Enrichment Of Metals In Sediments Research Articles

Influence of the Atlantic inflow on trace metal enrichments in sediments and particulate matter of the NW Alboran Sea (SW Mediterranean)

Trace metal contents and fluxes in downward particulate matter and dated sediment cores of the NW Alboran Sea are analysed in this study with the aim of assessing the role of the Atlantic inflow on their transport. Increases in Zn, Cu and Pb were detected in downward particulate matter collected by sediment traps after river flooding events and after the Aznalcollar mining spill. Their arrival coincided within the recently estimated time range for river particles discharged into the Gulf of Cádiz to reach the Alboran Sea, indicating that their transfer is enhanced during events of increased river inputs of contaminated particulate matter. This also suggests that the effects of potential tailing dam failures in the Gulf of Cádiz watersheds could reach the Alboran Sea. These trace metals also increased in the sediment cores from the continental rise since the second half of the 19th century, suggesting that contaminated particles have been continuously transferred towards the Mediterranean Sea since that time, when mining concessions and production increased in the SW Iberian Pyrite Belt.

The impact of two extensively-modified rivers (Georges and Cooks Rivers) on a receiving basin exhibiting minor ecological risk (Botany Bay) (Australia)

Botany Bay is a large, tide-dominated, drowned river valley on the eastern seaboard of Australia, which was initially planned as the first European settlement in the country. The Georges River has a large catchment (936.5 km 2) and comprises mainly undeveloped parkland (62%), while the Cooks River catchment is small (103 km 2) and substantially modified (90 %). The extent of anthropogenic change and level of ecologic risk were determined for these areas using sedimentary metals as an initial screening assessment of environmental condition of these waterbodies. Cooks River was assessed as one of the most anthropogenically-modified urban rivers on the east coast of Australia with sediments exhibiting severe metals enrichment and moderate ecologic risk. Georges River sediments were highly enriched with moderate to slight ecological risk. Both Georges and Cooks Rivers discharge to Botany Bay, which was mantled in highly metal-enriched sediments, but exhibited only minor ecological risk. These results illustrated an unusual example of an estuary significantly influenced by metal-enriched sediments, but exhibiting minimal ecological risk. This anomaly was due to high anthropogenic-metal concentrations in the fine fraction of surficial sediment, which were considerably diluted by abundant metal-poor coarse material resulting in low total metal concentrations and reduced adverse ecological risk. The low proportion of fine material in surficial sediment was possibly due to increased ambient wave and tidal energy in the bay. Size-normalised metal distributions show distinct dispersion pathways from Cooks and Georges Rivers to the mouth of Botany Bay. Stormwater was a major source of metals to the system, supplemented by leakage from waste dumps and secondary sourcing by remobilisation of enriched-legacy sediments.

Metal enrichment in sediments and bioaccumulation in edible bivalve Saccostrea cucullata from mudflats of a tropical estuary, India: a study to investigate toxicity and consumption suitability

Mudflat sediment cores from lower (C-1), middle (C-2), and lower regions of upper (C-3) Chapora Estuary were investigated for grain size composition, total organic carbon, total and bioavailable Fe, Mn, Cu, Co, Ni, and Zn to assess metal contamination. Accumulation of metals by Saccostrea cucullata was studied to understand metal toxicity. In core C-1, Fe, Mn, Cu, Co, Ni, and Zn showed an average concentration of 1.73%, 648ppm, 12ppm, 12ppm, 16ppm, and 25ppm, respectively, while core C-2 revealed their average concentration as 1.34%, 709ppm, 10ppm, 11ppm, 13ppm, and 28ppm respectively. In core C-3, an average concentration of Fe, Mn, Cu, Co, Ni, and Zn was 1.72%, 907ppm, 14ppm, 13ppm, 18ppm, and 31ppm respectively. Metals in sediments varied within the estuary due to hydrodynamics, discrepancies in metal sources and sand mining-induced remobilization of metals. Correlation and principal component analysis revealed Fe oxides as the key regulator of trace metal distribution in sediments along with clay and total organic carbon. Enrichment factor (EF) and geo-accumulation index (Igeo) showed more or less moderate contamination of Mn in core C-3. Also, the potential contamination index (PCI) indicated moderate contamination of Mn in core C-3 using the shale value as background concentration, whereas the application of upper crustal value revealed moderate contamination of Fe, Mn, Cu, Co, and Ni in core C-1, Mn, Co, and Ni in core C-2 and of Cu, Co, and Ni in core C-3. Mn was severely to very severely contaminated in core C-3. The mean probable effect level quotient and mean effect range median quotient showed medium to low-level contamination of Cu, Ni, and Zn. Metals were considerably allied to Fe-Mn oxide and organic/sulphide fractions which revealed their bioavailability. Mn was 36% in labile form (lower estuary) and indicated a high risk to biota. Mn, Ni, and Zn in Saccostrea cucullata exceeded the permissible limit and suggested toxicity and non-suitability for human consumption.

Plausible Emergence and Self Assembly of a Primitive Phospholipid from Reduced Phosphorus on the Primordial Earth.

How life arose on the primitive Earth is one of the biggest questions in science. Biomolecular emergence scenarios have proliferated in the literature but accounting for the ubiquity of oxidized (+ 5) phosphate (PO43-) in extant biochemistries has been challenging due to the dearth of phosphate and molecular oxygen on the primordial Earth. A compelling body of work suggests that exogenous schreibersite ((Fe,Ni)3P) was delivered to Earth via meteorite impacts during the Heavy Bombardment (ca. 4.1-3.8 Gya) and there converted to reduced P oxyanions (e.g., phosphite (HPO32-) and hypophosphite (H2PO2-)) and phosphonates. Inspired by this idea, we review the relevant literature to deduce a plausible reduced phospholipid analog of modern phosphatidylcholines that could have emerged in a primordial hydrothermal setting. A shallow alkaline lacustrine basin underlain by active hydrothermal fissures and meteoritic schreibersite-, clay-, and metal-enriched sediments is envisioned. The water column is laden with known and putative primordial hydrothermal reagents. Small system dimensions and thermal- and UV-driven evaporation further concentrate chemical precursors. We hypothesize that a reduced phospholipid arises from Fischer-Tropsch-type (FTT) production of a C8 alkanoic acid, which condenses with an organophosphinate (derived from schreibersite corrosion to hypophosphite with subsequent methylation/oxidation), to yield a reduced protophospholipid. This then condenses with an α-amino nitrile (derived from Strecker-type reactions) to form the polar head. Preliminary modeling results indicate that reduced phospholipids do not aggregate rapidly; however, single layer micelles are stable up to aggregates with approximately 100 molecules.

Sediment metal enrichment and ecological risk assessment of ten ports and estuaries in the World Harbours Project

Ten global harbours were assessed for sediment quality by quantifying the magnitude of anthropogenic change and ecological risk. Anthropogenic change (enrichment) was high for Derwent River and Sydney estuary, moderate for Santander Harbour, Rio de Janeiro and Dublin Port, slight for Hong Kong, minimal for Darwin. All 10 enrichment indices used showed similar results. Derwent River sediment was rated at high ecological risk, followed by Sydney and Santander estuaries with moderate risk. Auckland and Darwin sediments exhibited minimal ecological risk and sediment in the remaining harbours (Dublin, Hong Kong, Ravenna, Ria de Vigo and Rio de Janeiro) were assessed at slight ecological risk.The extraordinary variety of environments and types/quantities/qualities of data investigated resulted in as much a critique and development of methodology, as an assessment of human impact, including unique techniques for elemental normalisation and contaminant classification. Recommendations for an improved technical framework for sediment quality assessment are provided.

Historical anthropogenic heavy metal input to the south-eastern North Sea

The Helgoland Mud Area (HMA) in the German Bight, covering an area of approximately 500 km2, is one of a few depocentres for finer sediments in the North Sea. Radiocarbon and 210Pb analyses revealed continuous sedimentation over the last several centuries. Zinc (Zn) and lead (Pb) contents in the sediments show a distinct increase towards the youngest most sediments with the thickness of the heavy metal enriched sediments ranging from 15 to 103 cm. Stratigraphic data indicate that the onset of heavy metal enrichment is diachronous progressing north-westward over the depocentre, paralleled by a decrease in the thickness of the enriched layer. Beginning already during medieval times, the enhanced input of Zn and Pb seemingly is related to silver and zinc mining in the Harz Mountains and the Erzgebirge, well-known mining areas since the Bronze Age. Both regions are directly connected to the HMA by the Elbe and Weser rivers. Zn and Pb enrichment began in the south-eastern HMA and progressed subsequently with an average of 10 m per year north-westward, most likely triggered by variations in river discharge and by the hydrodynamic setting. Quantitative assessments of the Zn and Pb content in the sediments suggest that since the onset of enhanced Zn and Pb deposition, the anthropic Zn and Pb input in the HMA amounts to ~ 12,000 t and ~ 4000 t, respectively.

Geochemical Investigations of Fe-Si-Mn Oxyhydroxides Deposits in Wocan Hydrothermal Field on the Slow-Spreading Carlsberg Ridge, Indian Ocean: Constraints on Their Types and Origin

We have studied morphology, mineralogy and geochemical characteristics of Fe-oxyhydroxide deposits from metal-enriched sediments of the active (Wocan-1) and inactive (Wocan-2) hydrothermal sites (Carlsberg Ridge, Northwest Indian Ocean). Fe-oxyhydroxide deposits on the Wocan-1 site are reddish-brownish, amorphous and subangular. They occur in association with sulfides (e.g., pyrite, chalcopyrite and sphalerite) and sulfate minerals (e.g., gypsum and barite). The geochemical composition shows enrichment in transition metals (Ʃ (Cu + Co + Zn + Ni) = ~1.19 wt. %) and low (<0.4 wt. %) values of Al/(Al + Fe + Mn) ratio. The Wocan-2 samples show poorly crystallized reddish brown and yellowish Fe-oxyhydroxide, with minor peaks of goethite and manganese oxide minerals. The mineral assemblage includes sulfide and sulfate phases. The geochemical compositions show two distinct types (type-1 and type-2). The type-1 Fe-oxyhydroxides are enriched in transition metals (up to ~1.23 wt. %), with low values of Fe/Ti vs. Al/(Al + Fe + Mn) ratio similar to the Wocan-1 Fe-oxyhydroxides. The type-2 Fe-oxyhydroxides are depleted in transition metals, with Al/(Al + Fe + Mn) ratio of 0.003–0.58 (mean value, 0.04). The ridge flank oxyhydroxides exhibit an extremely low (mean value ~ 0.01) Fe/Mn ratio and a depleted concentration of transition metals. Our results revealed that the Wocan-1 Fe-oxyhydroxides and type-1 Fe-oxyhydroxides of the Wocan-2 site are in the range of Fe-oxyhydroxides deposits that are precipitated by mass wasting and corrosion of pre-existing sulfides. The type-2 Fe-oxyhydroxides are precipitated from sulfide alteration by seawater in an oxygenated environment relative to type-1. The association of biogenic detritus with the oxyhydroxides of the ridge flanks and the low Fe/Mn ratio suggests hydrogenous/biogenic processes of formation and masked hydrothermal signatures with distance away from the Wocan hydrothermal field.

Inherent bacterial community response to multiple heavy metals in sediment from river-lake systems in the Poyang Lake, China

Sediment is the one of most important storage of heavy metal. Microbiotas in sediment can be used as the effective indicators of heavy metals. The goal of this study was to understand the bacterial communities responding to heavy metal enrichment in sediments and prioritize some factors that affected significantly to bacterial community. Sediments were sampled from five river-lake systems in the Poyang Lake in dry season, and the bacterial community was analyzed using Illumina high-throughput sequencing. Relationships between sediment environment and the diversity and structure of bacterial communities were determined by correlation analysis and redundancy analysis (RDA). The result indicated that Cd and Sb were identified as the heavy metals of the great risk in sediments. Sediments from five river-lake systems shared 31.83% core operational taxonomic units (OTUs) of bacterial communities. Proteobacteria (33.54% of total sequences) and Actinobacteria (15.04%) were the dominant phyla across all sites. High enrichment of heavy metals (MRI and mCd) resulted in low diversity of bacterial communities (Simpson index). The RDA revealed pH, OC, mCd, and Efs of As, Pb, Cd were major factors related to bacterial community structure changes. The dominant phylum Actinobacteria was regarded as tolerant bacteria, while the dominant phylum Proteobacteria was named as resistant bacteria in sediment with high anthropogenic Cd enrichment.

Extreme spatial variability in riverine sediment load inputs due to soil loss in surface mining areas of the Lake Baikal basin

Surface mining can contribute to increasing riverine loads of potentially metal-enriched sediments. However, the related human disturbances and natural processes reflect a great complexity, which hinders quantitative understanding. We here consider the Zaamar Goldfield in Mongolia, one of the world's largest placer mining sites, located in the Tuul River basin (upper Lake Baikal basin). A main study aim is to investigate relations between patterns of increased sediment loads along the Tuul River and the (spatially variable) area coverage of active or recently abandoned placer mines in the river vicinity. Specifically, we compare observed loads derived from nested catchment areas with the output from spatially distributed soil erosion modelling. Results showed that riverine sediment loads in mining areas reflect soil losses both from soil erosion and direct human impacts (e.g. waste water discharge), which are two to three orders of magnitude higher than the input from natural areas dominated by soil erosion alone. Notably, the sediment load contributions from the mining areas were insensitive to changes in hydrometeorological conditions, whereas contributions from natural areas were much lower during drier periods (as expected when governed by soil erosion by water). Accordingly, the relative contribution to the total sediment load (TSL) of metal-enriched soil from mining areas is likely to be particularly pronounced (with estimated values of about 80% of TSL) under drier hydrometeorological conditions. This is consistent with observations of considerably elevated metal concentrations under low flow conditions and implies that if annual average discharge continues to decrease in the Tuul River as well as the entire Selenga River system, increased metal concentrations may be one of the consequences.

Hazardous metal pollution in a protected coastal area from Northern Patagonia (Argentina).

The San Antonio Bay is a protected natural coastal area of Argentina that has been exposed to mining wastes over the last three decades. Iron and trace metals of potential concern to biota and human health (Cd, Pb, Cu, and Zn) were investigated in the sediments from the bay and in the soils of the Pile (mining wastes). Concentrations of Cd (45mgkg-1), Pb (42,853mgkg-1), Cu (24,505mgkg-1), and Zn (28,686mgkg-1) in the soils Pile exceeded guidelines for agricultural, residential, and industrial land uses. Risk assessment due to exposure to contaminated soils (Pile) was performed. Hazard quotients were superior to non-risk (HQ >1) for all trace metals, while accumulative hazard quotient index indicated a high risk for children (HI=93) and moderate for adults (HI=9). In the bay, sediments closest to the Pile (mudflat and salt marsh) exceeded sediment quality guidelines for protection of biota. Results of different acid extraction methods suggest that most of the pseudototal content was potentially mobile. Principal component analysis indicated that the sites near the Pile (Encerrado channel) were more polluted than the distal ones. Tissues of Spartina spp. located within Encerrado channel showed the highest metal levels among all studied sites. These results show that the problem still persists and the mining wastes are the sources of the pollution. Furthermore, the Encerrado channel is a highly impacted area, as it is shown by their metal enriched sediments.

Heavy metal assessment in sediments of east coast of Tamil Nadu using energy dispersive X-ray fluorescence spectroscopy

Selected heavy metals (Cr, Co, Ni, Cu, Zn, As, and Pb) in sediments from Periyakalapattu to Parangipettai of east coast of Tamil Nadu were determined to assess the contamination status and potential ecological risk. The pollution indices such as enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), and pollution load index (PLI) were calculated to determine the contamination level and enrichment of metals in sediments. EF analysis suggested that anthropogenic influence on the environment has been significant in case of Cr. The values of CF indicate that the sediments are not contaminated with these heavy metals. Igeoresults reveal that the study area is not contaminated with respect to Cr, Co, Ni, Cu, Zn, As, and Pb. This results of Igeoare in good agreement with PLI. Based on the sediment quality guidelines, it is observed that Cr and Ni would be a concern for the ecotoxicological risk in study area.

Geochemical enrichment of metals in sediments and their relation with the organic carbon

ABSTRACTThis article aims to assess the concentrations of zinc (Zn) and nickel (Ni) and the organic matter (OM) content in different depth samples of sediments produced in this river basin of the Mãe d'Água dam. The sampling was carried out in June 2014, and four sediment cores in pre-defined points of the dam were sampled. A core sampler ‘Piston Core’ was used for the extraction of sediment cores. The sediments with fraction less than 63 μm were destined to the chemical analysis for the verification of the presence and concentration of trace elements: Ni and Zn. The acid digestion methodology employed is the EPA 3050, adopted by the US Environment Protection Agency, and the analyses were carried out in duplicates and for quality control we used two reference materials of the US Geological Survey: Green River Shale (SGR-1b) and Cody Shale (SCO-1). With the results obtained, all samples showed concentrations of Zn and Ni above the local background value and growth patterns, demonstrating the existence of enrichment of the sediments by these elements. The levels of OM when correlated at concentrations of Zn and Ni showed the growing enrichment in the sediment cores analysed, confirming the high affinity of these elements with the sediment compounds of fraction organic.

Seasonal variation and enrichment of metals in sediments of Rosetta branch, Nile River, Egypt.

This study investigated heavy metal pollution in sediments of the Rosetta branch of the River Nile of Egypt to quantify the toxic distribution potential of metals into the surrounding environment. Sediment samples were collected at 9 sites during in four seasons. Organic matter and total metal concentrations were determined using loss on ignition and inductively coupled plasma spectrometry, respectively. Principal component analysis has been applied to evaluate the metal sources and the relationships between metals in sediments. Metal concentrations showed the following order: winter > autumn > spring > summer. Mean concentrations of Cu, Zn, Cd, and Pb in sediments were above the average background value of metals in shale. Pb and Cd showed higher enrichment during all seasons at stations N3/N4, Zn at stations N1 to N4, and Cu at stations N6/N8. The variations in heavy metal total concentration and organic matter are due to different input sources, physico-chemical conditions, and adsorption/precipitation/redox conditions in sediments. Mean values of Geo-accumulation index (Igeo) for Fe, Mn, and Cu were below 0 which were classified as unpolluted during spring, summer, and autumn, except Cu increased from unpolluted to moderately polluted during winter. Igeo values for Cd, Pb, and Zn increased from unpolluted-moderately polluted to highly-very highlypolluted during autumn and winter. Pollution Load Index was recorded in highest values during winter, especially at Fuwwah/Basioun and in lowest values during summer at after the Edfina Barrage/before Kafer El-Zayat due to industrial/human activities. Both natural and anthropogenic sources contributed to the metal accumulations in sediments, and industrial, agricultural, and municipal sewage effluents discharged from non-point sources may be the main anthropogenic sources for metals in the Rosetta branch.

Seasonal variation and sources of dissolved trace metals in Maó Harbour, Minorca Island

The environmental conditions of semi-enclosed coastal water-bodies are directly related to the catchment, human activities, and oceanographic setting in which they are located. As a result of low tidal forcing, and generally weak currents, waters in Mediterranean harbours are poorly renewed, leading to quality deterioration. Here, we characterise the seasonal variation of trace metals (i.e. Co, Cd, Cu, Fe, Mo, Ni, Pb, and Zn) in surface waters, and trace metal content in sediments from Maó Harbour, a semi-enclosed coastal ecosystem in the NW Mediterranean Sea. Our results show that most of the dissolved trace metals in the waters of Maó Harbour exhibit a marked inner-outer concentration gradient, suggesting a permanent input into the inner part of the harbour. In general, metal concentrations in the waters of Maó Harbour are higher than those in offshore waters. Concentration of Cu (21±8nM), Fe (9.2±3.2nM) and Pb (1.3±0.4nM) are particularly high when compared with other coastal areas of the Mediterranean Sea. The concentration of some metals such as Cu and Zn increases during summertime, when the human population and boat traffic increase during the tourism season, and when resuspension from the metal enriched sediments is higher. The evaluation of the metal sources in the harbour reveals that, compared with other putative sources such as runoff, aerosol deposition and fresh groundwater discharges, contaminated sediments are the main source of the metals found in the water column, most likely through vessel-driven resuspension events. This study contributes to the understanding of the processes that control the occurrence and distribution of trace metals in Maó Harbour, thus aiding in the effective management of the harbour, and enhancing the overall quality of the seawater ecosystem.

Distribution and environmental impacts of heavy metals and radioactivity in sediment and seawater samples of the Marmara Sea

In this study, the natural and anthropogenic radioactivity levels in the sediment samples collected from the Marmara Sea in Turkey were determined. The average activity concentrations (range) of 226Ra, 238U, 232Th, 40K and 137Cs were found to be 23.8 (13.8–34.2) Bq kg−1, 18.8 (6.4–25.9) Bq kg−1, 23.02 (6.3–31.1) Bq kg−1, 558.6 (378.8–693.6) Bq kg−1 and 9.14 (4.8–16.3) Bq kg−1, respectively. Our results showed that the average activity concentrations of 226Ra, 238U and 232Th in the sediment samples were within the acceptable limits; whereas the average activity concentration of 40K in the sediment samples was higher than the worldwide average concentration. The average radium equivalent activity, the average absorbed dose rate and the average external hazard index were calculated as 100.01 Bq kg−1, 48.32 nGy h−1 and 0.27, respectively. The average gross alpha and beta activity in the seawater samples were found to be 0.042 Bq L−1 and 13.402 Bq L−1, respectively. The gross alpha and beta activity concentrations increased with water depth in the same stations. The average heavy metal concentrations (range) in the sediment samples were 114.6 (21.6–201.7) μg g−1 for Cr, 568.2 (190.8–1625.1) μg g−1 for Mn, 39.3 (4.9–83.4) μg g−1 for Cu, 85.5 (11.0–171.8) μg g−1 for Zn, 32.9 (9.1–73.1) μg g−1 for Pb and 49.1 (6.8–103.0) μg g−1 for Ni. S5 station was heavily polluted by Cr, Cu, Ni and Pb. The results showed that heavy metal enrichment in sediments of the Marmara Sea was widespread.

Geochemical assessment of trace metal pollution in sediments of the Cochin backwaters

ABSTRACTThe Cochin backwaters are facing widespread environmental pollution because of the release of solid wastes and liquid effluents from industrial, domestic, and agricultural sectors. The waters are contaminated with trace metals due to an inefficient waste disposal system. Here, the potential trace metal enrichment in sediments related to human activities was evaluated using an enrichment factor, contamination factor, geo-accumulation index, and pollution load index. Metal concentration ranges in sediments during the monsoon, post-monsoon, and pre-monsoon periods were as follows: Fe (15517–90885 µg/g), Mn (122.5–970.9 µg/g), Co (6.9–41.9 µg/g), Ni (12.9–62.9 µg/g), Cu (15.9–56.8 µg/g), Zn (58.7–888.7 µg/g), Cd (0.9–14.5 µg/g), and Pb (12.7–46.8 µg/g). Data on sediment trace metal concentrations are important for environmental forensic investigations, useful for monitoring (i.e., tracing) sources of contaminants (i.e., metal pollutants) and their impacts, and valuable for tracking the dispersal pathways of contaminants in estuarine environments.

Geochemical fractionation of Ni, Cu and Pb in the deep sea sediments from the Central Indian Ocean Basin: An insight into the mechanism of metal enrichment in sediment

Metal speciation study in combination with major element chemistry of deep sea sediments provided possible metal enrichment pathways in sediments collected from environmentally different locations of Central Indian Ocean Basin (CIB). Metal speciation study suggests that Fe–Mn oxyhydroxide phase was the major binding phase for Ni, Cu and Pb in the sediments. The second highest concentrations of all these metals were present within the structure of the sediments. Easily reducible oxide phase (within the Fe–Mn oxyhydroxide binding phases) was the major host for all the three metals in the studied sediments. Major element chemistry of these sediments revealed that there was an increased tendency of Cu and Ni to get incorporated into the deep sea sediment via the non-terrigenous Mn-oxyhydroxide fraction, whereas, Pb gets incorporated mostly via amorphous Fe-hydroxides into the sediment from the CIB. This is the first attempt to provide an insight into the mechanism of metal enrichment in sediment that host vast manganese nodule.

Aquatic sediments pollution estimate using the metal fractionation, secondary phase enrichment factor calculation, and used statistical methods.

The sequential extraction procedure of the European Community Bureau of Reference (BCR) was applied for the fractionation of Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mn, and V in the Serbian river sediments. The aim of this paper was to describe a new approach in detection of anthropogenic elements in sediments, related to the Serbian river courses in order to assess their metal contamination. For sediment pollution evaluation, the risk assessment code (RAC) and the secondary phase enrichment factor (KSPEF) were used. Metal fractionation showed more easily mobilized forms predominant for copper, zinc, cadmium, manganese, and lead, which can be one of the indicators for anthropogenic source input. Chromium, nickel, iron, and vanadium found in the residual fraction indicate these metals may be an indicator for natural sources input. Based on RAC classification, results of sediments show no risk (Cr and V), low risk (Ni, Pb, and Fe), medium risk (Cu), high risk (Cd and Zn), and very high risk (Mn). The mean values of KSPEF were Cd>Cu>Zn>Ni>Mn>Pb>Fe>Cr>V, decreasing scale of no to moderately severe enrichment. The sediments were found to be contaminated by heavy metals to various extents, mostly Cd, Cu, and Zn. Research has shown the importance of KSPEF in quantifying degree of metal enrichment in sediments using results of sequential extraction. With the application of this factor, which is not frequently used in the scientific literature, the results obtained with sequential extraction can be used not only for assessment of mobility but also to quantify the metal pollution.

Assessment and evaluation of metal contents in sediment and water samples within an urban watershed: an analysis of anthropogenic impacts on sediment and water quality in Central Brazil

The aim of this study was to assess the distribution of metals in sediments and surface water within the Lago Paranoa catchment in Central Brazil, and to evaluate metal enrichments due to anthropogenic activities. Concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti and Zn were analyzed in sediment samples from sediment sources under different land uses, in alluvial sediment profiles, and in water samples. Principal component analysis was used to investigate the impact of different land use types on metal concentrations in source sediments. The anthropogenic impact of different land uses on metal concentrations in sediments was quantified by the calculation of enrichment factors, using the local geological background as reference. The data showed that different anthropogenic activities are related to specific metal enrichments in source and alluvial sediments. Particularly urban areas with high-density block development were characterized by higher enrichments of Cd, Cr, Pb, Sr and Zn compared to the local background values. Sediments from agricultural areas had higher concentrations of Cr, Cu and Ni compared to urban areas, which is caused by higher contents of clay and not due to human impact. The concentrations of Cd, Cr, Cu and Pb in surface water samples of the main rivers discharging into Lago Paranoa were very low. The values of Al, Fe, Mn, Sr and Zn differed between the sub-catchments and showed seasonal variation. Metal concentrations depended substantially on terrestrial inputs from anthropogenic and natural sources. The analysis of effluent water samples indicated that there is a temporary metal input into the lake from the two wastewater treatment plants, which might have caused metal enrichments in sediments and water. The regression analyses showed that there is a strong correlation between metal concentrations in alluvial sediments and corresponding water samples, as well as between metal accumulation in the alluvial sediments and shares of urban areas in the sub-catchment.

Using airborne hyperspectral data to characterize the surface pH and mineralogy of pyrite mine tailings

Acid mine drainage (AMD) is a key concern of the mining industry due to its impact on the quality of water and soils surrounding mine waste deposits. Acid mine drainage derives from the oxidation of metal sulphides, e.g. pyrite (FeS2), exposed to oxygen and water. The leachate acidity is capable of releasing heavy metals contained in the mining waste rock, which can affect water quality and lead to metal enrichment in sediments and potentially resulting in ecosystem degradation. Predicting tailings leachate pH is key to the management of sulfide-bearing mine wastes and is an emerging remote sensing application with limited studies having been realized. Such a capability would supplement traditional methods (i.e. ground surveys) that are challenging to implement due to the extent and large volume of mine waste.This study reports regional scale tailings mineral maps generated from airborne hyperspectral information of the Sotiel-Migollas complex in Spain and pinpoints sources of AMD. The extraction of spectral endmembers from imagery revealed twenty six endmembers for tailings material that represent mostly mineral mixtures. From these, eleven spectral groups were defined, each encompassing minor variations in mineral mixtures. The mineral maps resulting from the use of these endmembers for the detailed investigation of four tailings serve as indicators of the metal, sulphate, and pH levels of the AMD solution at the time of mineral precipitation. Predicted mineralogy was assessed using spectra from samples collected in the field and associated X-ray diffraction measurements.We also discuss the relative merits of the minerals maps of this study and soil leachate pH maps that we previously reported for the same locality using the same airborne data. The pH maps tend to provide predictions consistent with the mineralogy predicted from the mineral maps and the field and laboratory evidence. The pH maps offer information on the pH conditions of the tailings thus giving an insight on the different types of oxidation reactions that may occur.