Effect Range Median Research Articles

Leaching Behavior and Potential Environmental Effects of Trace Elements in Coal Gangue of an Open-Cast Coal Mine Area, Inner Mongolia, China

In order to better understand the role of coal gangue in potential environmental and ecological risks, the leaching behavior of trace elements from coal gangue has been investigated in an open-cast coal mine, Inner Mongolia, China. Four comparative column leaching experiments were conducted to investigate the impacts of leaching time, pH values and sample amount on the leaching behavior of trace elements. Enrichment factors (EF), maximum leached amount (Lam), maximum leachability (Lrm), effects range low (ERL) and effects range median (ERM) were employed to evaluate potential environmental and ecological hazards resulting from the leaching behavior of environment-sensitive trace elements from coal gangue. Leaching time and sample amount display important effects on trace element concentrations, leached amounts and leachability. The pH values exhibit a weak influence on the leaching behavior of the selected trace elements (e.g., As, V, Cr, Co, Ni, Cu, Zn, Se, Cd, Sn, Pb and Hg). The coal gangue are enriched in As, Co, Se and Pb and, in particular, show higher environmental pollution levels of As and Se (EF > 2). Lam values suggest that all of the elements investigated do not show potential risk to soils and vegetation, but have a high hazard risk for ground water. Elements including Ni, As, Cr and Zn are inclined to show high or moderate biological toxicity.

Spatial distribution and seasonal variation of the trace hazardous element contamination in Jakarta Bay, Indonesia

The Jakarta Bay Ecosystem is located in the vicinity of the megacity Jakarta, the capital city of Indonesia. Surrounding rivers and canals, carrying solid and fluid waste from households and several industrial areas, flow into the bay. Therefore, the levels of selected trace hazardous elements in water, surface sediments and animal tissues were determined. Samples were collected from two different seasons. The spatial distribution pattern of trace elements in sediment and water as well as the seasonal variation of the contamination were assessed. Quality assessment of sediment using the effects range median (ERM) showed that the concentrations of Hg, Cu and Cr at some stations exceeded the recommended values. Moreover, the concentrations of several trace hazardous elements in the sediments exceeded previously reported toxicity thresholds for benthic species.

Heavy metal pollution in sediments and mussels: assessment by using pollution indices and metallothionein levels.

In the present work, the concentration of eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) was determined in the sediments and transplanted and native mussels (Mytilus galloprovincialis). The study was conducted in Turkish marinas, shipyards, and shipbreaking yards. The effect of metal pollution was evaluated by determining the levels of metallothionein (MT) in the mussels. The extent of contamination for each single metal was assessed by using the geoaccumulation index (I geo) and enrichment factor (EF). Whereas, to evaluate the overall metal pollution and effect, the pollution load index (PLI), modified contamination degree (mC d), potential toxicity response index (RI), mean effects range median (ERM) quotient (m-ERM-Q), and mean PEL quotient (m-PEL-Q) were calculated. The influence of different background values on the calculations was discussed. The results indicated a significant metal pollution caused by Cu, Pb, and Zn especially in shipyard and shipbreaking sites. Higher concentrations of MT were observed in the ship/breaking yard samples after the transplantation.

Trace Metal Concentrations in Marsh Profiles Under the Influence of an Emerging Delta (Atchafalaya River and Wax Lake Delta) Overlying a Several Thousand Year Old (Former)Mississippi River Delta Lobe

ABSTRACTThere are concerns over the increasing concentrations of trace metals being found in the environment. Deltas are essentially integrators of watershed contamination as they are the repositories of sediment transported from and through the watershed. In order to assess changes in trace metal concentrations transported by the Mississippi River–Atchafalaya River systems, vibracores were collected from three coastal freshwater marsh sites under the influence of the Atchafalaya River and emerging Wax Lake Delta (WLD). The cores extended to a depth of 4 m which included deposits of an earlier Mississippi River Delta lobe. C-14 dating showed an age at the lower depth corresponding to approximately 3500 years ago. Vertical profile distribution of metals and metalloids were measured and comparisons between older deposits and concentrations in recent deposits were made. Concentrations of As, Cr, Cu, Ni, Zn, Mo, V, Co, and Hg metals were measured in the profiles along with Fe, Mn, and Al. There was no significant increase in heavy metals or metalloids in recent years as compared to more than 3000-year-old sediment associated with an earlier Mississippi River Delta lobe. Results show that sediment diversion through the Wax Lake Outlet did not increase concentrations of these metals in surface marsh soils. The metal concentrations in the marsh profile were compared to ERL (effects range low) and ERM (effects range medium) values to allow an ecotoxicological assessment. Arsenic was below the ERM values but was greater than the ERL which indicate a potential toxicity under certain conditions. All other metal/metalloids measured were below ERL limits. This study suggests that planned Mississippi River sediment diversions designed to slow the rate of coastal land loss are not likely to lead to trace metals contamination.

Aliphatic and polycyclic aromatic hydrocarbons in the bottom sediments from Klaipėda Harbour, Lithuania (Baltic Sea)

ABSTRACTA total of 22 bottom surface sediment samples were collected from Klaipėda Harbour, Lithuania (Baltic Sea). Sediment parameters, such as grain size and concentrations of total organic carbon, aliphatic hydrocarbons (ALHs) and polycyclic aromatic hydrocarbons (PAHs), were determined. Hydrocarbon contamination levels in the sediments were estimated based on classifications provided in the literature, and potential biological effects were assessed based on the effects range low–effects range median values of the Sediment Quality Guidelines and on the total toxic benzo(a)pyrene equivalent. The results demonstrated that concentrations of PAHs and total aliphatic hydrocarbons in the sediments varied between 1.6 and 5456 ng g−1 d.w. and 6.9 and 727 μg g−1 d.w., respectively. In most cases, the concentrations of ALHs and PAHs in the sediments indicated low to moderate levels of pollution and were not observed to have any significant adverse effects on living biota. To determine possible sources of hydrocarbons, hydrocarbon compositions were analysed, and ALHs’ and PAHs’ specific diagnostic ratios were calculated. According to the results, the Klaipėda Harbour bottom sediments were dominated by PAHs of pyrogenic origin, whereas the origin of ALHs was mixed, that is, anthropogenic with a biogenic (aquatic and terrestrial) input.

Characteristics and risk assessment of organochlorine pesticide residues in surface sediments collected at the Qingshitan Reservoir

ABSTRACTAn ultrasonic extraction – gas chromatography – electron capture detector analytical method was used to measure the concentration and types of organochlorine (OC) pesticides in sediment to obtain a better understanding of the characteristics and hidden ecological risks associated with OC pesticide exposure in surface sediment of the Qingshitan Reservoir. Fifteen types of OC pesticides were detected in the sediment, and the sum concentration of these chemicals was in the 149.32–490.19 ng/g range (mean value: 319.39 ng/g). The concentrations of detected OC pesticides occurred in the following order: hexachlorohexanes (HCHs) (mean value: 200.17 ng/g) > DDTs (mean value: 36.92 ng/g) > heptachlors (mean value: 32.74 ng/g) > methoxychlor (mean value: 24.13 ng/g). There was a 100% detection rate for HCH isomers, and their concentrations occurred in the following order: β-HCH > δ-HCH > γ-HCH > α-HCH. β-HCH was the main component of HCHs. Ratios between α-HCH/γ-HCH and β-/(α+γ)-HCH were used to investigate the sources of pollution. Most of the surveyed areas were polluted by lindane, which originated from past pesticide residue usage, and no new inputs of HCHs were found. DDT was the major component of the DDTs, and accounted for 52%–87% of the DDTs. The ratios of (DDE+DDD)/DDT at all sample collection points were less than 1, indicating that degradation rate of DDTs in sediment was low and there was a new input of DDTs in these surveyed areas. The ratio of DDD/DDE was less than 1 at most of the sample collection points, indicating that the degradation of DDT in the sediments primarily took place under aerobic conditions. Comparison of OC pesticide residual levels in the underwater sediment collected at the Qingshitan Reservoir to other states and countries showed the pollution level of these chemicals of the Qingshitan Reservoir was relatively high. The ecological risk was assessed based on guideline values of effects range-low (ERL) and effects range-medium (ERM). The results showed that DDD, DDE, DDTs and endrin residues in the sediment posed a moderate ecological risk, but DDT and γ-HCH showed high ecological risk. These OC pesticides might adversely affect biological systems, and need to be addressed.

Changes in Cd and Zn bioavailability upon an experimental resuspension of highly contaminated coastal sediments from a tropical estuary

Bioavailability evaluations can be an important tool to determine the quality of dredging sediments. Sequential extractions are commonly used to assess the different chemical forms of trace metals in coastal sediments; however, sometimes they are expensive and time-consuming. Additionally, these analyses do not represent possible changes due to resuspension during and after dredging activity. Newer, easier options to evaluate bioavailability are necessary to understand and preview bioavailability changes resulting from trace metals in dredging and disposal areas. This study aims to evaluate changes in Cd and Zn bioavailability due to sediment resuspension in a highly contaminated area in Sepetiba Bay, Brazil. Twelve surface sediment samples from this location were submitted to a resuspension experiment during two different time intervals (1 and 24 h). The extraction of potentially bioavailable (1 mol L−1 HCl-extractable) fractions and strongly bound (concentrated HNO3-extractable) fractions were sequentially carried out. More than 50 % of the concentrations were in potentially bioavailable fractions. Bioavailability change indexes were proposed; these were estimated as relative changes in bioavailability percentage after resuspension. However, two of these stations presented increases in the Cd and Zn HCl-extractable fractions after sediment resuspension above effects range low and effects range medium National Oceanic and Atmospheric Administration which are the same limits adopted for Brazilian environmental jurisdiction. Positive correlation of Zn and Cd with TOC in strongly bound fractions evidenced the importance of organic matter binding to preserve metals in this fraction. Fe and Mn partitioning was a major geochemical control on bioavailability of Cd and Zn upon short-time resuspension periods.

Distribution and risk assessment of hydrocarbons (aliphatic and PAHs), polychlorinated biphenyls (PCBs), and pesticides in surface sediments from an agricultural river (Durance) and an industrialized urban lagoon (Berre lagoon), France.

The distributions of organic pollutants (like hydrocarbons, polychlorinated biphenyls (PCBs), and pesticides) and the risks on the ecosystem were studied in the Durance River and the Berre lagoon (France). High levels of aliphatic hydrocarbons were observed in all stations (1399 to 11,202 μg kg(-1) dw). The n-alkanes were mainly from terrigenous origin confirmed by the values of different ratios calculated (carbon preference index (CPI), natural n-alkanes ratio (NAR), terrigenous/aquatic ratio (TAR), and ratio of low molecular weight to high molecular weight (LMW/HMW)). Total polycyclic aromatic hydrocarbon (PAH) concentrations in the surface sediments of the Durance River and Berre lagoon are 57-1528 and 512-863 μg kg(-1) dw, respectively. Several ratios between parent polycyclic aromatic hydrocarbons showed that the sources of hydrocarbons in the sediments were generally more pyrolytic than petrogenic. The sum of seven PCB contents ranged from 0.03 to 13.13 μg kg(-1) dw. Higher levels of PCBs were detected in sediments from the northern parts of the Berre lagoon (stations B1 and B3). Total pesticides contents ranged from 0.02 to 7.15 μg kg(-1) dw. Among these compounds, ∑DDE and ∑DDT contents ranged, respectively, from 0.35 to 1.65 and from 0.37 to 1.52 μg kg(-1) dw. However, PAH and PCB levels are not high enough to be a threat to aquatic organisms and human beings. Total PAH levels were below the effects range low (ERL) of 3500 μg kg(-1) dw. For PCBs, only two stations (B1 and B3) are higher than the effect range median (ERM) of 180 μg kg(-1) dw. For endrin (pesticide), the concentrations are between the ERL (0.02 μg kg(-1) dw) and the ERM (45 μg kg(-1) dw).

Identification of hot spots within harbour sediments through a new cumulative hazard index. Case study: Port of Bari, Italy

While numerous quality guidelines unquestionably drive the management of harbour sediments, port managers increasingly require easy-to-use tools supporting them in assessing the sediment quality. In this work, a new hazard index, named cumulative Normalized and Weighted Average Concentration (c_NWAC), is proposed, considering the concentrations of main hazardous, toxic and bio-accumulative sediment contaminants. This index is an upgraded version of the previously introduced NWAC index, which considered only the metal concentrations. The c_NWAC values range from 0 to 10 scores, and their visualization on a colour base code map leads to an easy identification of hotspots. The applicability of the new index was verified using a dataset derived from the analyses of 42 samples collected at different depths of the seabed of the Port of Bari (Italy). The concentrations of 58 parameters were considered, namely 11 metals and metalloids, 17 congeners of polychlorinated biphenyls (PCBs), 16 congeners of polycyclic aromatic hydrocarbons (PAHs), further 11 organic micropollutants, total organic carbon (TOC) and nutrients (Ntot, Ptot). For the study area, the obtained c_NWAC values resulted well correlated to the corresponding values of the commonly used mean Effects Range Median quotient (mERMq), and similar hazard categories were developed for the new index, even if the latter do not necessarily explain the real sediment toxicity, because they were derived from a different sediment dataset and different test species.Moreover, the hazard predictive ability of the new index was verified (with satisfactory results) by testing the considered samples by eco-toxicological assays, using three different biological species, and comparing the obtained results to the corresponding hazard categories developed for c_NWAC.

Heavy metals and polycyclic aromatic hydrocarbons in surface sediments of Karoon River, Khuzestan Province, Iran.

Karoon is the longest river in Iran and provides water for industries located along its banks, such as metal, petrochemical, and oil industries. It is also the source of drinking water for cities such as Ahwas, Abadan, and Khorramshahr. In this study, 34 and 18 surface sediment samples were collected and analyzed for heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and polycyclic aromatic hydrocarbons (PAHs). The measured concentrations of heavy metals were compared with US EPA sediment quality guidelines, and the results showed that Cu concentration was above the threshold effect level (TEL) in 65.67% of the samples and Hg concentration was above the effect range median (ERM) in some samples. The results revealed that Hg was severely enriched (5 < enrichment factor < 20) and classified in very high ecological risk index category. It is the major metallic contaminant in the study area. The total PAH concentrations ranged from 11.54-117,730 μg/kg, with the mean value of 7034.55 μg/kg dominated by lower molecular weight (LMW) PAHs. The total potentially carcinogenic PAHs (∑cPAHs) in sediment samples ranged from 2.09 to 31,930 μg/kg, indicating high carcinogenic potential of sediments in the study area. The total toxic equivalent (TEQ) values ranged from 1.06 to 7228.7 μg/kg. Maximum TEQ occurred in Abadan oil refinery station followed by Khorramshahr soap factory and Abadan petrochemical complex. Principal component analysis and cluster analysis also revealed the relationships between the studied parameters and identified their probable sources.

Distribution and assessment of heavy metals in the aquatic environment of Lake Manzala, Egypt

Analysis of trace metals from sediment and fish collected from eight locations in Lake Manzala, Egypt, during May, June and July of 2011, indicated anthropogenic impacts. The highest concentrations of metals, except Mn and Sr, were detected at Bahr Al-Baqar (S1) which drains from Cairo. At the other sampling locations, the concentrations of selected trace metals fall below the levels of concern while the geo-accumulation index (Igeo) suggests unpolluted conditions for the majority of the studied metals at most sites. However, near the Bahr Al-Baqar (S1) drain concentrations of Ag, Hg and Zn fall above the Long and Morgan's (1990) effects range low (ERL) while Pb was above their effects range median (ERM). Igeo values suggest unpolluted to moderately polluted condition for As and Sn, moderately polluted conditions for Zn, moderate to extremely polluted conditions for Ag, and severely to extremely polluted conditions for Pb at Bahr Al-Baqar. Two sites (Legan, S5, and Al-Ginka, S8) were indicated by Igeo as moderately polluted for Ag while two other sites (West of Bashar, S3, and Al Dehdy, S6) were indicated as unpolluted to moderately polluted for Ag. The Legan and Al-Ginka sites were also indicated as being moderately polluted for Zn. Similar to the sediments, the highest concentrations of metals in fish tissue were from Bahr Al-Baqar (S1). Al concentrations at all sites were comparable to concentrations known to cause lesions in fish. At all sites concentrations of selected trace metals in fish tissue were below the limits set by the FAO.

An assessment of metal contamination in the shelf sediments at the southern exit of Bosphorus Strait, Turkey

Concentrations and areal distribution of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were determined in the surficial sea bottom sediments along the coastal areas of Istanbul at the southern exit of the Bosphorus Strait, İstanbul, Turkey. The pollution status of shelf sediments was evaluated by employing pollution indicators (enrichment factors, geo-accumulation, and ecological risk indexes) and sediment quality guidelines (threshold effect level/probable effect level, effect range median (ERM)/effect range low). The results demonstrated that Cd, Cr, Zn, Cu, and Pb were enriched minor to moderate. The net sediment transport patterns show terrestrial inputs in front of the short streams. Another polluted region is at the western margin of the southern Bosphorus exit, where sediment transport is mainly controlled by the secondary currents driven by the Bosphorus jet, and depending on a sand ridge extending offshore. Based on the sediment quality guidelines, Cu, Pb, As, and Cr were likely the most dangerous chemicals to pose environmental risk, and may show toxic biological results. The areal distribution of ecotoxicological index (m-ERM-Q) suggested that 20% of the sediment sample sites fall in the medium–high priority zone and scattered at some specific areas along the coast.

The State of Marine Pollution in the Waters adjacent to Shipyards in Korea -3. Evaluation of the Pollution of Heavy Metals in Offshore Surface Sediments around Major Shipyards in Summer 2010

In order to evaluate the pollution of heavy metals in offshore surface sediments around shipyards in Korea, surface sediment samples were collected at eleven stations around four major shipyards located in the southeastern coast of Korea in summer 2010 and nine kinds of heavy metals such as copper(Cu), zinc(Zn), cadmium(Cd), lead(Pb), chrome(Cr), arsenic(As), mercury(Hg), iron(Fe) and aluminum(Al) in sediments were analyzed. The concentrations of Cu at all sampling stations were in the range of 47.10~414.96 ㎎/㎏ and exceeded TEL(Threshold Effects Level) 20.6㎎-Cu/㎏ of Korean marine environmental standards for offshore sediments and ERL(Effect Range-Low) 34.0㎎-Cu/㎏. The concentrations of Cu at seven stations around four shipyards were 65.18~414.96㎎/㎏ and exceeded PEL(Probable Effects Level) 64.4㎎-Cu/㎏ of Korean marine environmental standards for offshore sediments. The concentration of Cu at one station around B-shipyard was 414.96 ㎎/㎏ and exceeded ERM(Effect Range-Median) 270.0㎎-Cu/㎏. The concentrations of Zn at all stations were in the range of 135.09~388.79㎎/㎏ which exceeded ERL 150.0㎎-Zn/㎏. The concentrations of Zn at seven stations around four shipyards were 157.57~388.79㎎/㎏ and exceeded PEL 157.0㎎-Zn/㎏. The concentration of Zn at one station around B-shipyard was 388.79㎎/㎏ and was approaching ERM 410.0㎎-Zn/㎏. The concentrations of Cd at all stations were in the range of 0.11~0.54㎎/㎏ and were below TEL 0.75㎎-Cd/㎏ and ERL 1.2㎎-Cd/㎏. The concentrations of Pb at all stations were in the range of 18.04~105.62㎎/㎏ . The concentrations of Pb at two stations around B-shipyard were 73.87~105.62㎎/㎏ which exceeded TEL 44.0㎎-Pb/㎏ and ERL 46.7㎎-Pb/㎏, and were below PEL 119.0㎎-Pb/㎏ and ERM 218.0㎎-Pb/㎏. The concentrations of Cr at all stations were in the range of 51.26~85.39㎎/㎏ . The concentration of Cr at one station around B-shipyard was 85.39㎎/㎏ and exceeded ERL 81.0㎎-Cr/㎏. The concentrations of As at all stations were in the range of 8.70~22.15㎎/㎏ which exceeded ERL 8.2㎎-As/㎏ and were below ERM 70.0㎎-As/㎏. The concentrations of As at eight stations around A-shipyard, B-shipyard and D-shipyard were 14.93~22.15㎎/㎏ which exceeded TEL 14.5㎎-As/㎏ and were below PEL 75.5㎎-As/㎏. The concentrations of Hg at all stations were in the range of 0.02~0.35㎎/㎏. The concentrations of Hg at three stations around A-shipyard were 0.11~0.13㎎/㎏ which were almost equal to TEL 0.11㎎-Hg/㎏. Those at two stations around B-shipyard were 0.27~0.35㎎/㎏ which exceeded TEL 0.11㎎-Hg/㎏ and ERL 0.15㎎-Hg/㎏, and were below PEL 0.62㎎-Hg/㎏ and ERM 0.71㎎-Hg/㎏ . The concentrations of Fe and Al at all stations were in the range of 2.90~3.66 % and 3.12~6.80 %, respectively. These results imply that heavy metals such as copper, zinc, lead, arsenic and mercury were likely to be transferred to marine environment from shipyards, especially from B-shipyard.

Distribution, Sources, and Potential Ecotoxicological Risk of Polycyclic Aromatic Hydrocarbons in Surface Sediments from Bahía Blanca Estuary, Argentina.

Thirty-four surface sediment samples were collected from Bahía Blanca Estuary, Argentina, to evaluate polycyclic aromatic hydrocarbon (PAH) contamination and ecotoxicity risk by applying sediment-quality guidelines (SQGs) and toxic equivalent factors (TEQ). Total concentrations of 17 parent PAHs, including the 16 United States Environmental Protection Agency priority PAHs, were measured using gas chromatography-mass spectrometry, and their levels ranged from 19.7 to 30,054.5ng/g dry weight. The greatest values were found near the urban/industrial core and decreasing as the distance from that site increased. Molecular ratios determined mixed sources of PAHs with a slight imposition of pyrolitic over the petrogenic inputs. The ecotoxicological evaluation, based on the SQG model, showed that some of the individual PAHs were in excess of the effects range low (ERL) and the effects range median's threshold; then, predicted occasional (ERL) and frequent adverse effects over the surrounding biota at the area of study were determined. Total PAH levels were expressed as benzo-a-pyrene TEQ and compared with literature data.

Fraction distribution and risk assessment of heavy metals in waste clay sediment discharged through the phosphate beneficiation process in Jordan.

Heavy metal contamination of clay waste through the phosphate beneficiation process is a serious problem faced by scientists and regulators worldwide. Through the beneficiation process, heavy metals naturally present in the phosphate rocks became concentrated in the clay waste. This study evaluated the concentration of heavy metals and their fractions in the clay waste in order to assess the risk of environmental contamination. A five-step sequential extraction method, the risk assessment code (RAC), effects range low (ERL), effects range medium (ERM), the lowest effect level (LEL), the severe effect level (SEL), the redistribution index (U tf), the reduced partition index (I), residual partition index (I R), and the Nemerow multi-factor index (PC) were used to assess for clay waste contamination. Heavy metals were analyzed using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Correlation analyses were carried out to better understand the relationships between the chemical characteristics and the contents of the different phase fractions. Concentrations of Cd and Cu confirmed that both were bound to the exchangeable fraction (F1) and the carbonate fraction (F2), presenting higher mobility, whereas Pb was most abundant in the Fe-Mn oxide fraction (F3) and organic matter fraction (F4). The residual fraction (F5) contained the highest concentrations (>60%) of As, Cr, Mo, V, and Zn, with lower mobility. Application of the RAC index showed that Cd and Cu should be considered a moderate risk, whereas As, Cr, Mo, Pb, and Zn presented a low risk. Cadmium and Cu contents in mobile fractions F1 and F2 were higher than ERL but lower than ERM. On the other hand, As, Pb, and Zn contents of mobile fractions F1 and F2 were lower than ERL and ERM guideline values. Moreover, total Pb concentrations in the clay waste were below the lowest effect level (LEL) threshold value period, Cr and Zn values in the clay waste were determined to have exceeded the severe effect level (SEL) limit values, whereas Cd and Cu level ranges between LEL and SEL indicate moderate contamination. I R values of heavy metals in the clay waste confirmed that Cd and Cu were bound to the exchangeable and carbonate fractions and presented higher mobility, whereas As, Cr, Mo, Pb, V, and Zn were bound to organic or residual fractions and consequently exhibit lower mobility. A Nemerow multi-factor index revealed that the mine site contains high levels of Cd, Cu, V, and Zn pollution. As and Cr were found at a moderate level of contamination, whereas Pb was present at a safe level of contamination. The order of the comprehensive contamination indices was Cd > Cu > Mo > Zn > V > Cr > As > Pb, indicating that the assessment of clay waste, especially with Cd and Cu, should be undertaken to control heavy metal contamination in adjacent urban and mine areas at the Eshidiya mines.

Metals bioavailability in surface sediments off Nile delta, Egypt: Application of acid leachable metals and sequential extraction techniques.

Surface sediments from Nile Delta coast were analyzed for texture, CaCO3, organic matter, fractionation, and acid leachable metals (Cr, Fe, Mn, Ni, Pb, and Zn). The distribution pattern of acid leachable heavy metals in the sediment follows the sequence: Fe>Mn>Pb>Zn>Ni>Cr. All the acid leachable metals didn't exceed the sediment quality guidelines values (effects range low (ERL) and effects range medium (ERM)) and therefore doesn't represent a danger to marine organisms. The correlation of acid leachable Fe, Ni, and Mn indicates a similarity in the association of metals of similar origin. The negative correlation of sand with acid leachable Cr, Fe, Ni, Pb, and Zn indicates that these elements can be easily released by ion exchange processes due to the electrostatic interaction of trace metals as they are weakly bound and is bioavailable to the liquid phase. The acid leachable Cr, Pb, and Zn indicate their association with the CaCO3, while acid leachable Fe, Mn, and Ni are hardly combined with carbonates. All the contents of acid leachable metals are negatively correlated or uncorrelated with OM, which indicates that the studied heavy metals are hardly combined with OM. The results of the partitioning study showed that the residual form was the dominant fraction of the Cr, Fe, and Ni among most of the studied locations. Among the non-lithogenic fractions, the Fe-Mn oxy-hydroxide is the main scavenger for all metals. In terms of risk assessment code (RAC) value, a decrease order in environmental risk by heavy metals was Pb>Mn>Zn>Ni>Cr>Fe. Although the results of the two techniques were not consistent with each other in terms of predicting the metals bioavailability, a combination of total metal concentrations, acid leachable metals, and sequential extraction analysis is necessary to acquire the comprehensive information on the baseline, anthropogenic input, and bioavailability of heavy metals.

Distribution, source, and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Hun River, northeast China

In this study, the occurrence and distribution of 16 polycyclic aromatic hydrocarbons (PAHs), listed by the United States Environmental Protection Agency (US EPA), were investigated in surface sediment samples from the Hun River, northeast China. The data was then used to assess the potential ecological risk. The results indicated 15 PAHs were detected in these sediments, and the total concentrations of the 15 PAHs (not including naphthalene) ranged from 82.96 to 39,292.95ngg(-1) dry weight (dw), with an average value of 3705.54ngg(-1) dw, and 4-ring PAHs were the dominant compounds at most sites. The diagnostic parameters such as anthracene/(anthracene + phenanthrene), fluoranthene/(fluoranthene + pyrene), and indeno[1,2,3-cd]pyrene/(indeno[1,2,3-cd]pyrene + benzo[g,h,i]perylene) showed that they had been emitted from a number of different sources, especially the pyrolytic emissions. The results of the ecological risk assessment, which compared the PAH concentrations with the effect range low (ERL) and the effect range median (ERM) values, indicated that several individual PAH concentrations at four sites in the downstream section of the Hun River were higher than the ERM, suggesting that there was a potential ecological risk in these areas.

Multivariate Analyses and Evaluation of Heavy Metals by Chemometric BCR Sequential Extraction Method in Surface Sediments from Lingdingyang Bay, South China

Sediments in estuary areas are recognized as the ultimate reservoirs for numerous contaminants, e.g., toxic metals. Multivariate analyses by chemometric evaluation were performed to classify metal ions (Cu, Zn, As, Cr, Pb, Ni and Cd) in superficial sediments from Lingdingyang Bay and to determine whether or not there were potential contamination risks based on the BCR sequential extraction scheme. The results revealed that Cd was mainly in acid-soluble form with an average of 75.99% of its total contents and thus of high potential availability, indicating significant anthropogenic sources, while Cr, As, Ni were enriched in the residual fraction which could be considered as the safest ingredients to the environment. According to the proportion of secondary to primary phases (KRSP), Cd had the highest bioavailable fraction and represented high or very high risk, followed by Pb and Cu with medium risks in most of samples. The combined evaluation of the Pollution Load Index (PLI) and the mean Effect Range Median Quotient (mERM-Q) highlighted that the greatest potential environmental risk area was in the northwest of Lingdingyang Bay. Almost all of the sediments had a 21% probability of toxicity. Additionally, Principal Component Analysis (PCA) revealed that the survey region was significantly affected by two main sources of anthropogenic contributions: PC1 showed increased loadings of variables in acid-soluble and reducible fractions that were consistent with the input from industrial wastes (such as manufacturing, metallurgy, chemical industry) and domestic sewages; PC2 was characterized by increased loadings of variables in residual fraction that could be attributed to leaching and weathering of parent rocks. The results obtained demonstrated the need for appropriate remediation measures to alleviate soil pollution problem due to the more aggregation of potentially risky metals. Therefore, it is of crucial significance to implement the targeted strategies to tackle the contaminated sediments in Lingdingyang Bay.

Source identification and assessment of sediment contamination of trace metals in Kogarah Bay, NSW, Australia.

The distribution of trace metals (spatial and temporal) and sedimentary fractions were investigated to identify the concentrations and sources of trace metals within Kogarah Bay, NSW, Australia. A total of 59 surface sediments and six subsurface samples from core of the sediment were collected. The contamination factor and pollution load index indices used to evaluate environmental effects of trace metals. The study area was found to be uncontaminated with Cr and Ni, moderately contaminated with As and considerably contaminated with Cu, Zn and Pb. The concentrations of Cr and Ni were below both effect range low and effect range median, while As, Cu, Zn and Pb were slightly above effect range low. The highest concentrations of these trace metals such as Cu, Zn and Pb were found in the north, northwest and southeast of the bay, close to discharge points, stormwater outlets and around boatyards and watercrafts. The spatial distributions of metals were strongly related to muddy particles and organic matter. The temporal sediments of metals declined with increased sediment depth, which reflects accumulation of trace metals since European settlement in this area. Furthermore, the source of the trace metals was found to be stormwater outlets, gasoline fumes, boatyards and other human activities.

Assessment of trace metals contamination level, bioavailability and toxicity in sediments from Dakar coast and Saint Louis estuary in Senegal, West Africa

Trace metals have the potential to associate with sediments that have been recognised as significant source of contamination for the benthic environment. The current study aims assessing the trace metals contamination level in sediments from Dakar coast and Saint Louis estuary, and to examine their bioavailability to predict potential toxicity of sediments. Surface sediment samples were collected between June 2012 and January 2013 in three sampling periods from eight stations. Trace metals were analysed using inductively coupled plasma-optical emission spectrometer. Geoaccumulation indexes (Igeo) showed strong pollution by Cd, Cr, Cu and Pb confirmed by enrichment factor (EF) suggesting that these metals derived from anthropogenic sources. Toxicity indexes exceeded one in several sites suggesting the potential effects on sediment-dwelling organisms, which may constitute a risk to populations’ health. However, seasonal variability of metal bioavailability was noted, revealing the best period to monitor metal contamination. From an ecotoxicological point of view, concentrations of Cd, Cr, Cu and Pb were above the effects range low threshold limit of the sediment quality guidelines for adverse biological effects. In addition, with Pb concentrations above the effect range medium values in some sites, biological effects may occur.