Papers by Gert-Jan de Maagd
Water Research, 1999
AbstractÐAlthough the presence of hepatotoxins in surface and drinking water is regarded as an ec... more AbstractÐAlthough the presence of hepatotoxins in surface and drinking water is regarded as an ecotoxicological and human health problem, limited knowledge exists on the fate of these compounds. Therefore the n-octanol/water distribution ratio (D ow ) of the hepatotoxin microcystin-LR (MC-LR) was determined in order to enable the prediction of the fate of this compound in the aquatic environment. The presence of two free ionizable carboxyl groups and one free ionizable amino group in MC-LR suggest that its speciation and partitioning between octanol and water is pH dependent. This was experimentally studied and con®rmed in the present study. The log D ow of MC-LR decreased from 2.18 at pH = 1 to À1.76 at pH = 10. From the low log D ow values, especially at the basic pH region at which the toxin producing cyanobacteria¯ourish, a low tendency to bioconcentrate from water in biota can be expected. #
Sorption Coefficients of PAH for Two Lake Sediments
Polycyclic Aromatic Compounds, 1995
... negative Kp's. TABLE 1 Sorption coefficients obtained from 48 hr batch experiments using... more ... negative Kp's. TABLE 1 Sorption coefficients obtained from 48 hr batch experiments using high concentrations of PAH compound I(p OVP (st.dev) Kp KM (st.dev) naphthalene - 30 (50) # 1100 (200) * ... compound K, OVP (st.dev) K, KM (st.dev) naphthalene nd 750 (200) * ...
Integrated Environmental Assessment and Management, 2009
This is 1 of 12 papers prepared by participants attending the workshop ''Risk Assessment in Europ... more This is 1 of 12 papers prepared by participants attending the workshop ''Risk Assessment in European River Basins-State of the Art and Future Challenges'' held in Liepzig, Germany on 12-14 November 2007. The meeting was organized within the framework of the European Commission's Coordination Action RISKBASE program. The objective of RISKBASE is to review and synthesize the outcome of European Commission FP4-FP6 projects, and other major initiatives, related to integrated risk assessment-based management of the water/ sediment/soil environment at the river basin scale.
GENOTOXICITY TESTING USING THE MUTATOX™ ASSAY: EVALUATION OF BENZO[a]PYRENE AS A POSITIVE CONTROL
Environmental Toxicology and Chemistry, 1997
In a study on bioassay-directed chemical factionation of sediment extracts, problems were encount... more In a study on bioassay-directed chemical factionation of sediment extracts, problems were encountered using benzo(a)pyrene (BaP) as a positive control in the Mutatox™ bacterial genotoxicity assay. Genotoxic responses of tests with this compound, prescribed by the Mutatox supplier, could only be measured using supersaturated concentrations that exceeded its aqueous solubility more than 250 times. Additional to three obvious requirements for
Sorption Coefficients of Polycyclic Aromatic Hydrocarbons for Two Lake Sediments: Influence of the Bactericide Sodium Azide
Environmental Toxicology and Chemistry, 1998
Sorption coefficient s (K{sub p}s) of a series of polycyclic aromatic hydrocarbons (PAHs) were de... more Sorption coefficient s (K{sub p}s) of a series of polycyclic aromatic hydrocarbons (PAHs) were determined in two Dutch freshwater lake sediments to improve the insight into sorption in the aquatic environment. The influence of experimental factors, such as compound concentration, equilibration time, and influence of a bactericide on K{sub p}, was studied. No significant influence of compound concentration on K{sub
PHYSICOCHEMICAL PROPERTIES OF POLYCYCLIC AROMATIC HYDROCARBONS: AQUEOUS SOLUBILITIES, n-OCTANOL/WATER PARTITION COEFFICIENTS, AND HENRY’S LAW CONSTANTS
Environmental Toxicology and Chemistry, 1998
... than the ones determined with a shake-flask method (Table 1). Analysis of variance ... The pr... more ... than the ones determined with a shake-flask method (Table 1). Analysis of variance ... The presently determined physicochemical data form a consistent dataset, which is reflected in high ... apply for unsubstituted PAHs and cannot be used to predict physico-chemical properties of ...
Environmental Science & Technology, 1999
Bioavailable concentrations of hydrophobic organic substances in aqueous tests often decrease as ... more Bioavailable concentrations of hydrophobic organic substances in aqueous tests often decrease as a result of (bio)sorption, volatilization, or degradation. In the present study, partitioning driven administering (PDA) is introduced as an approach to maintain constant exposure levels of hydrophobic organics in aqueous tests. The working principle of PDA is to control dissolved concentrations by partitioning from a dominating solid phase. For this purpose, test compounds are loaded on an octadecyl Empore disk, which subsequently is placed in an aqueous test system. Stable aqueous concentrations for a range of halogenated aromatic substances (log K OW 3.9-7.1) were established within minutes to hours, and the resulting concentrations indicate that equilibrium partitioning governs the release from the disk. Furthermore, PDA's capability to maintain stable concentrations against a depletion process was demonstrated, and PDA was successfully applied to dose 1,3,5tribromobenzene and hexachlorobenzene in algal toxicity tests. Finally, the feasibility to administer concentrations up to aqueous solubility, to administer mixtures, and to dominate the fugacity of multicompartment systems is discussed.
Lipid Content and Time-to-Death-Dependent Lethal Body Burdens of Naphthalene and 1,2,4-Trichlorobenzene in Fathead Minnow (Pimephales promelas)
Ecotoxicology and Environmental Safety, 1997
For naphthalene (NAPH) and 1,2,4-trichlorobenzene (TCBz), lethal body burdens (LBB) of 8 +/- 3.1 ... more For naphthalene (NAPH) and 1,2,4-trichlorobenzene (TCBz), lethal body burdens (LBB) of 8 +/- 3.1 mmol/kg wet wt (ww) and 14 +/- 4.5 mmol/kg (ww), respectively, were determined in fathead minnow (Pimephales promelas). LBBs of both compounds were found to increase with increasing lipid content and time-to-death of fish within the same aquarium. The correlation with time-to-death suggests that besides lipid content at least one other factor causes intraspecies variation in LBBs. When intraspecies variation is excluded by comparing mean LBBs from different aquaria and exposure regimes, LBBs still vary with time-to-death. In contrast to the situation within one aquarium, between different aquaria and exposure regimes often a decrease in LBB with time-to-death is found. The present study and others indicate that LBBs can vary with time-to-death. Therefore, a time-independent LBB cannot be assumed.
Archives of Environmental Contamination and Toxicology, 2010
Polycyclic aromatic hydrocarbons (16 EPA list) were determined in oils, fish feed, and fillets fr... more Polycyclic aromatic hydrocarbons (16 EPA list) were determined in oils, fish feed, and fillets from gilthead sea bream fed through a full production cycle (14 months) with feed containing different proportions of fish oil replaced by vegetable oils, followed by a finishing phase with fish oil. At the beginning of the study, fish presented 46.6 lg/kg fresh weight of the sum of PAHs in fillet and a benzo[a]pyrene equivalent value of 9.1 lg/kg fresh weight. These levels decreased after 330 days of rearing to values around 2 lg/kg. Although the concentration increased again during the finishing phase, they remained low. These low concentrations of PAHs could be the result of a dilution process associated with fish growth and with the detoxification pathways, both favored by the low levels of PAHs present in the feeds and the lack of any other potential source of contamination during the whole rearing period.
No influence after various exposure times on the biotransformation rate constants of benzo(a)anthracene in fathead minnow (Pimephales promelas)
Aquatic Toxicology, 1998
... Aquatic Toxicology 40 (1998) 157 169 No influence after various exposure times on the biotran... more ... Aquatic Toxicology 40 (1998) 157 169 No influence after various exposure times on the biotransformation rate constants of benzo(a)anthracene in fathead minnow (Pimephales promelas P. GertJan de Maagd'1 *, Jeroen de Poorte ... (1994): c=Gerhart and Carlson (1978): d ...
Executive summary 3 1 Introduction 7
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Papers by Gert-Jan de Maagd