Heavy metals in somerset marine organisms

Several independent studies of heavy metal pollution in the Severn Estuary and Bristol Channel are in progress. The County Health Department and Public Analyst have been examining the accumulation of metals in marine shore animals and the food chain, and report their results and conclusions.     

The dependence of organohalogen compound concentrations on herring age and size in the Bothnian Sea, northern Baltic

The concentrations and composition profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, polybrominated diphenyl ethers and polychlorinated naphthalenes were determined in herring individuals collected from the commercial catches of the Bothnian Sea, northern Baltic. The median age of herring was 5.0 years and in the muscle the median toxic equivalent concentration of PCDD/Fs was 5.6 WHO(PCDD/F)-TEQ pg/g fresh weight (fw) and that of PCBs 2.7 WHO(PCB)-TEQ pg/g fw. The median sum concentration of PBDEs was 1.4 ng/g fw and that of PCNs 0.1 ng/g fw. Differences in age-dependent accumulation between the organohalogen groups and individual congeners were major. In the Bothnian Sea the content of organohalogen compounds in herring is obviously elevated due to the availability and large proportion of Mysis crustaceans in their diet. More intensive fishing could reduce the concentrations of organohalogens, including the abundant, accumulative and toxic 2,3,4,7,8-PeCDF congener in the Baltic herring catch.     

Heavy metals in the Bombay harbour area

Bombay harbour is one of the major sinks, on the western peninsula of the Indian subcontinent, receiving anthropogenic pollutants including heavy metals, radionuclides and hydrocarbons in addition to sewage. To evaluate possible impacts of a few heavy metals on the harbour ecosystem, the distribution patterns of Zn, Mn, Cu, Fe, Co, Ni, Cd, Cr, Pb and Sr in water, sediment and two benthic species, the blood clam Anadara granosa and gobiid mudskipper Boleophthalmus boddaerti were studied over the period 1976–1980. The present levels of the ten elements in biotic and abiotic matrices were found to be far below those that are known to affect adversely the life and quality of benthic communities. Furthermore, the concentrations of these elements in various compartments neither revealed any systematic temporal or spatial fluctuations nor reflected the substantial incease in the total budget over the past 8–12 years. Also these levels were within the range reported in the nearshore and oceanic environs along the west coast. In view of this, the poor growth and high percentage mortality observed in the clam Anadara granosa fished from the Sewri clam bed compared to that of the stock harvested from the Trombay region in the harbour may well be due to anoxic conditions caused by organic pollutants present in the domestic sewage and industrial wastes released in the vicinity of the Sewri clam bed.     

Heavy metals in organic phases of river and estuarine sediment

Analysis of sediments taken from various levels in the lightly polluted River Blyth in Northumberland shows that quite high concentrations of metals can be accumulated in sediments.     

Heavy metals in the hydrological cycle: Trends and explanation

This paper reviews the major sources and transport characteristics of heavy metals in the hydrological cycle. It is demonstrated that heavy metal releases to the environment have changed from 19th and early 20th century production-related activities to consumption-oriented factors in more recent times. The relative roles of particle size, sorption and desorption processes, partitioning and the chemical speciation of heavy metals on fine sediments are identified to understand the likely fate of heavy metals released into fluvial systems. It is argued that the spatial and temporal distribution of heavy metals in the river corridor depends not only on an understanding of metal solubility and speciation, but also on an understanding of sediment dynamics which control, for example, floodplain alluviation and the accumulation of metals in the bottom sediments of contaminated rivers, lakes and reservoirs. Existing long- and short-term records are examined to identify the current state of knowledge about the factors which affect heavy metal releases into aquatic environments. With limited exceptions, it is shown that few long-term studies of trends in heavy metal transport are available although, for some major rivers, limited data on trends in metal concentration exists. Palaeolimnological reconstruction techniques, based on an analysis of lake and reservoir sediments, are identified as a possible means of supplementing monitored records of heavy metal transport. Although numerous studies have suggested that trends in atmospheric contamination, mining and urbanization may be identified in the bottom sediment record, other research has shown that the radionuclide-based chronology and the heavy metal distribution within the sediment are more likely to be a function of post-depositional remobilization than the history of metal loading to the basin. Despite these limitations, it is shown that the incorporation of reservoir bottom sediment analysis into a heavy metal research programme, based in river corridors of Midland England, provides an opportunity to identify and quantify the relative contribution of point and non-point contributions to the heavy metal budget and to relate trends in metal contamination to specific periods of catchment disturbance.     

Heavy metals in animals from the north east coast

Analyses of cadmium, zinc, copper and nickel in the tissues of fish and crustaceans from inshore waters off the Northumberland coast reveal some surprisingly high values.