The recent sedimentary history and contemporary budgets of zinc, copper and lead in Lough Neagh, Northern Ireland

Abstract

The sedimentary record and the contemporary budgets of zinc, copper and lead were measured in Lough Neagh. The sedimentary record provides an historical perspective to changing trace metal concentrations. Contemporary measurements identify trace metal sources, the relative contribution of each source to the total input, and infer the amount of each element retained in the sediment. A comparison of the recent sedimentary flux and the contemporary budgets assesses the accuracy of sediments in predicting trace metal contamination.

The sedimentary record shows that trace metal contamination in Lough Neagh began in the early 1800s. The increase in contamination is attributed to anthropogenic inputs as a result of industrialization. A recent decrease in trace metal concentrations has been attributed to decreasing atmospheric inputs to Lough Neagh. Anthropogenic fluxes suggest that Lough Neagh is in a location receiving medium zinc inputs, low lead inputs and high copper inputs.

Contamination by zinc, copper and lead is part of a regional or global pattern, with an additional local contribution to the copper input. The contemporary budget identifies atmospheric, wastewater and natural catchment inputs as the main sources of zinc, copper and lead to Lough Neagh. Natural catchment inputs are the main source of zinc and copper, accounting for over 70% of total inputs. The largest input of lead comes from the atmosphere (nearly 50% of the total input). Of the anthropogenic sources, the atmosphere is by far the most important for all three elements, contributing over 65% to total anthropogenic inputs.

The comparison between the budget and the sedimentary record shows that the values are within the same order of magnitude, although the sedimentary values exceed the budget values by 2-3 times. Possible sources of imprecision have been identified in both the sedimentary and contemporary measurements which, if taken into consideration, reduce the difference significantly. Given the uncertainties in measuring the sedimentary and contemporary fluxes, the palaeolimnological technique provides a reliable estimate of past and present environmental contamination.

Date of Award	Sept 1990
Original language	English