Joost Stronkhorst - Academia.edu (original) (raw)

Papers by Joost Stronkhorst

Environmental Pollution, 2003

resources near dumping sites are adversely affected by physical disturbances, but a causal link t... more resources near dumping sites are adversely affected by physical disturbances, but a causal link to contaminant damage could not be found.

Environmental Pollution, 2003

resources near dumping sites are adversely affected by physical disturbances, but a causal link t... more resources near dumping sites are adversely affected by physical disturbances, but a causal link to contaminant damage could not be found.

Archives of Environmental Contamination and Toxicology, 1998

The incorporation of toxicological data from bioassays can improve the present system of sediment... more The incorporation of toxicological data from bioassays can improve the present system of sediment quality criteria in the Netherlands. The use of acute lethality toxicity tests alone does not however provide sufficient discrimination and sensitivity for predicting ecological effects of slightly and moderately contaminated dredged material. Sublethal endpoints are needed for the assessment of environmental hazards of such dredged material. In this study, two approaches were used to identify toxicity of marine sediments collected from 16 locations classified as “slightly and moderately contaminated” on the basis of chemical data: (1) a comparison of growth vs. mortality as different endpoints in the marine amphipod Corophium volutator (Pallas); (2) an investigation on the use of sediment dilutions to characterize the degree of toxicity. The influence of sediment storage time on toxicity was also evaluated. In four out of 16 locations, mortality over 10 days of exposure ranged 80–100%; in two out of 16 locations mortality ranged 40–60%. In the other 10 locations, mortality was below 15%. Results on growth showed that in all locations final dry weight values were significantly lower (a factor of 1.5 to 3) than in controls. Results of dilution experiments showed that if sediments were diluted with a reference sediment of similar physicochemical characteristics, total concentrations of metals, mineral oil, and PAHs decreased as expected and so did the effects on C. volutator. In the 100% contaminated sediments growth was reduced by 32–60% compared to controls. The dilution rate necessary to reduce toxicity to the EC10 value for growth of C. volutator was considered an appropriate endpoint for the evaluation. When sediments were stored for a period of 3–5 months at 4°C and retested, effects on mortality and growth decreased, although some effects on growth were still measured after 5 months of storage. The experiments illustrate the usefulness of ecotoxicity assessment to evaluate contaminted dredged material.

Bulletin of Environmental Contamination and Toxicology, 1994

Archives of Environmental Contamination and Toxicology, 2003

The status of the contamination of Dutch marine harbor sediments was reevaluated after a period i... more The status of the contamination of Dutch marine harbor sediments was reevaluated after a period in which emissions from point sources had been greatly reduced. Data on sediment chemistry from 1999 and 2000 were assessed against screening levels (SLs) selected from available sediment quality guidelines and representing a low probability of adverse biological effects. This yielded a ranking of the environmental hazard of 22 contaminants. Most of the sediments were silty material; every year 15 to 25 million m3 of such material is dredged from Dutch harbors. Some 34% of the volume exceeded one or more SLs. The contaminants of concern were tributyltin (TBT), mineral oil (petroleum hydrocarbons), polychlorinated biphenyls (PCBs), and mercury. The PCB and mercury contamination is the legacy of historic inputs; the TBT and mineral oil contamination is related to present-day shipping activity. Concentrations of trace metals, rare earth elements, organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAHs) were low and apparently of minor environmental concern. It is concluded that the risk assessment would be improved by laboratory testing of adverse biological effects.

Aquatic Ecology, 1988

The error inin vivo 14C incubator measurements of primary production in the Eastern Scheldt when ... more The error inin vivo 14C incubator measurements of primary production in the Eastern Scheldt when neutral density filters were used and the error obtained when no account was taken of the spectral changes in submarine irradiance that occur with increasing depth, were evaluated theoretically. By multiplying the photosynthetic action spectra of two marine algae by calculated irradiance in the euphotic layer using Kd and Kd(λ) respectively, the gross primary production P[Ed(400–700)] and P[Ed(λ)] was computed. In the green-brown waters of the Eastern Scheldt estuary the use of neutral density filters was sufficient to simulate the underwater light conditions. In clear waters it can cause an overestimation of the gross production.

Environmental Toxicology and Chemistry, 1999

ABSTRACT The presence of tributyltin (TBT) in silty sediments is regarded as a long—term threat t... more ABSTRACT The presence of tributyltin (TBT) in silty sediments is regarded as a long—term threat to marine and estuarine environments due to its persistence. The bioaccumulation kinetics and toxicity of TBT in the deposit—feeding heart urchin Echinocardium cordatum was studied in silty sediment spiked with TBT and equilibrated prior to the 28-d exposure. An additional 10-d acute toxicity test was carried out with the burrowing amphipod Corophium volutator in the same sediment. Because E. cordatum has a low lipid content and apparently high elimination and metabolic rates, only a moderate degree of TBT bioaccumulation was observed, with biota—sediment accumulation factors (BASFs) of 0.09 to 0.21 (dry weight basis) and biota accumulation factors (BAFs) of 180 to 843 (wet weight basis). The lethal body residue in E. cordatum (soft tissue and skeleton) was 0.8 to 3.4 nmol TBT+/g wet weight which, considering the differences in lipid content, is comparable to data on other taxonomic groups. For E. cordatum and C. volutator, the LC50s for pore water (222 and 329 ng Sn/L) were also close to reported values for aquatic and benthic organisms. The TBT concentrations in the pore water of the silty sediment were much lower than might be expected from the octanol—water partition coefficient. The measured sediment—water partitioning coefficient Kp was 8,700 L/kg dry weight. Consequently, toxicity was observed at a relatively high TBT concentration in the bulk sediment with LC50s for E. cordatum and C. volutator of 1,594 and 2,185 ng Sn/g dry weight, respectively. The results show that TBT is highly toxic to the benthic species investigated and sorption in the silty sediment strongly reduced the bioavailability of the compound.

Journal of Aquatic Ecosystem Health, 1995

In the Netherlands, the decision to permit the dumping of dredged material into the sea depends o... more In the Netherlands, the decision to permit the dumping of dredged material into the sea depends on the concentrations of about 33 chemical compounds (Anonymous, 1994a). This evaluation of dredged material quality can be improved by the use of bioassays in its assessment. In this note the use of bioassays in the evaluation of lightly contaminated marine dredged material from the Netherlands is illustrated with preliminary results of bioassays with Corophium volutator and Crassostrea gigas. It is concluded that the inclusion of bioassays in the assessment of lightly contaminated sediment is useful.

Marine Pollution Bulletin, 1993

The contaminated Scheldt estuary is a wetland of international importance for waterbirds. In eggs... more The contaminated Scheldt estuary is a wetland of international importance for waterbirds. In eggs of Common Terns (Sterna hirundo) from the brackish zone, concentrations of Hg, Cr, Cu, Cd, Zn, and PAHs did not exceed no-observed effect levels reported in the literature. Eggshell thickness did not differ from the pre-DDT period. However, concentrations of PCB-118 (0.1–0.7 μg g−1 WW) may indicate adverse effects on reproductive success. In terns' eggs from the marine zone, PCB-118 did not exceed the no-observed effect concentration.In eggs of Black-headed Gulls (Larus ridibundus) concentrations of HCB, lindane, DDT and dieldrin are low and showed no spatial gradient. PCB levels, on the other hand, are high in the brackish zone where adults forage on intertidal flats and eight times lower in eggs from the North Sea coast where adults feed mainly inland. No adverse effect on breeding success of Black-headed Gulls was observed in the field. The estimated biomagnification factor for PCB-153 for Oystercatcher (Haematopus ostralegus) is higher than for terns and gulls.

Marine Pollution Bulletin, 2003

Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide,... more Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity identification evaluation (TIE) phase I manipulations and tested for toxicity with four bioassays: the amphipod Corophium volutator (survival as an endpoint), the sea urchin Psammechinus miliaris (fertilization, embryo development) and the bacterium Vibrio fischeri (bioluminescence inhibition).The graduated pH manipulations identified the prominent toxicity of ammonia in the amphipod and sea urchin embryo tests, and also sulfide toxicity in the bacterium test. In two of the three samples tested with the amphipods, sea urchin embryos and bacteria, a small but significant reduction in interstitial water toxicity was achieved by removing persistent compounds through C18 solid phase extraction. EDTA chelation resulted in a slight detoxification of the interstitial water for the amphipods and sea urchin embryos, but this was not related to any measured trace metals. Despite the presence of toxic levels of ammonia and sulfide in the harbor sediments, we established the adverse biological effects of persistent constituents by means of the TIE manipulations and in vivo interstitial water bioassays.

Aquatic Ecology, 1993

The ecotoxicological effects of pollution in the Scheldt estuary is evaluated for several routes ... more The ecotoxicological effects of pollution in the Scheldt estuary is evaluated for several routes of exposure by comparing observed concentrations of micro-contaminants in water and tissues of biota with toxicity data in literature. Ecological risks are estimated for dissolved trace metals according to the method of VAN STRAALEN (1990) using published data on NOECs from aquatic toxicity tests concerning reproduction, mortality and growth for cold blooded marine and estuarine organisms. Of eight investigated trace metals, zinc and nickel cause the highest risks, both affecting up to 4% of the aquatic species. The occurrence of bioaccumulation of PCBs and cadmium is investigated in several trophic levels. High concentrations of PCBs are observed in tissues of biota and may indicate adverse effects on top predators (seals, terns), especially in the brackish zone. Environmental risks of other organic micro-contaminants have not been indicated due to the limited number of data on toxicity or environmental concentrations. The effects of a mixture of pollutants in sediments from the Scheldt estuary were investigated with an oyster larvae bioassay showing an increased toxicity in upstream direction. Moreover, in the upper part of the estuary, preconditions regarding the oxygen concentration are not met and overshadow the toxic effects of pollution with micro-contaminants. Especially in the less contaminated part of the estuary more ecotoxicolgical research is required to perform an integral risk evaluation. At present, still little is known about effects that may occur in the field.

Environmental Toxicology and Chemistry, 2003

Environmental Toxicology and Chemistry, 2002

The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dut... more The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dutch coast was investigated using the dioxin receptor-chemically activated luciferase gene expression (DR-CALUX) bioassay. The DR-CALUX response varied between 0.2 and 136 ng/kg dry weight expressed in units of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalency quotients (TEQ). The highest CALUX-TEQ values (Ͼ50 ng TEQ/kg dry wt) were found in sediments from the center of the Port of Rotterdam and from the North Sea canal near Amsterdam. The DR-CALUX activity of harbor sediments was classified by setting guideline values. None of the 257 harbor sediment samples investigated exceeded the maximum value of 1,000 ng TEQ/ kg, while 94% of the samples fail the target value of 2 ng TEQ/kg. Threshold values (25 and 50 ng TEQ/kg) are intended as pass/ fail criteria for offshore disposal of dredged material and were exceeded in 12 and 3% of the samples, respectively. DR-CALUX response did not always match with contamination of polychlorinated biphenyls (PCBs) as determined in bulk sediments (⌺ 7 -PCB ranging from Ͻ1 to 456 g/kg dry wt). Concentrations of planar PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinateddibenzofuranes (PCDFs), polybrominated biphenyls (PBBs), and polybrominated-diphenylethers (PBDEs) were determined in 20 selected sediment extracts. On average, PCDD/Fs explained 50% of the DR-CALUX activity and planar PCBs 6%. Further research is needed to elucidate the unexplained part of the DR-CALUX response. The DR-CALUX is a highly sensitive and reproducible bioassay that can usefully complement standard PCB analysis, improving the hazard assessment of the disposal of dredged material in the North Sea.

Marine Pollution Bulletin, 1997

Dredge material from an entrance waterway to the port of Rotterdam and sediments from the North S... more Dredge material from an entrance waterway to the port of Rotterdam and sediments from the North Sea off-shore disposal site were tested for toxicity using three different sediment bioassays. The goals of the study were to evaluate if bioassays generate useful additional information to chemical based sediment quality criteria, and to investigate potential changes in toxicity of dredge material after off-shore disposal. Sediment elutriates were tested with larvae of the oyster Crassostrea gigas, whole sediments with the infaunal amphipod Bathyporeia sarsi, and sediment suspensions with the blue mussel Mytilus edulis. The contamination of the investigated dredge material was low according to the limited set of chemical parameters that was analysed. Nevertheless the three bioassays showed that some of the dredge material samples significantly affected the survival of oyster larvae and the amphipod B. sarsi, as well as the aerial survival time of mussels. Toxicity was reduced at the off-shore disposal site, probably due to the dispersal of the most polluted finer sediment fractions by strong residual currents. It is concluded that the sediment bioassays used for this study are a meaningful tool that should be incorporated in decision making frameworks for the management of dredge material.

Environmental Pollution, 2003

The environmental impact and recovery associated with the long and uninterrupted disposal of larg... more The environmental impact and recovery associated with the long and uninterrupted disposal of large volumes of moderately contaminated dredged material from the port of Rotterdam was studied at nearby dumping sites in the North Sea. Observations were made on sediment contamination, ecotoxicity, biomarker responses and benthic community changes shortly after dumping at the ‘North’ site had ceased and at the start of disposal at the new dumping site ‘Northwest’. During the period of dumping, very few benthic invertebrates were found at the North site. Concentrations of cadmium, mercury, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and tributyltin (TBT) in the fine sediment fraction (<63 μm) from this site were 2–3 times higher than at the reference site. In four different bioassays with marine invertebrates the sediments showed no acute toxic effects. In tissue (pyloric caeca) of resident starfish Asterias rubens, residual levels of mercury, zinc, PCBs and dioxin-like activity were never more than twice those at the reference site. Four different biomarkers (DNA integrity, cytochrome P450 content, benzo[a]pyrene hydroxylase activity and acetylcholinesterase inhibition) were used on the starfish tissues, but no significant differences were found between North and the reference site. Minor pathological effects were observed in resident dab Limanda limanda. One year after dumping had ceased at the North site, a significant increase in the species richness and abundance of benthic invertebrates and a concomitant decrease in the fine sediment fraction of the seabed were observed. After 8.2 million m3 of moderately contaminated dredged material had been dumped at the new dumping site Northwest, the species richness and abundance of benthic invertebrates declined over an area extending about 1–2 km eastwards. This correlated with a shift in sediment texture from sand to silt. The contamination of the fine sediment fraction at the Northwest location doubled. It is concluded that marine benthic resources at and around the dumping sites have been adversely affected by physical disturbance (burial, smothering). However, no causal link could be established with sediment-associated contaminants from the dredged spoils.

Marine Pollution Bulletin, 1992

Temporal trends and length-concetration relationships are presented for data from the Joint Monit... more Temporal trends and length-concetration relationships are presented for data from the Joint Monitoring Programme for microcontaminants in the blue mussel Mytilus edulis and flounder Platichthys flesus from the Ems Dollard and Western Scheldt estuaries in the Netherlands over the period 1985 to 1990. Statistical analyses were carried out in conformity with ICES procedures.The analyses show only a decrease in levels of dieldrin in mussels from the Western Scheldt. Cadmium concentrations in flounders from the Ems Dollard have increased. No linear trend has been detected in either estuary for the other contaminants (PCB, PAH, pp′DDE, lindane, Hg, As, Cu, Cr, Zn, Pb, Ni). The importance of taking the fat weight into account in analysing PCB trend and length relationship is illustrated.Concentrations of PCB, PAH, chromium and nickel in mussels and PCB in livers of flounders decrease with increasing size. Mercury concentrations in flounders increase with length.

Environmental Pollution, 2003

resources near dumping sites are adversely affected by physical disturbances, but a causal link t... more resources near dumping sites are adversely affected by physical disturbances, but a causal link to contaminant damage could not be found.

Environmental Pollution, 2003

resources near dumping sites are adversely affected by physical disturbances, but a causal link t... more resources near dumping sites are adversely affected by physical disturbances, but a causal link to contaminant damage could not be found.

Archives of Environmental Contamination and Toxicology, 1998

The incorporation of toxicological data from bioassays can improve the present system of sediment... more The incorporation of toxicological data from bioassays can improve the present system of sediment quality criteria in the Netherlands. The use of acute lethality toxicity tests alone does not however provide sufficient discrimination and sensitivity for predicting ecological effects of slightly and moderately contaminated dredged material. Sublethal endpoints are needed for the assessment of environmental hazards of such dredged material. In this study, two approaches were used to identify toxicity of marine sediments collected from 16 locations classified as “slightly and moderately contaminated” on the basis of chemical data: (1) a comparison of growth vs. mortality as different endpoints in the marine amphipod Corophium volutator (Pallas); (2) an investigation on the use of sediment dilutions to characterize the degree of toxicity. The influence of sediment storage time on toxicity was also evaluated. In four out of 16 locations, mortality over 10 days of exposure ranged 80–100%; in two out of 16 locations mortality ranged 40–60%. In the other 10 locations, mortality was below 15%. Results on growth showed that in all locations final dry weight values were significantly lower (a factor of 1.5 to 3) than in controls. Results of dilution experiments showed that if sediments were diluted with a reference sediment of similar physicochemical characteristics, total concentrations of metals, mineral oil, and PAHs decreased as expected and so did the effects on C. volutator. In the 100% contaminated sediments growth was reduced by 32–60% compared to controls. The dilution rate necessary to reduce toxicity to the EC10 value for growth of C. volutator was considered an appropriate endpoint for the evaluation. When sediments were stored for a period of 3–5 months at 4°C and retested, effects on mortality and growth decreased, although some effects on growth were still measured after 5 months of storage. The experiments illustrate the usefulness of ecotoxicity assessment to evaluate contaminted dredged material.

Bulletin of Environmental Contamination and Toxicology, 1994

Archives of Environmental Contamination and Toxicology, 2003

The status of the contamination of Dutch marine harbor sediments was reevaluated after a period i... more The status of the contamination of Dutch marine harbor sediments was reevaluated after a period in which emissions from point sources had been greatly reduced. Data on sediment chemistry from 1999 and 2000 were assessed against screening levels (SLs) selected from available sediment quality guidelines and representing a low probability of adverse biological effects. This yielded a ranking of the environmental hazard of 22 contaminants. Most of the sediments were silty material; every year 15 to 25 million m3 of such material is dredged from Dutch harbors. Some 34% of the volume exceeded one or more SLs. The contaminants of concern were tributyltin (TBT), mineral oil (petroleum hydrocarbons), polychlorinated biphenyls (PCBs), and mercury. The PCB and mercury contamination is the legacy of historic inputs; the TBT and mineral oil contamination is related to present-day shipping activity. Concentrations of trace metals, rare earth elements, organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAHs) were low and apparently of minor environmental concern. It is concluded that the risk assessment would be improved by laboratory testing of adverse biological effects.

Aquatic Ecology, 1988

The error inin vivo 14C incubator measurements of primary production in the Eastern Scheldt when ... more The error inin vivo 14C incubator measurements of primary production in the Eastern Scheldt when neutral density filters were used and the error obtained when no account was taken of the spectral changes in submarine irradiance that occur with increasing depth, were evaluated theoretically. By multiplying the photosynthetic action spectra of two marine algae by calculated irradiance in the euphotic layer using Kd and Kd(λ) respectively, the gross primary production P[Ed(400–700)] and P[Ed(λ)] was computed. In the green-brown waters of the Eastern Scheldt estuary the use of neutral density filters was sufficient to simulate the underwater light conditions. In clear waters it can cause an overestimation of the gross production.

Environmental Toxicology and Chemistry, 1999

ABSTRACT The presence of tributyltin (TBT) in silty sediments is regarded as a long—term threat t... more ABSTRACT The presence of tributyltin (TBT) in silty sediments is regarded as a long—term threat to marine and estuarine environments due to its persistence. The bioaccumulation kinetics and toxicity of TBT in the deposit—feeding heart urchin Echinocardium cordatum was studied in silty sediment spiked with TBT and equilibrated prior to the 28-d exposure. An additional 10-d acute toxicity test was carried out with the burrowing amphipod Corophium volutator in the same sediment. Because E. cordatum has a low lipid content and apparently high elimination and metabolic rates, only a moderate degree of TBT bioaccumulation was observed, with biota—sediment accumulation factors (BASFs) of 0.09 to 0.21 (dry weight basis) and biota accumulation factors (BAFs) of 180 to 843 (wet weight basis). The lethal body residue in E. cordatum (soft tissue and skeleton) was 0.8 to 3.4 nmol TBT+/g wet weight which, considering the differences in lipid content, is comparable to data on other taxonomic groups. For E. cordatum and C. volutator, the LC50s for pore water (222 and 329 ng Sn/L) were also close to reported values for aquatic and benthic organisms. The TBT concentrations in the pore water of the silty sediment were much lower than might be expected from the octanol—water partition coefficient. The measured sediment—water partitioning coefficient Kp was 8,700 L/kg dry weight. Consequently, toxicity was observed at a relatively high TBT concentration in the bulk sediment with LC50s for E. cordatum and C. volutator of 1,594 and 2,185 ng Sn/g dry weight, respectively. The results show that TBT is highly toxic to the benthic species investigated and sorption in the silty sediment strongly reduced the bioavailability of the compound.

Journal of Aquatic Ecosystem Health, 1995

In the Netherlands, the decision to permit the dumping of dredged material into the sea depends o... more In the Netherlands, the decision to permit the dumping of dredged material into the sea depends on the concentrations of about 33 chemical compounds (Anonymous, 1994a). This evaluation of dredged material quality can be improved by the use of bioassays in its assessment. In this note the use of bioassays in the evaluation of lightly contaminated marine dredged material from the Netherlands is illustrated with preliminary results of bioassays with Corophium volutator and Crassostrea gigas. It is concluded that the inclusion of bioassays in the assessment of lightly contaminated sediment is useful.

Marine Pollution Bulletin, 1993

The contaminated Scheldt estuary is a wetland of international importance for waterbirds. In eggs... more The contaminated Scheldt estuary is a wetland of international importance for waterbirds. In eggs of Common Terns (Sterna hirundo) from the brackish zone, concentrations of Hg, Cr, Cu, Cd, Zn, and PAHs did not exceed no-observed effect levels reported in the literature. Eggshell thickness did not differ from the pre-DDT period. However, concentrations of PCB-118 (0.1–0.7 μg g−1 WW) may indicate adverse effects on reproductive success. In terns' eggs from the marine zone, PCB-118 did not exceed the no-observed effect concentration.In eggs of Black-headed Gulls (Larus ridibundus) concentrations of HCB, lindane, DDT and dieldrin are low and showed no spatial gradient. PCB levels, on the other hand, are high in the brackish zone where adults forage on intertidal flats and eight times lower in eggs from the North Sea coast where adults feed mainly inland. No adverse effect on breeding success of Black-headed Gulls was observed in the field. The estimated biomagnification factor for PCB-153 for Oystercatcher (Haematopus ostralegus) is higher than for terns and gulls.

Marine Pollution Bulletin, 2003

Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide,... more Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity identification evaluation (TIE) phase I manipulations and tested for toxicity with four bioassays: the amphipod Corophium volutator (survival as an endpoint), the sea urchin Psammechinus miliaris (fertilization, embryo development) and the bacterium Vibrio fischeri (bioluminescence inhibition).The graduated pH manipulations identified the prominent toxicity of ammonia in the amphipod and sea urchin embryo tests, and also sulfide toxicity in the bacterium test. In two of the three samples tested with the amphipods, sea urchin embryos and bacteria, a small but significant reduction in interstitial water toxicity was achieved by removing persistent compounds through C18 solid phase extraction. EDTA chelation resulted in a slight detoxification of the interstitial water for the amphipods and sea urchin embryos, but this was not related to any measured trace metals. Despite the presence of toxic levels of ammonia and sulfide in the harbor sediments, we established the adverse biological effects of persistent constituents by means of the TIE manipulations and in vivo interstitial water bioassays.

Aquatic Ecology, 1993

The ecotoxicological effects of pollution in the Scheldt estuary is evaluated for several routes ... more The ecotoxicological effects of pollution in the Scheldt estuary is evaluated for several routes of exposure by comparing observed concentrations of micro-contaminants in water and tissues of biota with toxicity data in literature. Ecological risks are estimated for dissolved trace metals according to the method of VAN STRAALEN (1990) using published data on NOECs from aquatic toxicity tests concerning reproduction, mortality and growth for cold blooded marine and estuarine organisms. Of eight investigated trace metals, zinc and nickel cause the highest risks, both affecting up to 4% of the aquatic species. The occurrence of bioaccumulation of PCBs and cadmium is investigated in several trophic levels. High concentrations of PCBs are observed in tissues of biota and may indicate adverse effects on top predators (seals, terns), especially in the brackish zone. Environmental risks of other organic micro-contaminants have not been indicated due to the limited number of data on toxicity or environmental concentrations. The effects of a mixture of pollutants in sediments from the Scheldt estuary were investigated with an oyster larvae bioassay showing an increased toxicity in upstream direction. Moreover, in the upper part of the estuary, preconditions regarding the oxygen concentration are not met and overshadow the toxic effects of pollution with micro-contaminants. Especially in the less contaminated part of the estuary more ecotoxicolgical research is required to perform an integral risk evaluation. At present, still little is known about effects that may occur in the field.

Environmental Toxicology and Chemistry, 2003

Environmental Toxicology and Chemistry, 2002

The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dut... more The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dutch coast was investigated using the dioxin receptor-chemically activated luciferase gene expression (DR-CALUX) bioassay. The DR-CALUX response varied between 0.2 and 136 ng/kg dry weight expressed in units of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalency quotients (TEQ). The highest CALUX-TEQ values (Ͼ50 ng TEQ/kg dry wt) were found in sediments from the center of the Port of Rotterdam and from the North Sea canal near Amsterdam. The DR-CALUX activity of harbor sediments was classified by setting guideline values. None of the 257 harbor sediment samples investigated exceeded the maximum value of 1,000 ng TEQ/ kg, while 94% of the samples fail the target value of 2 ng TEQ/kg. Threshold values (25 and 50 ng TEQ/kg) are intended as pass/ fail criteria for offshore disposal of dredged material and were exceeded in 12 and 3% of the samples, respectively. DR-CALUX response did not always match with contamination of polychlorinated biphenyls (PCBs) as determined in bulk sediments (⌺ 7 -PCB ranging from Ͻ1 to 456 g/kg dry wt). Concentrations of planar PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinateddibenzofuranes (PCDFs), polybrominated biphenyls (PBBs), and polybrominated-diphenylethers (PBDEs) were determined in 20 selected sediment extracts. On average, PCDD/Fs explained 50% of the DR-CALUX activity and planar PCBs 6%. Further research is needed to elucidate the unexplained part of the DR-CALUX response. The DR-CALUX is a highly sensitive and reproducible bioassay that can usefully complement standard PCB analysis, improving the hazard assessment of the disposal of dredged material in the North Sea.

Marine Pollution Bulletin, 1997

Dredge material from an entrance waterway to the port of Rotterdam and sediments from the North S... more Dredge material from an entrance waterway to the port of Rotterdam and sediments from the North Sea off-shore disposal site were tested for toxicity using three different sediment bioassays. The goals of the study were to evaluate if bioassays generate useful additional information to chemical based sediment quality criteria, and to investigate potential changes in toxicity of dredge material after off-shore disposal. Sediment elutriates were tested with larvae of the oyster Crassostrea gigas, whole sediments with the infaunal amphipod Bathyporeia sarsi, and sediment suspensions with the blue mussel Mytilus edulis. The contamination of the investigated dredge material was low according to the limited set of chemical parameters that was analysed. Nevertheless the three bioassays showed that some of the dredge material samples significantly affected the survival of oyster larvae and the amphipod B. sarsi, as well as the aerial survival time of mussels. Toxicity was reduced at the off-shore disposal site, probably due to the dispersal of the most polluted finer sediment fractions by strong residual currents. It is concluded that the sediment bioassays used for this study are a meaningful tool that should be incorporated in decision making frameworks for the management of dredge material.

Environmental Pollution, 2003

The environmental impact and recovery associated with the long and uninterrupted disposal of larg... more The environmental impact and recovery associated with the long and uninterrupted disposal of large volumes of moderately contaminated dredged material from the port of Rotterdam was studied at nearby dumping sites in the North Sea. Observations were made on sediment contamination, ecotoxicity, biomarker responses and benthic community changes shortly after dumping at the ‘North’ site had ceased and at the start of disposal at the new dumping site ‘Northwest’. During the period of dumping, very few benthic invertebrates were found at the North site. Concentrations of cadmium, mercury, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and tributyltin (TBT) in the fine sediment fraction (<63 μm) from this site were 2–3 times higher than at the reference site. In four different bioassays with marine invertebrates the sediments showed no acute toxic effects. In tissue (pyloric caeca) of resident starfish Asterias rubens, residual levels of mercury, zinc, PCBs and dioxin-like activity were never more than twice those at the reference site. Four different biomarkers (DNA integrity, cytochrome P450 content, benzo[a]pyrene hydroxylase activity and acetylcholinesterase inhibition) were used on the starfish tissues, but no significant differences were found between North and the reference site. Minor pathological effects were observed in resident dab Limanda limanda. One year after dumping had ceased at the North site, a significant increase in the species richness and abundance of benthic invertebrates and a concomitant decrease in the fine sediment fraction of the seabed were observed. After 8.2 million m3 of moderately contaminated dredged material had been dumped at the new dumping site Northwest, the species richness and abundance of benthic invertebrates declined over an area extending about 1–2 km eastwards. This correlated with a shift in sediment texture from sand to silt. The contamination of the fine sediment fraction at the Northwest location doubled. It is concluded that marine benthic resources at and around the dumping sites have been adversely affected by physical disturbance (burial, smothering). However, no causal link could be established with sediment-associated contaminants from the dredged spoils.

Marine Pollution Bulletin, 1992

Temporal trends and length-concetration relationships are presented for data from the Joint Monit... more Temporal trends and length-concetration relationships are presented for data from the Joint Monitoring Programme for microcontaminants in the blue mussel Mytilus edulis and flounder Platichthys flesus from the Ems Dollard and Western Scheldt estuaries in the Netherlands over the period 1985 to 1990. Statistical analyses were carried out in conformity with ICES procedures.The analyses show only a decrease in levels of dieldrin in mussels from the Western Scheldt. Cadmium concentrations in flounders from the Ems Dollard have increased. No linear trend has been detected in either estuary for the other contaminants (PCB, PAH, pp′DDE, lindane, Hg, As, Cu, Cr, Zn, Pb, Ni). The importance of taking the fat weight into account in analysing PCB trend and length relationship is illustrated.Concentrations of PCB, PAH, chromium and nickel in mussels and PCB in livers of flounders decrease with increasing size. Mercury concentrations in flounders increase with length.