The Dart estuary, Devon, UK: a case study of chemical dynamics and pollutant mobility

Abstract

Water, sediments and gill and digestive gland tissues of adult common shore crab (Carcinus maenas), collected at Noss Marina, Sandquay (Britannia Royal Naval College), the Dartmouth Pier, Warfleet Cove and Sugary Cove in the Dart estuary, Devon, UK, were analysed for major, minor and trace elements in spring 2004. Total acid-available measurements analysed included the truly dissolved component and acid-available sediments. Trace metal concentrations are associated largely with particulate and micro-particulate/colloidal phases, the latter being able to pass through standard filter papers. Wide ranges of chemical concentrations were found in the water, sediments and tissues at all the locations. In the water column, 48% of the variance is linked to the sea-salt component (Cl, Na, K, Ca, Mg, B, Li and Sr) and the sediment-associated acid-available fractions are linked to Fe-rich lithogenous materials (Ba, Co, Cu, Fe, Mn, V and Zn). In the sediments, trace elements of Cd, Co, Cr, Fe, Pb, Mn, Ni and V are correlated with the sea salts and associated with the fraction of fine sediments within the total sediment. In the gills and the digestive gland tissues of crabs, high concentrations of Al, Cu and Fe are found and there are correlations between acid-available trace metals of Cu, Cr, Fe, Mn, Ni, Sr and Zn. The relationships between trace metal contaminants, their site-specific concentrations, their temporal and spatial variability and the effects of human activities, such as moorland/agriculture with historic mining and recreational activities in the lower Dart estuary, are discussed.

The attitudes of recreational user representatives to pollution reduction and the implementation of the European Water Framework Directive

“…In addition, most of the representatives mention the severity of isolated pollution incidents, usually occurring after heavy rain often involving agricultural run-off into rivers. These concerns are consistent with much of the literature on the subject (see, for example, Langford et al, 2000;Schuwerack et al, 2007), which documents the impact of pollution incidents in a range of water environments.…”

Heavy metals, metalloids and other hazardous elements in marine plastic litter

“…The presence of plastic litter containing hazardous elements represents a potential source of localised contamination in the marine environment. For example, the highest concentrations of Cd and Pb in the plastics category are three to four orders of magnitude higher than the respective median concentrations in sandy sediment from the south west coast of the UK (0.5 and 12.6 g g -1 ; Schuwerack et al, 2007); consequently, the presence of just 0.1% of plastic fragments among the sediment may result in an order of magnitude elevation in the net content of Cd and Pb. Clearly, the risks and impacts associated with these elements will depend on their mobilities and bioaccessibilities in the polymeric matrix.…”

Cadmium, lead and bromine in beached microplastics

“…For Cd and Pb, estimates of 30 g were obtained for both beaches, while for Br, estimates of 59 g and 37 g were obtained for Whitsand and Woolacombe, respectively. The quantities of plastic-bound Cd and Pb exceed the respective mean quantities in local beach sand (< 1 g and about 10 g) and in local crab tissue (1 and 2 g) (Schuwerack et al, 2007), the latter representing an important dietary component of many seabirds (Schwemmer and Garthe, 2005).…”