Total mercury and methylmercury in sediments and in the polychaeteNereis diversicolor at Groot Buitenschoor (Scheldt estuary, Belgium)

Abstract

Abstract. Total mercury (Hg) and methylmercury (MeHg) concentrations were determined in sediments and in the polychaete worm Nereis diversicotor at 13 stations of a brackish water intertidal nmdflat of the Scheldt estuary. Hg and MeHg concentrations in sediments ranged from 144 to 1192 ng g-~ dw and from 0.8 to 6 ng g-~ dw, respectively. Both Hg and MeHg concentrations increased with an increase of organic matter (OM) content and fine grain fraction. In contrast, Hg accumulation hy N. diversicolor was significantly (p < 0.05) higher at stations with sandy sediments (mean value: 125 ng g-i dw) than at stations with muddy sediments (mean value, 80 ng g-~), probably because Hg availability for bioaccumulation at muddy stations was reduced by high OM content of the muddy sediments. MeHg accounted for an average of 0.7% of the total Hg in sediments and 18% of the total Hg in N. divelwicolor. Seasonal variations significantly affected Hg concentrations in sediments and MeHg in N. divezwicotor. Total Hg concentrations in sediments were significantly (p < 0.05) higher in autumn and winter than in spring and summer whereas MeHg concentrations were lowest in winter compared to the other seasons. On the other hand, total Hg concentrations in the worms were lowest in spring whereas MeHg concentrations were significantly (p < 0.01) higher in spring and summer than in autumn and winter.

Trace Metal Contamination of Water in the Lubumbashi River Basin, Kafubu, Kimilolo and Kinkalabwamba Rivers in Lubumbashi City, Democratic Republic of Congo

“…2). The low water pH below the WHO, EPA and EU recommended pH values of 6.5-8.5 in most of the rivers increases metal bioavailability to organisms dwelling in those rivers and the high water pH values reduce metal bioavailability in the six other rivers as alkaline pH plays the role of trapping heavy metals [5,[17][18][19].…”

“…For the WHO guidelines for drinking-water quality, USEPA drinking-water standards and health advisories, and EU drinking-water regulations [13][14][15] [12,[18][19][20][21]. Similarly, the highest mean concentrations of Cd and Pb in sediment of Kafubu river at its confluence with Lubumbashi river (56 mgkg -1 dw and 342 mgkg -1 dw, respectively)…”

Assessment of Trace Metal Contamination of Sediments in the Lubumbashi River Basin, Kafubu, Kimilolo and Kinkalabwamba Rivers in Lubumbashi City, Democratic Republic of Congo

“…The very low OM content of the sediments and the pH in that river increase the metal bioavailability to organisms dwelling in those sediments. It has been reported that pH and organic matter are among the factors which favor heavy metal retention in soils [30,35], and that organic-rich soils or sediments play, for the same reasons as those presenting alkaline pH, the role of trapping heavy metals [6,7,35,36]. , respectively) and that of Pb in sediment of Kafubu river at its confluence with Lubumbashi river dw) and at the confluence of Lubumbashi river with Kafubu river (342 mgkg -1 dw), were higher than those respectively reported for the sediments of Winterbeek river [38].…”

“…Sediments have a high storage capacity of chemical pollutants [1,2] and act as a sink for trace metals [3][4][5][6][7]. sediments and in the water column, especially invertebrates and fish, but also for humans through human food chain [1,3,8,[13][14][15].…”

“…As those people use rivers and streams as water source for their drinking, cooking, washing, irrigation and recreation needs, river sediments heavily polluted by trace metals represent a great risk for public health. Indeed, resuspension events from natural or anthropogenic origin can disturb the biogeochemistry of sediments and potentially result in the remobilization of trace metals from sediment particles to the water column [7,[20][21][22][23]. The use of metal polluted water for irrigation can also cause the death of crops or interfere with the uptake of essential nutrients [19,[24][25][26].…”