Heavy-metal pollution and its effects on recent foraminiferids from Southampton Water, Southern England, U.K.

Sharifi, Abdol Rahim (1991) Heavy-metal pollution and its effects on recent foraminiferids from Southampton Water, Southern England, U.K. University of Southampton, Doctoral Thesis.

Abstract

A study of heavy-metals in estuarine sediments and Recent calcareous foraminiferids from Southampton Water revealed that they are good indicators of heavy-metal pollution. Local industries appear to be the main contributors of the metals Cu, Zn, Ni, Pb and Co to a limited extent, into the region. Cd appears to have other domestic sources of input such as sewage and rivers. It seems that domestic and industrial sources of input of Cr exist within the region. The overall concentrations of Cu, Zn and Pb in sediments have increased since the introduction of local industrial discharges into the region although their values have declined over the last decade. Sites located along the western bank of Southampton Water such as Fawley and its adjacent sites are relatively more-polluted than those situated on its eastern and central part. In general the overall environmental quality of the estuary is acceptable given the diverse industrial and shipping activity. Observational data have been obtained through detailed investigations of sediment samples (Van Veen grab sampler) foraminiferid tests separated from these sediment, sediment cores (gravity corer) and through in-vitro culturing experiments of a foraminiferid species. Chemical analysis of sediments and foraminiferids for Cu, Cr, Ni, Zn, Co, Cd and Pb were made using AAS and ICP-MS. The analytical data were processed using regression and canonical variate techniques. Heavy-metals have a marked effect upon foraminiferid distribution and abundance. Some species are able to tolerate pollution and their relative abundance increases at effluent discharge points, whereas other species develop test deformities. Among the identified species three were the most abundant and appear to be excellent pollution (heavy-metal) indicators. These are Ammonia beccarii (Linné, Haynesina germanica (Ehrenberg) and Elphidium excavatum (Terquem). The species E.excavatum is more pollution (heavy-metal) tolerant than H.germanica and A.beccarii, the order of this tolerance is E.excavatum > H.germanica > A.beccarii. The relatively high values of metals in the environment seem to be responsible for test deformities found in foraminiferids. This is supported (core studies) by the absence of deformed specimens in sediments deposited prior to the anthropogenic metal discharges into the region. Additional evidence is the presence of higher values of metals within deformed specimens and the existence of a direct relationship between the proportion of abnormal individuals and heavy-metal concentrations in sediments. A direct relationship exists between concentrations of metals Cu, Ni,Zn,Pb and to a certain extent Cd within the tests of A.beccarii, H.germanica and E.excavatum and that of leachable amounts of these elements within the fine-grained sediments. The presence of Cu, Zn, Ni, Pb Cr, Co and Cd in trace levels within the tests may be due in part to a physiological need by these species as they were present within all examined specimens (deformed and non-deformed). The species A.beccarii, H.germanica and E.excavatum are able to accumulate small amounts of metals within their protoplasm. Metal uptake (incorporation) appears to affect the metabolism of species and this disturbance reduces the ability of organisms to develop normal chambers.

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