Impact of heavy metals on bacterial communities from mangrove soils of the Mahanadi Delta (India)

This study aimed to assess soil nutrient status and heavy metal content and their impact on the predominant soil bacterial communities of mangroves of the Mahanadi Delta. Mangrove soil of the Mahanadi Delta is slightly acidic and the levels of soil nutrients such as carbon, nitrogen, phosphorous and potash vary with season and site. The seasonal average concentrations (μg/g) of various heavy metals were in the range: 14 810–63 370 (Fe), 2.8–32.6 (Cu), 13.4–55.7 (Ni), 1.8–7.9 (Cd), 16.6–54.7 (Pb), 24.4–132.5 (Zn) and 13.3–48.2 (Co). Among the different heavy metals analysed, Co, Cu and Cd were above their permissible limits, as prescribed by Indian Standards (Co=17 μg/g, Cu=30 μ g/g, Cd=3–6 μ g/g), indicating pollution in the mangrove soil. A viable plate count revealed the presence of different groups of bacteria in the mangrove soil, i.e. heterotrophs, free-living N₂ fixers, nitrifyers, denitrifyers, phosphate solubilisers, cellulose degraders and sulfur oxidisers. Principal component analysis performed using multivariate statistical methods showed a positive relationship between soil nutrients and microbial load. Whereas metal content such as Cu, Co and Ni showed a negative impact on some of the studied soil bacteria.     

Background metal levels determination in bivalves – quality assessment of the European Water Framework Directive

Background levels of metals (Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn) in biomonitors (Mytilus galloprovincialis mussels and Crassostrea gigas oysters), in estuarine waters within the Basque Country (south-east Bay of Biscay) are estimated using non-parametric statistical tools and data are presented graphically, with the aim of being used in assessing the ecological status, within the European Water Framework Directive (WFD). The basis for this study was the statistical analysis of data compiled from monitoring programmes undertaken along the Basque coast, between 1990 and 2008. For this analysis, a heuristic method was adapted and used. Results showed different metal background ranges throughout the year for both mussels and oysters. Values corresponding to the upper limit of the background range (i.e. value of the upper whisker of the box-plot) are proposed as the ‘high/good’ status boundary, according to the WFD.     

Geochemical forms of trace metals in mangrove sediments—Red Sea (Egypt)

Seven sediment samples from mangrove sediments of the Red Sea were taken in order to evaluate the possible contamination of the sediments by trace metals (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), lead (Pb) and cadmium (Cd)). Sequential extraction techniques were performed to study the different geochemical forms of these metals. X-ray diffraction analysis has been performed to correlate the mineralogical composition with the geochemical forms of the studied elements. The results of Fe and Mn contents indicate that they are in large part from lithogenous origin. The elevated concentrations are associated with the residual form ranged from 70 to 93% for Fe and 46 to 70% for Mn. The percentage of Zn, Cu, Cd and Pb in the non-residual form was much greater than that of the residual fractions. This reflects the high mobility and bioavailability of these metals in mangrove sediments of the Red Sea. X-ray diffraction analysis revealed the presence of silicate components including quartz, feldspars and clay minerals in some locality. Non-silicate components recorded in the study area as calcite as well as, Mg-calcite. Quantitatively both components i.e. silicate and carbonate varied according to their source material.     

Biochemical biomarkers and overall health status of mussels Mytilus galloprovincialis exposed to nickel and chromium

This study examined the effects of nickel and chromium exposure on two biochemical biomarkers, glutathione peroxidase (GPX) and acetylcholinesterase (ACHE), in parallel with an indicator of overall health, Scope for Growth (SFG), in the mussel Mytilus galloprovincialis to evaluate their ecological relevance and to assess their potential use as biomarkers of Ni and Cr pollution. SFG integrates major physiological responses into an index that represents the energy status of the animals and is considered an ecologically relevant biomarker. Following exposure to a range of Ni and Cr concentrations effects of Ni and Cr were evident on GPX and SFG but not on ACHE. Accumulation in the mussels’ tissues increased according to exposure concentrations. Adverse effects on the energy status and induction of GPX were found at the higher exposure concentrations while possible hormetic effects on the energy status and moderate GPX suppression were associated with lower exposure concentrations. Nevertheless GPX was negatively correlated with SFG suggesting that GPX responses reflect the overall health of the organisms and thus show potential as an early warning signal of population level effects of Ni and Cr. On the other hand, our results indicate that ACHE is not a suitable biomarker for Ni and Cr pollution.     

Trace metals in fish of economic interest from the west of Alexandria,Egypt

The concentration of some heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, and Zn) in the muscle, liver, and gills in eight fish species, Caranx crysos, Euthynnus alleferatus, Scomberomorus commerson, Sphyraena viridensis, Sargus sargus, Siganus rivulatus, Mugil species, and Sardinella aurita were collected seasonally from the Mediterranean Sea in the region of Alexandria. The highest concentrations of Cd, Cu, Fe, and Zn were measured in liver tissue, while gill tissue yielded the highest concentrations of Mn, Ni, and Pb. Muscle is the organ of poor accumulation factor for all metals under investigation. Concentration of cadmium in muscle in Mugil species exceeds the permissible limit in summer, while Siganus rivulatus exceeds it in the summer and autumn seasons. On the other hand, copper, nickel, lead, and zinc are still much lower than the permissible levels. The metal pollution index (MPI) for metals was studied, revealing that Siganus rivulatus, Mugil species and Sardinella aurita had the highest MPI. Provisional tolerable daily intake (PTDI) indicates that the concentration levels of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in the muscle of all fish species under investigation are much lower than recommended PTDI values, and accordingly there is no risk for the human consumption of these fish species.     

The Influence of Anthropogenic Contamination On Metals Release From Coastal Sediment Suspensions with Aerated Sea Water

The zinc, cadmium, copper and lead release from the uncontaminated and contaminated coastal sediments with aerated sea water was studied. the metals transfer to the dissolved forms was monitored during one-two months by differential pulse anodic voltammetry (DPASV). the sediments with different initial degree of contamination were sampled in the Peter the Great Bay, Sea of Japan around Vladivostok-the biggest city in Russian Far East. Sediment contamination by metals led to increased release to solution of zinc due to sulphide oxidation and cadmium on account of organic matter decomposition. the copper behaviour was complicated by strong binding with organic matter and enhancements of copper release can only be seen in sediment with a low organic matter content. Significant lead transfer to dissolved forms was not observed regardless of sediment contamination. the temperature affected the release of cadmium and copper through enhanced organic matter destruction. the dissolved metal fluxes from the sediment transformation are compared with metal fluxes towards bottom. Such comparisons show that second contamination by dissolved metals of the studied coastal environment may be important for cadmium only.     

Distribution and speciation of heavy metals in Apulian coastal sediments

In the framework of the Interreg II Project Italy–Greece, distribution and speciation of trace metals in surface coastal sediments of Apulian regions were studied. A sequential extraction technique was used to determine the chemical association of heavy metals (Zn, Pb, Ni, Fe, Cr, Mn, Cu and Cd) with major sedimentary phases (acid soluble phases, easily reducible fraction and oxidizable matter). The relationship between the metals' content and the grain-size composition of the sediments was also considered: generally the elements resulted associated with the fine fraction, even if in some cases (Cu in the oxidizable phase) the opposite behaviour was observed. The studied area is not particularly polluted, except for some defined zones, as for example Brindisi's harbour. Speciation analysis revealed that the major part of the heavy metals are not easily mobilizable and bioavailable. Even in this case, there are some exceptions to the general behaviour: Cu and Pb in several samples are largely present in the oxidizable phase, which even if not immediately available can become a source of associated elements when redox conditions change.     

Tessaria absinthioides: a possible bio‐monitor for Cd,Pb, and Cu,in the middle and lower basin of the loa river,North Chile

Some ecotoxic metals such as Cd, Pb, and Cu in Tessaria absinthioides were quantified to study its possible use as a bio‐indicator and/or bio‐monitor of these metals. This plant was chosen for its abundance in the area under study, along Chile and even in southern Latin America. For Cd, Pb, and Cu in all three parts of the plant (leaves, stems and roots) a different concentration pattern in each sampling areas was observed. In sampling areas Coya Sur and La Cascada copper and cadmium concentration decrease in order: leaves > roots > stems. In samples collected in Xalquincha the lowest concentrations of Cd and Pb were observed in stems. A maximum of cadmium concentration (9ug/gd.w. in leaves) was found in samples from La Cascada, a inflow to river Loa in Calama. High concentrations of lead were found in roots and leaves. Collected data demonstrate that the main pathway for cadmium is from ground water via roots into the plant. Some data obtained for lead and copper indicate that the influence of dust particles adsorbed on leaves and stems can be higher than uptake from ground water.     

An evidence of salinity impact on the bioaccumulation of heavy metals in fishes collected from the Messolonghi lagoon in Greece

The impact of salinity and water exchange rate on the accumulation of heavy metals in the benthic fish Zosterissesor ophiocephalus, collected from the shallow sublagoons Tholi and Paleopotamos, was studied. Both sublagoons are influenced by the intensive agricultural activity of the surrounding area in terms of the chemical substances’ drainage, and by the untreated sewage discharges of an urbanized area with Paleopotamos being affected in lesser extent. Paleopotamos is characterised by restricted water renovation, resulting to much higher salinity than Tholi. The bioaccumulation of the heavy metals studied (Manganese, Zinc and Copper), reveals differences among the metals with females showing higher values. Specimens from Paleopotamos showed statistically significant higher bioaccumulation of the heavy metals in both sexes, which is attributed to the extremely high salinity of this sublagoon.     

北部湾潮间带沉积物中重金属和多氯联苯的分布特征及生态风险评价

选择北部湾9个典型采样点,研究了潮间带沉积物中重金属和多氯联苯(PCBs)的分布特征和生态风险.分析结果表明,Hg、As、Cu、Pb、Zn、Cd、Cr等重金属和总PCBs的平均含量分别为0.100、10.00、19.89、45.97、208.65、0.098、17.86 mg.kg-1和1.48!g.kg-1.重金属和PCBs表现出不同的空间变化规律.相关性分析表明,北部湾潮间带的重金属主要来自人为污染;沉积物的粒度参数和有机质含量等性质特征是影响PCBs分布和迁移的重要因素;重金属和PCBs总量之间不存在明显的相关性.生态风险评价结果表明,PCBs和Cd是北部湾潮间带最主要的生态风险因子,Zn和PCBs是优势污染物;研究区域总体处于中等生态风险等级,表明沿岸港口和临海工业等人为活动已经对北部湾滨海地区造成了一定的环境压力.