Cadmium Distribution in Sediment and the Lugworme Arenicola marina in a Low Concentration Exposure Experiment

Abstract

In the central and southern North Sea, and in the Dutch coastal zone, total cadmium (Cd) concentrations in water are 0.02 ± 0.01 µg/L and 0.06 ± 0.02 µg/L, respectively. Cadmium in the estuarine waters of the Dutch Wadden Sea varied from 0.03 ± 0.01 µg/L in the western part to 0.08 ± 0.03 µg/L in the eastern part (van Zeijl et al. 1994). In whole sediment, the Cd background concentration for the Wadden Sea is 0.5 ± 0.01 µg/g dry weight (dw), whereas the reference concentration is 0.08 ± 0.02 µg/g dw (Anon 1994). The concentrations of total-Cd in surface bulk sediments (0-2 cm) of the central North Sea (Oyster Grounds), and of intertidal mud-flats in the western Wadden Sea varied from 0.05 to 0.15 µg/g dw and from 0.13 to 0.46 µg/g dw, respectively (calculated from Kahn et al. 1992). These concentration ranges match the reference Cd concentration for Wadden Sea whole sediment (0.5 ± 0.01 µg/g dw; Anon 1994). Cadmium concentrations in surface sediments of the Dutch coastal zone and estuaries are only slightly elevated compared to the 0.2 µg/g dw, considered as the background concentration in pristine areas, but well below the level of 10 µg/g dw at heavily contaminated sites (Bryan and Langston 1992).The relationship between cadmium levels in sediments and the biota is uncertain and contradictory. Bryan and Hummerstone (1973) described already 2 decades ago a linear relationship between cadmium concentrations in the polychaete worm Nereis diversicolor and in surface sediments. However, in the closely related polychaete Nereis virens, cadmium is absorbed from the interstitial water rather than from sediment particles (Ray et al. 1980). Also, more recent data indicate that uptake from sediment fractions either does not occur or the availability of sediment-bound metals to benthic biota is very restricted (Samant et al. 1990;Bryan and Langston 1992). In general, macrobenthic organisms accumulate cadmium from the water by absorption and diffusion across the body surface and by ingestion of food and particulates. Cadmium concentrations in blood, intestine and body-wall of the polychaete worm Arenicola marina from the field varied from 5-25 ng/mL, 0.2-3.6 µg/g dw, and 0.5-1.5 µg/g dw, respectively (Everaarts unpublished data).The present experimental laboratory study reports on the distribution of cadmium in the sediment column, and the uptake in the blood/coelomic fluid, intestine and body-wall of lugworms at low cadmium concentration exposure. The aim of the study was to determine possible interaction between the vertical distribution of sediment-bound cadmium and the bioturbating activity of lugworms.

Cadmium dynamics in estuarine sediments: Effects of salinity and lugworm bioturbation

“…Three hundred millilters of seawater was then added to each tube. Water was carefully changed on days 1,3,4,6,8,11,13,14,15,18, and 20 of the experiment and samples of overlying water of each core were taken for determination of 109 Cd. One core from each group was removed at days 1, 7, 14, and 21 and sectioned as described below.…”

“…The potential exposure of lugworms to Cd or other particle‐reactive pollutants may be modified by the lugworm itself due to its ability to modify its immediate surroundings [12,13]. The lugworm has been shown in laboratory experiments to increase the transfer of Cd from water to sediment and the distribution of Cd within sediments [5,14]. However, bioturbation in general is thought to promote the subsequent release of Cd back to the water phase [15,16].…”

Chemical partitioning of sediment contamination by heavy metals in the San Pedro River, Sonora, Mexico

“…Figure 3 shows metal distribution for both the residual fraction (V) and the non residual fraction (I, II, III and IV). In the non residual fraction, metals are bound to materials which are components of the sediment such as clays, oxides and hydroxides of iron and manganese, and organic matter (Everaarts and SaralaDevi, 1996;Ramos et al, 1999). In this fraction, metals are free or linked by ionic interactions, hydrogen bridges and covalent bonds (Lee, 1975), and are potentially bioavailable (González et al, 1998;García et al, 2004 Another important geochemical fraction was the organicysulfides fraction; with high percentage values of the non residual fraction total concentration (Figure 3) but still lower than those of the Fe and Mn oxides fraction that go as follows: Cu (18 -45%), Fe (0.54 -2.3%), Mn (5 -22%) and Zn (11 -32%) .…”