes. Geochemical comparison between leaching behavior of the two types of sediments reveals a major ability of overbank sediments in transferring heavy metals to the water flow.     

Influence of Organic Matter Vis-à-Vis Humic Acid on the Transformation of Inorganic and Organic Forms of Nitrogen in a Typic Haplustept Soil

A laboratory experiment was conducted to study the changes in inorganic and organic forms of nitrogen (N) in a Typic Haplustept soil treated with mustard cake vis-à-vis humic acid in the presence and absence of inorganic N. Results revealed that irrespective of treatments, significantly higher amount of soluble nitrate (NO₃^-), hydrolysable ammonium (NH₄⁺), non-hydrolysable and total N were accumulated in the soil treated with mustard cake in the presence of inorganic N. However, on the other hand, a humic acid-treated system showed significantly higher content of exchangeable NH₄⁺ and hexosamine N. Application of humic acid alone leads to the accumulation of a significantly higher amount of total hydrolysable and unidentified N in the soil. Among the different treatments, NH₄⁺ fixation was more in mustard cake followed by humic acid-treated soil. Humic acid is more susceptible to mineralization than mustard cake, particularly with respect to total N accumulation in soils.     

Distribution and Transport of Residual Lead and Copper Along Soil Pro?les in a Mining Region of North China

Residual heavy metals are commonly considered to be immobile in soils,leading to an underestimation of their environmental risk.This study investigated the distribution and transport of residual heavy metals along soil pro?les,using the Xiaoqinling gold mining region in North China as a case study.Soil samples were collected at three depths from three locations near the tailing heap.The speciation of copper(Cu) and lead(Pb)(exchangeable,carbonate-bound,Fe-Mn oxide-bound,organic matter-bound,and residual fractions) was determined using a sequential extraction procedure.The residual fraction's morphology was observed using scanning electron microscopy(SEM).Results showed that metal fraction distributions along the soil pro?les were in?uenced by each fraction's mobility.Residual fraction with high chemical stability can not be transformed from or into other fractions.This led to the conclusion that the high concentration of residual metals in soils mainly resulted from residual fraction transport.The SEM analysis showed that ?ne particles(submicrons) were mainly attached to large particles and were likely released and transported by water?ow.The more sorptive fractions(non-residual fractions) were mainly retained in the top soil,and the more mobile fractions(residual fraction) were mainly leached to the deep soil.Cu and Pb concentrations in the residual fraction decreased slightly and those in the non-residual fractions decreased signi?cantly with soil depth.These suggest a relatively higher residual metal mobility along the soil pro?les.Therefore,residual metals can be transported in soils and their environmental risk can not be ignored in assessing soil contamination.     

Ozone Formation Potentials of Volatile Organic Compounds and Ozone Sensitivity to Their Emission in the Megacity of São Paulo, Brazil

In the present study, a three-dimensional Eulerian photochemical model was employed to estimate the impact that organic compounds have on tropospheric ozone formation in the Metropolitan Area of São Paulo (MASP). In the year 2000, base case simulations were conducted in two periods: August 22–24 and March 13–15. Based on the pollutant concentrations calculated by the model, the correlation coefficient relative to observations for ozone ranged from 0.91 to 0.93 in both periods. In the simulations employed to evaluate the ozone potential of individual VOCs, as well as the sensitivity of ozone to the VOC/NO _x emission ratio, the variation in anthropogenic emissions was estimated at 15% (according to tests performed previously variations of 15% were stable). Although there were significant differences between the two periods, ozone concentrations were found to be much more sensitive to VOCs than to NO _x in both periods and throughout the study domain. In addition, considering their individual rates of emission from vehicles, the species/classes that were most important for ozone formation were as follows: aromatics with a kOH?>?2?×?10⁴ ppm^?1 min^?1; olefins with a kOH?<?7?×?10⁴ ppm^?1 min^?1; olefins with a kOH?>?7?×?10⁴ ppm^?1 min^?1; ethene; and formaldehyde, which are the principal species related to the production, transport, storage and combustion of fossil fuels.     

Investigation of Soil Concentrations of Persistent Organic Pollutants, Trace Elements, and Anions Due to Iron–Steel Plant Emissions in an Industrial Region in Turkey

The spatial distribution of several air pollutants emitted from iron–steel industries in Hatay-Iskenderun industrial region in Turkey was investigated by measuring their concentrations in soil. Collected soil samples (n?=?20) were analyzed for persistent organic pollutants (POPs; i.e., polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers, and polychlorinated naphthalenes), anions, and trace elements. Generally, all measured POP concentrations and marker trace elements for iron–steel industry (Zn, Pb, and Cu) were high relative to those reported previously for rural and urban areas around the world, and they were comparable to those measured recently in a similar industrial region (Aliaga, Izmir, Turkey). For all investigated POPs, elements, and anions, the highest concentrations were measured at points located north of the iron–steel industries where their emissions are transported by the prevailing southerly winds. The spatial distribution and levels of POPs, elemental, and anionic concentrations indicated that the iron–steel plants in Hatay-Iskenderun region are important sources for these pollutants. Statistically significant relationships between several organic and inorganic pollutants further confirmed that they are emitted by common sources (iron–steel plants).     

Comparison of Soil Physical Properties between a Permanent Fallow and a Long-Term Rice–Wheat Cropping with Inorganic and Organic Inputs in the Humid Subtropics of Eastern India

A comparison was made between a long-term rice–wheat cultivation with fertilizer nitrogen–phosphorus–potassium (NPK) or added organics [farmyard manure (FYM), paddy straw (PS), green manure (GM)] and a permanent fallow on bulk density (BD), saturated hydraulic conductivity (K_sat), available water capacity (AWC), maximum water-holding capacity (MWHC), aggregation, and soil organic carbon (SOC) dynamics on an Inceptisol of humid subtropics of eastern India. Continuous cropping caused a net decrease in SOC content. Undisturbed fallow was comparable to soils with FYM, PS, and GM amendments in structural and hydrophysical properties. Maximum WHC and AWC values were in the order of FYM followed by PS, GM, fallow, NPK, and control. The relative efficacy of the organics for physical buildup was FYM > PS > GM, which increased structural indices. This study represents further steps toward understanding the ecological importance of fallow management and integrated use of balanced fertilizer and organics.     

Investigating speciation and toxicity of heavy metals in anoxic marine sediments—a case study from a mariculture bay in Southern China

Purpose

The pollution of marine sediments by heavy metals is still a major concern, especially in zones affected by industry or mariculture. Toxicity of sediment heavy metal contents may be assessed using sequential extraction (SE) procedures, minding inherent constraints of such approaches. In this study, we investigated heavy metal speciation and toxicity in anoxic marine sediments in Zhelin Bay, a mariculture bay in Southern China, using an SE and acid volatile sulfur-simultaneously extracted metals (AVS-SEM) approach.

Materials and methods

Speciation of Cd, Cu, Ni, Pb, and Zn were studied by a modified SE of five fractions, adapted to separate organic and sulfidic metal fractions in anoxic sediments: F1 weak acid soluble (readily available), F2 reducible fraction, F3 organic matter-bound fraction, F4 sulfide-bound fraction, and F5 residually bound fraction. Toxicity predictions based on the sum of non-residual (NR) metal fractions from sequential extraction were compared to predictions based on AVS-SEM.

Results and discussion

Results showed that Cd, Ni, and Pb predominantly occurred in the weak acid soluble fraction (F1), residual fraction (F5), and sulfide-bound fraction (F4), respectively; Cu and Zn were mainly obtained in F4 and F5. Based on the distribution of indicator elements for metal fractions, the SEM from AVS extraction included different yields of non-residual and residual fractions besides the sulfidic fraction. Estimates for potential heavy metal toxicity based on NR metals of the SE procedure were thus based on a better-defined speciation compared to the simplistic approach of the AVS-SEM method.

Conclusions

Based on the contents of NR metals and normalizing them by organic matter content, toxic effects are not expected for any of the sampling sites, irrespective of the presence or absence of mariculture. Using Pearson correlation analysis to identify predominant fractions influencing toxicity, we conclude that toxicity of heavy metals in anoxic sediments can be well predicted by their non-residual heavy metal contents.

     

Kinetics of K Desorption from Soils in a Constant Electric Field (Electro-Ultrafiltration) and Its Application

Kdesorption from soils in a constant electric field (field strength:44.5Vcm^-1) by means of electro-ultrafil-tration (EUF) followed second-order kinetics and could be described by the equation dd/dt=k(D-d)2. From theequation, such kinetic parameters relating to K desorption from soils as the maximum desorbable quantity D, quantity of K desorbed within 40 minutes d40, initial desorption rate Vo, desorption rate constant k and half-time t1/2 could be calculated. An expression which describes the relationships between the kinetic parameters on the one hand and the responses of barley to fertilizer-K in the field experiments in different sites and the potassium-supplying power of soils on the other was established. Vo, D and d40 were significantly correlated with barley relative yield, K uptake by barley and the content of soil available potassium. The rate constants of K desorption varied between 4.42×10^-4-1.80×10^-3kg mg^-1 min^-1 and highly correlated with the relative yield of barley.     

Absorption and biological activity of phytochemical-rich extracts from açai (Euterpe oleracea Mart.) pulp and oil in vitro

Polyphenolic extracts from various fruits and vegetables have been shown to exert growth inhibitory effects in cell culture studies. Whereas individual polyphenolic compounds have been extensively evaluated, understanding of the biological activity of polyphenolic extracts from natural sources is limited and critical to the understanding of their potential effects on the human body. This study investigated the absorption and antiproliferative effects of phytochemical extracts from acai pulp and a polyphenolic-enriched acai oil obtained from the fruit pulp of the acai berry ( Euterpe oleracea Mart.). Chemical composition, antioxidant properties, and polyphenolic absorption of phytochemical fractions in a Caco-2 monolayer were determined, along with their cytotoxicity in HT-29 human colon adenocarcinoma cells. Standardized extracts were characterized by their predominance of hydroxybenzoic acids, monomeric flavan-3-ols, and procyanidin dimers and trimers. Polyphenolic mixtures (0-12 microg of gallic acid equiv/mL) from both acai pulp and acai oil extracts inhibited cell proliferation by up to 90.7%, which was accompanied by an increase of up to 2.1-fold in reactive oxygen species. Absorption experiments using a Caco-2 intestinal cell monolayer demonstrated that phenolic acids such as p-hydroxybenzoic, vanillic, syringic, and ferulic acids, in the presence of DMSO, were readily transported from the apical to the basolateral side along with monomeric flavanols such as (+)-catechin and (-)-epicatechin. Results from this study provide further evidence for the bioactive properties of acai polyphenolics and offer new insight on their composition and cellular absorption.     

Relative Efficacy of a Drinking‐Water Treatment Residual and Alum in Reducing Phosphorus Release from Poultry Litter

Abstract

Amending poultry litter with alum (aluminum sulfate) effectively reduces soluble phosphorus (P) concentrations, but the practice can be expensive. Aluminum (Al)‐based drinking‐water treatment residuals (WTRs) can be obtained free of charge and are enriched in Al hydr(oxides) that make them efficient P sorbents. Substituting Al‐WTRs for alum would be a cost‐effective practice to reduce soluble P in manures when compared with alum‐only use. The research studied the reductions in soluble P, Al, and total organic carbon (TOC) concentrations in suspensions prepared by mixing variable Al‐WTR and alum rates (0 to 25% by weight) with poultry litter. Suspensions were maintained at pH of 6.5 during the sorption step, and allowed to react up to 50 d, without shaking. On a per‐mole of oxalate‐extractable Al basis, the Al‐WTR was nearly as effective as alum in reducing P release. Increasing mixed alum/WTR mass loads resulted in greater soluble P reduction, simply due to increased molar Al/P ratios. Contact time did not significantly influence soluble P reduction. Two significant advantages of Al‐WTRs compared to alum indicated by this study are cost effectiveness and significantly less release of dissolved Al. Soluble Al and TOC concentrations were least for suspensions with the lowest soluble P levels, suggesting that P was removed from solution as an organo‐Al‐P amorphous phase. The amount of P desorbed from the mixtures decreased to <1% with increasing molar Al/P ratios ≥1. Results suggest that Al‐WTR application with or without alum can reduce soluble P in poultry litter; however, field validation of the amendment effectiveness is needed.     

Chemical fractions of copper and zinc in organic‐rich particles from aqueous extracts of a metal‐contaminated granite soil

Abstract

Chemical fractions of copper (Cu) and zinc (Zn) in the organic‐rich particles collected from filtered aqueous extracts (<20 μm) of an acid soil were determined. A sequential extraction procedure was used to partition the particulate Cu and Zn into four operationally defined chemical fractions: adsorbed (ADS), iron (Fe) and manganese (Mn) oxides bound (FeMnOX), organic matter bound (OM) and residual (RESD). Total extractable concentrations of Cu and Zn in the fine particles were higher than their total concentrations in the original bulk soil. The concentration of particulate Cu was usually much higher than that of particulate Zn. Addition of lime stabilized sewage sludge cake and/or inorganic metal salts markedly increased the concentrations of particulate Cu and Zn in aqueous extracts, especially from limed soil. The proportional distributions of particulate Cu and Zn were quite similar. The two particulate metals were present predominantly in the ADS and FeMnOX fractions, with less (about 20%) in the OM and RESD fractions. Some of the ADS metal fraction was associated with dissolved organic substances. The concentrations of particulate Cu and Zn in the various extractable fractions were significantly affected by the application of lime, lime stabilized sewage sludge cake, or inorganic metal salts.     

Effect of Organic Residues with Varied Carbon–Nitrogen Ratios on Grain Yield,Soil Health,and Nitrous Oxide Emission from a Rice Agroecosystem

Experiments were conducted in an attempt to study the impact of using different organic residues as fertilizers on grain yield, magnitude of nitrous oxide (N₂O) emissions, and soil characteristics. Five fertilizer treatments including conventional nitrogen (N) fertilizer, cow manure, rice straw, poultry manure, and sugarcane bagasse were applied in the rice field in 2012. The maximum reduction in seasonal N₂O emissions (10–27%) was observed under the influence of rice straw application over conventional N fertilizer. The experiment was repeated for a second season in 2013 with the same treatments for further confirmation of the results obtained during the first year of experimentation. The application of rice straw also showed a slight advantage by increasing grain yield (4.38 t ha^?1) compared to control. Important soil properties and plant growth parameters were studied and their relationships with N₂O emission were worked out. The incorporation of organic residues helped in restoring and improving the soil health and effectively enhancing grain yield with reduced N₂O emission from rice fields.     

Desorption and transformation of zinc in a mollisol and its uptake by plants in a rice–wheat rotation fertilized with either zinc-enriched biosludge from molasses or with inorganic zinc

Laboratory and greenhouse investigations were carried out with ⁶⁵Zn-labeled sources to study the kinetics of desorption, transformation, and availability of Zn applied to soil as zinc-enriched biosludge from distillery molasses (ZEMB) or as zinc sulfate heptahydrate (ZSH). Desorption (0.5 to 72 h) of added Zn by the column method followed a biphasic kinetics with an initial (up to 12 h) faster phase followed by a slower desorption phase. The desorption rate coefficient (K) of the latter phase and the amount of Zn desorbed during 12 to 72 h were significantly higher with ZEMB than with ZSH. Sequential extraction of Zn added as ZEMB and ZSH showed that Zn added as ZEMB was present in higher proportion as water soluble + exchangeable, carbonate bound, organically bound, and reducible fractions than Zn applied as ZSH, which showed a higher proportion of residual fraction. Under greenhouse conditions, dry matter yield (35 days) and total Zn uptake by rice fertilized with ZSH applied at 5 kg Zn ha⁻¹ were statistically similar to those of rice treated with 2.5 kg Zn ha⁻¹ supplied as ZEMB. The highest Zn uptake (167.08 μg pot⁻¹) by rice was recorded in the treatment with 5 kg Zn ha⁻¹ as ZEMB. For wheat plants grown after the harvest of rice, significantly higher dry matter yield over control was recorded in the treatment with ZEMB applied at 5 kg Zn ha⁻¹ to rice. Total Zn uptake by wheat was statistically similar for both ZEMB and ZSH treatments at 5 kg Zn ha⁻¹ dose. Both zinc derived from fertilizer and the percent utilization of fertilizer Zn by rice and by the subsequent wheat crop were significantly higher with ZEMB than with ZSH. Patent filed No. 757/MUM/2007 dated 19.04.2007     

Effects of heavy metals from mining and industry on some rivers in Poland: An already exploded chemical time bomb?

Upper Silesia has rich deposits of hard coal and substantial deposits of zinc, lead and iron ores. the watersheds of two rivers cut right through the zinc and lead ore mining region and most of the tailing drainage water is contaminated with heavy metals. in total, about 807 tyr-1 of zinc, 67t yr-1 of lead and 17 tyr-1 of cadmium are discharged with the drainage and process waste water. in the Upper Silesia many industrial plants also discharge waste water contaminated with heavy metals. the Bukowno Complex is the most important regional source of heavy metals and the Biala Przemsza River is the main receiver of waste waters from this complex. Measured data at a cross-section of this river are given. It is shown by a simplified calculation that lead and zinc are transported downstream to the Vistula River and later to the Baltic Sea, or are deposited in the river bed. It is shown that there are many other possible sources of heavy metals. Atmospheric deposition of metals on the surface leads to surface runoff, accumulation in plants, and subsequently discharge with animal or human excreta. Contaminated sediments will continue to pollute the overflowing river water, perhaps for centuries. Mobilization of heavy metals and factors affecting that process are discussed in relation to providing safe drinking water now and in the future. It is emphasized that the drinking water quality is already threatened.     

Distribution of Heavy Metals and Minerals in the Various Size Fractions of Soil from Copșa Mică, România

The Cop?a Mic? area is one of the most polluted anthropic sites in Romania. Because higher heavy metal concentrations occur in finer fractions, this research focuses on the size fraction <?500 μm. Two kilograms soil sample was sieved on the 500-μm sieve and was air classified into size fractions down to the low micrometer range. The size fraction’s composition was investigated by ICP-OES IC, XRD, and FTIR spectrometry. Approximately 80 and 62% of the material was smaller than 2 mm and <?500 μm, respectively. The predominant size fraction had a mass median diameter (MMD) of approximately 75 μm. The smallest size fraction with a MMD of 2.2 μm had a share of 3.6% and contained the highest amount of heavy metals. The concentrations of Pb, Zn, Cd, Cu, Sb, and As exceeded the legally regulated values for soils according to Romanian legislation. The respective concentrations were 26,900, 27,600, 415, 2130, 466, and 915 mg·kg^?1. In the coarser size fractions 5, 4, and 3, the predominant minerals were quartz and alkaline feldspar, while in the finer size fractions 1 and 2, the clay minerals and total carbon (TC) were predominant. Illites and montmorillonites in the fine fraction composition retain heavy metals due to the high levels of cation exchange capacity. Black carbon accumulated in soil acts as a heavy metal adsorbent due to its porosity and high specific surface area. The good correlation between heavy metals and TC in the top soil can be an indicator of the level of heavy metal pollution.     

Distribution of Metals in Vadose Zone of the Alluvial Plain in a Mining Creek Inferred from Geochemical, Mineralogical and Geophysical Studies: The Beal Wadi Case (Cartagena�CLa Union Mining District, SE Spain)

The assessment of metals dispersal in polluted mining areas is a very complex issue, usually needing data from several analytical techniques in a joint approach. The present work focuses on the impact of the mining activity on lowlands alluvial plain sediments from an ephemeral creek, their role as source or sink of pollution and the spatial distribution of metals within the zone. In-depth distribution of elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, S, Ti and Zn) coming from mining activities was investigated by using X-ray fluorescence techniques and their mineralogical form using X-ray diffraction. A 2-D electrical resistance tomography field survey was carried out throughout at the creek bed to interpret the potential relationships between chemical, mineralogical and geophysical parameters. The application of leaching procedure (DIN 38414-S4 test) allows us to know the sediment??s heavy metals hazard and their potential mobility when changing redox conditions. From the results it was found that redox process of sulphur and the presence of carbonate influence the distribution of metals along the profile. In the present work, the precipitation of carbonates seems the most important process, especially for elements such as Zn and Mn. Secondary precipitation of sulphides enables the trapping of metals at sulphur-rich levels.