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The coastal population in East Africa is growing rapidly but sewage treatment and recycling facilities in major cities and towns are poorly developed. Since estuarine mangroves are the main hotspots for pollutants, there is a potential for contaminants to accumulate in edible fauna and threaten public health. This study analysed trace metals in muscle tissues of the giant mud crabs (Scylla serrata) and the giant tiger prawns (Penaeus monodon) from the Tanzanian coast, in order to determine the extent of bioaccumulation and public health risks. A total of 180 samples of muscle tissues of S. serrata and 80 of P. monodon were collected from nine sites along the coast. Both species showed high levels of trace metals in the wet season and significant bioaccumulation of As, Cu and Zn. Due to their burrowing and feeding habits, mud crabs were more contaminated compared to tiger prawns sampled from the same sites. Apart from that, the measured levels of Cd, Cr and Pb did not exceed maximum limits for human consumption. Based on the current trend of fish consumption in Tanzania (7.7 kg/person/year), the measured elements (As, Cd, Co, Cu, Mn, Pb and Zn) are not likely to present health risks to shellfish consumers. Nevertheless, potential risks of As and Cu cannot be ruled out if the average per capita consumption is exceeded. This calls for strengthened waste management systems and pollution control measures.

Coastal systems act as a boundary between land and sea. Therefore, assessing pollutant concentrations at the coast will provide information on the impact that land-based anthropogenic activities have on marine ecosystems. Sediment and fauna samples from 13 stations along the whole coast of Cameroon were analyzed to assess the level of trace metal pollution in sediments and intertidal fauna. Sediments showed enrichment of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn. However, pollution of greater concern was observed for Cd, Cr, Cu, Ni, and Zn at the northern stations. Some sites recorded trace metal levels higher than recommended in sediment quality guidelines. Species diversity was low, and high bioaccumulation of trace metals was observed in biological samples. Some edible gastropod species accumulated trace metals above the safety limits of the World Health Organization, European Medicine Agency, and the US Environment Protection Agency. Although industrial pollution is significant along Cameroon's coast, natural pollution from the volcano Mount Cameroon is also of concern.

Predicting metal concentrations in surface waters is an important step in the understanding and ultimately the assessment of the ecological risk associated with metal contamination. In terms of risk an essential piece of information is the accurate knowledge of the partitioning of the metals between the dissolved and particulate phases, as the former species are generally regarded as the most bioavailable and thus harmful form. As a first step towards the understanding and prediction of metal speciation in the Scheldt Estuary (Belgium, the Netherlands), we carried out a detailed analysis of a historical dataset covering the period 1982-2011. This study reports on the results for two selected metals: Cu and Cd. Data analysis revealed that both the total metal concentration and the metal partitioning coefficient (Kd) could be predicted using relatively simple empirical functions of environmental variables such as salinity and suspended particulate matter concentration (SPM). The validity of these functions has been assessed by their application to salinity and SPM fields simulated by the hydro-environmental model SLIM. The high-resolution total and dissolved metal concentrations reconstructed using this approach, compared surprisingly well with an independent set of validation measurements. These first results from the combined mechanistic-empirical model approach suggest that it may be an interesting tool for risk assessment studies, e.g. to help identify conditions associated with elevated (dissolved) metal concentrations., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Muddy sediments of the Belgian Continental Zone (BCZ) are contaminated by metals such as Co, As, Cd, Pb, and Ni. Previous studies have suggested that mineralization of phytodetritus accumulating each year on sediments might cause secondary contaminations of the overlying seawater (metal effluxes). The aim of the present research was to investigate these effluxes using a microcosm approach. Muddy sediments were placed in microcosms (diameter: 15 cm) and overlaid by phytodetritus (a mix of Phaeocystis globosa with the diatom Skeletonema costatum). The final suspension was 130.6 mg L(-1) (dw) and the final chlorophyll a content was 750 ± 35 μg L(-1) (mean ± SD). Natural seawater was used for controls. Microcosms were then incubated in the dark at 15°C during 7 days. Metals were monitored in overlying waters and microbial communities were followed using bacterial and nanoflagellate DAPI counts, thymidine incorporation, community level physiological profiling (CLPP) and fluorescein diacetate analysis (FDA). Benthic effluxes observed in sediments exposed to phytodetritus were always more elevated than those observed in controls. Large effluxes were observed for Mn, Co and As, reaching 1084 nmol m(-2)day(-1) (As), 512 nmol m(-2)day(-1) (Co), and 755 μmol m(-2)day(-1) (Mn). A clear link was established between heterotrophic microbial activity and metal effluxes. The onset of mineralization was very fast and started within 2h of deposition as revealed by CLPP. An increased bacterial production was observed after two days (8.7 mg Cm(-2)day(-2)) and the bacterial biomass appeared controlled by heterotrophic nanoflagellates. Calculations suggest that during phytoplankton blooms the microbial activity alone may release substantial amounts of dissolved arsenic in areas of the BCZ covered by muddy sediments., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The influence of trace metal pollution on the community structure of soft bottom molluscs was investigated in intertidal areas of the Dar es Salaam coast. Significant enrichment of As, Mn, Mo, Sb, and Zn in sediments was recorded. Redundancy analysis indicated that trace metal pollution contributed 68% of the variation in community structure. Monte Carlo permutation test showed that As and Sb contributed significantly to variation in species composition. T-value biplots and van Dobben circles showed that the gastropods Acteon fortis, Assiminea ovata, and Littoraria aberrans, were negatively affected by As and Sb, while the bivalve Semele radiata and the gastropod Conus litteratus were only negatively affected by As. Bioaccumulation of As, Cd, Cu, Mo and Zn occurred in the bivalve Mactra ovalina and the gastropod Polinices mammilla. This calls for regular monitoring and management measures., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Our current view about the relationship between metals and bacteria in marine sediments might be biased because most studies only use ex situ approaches to quantify metals. The aim of the present research was to compare ex situ and in situ methods of metal measurement (DET and DGT--diffusive equilibration or diffusive gradients in thin-films) and relate the results with two commonly used microbiological variables (bacterial biomass and bacterial diversity as revealed by DGGE). No previous studies have used such in situ approaches in microbial ecology. For biomass and most of the investigated trace metals (Ag, Cd, Sn, Cr, Ni, Cu, Pb, and Al) no significant correlations were found. The exceptions were Fe, Mn, Co, and As which behave like micronutrients. For bacterial diversity, no relevant relationships were found. We conclude that in situ methods are more adapted tools for microbial ecologists but that ex situ approaches are still necessary., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In this study, concentrations of 16 elements were quantified in muscles and livers of 141 fishes belonging to five commercially species. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The grunt, flathead, greasy grouper, tiger-tooth croaker and silver pomfret fish species were obtained from Abadan, Deylam, Bushehr-Nirogah, Dayyer port, Lengeh port and Abbas port in Hormozgan, Bushehr and Khozesran provinces at the Iranian waters of the Persian Gulf. The contents of Al, As, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, Sb, Tl, V and Zn in fish muscles and livers were determined by Inductively Coupled Plasma Mass Spectrometry (ICP MS), after digestion in a CEM (Mars 5) microwave oven using nitric acid and hydrogen peroxide. Our results indicated that almost all metals were more accumulated in younger flathead, greasy grouper and tiger-tooth fishes. Contrary to the other fish species, grunt seems to stronger accumulating elements in the older fishes. Strong and positive correlations were observed in three or more of the fish species between V, Al, Fe, Tl, Co and Pb. The results confirmed that fish muscle and liver tissues appeared to be good bio-indicators for identification of coastal areas exposed to metallic contaminants. The results also showed that the element levels in the muscles of all fishes in our study were lower than the maximum allowable concentrations and pose no threat to public health, except for arsenic.

Correlations between trace metals in dissolved and particulate phases, zooplankton, mussels and sediments in Lake Balaton were investigated. The degree of correlation between the various metals was different in each of the investigated compartments. Particulate metal concentrations (microg g(-1)) were anti-correlated with suspended particulate matter (SPM) (mg l(-1)), indicating a dilution effect, while total metal concentrations in the water column (microg l(-1)) were highly correlated with SPM, implying a major influence of the turbidity on the total metal concentrations. Between compartments, not many significant correlations were recognized. Only Ba, Ca, Sr and Mg are correlated in the sediments and in the particulate phase, suggesting common sources for both compartments. Partitioning coefficients (Kd) of trace metals between dissolved and particulate phases are generally low, typical for natural water and fairly stable over the lake. Most of the trace metals (Zn, Co, Cd and Pb) exist in the particulate phase (for about 70% of the total metal load). Cu and Ni are exceptions, showing a more equal distribution. Bioconcentration factors (BCF) of zooplankton and mussels were comparable to those of other natural waters. A negative biomagnification from suspended particulate matter to zooplankton and from sediment to mussel was recognized for all trace metals, except a small enrichment of Zn in zooplankton and Cd in mussel. Four factors were recognized in SPM and in sediments but they did not contain the same group of metals. Cluster analysis showed that metal accumulations in the sediments were different between northern and southern shores and in SPM between western and eastern areas.