Aimo Oikari

Bioavailability of organic pollutants in boreal waters with varying levels of dissolved organic material

Abstract Dissolved organic matter (DOM) in 20 surface waters in Eastern Finland were characterized to examine relationships between structural and compositional properties of DOM and partition coefficients ( K p ) describing sorption of four model contaminants to DOM and the bioavailability of contaminants by Daphnia magna . The hydrophobic acids (HbA), hydrophobic neutrals (HbN) and hydrophilic (HI) fractions of DOM were separated by XAD-8 resin. The K P s were measured by equilibrium dialysis. Model contaminants were benzo(a)pyrene (BaP), naphthalene (NAPH), 3.3′,4.4′-tetrachlorobiphenyl (TCB) and dehydroabietic acid (DHAA). DOM concentrations varied from 2.0 to 38.3 mg org. C/l in the water series. The percentage of HbA and the aromaticity of DOM, as indicated by the absorptivity at 270 nm (A 270 ) and hydrogen/carbon ratio (H/C ratio), increased with increasing DOM concentration. Significant correlations were observed between K P of BAP, A 270 and HbA content of the DOM from different sources. For the other contaminants similar kinds of relationships between K p s and quality parameters of DOM could not be found. The bioavailability of model compounds was decreased by increasing DOM concentration in the water series. For all four model contaminants, measured bioconcentration factors (BCF) correlated well with the A 270 of a water and HbA content of the DOM. These results show that the total DOM concentration is an important factor controlling the bioavailability of xenobiotics in natural waters. Besides the quantity also the quality of DOM, like proportion of HbA, can contribute in bioavailability.

Effects of XAD-8 fractions of dissolved organic carbon on the sorption and bioavailability of organic micropollutants

The dissolved organic carbon (DOC) from a stream water near a peat deposit was fractionated into hydrophobic-acid (HbA), hydrophobic-neutral (HbN), and hydrophilic (Hl) subcomponents by XAD-8 chromatography. The capacity of these fractions and the total (unfractionated) water to bind hydrophobic organic contaminants was measured by equilibrium dialysis, and the effect of binding on contaminant bioavailability was measured inDaphnia magna. Model contaminants were the poly cyclic aromatic hydrocarbons, naphthalene (NPH) and benzo(a)pyrene (BaP), and the polychlorinated biphenyl, 2,2′,5,5′-tetrachlorobiphenyl (TCB).Both BaP and TCB exhibited high partition coefficients (Kps) for binding to both the total DOC and the hydrophobic components of the DOC. BaP had a higher affinity for binding to the HbA fraction, while TCB (and 3 other PCBs had a higher affinity for the HbN fraction. The Kps for binding to the Hl fraction were twofold to tenfold lower than for binding to the hydrophobic fractions. The less hydrophobic compound, NPH, had a much lower Kp, and little difference was seen between the fractions. The total water and the different DOC fractions reduced the uptake and accumulation of BaP and TCB byD. magna in proportion to the capacity of the DOC for binding the contaminants. Data were consistent with the hypothesis that a contaminant bound to DOC (total water or any of the fractions) is unavailable for uptake by biota. Uptake of NPH was not substantially affected by the DOC, consistent with its lower Kp.

Assessing the impact of complexation by EDTA and DTPA on heavy metal toxicity using microtox bioassay

The influence of complexation by ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) on the toxicity of iron(III), cadmium, copper, mercury, lead and zinc was investigated. Microtox bioassay, based on measuring the bioluminescence of Photobacterium phosphoreum, was used as an indication of toxicity. The reproducibility of data revealed correlation coefficients between 0.936–1.000. The results suggest that the complexation by these chelating agents increases the toxicity of iron, has very low or no influence on the toxicity of Cu, Cd and Hg, and reduces noticeably the toxicity of Zn and Pb. The slopes of the dose-response curves were steeper for metal complexes than for metals, suggesting that the mechanism of action of the toxicity changes during complexation. The inhibitory effect of EDTA and DTPA on metal toxicity is explained to be due to binding the reactive sites of the heavy metal ions and thus preventing their normal action.

The anti-inflammatory drugs diclofenac, naproxen and ibuprofen are found in the bile of wild fish caught downstream of a wastewater treatment plant.

Pharmaceutical residues are ubiquitous in rivers, lakes, and at coastal waters affected by discharges from municipal wastewater treatment plants. In this study, the presence of 17 different pharmaceuticals and six different phase I metabolites was determined in the bile of two wild fish species, bream (Abramis brama) and roach (Rutilus rutilus). The fish were caught from a lake that receives treated municipal wastewater via a small river. Prior to analyses, the bile content was enzymatically hydrolyzed to convert the glucuronide metabolites into the original pharmaceuticals or phase I metabolites. The solid phase extracts of hydrolyzates were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring mode. The anti-inflammatory drug naproxen could be detected in all the six bream and roach bile samples. Diclofenac was found in five of the bream and roach samples, while ibuprofen was detected in three bream and two roach samples. The observed bile concentrations of diclofenac, naproxen, and ibuprofen in bream ranged from 6 to 95 ng mL(-1), 6 to 32 ng mL(-1), and 16 to 34 ng mL(-1), respectively. The corresponding values in roach samples ranged from 44 to 148 ng mL(-1), 11 to 103 ng mL(-1) and 15 to 26 ng mL(-1), respectively. None of the other studied compounds could be detected. The study shows that pharmaceuticals originating from wastewater treatment plant effluents can be traced to the bile of wild bream and roach living in a lake where diclofenac, naproxen, and ibuprofen are present as pollutants.

Toxicological effects of dehydroabietic acid (DHAA) on the trout, Salmo gairdneri Richardson, in fresh water

Abstract Toxicological and physiological effects of dehydroabietic acid (DHAA), a major poison to fishes in pulp and paper mill effluents, were studied by two experiments with rainbow trout, Salmo gairdneri Richardson: in the first, fish were acutely exposed for 4 days to an average DHAA concentration of 1.2 mg l −1 (Exp. I) and in the second for 30 days to an average of 20 μg DHAA l −1 (Exp. II). Compared to the controls, fish of Exp. I displayed a decreased relative weight of liver, an increased blood haematocrit, and increased haemoglobin as well as plasma protein concentrations. The aspartate aminotransferase activity of heart muscle was significantly elevated, as was also the lactate dehydrogenase (LDH) of white muscle tissue. In the blood plasma, the proportion of muscle type LDH activity was simultaneously increased. UDP-glucuronyl-transferase activities of liver and kidney were strongly decreased. Results suggest an increased and altered use of body energy reserves, decreased plasma volume and impaired liver function. Fish of Exp. II showed an increased relative weight of spleen. In addition, liver and gill LDH shifted towards heart-type. We conclude that 20 μg l −1 is close to the “minimum effective concentration” of DHAA to rainbow trout.

Biotransformation and other toxicological and physiological responses in rainbow trout (Salmo gairdneri Richardson) caged in a lake receiving effluents of pulp and paper industry

Abstract Hatchery reared immature rainbow trout ( Salmo gairdneri Richardson) were transferred to eight field stations at the southern Lake Saimaa (SE Finland). They were caged in the receiving water body of effluents from a mill producing chlorine bleached kraft pulp and printing paper. The controls were caged upstream to the sewer. The microsomal cytochrome P -450 content, NADPH cytochrome c reductase and monooxygenase enzyme activities as well as conjugation reactions with glucuronic acid and glutathione were studied in the liver, kidney and gills. Conjugated metabolites of chlorophenolics in the bile and some physiological blood parameters were investigated. The caging in polluted water increased the monooxygenase enzyme activities. Compared to control trout, up to 7 times induction of liver 7-ethoxyresorufin O -deethylase (EROD) activity was observed at the nearest caging station, 3 km from the effluent outlet. Activity of EROD was the best indicator for the induction caused by pulp and paper mill effluent, however, pentoxyresorufin O -dealkylase was also responsive. Analysis of conjugated chlorinated phenolics in the bile showed highest concentrations at the caging station nearest to the mill and displayed good distance related decreases. The levels of conjugated toxicants found in control fish indicated a low contamination of the whole southern Lake Saimaa.

Ecotoxicological aspects of pulp and paper mill effluents discharged to an inland water system: Distribution in water, and toxicant residues and physiological effects in caged fish (Salmo gairdneri)

Abstract Simultaneous studies were conducted on concentrations of chlorinated phenolics (CP) and resin acids (RA) in bleached kraft pulp mill effluents (BKME), their distribution in the receiving water, their uptake and accumulation in the blood plasma of rainbow trout caged in the recipient, as well as short-term physiological effects developed in fish. RA disappeared from the lake water much faster than most of the CP. Some of the BKME-related substances (e.g. 2,4,6-trichlorophenol, 4,5,6-trichloroguaiacol, tetrachloroguaiacol and dehydroabietic acid) were also detected upstream from the mill, thus implying a low-level contamination of this water system in general. In the blood plasma of caged trout free RA were detected up to 3 km from the sewer, but free CP were analysed as far as 11 km from the mill. During the 10-day caging period a partial inhibition of liver UDP-glucuronosyltransferase was observed even at 11 km from the BKME source. Brain acetylcholinesterase activity showed that BKME did not work like anticholinesterase agents, whereas a decrease of plasma cholinesterase activity was developed in a few days in the nearest 6 km from the sewer. Trout exposed at 6–11 km from the sewer displayed increased blood haemoglobin and decreased plasma protein concentrations. The plasma ionic picture (Na, Cl, Mg) indicated only negligible effects on fish osmoregulation.

Uptake from water, biotransformation, and biliary excretion of pharmaceuticals by rainbow trout

An urgent need exists to assess the exposure of fish to pharmaceuticals. The aim of the present study was to assess the uptake and metabolism of waterborne pharmaceuticals in rainbow trout (Oncorhynchus mykiss). A further objective was to determine the possibility of monitoring exposure to low levels of pharmaceuticals by bile assays. Rainbow trout were exposed for 10 d under flow-through conditions to mixtures of five pharmaceuticals (diclofenac, naproxen, ibuprofen, bisoprolol, and carbamazepine) at high and low concentrations. The low concentration was used to mimic the conditions prevailing in the vicinity of the discharge points of wastewater treatment plants. The uptake and the bioconcentration were determined by blood plasma and bile analyses. The average bioconcentration factor in plasma ranged from below 0.1 for bisoprolol to 4.9 for diclofenac, the values being approximately similar at low and high ambient concentrations. The biotransformation of diclofenac, naproxen, and ibuprofen was considered efficient, because several metabolites could be detected in concentrations clearly exceeding those of the unmetabolized compounds. The glucuronides were the dominant metabolites for all three pharmaceuticals. The total bioconcentration in the bile was two to four orders of magnitude higher than in the plasma. The results of this work show that the exposure of fish to pharmaceuticals in environmentally relevant concentrations may be monitored by blood plasma and bile analyses, the latter allowing detection at markedly lower ambient concentration.

Metabolites of the Aquatic Pollutant Diclofenac in Fish Bile

The uptake and metabolism of anti-inflammatory drug diclofenac (DCF) was studied by exposing rainbow trout (Oncorhynchus mykiss) to DCF intraperitoneally, and via water at concentration of 1.7 μg L(-1). The bile was collected and the formed metabolites were identified. The identification was based on the exact mass determinations by a time-of-flight mass analyzer and on the studies of fragments and fragmentation patterns of precursor ions by an ion trap mass analyzer. The main metabolites found were acyl glucuronides of hydroxylated DCFs. In addition, one ether glucuronide of hydroxylated DCF was found. Also, unmetabolized DCF was detected in the bile. The total bioconcentration factors (BCF(total-bile) for DCF and its metabolites) in rainbow trout bile, varied between individuals and was roughly estimated to range from 320 to 950. These findings suggest that fish living downstream the wastewater treatment plants (WWTPs) and which are chronically exposed to the drug may accumulate the drug and its metabolites in the bile.

Mixed function monooxygenase of fish as an indicator of pollution of aquatic environment by industrial effluent.

The aquatic environment is subject to a heavy and diverse pollutant loading, particularly in industrial districts. The response to this loading by aquatic animals is largely unknown. An enzyme system that in mammals responds readily to the presence of foreign chemicals is the mixed function monooxygenase (MFO) system, the very enzymes involved in the elimination of foreign compounds. The MFO enzymes are induced by a large number of xenobiotics thus increasing the rate of their elimination (Remmer, 1972). On the other hand certain hepatotoxic compounds and ‘dirty’ environment have the opposite effect according to Sasame et al. (1968) and Vesell et al. (1973). It has been reported by Dewaide (1971) and Payne and Penrose (1975) that fish in polluted water have a higherin vitro capacity to metabolize foreign compounds than those in clean water. In this study pike (Esox lucius L.) from heavily polluted Lake Vatianjärvi in the central Finland were studied and a largely opposite result is obtained.