| 1. |
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| 2. |
- Agrell, Cecilia, et al.
(author)
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Evidence of Latitudinal Fractionation of Polychlorinated Biphenyl Congeners along the Baltic Sea Region
- 1999
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 33:8, s. 1149-1156
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Journal article (peer-reviewed)abstract
- Annual cycles of the atmospheric concentrations of PCBs were determined at 16 (mostly rural) stations around the Baltic Sea between 1990 and 1993. The concentration levels of individual congeners were found to be influenced by their physical-chemical properties, ambient temperature, and geographical location. Median levels of PCBs were similar at all stations except at one urban site near Riga. A latitudinal gradient with higher levels in the south was found for the sum of PCB as well as for individual congeners, and the gradient was more pronounced for the low volatility congeners. As a result, the high volatility congeners increased in relative importance with latitude. Generally, PCB concentrations increased with temperature, but slopes of the partial pressure in air versus reciprocal temperature were different between congeners and between stations. In general, the low volatility congeners were more temperature dependent than the high volatility PCB congeners. Steep slopes at a sampling location indicate that the concentration in air is largely determined by diffusive exchange with soils. Lack of a temperature dependence may be due to the influence of long-range transported air masses at remote sites and due to the episodic or random nature of PCB sources at urban sites.
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| 3. |
- Agrell, Cecilia, et al.
(author)
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PCB congeners in precipitation, wash out ratios and depositional fluxes within the Baltic Sea region, Europe
- 2002
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In: Atmospheric Environment. - 1352-2310. ; 36:2, s. 371-383
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Journal article (peer-reviewed)abstract
- Concentrations of PCB congeners were determined in precipitation and the annual and seasonal depositional fluxes were calculated for 16 (mostly rural) stations around the Baltic Sea during 1990-1993. The concentrations of individual congeners in precipitation were found to be influenced by atmospheric concentrations of PCBs, ambient temperature, precipitation volume and physico-chemical properties of the compounds. Median levels of PCBs in precipitation differed one order of magnitude between stations. When analyzing all data together to obtain regional trends, concentrations of PCBs in precipitation decreased with increasing temperature. This relationship was the same for all stations but differed in the magnitude of the slope for individual congeners. Low chlorinated PCB congeners showed steeper slopes for the temperature relationship than did high chlorinated congeners, a result explained by high atmospheric concentrations of the low chlorinated congeners during low temperatures. Annual wash out ratios were between 31 and 72 x 103 and tended to be higher for the high chlorinated congeners. Wash out ratios decreased with increasing temperature for all congeners except PCB-33. At snow scavenging events, the wash out ratio of PCBs increased with a factor of 2. Latitudinal trends for PCB concentrations in precipitation and deposition were generally not statistically significant. The calculated yearly deposition of PCBs to the Baltic Sea was 390 and 5-18 kg for individual congeners, with PCB-138 having the highest flux. Deposition of PCB congeners varied seasonally, with a factor between 2 and 3, and was generally highest during fall. Relatively higher deposition of low chlorinated congeners compared to high chlorinated congeners was found during winter. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Backe, Cecilia, et al.
(author)
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Polychlorinated biphenyls in the air of southern Sweden - spatial and temporal variation
- 2000
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In: Atmospheric Environment. - 1352-2310. ; 34:9, s. 1481-1486
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Journal article (peer-reviewed)abstract
- Polychlorinated biphenyls in the lower atmosphere were studied over a regional area covering approximately 11000 km(2) in southern Sweden. Sampling were performed in 1992-1993, continuously during one year, where samples from 11 sampling-sites (in all 260 samples) were analysed. PCB concentrations ranged over two order of magnitudes, 7-983 pg m(-3). Differences in PCB concentrations among the sampling sites revealed a large number of high-concentration outliers, mainly originating from one suburban site. Smaller differences in PCB concentrations between sites probably originated from varying geographical and meteorological conditions, that affected exchange processes between air and surfaces differently at the sampling sites. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Berglund, Olof, et al.
(author)
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Factors influencing organochlorine uptake in age-0 brown trout (Salmo trutta) in lotic environments
- 1997
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 54:12, s. 2767-2774
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Journal article (peer-reviewed)abstract
- In 1994 and 1995, we investigated the relationship between stream morphology and water chemistry and levels of organochlorines (HCB, PCB, and DDT) in young-of-the-year brown trout (Salmo trutta) from 25 streams in southern Sweden. Contrary to earlier findings for lakes, we found a positive relationship between trophic status (total phosphorus) and uptake of persistent pollutants in stream biota (trout). This difference between benthic, stream environments and pelagic, lake environments may be related to processes affecting pollutant uptake, i.e., pollutant "spiralling" or the shift from heterotrophy to autotrophy in streams. Land use in the catchment area of the streams also affected pollutant levels in trout, with higher levels in agricultural landscapes and lower levels in forested areas. Size of catchment area, however, did not influence uptake of pollutants in trout. The results indicate that eutrophication of streams by agricultural activities and excessive nutrient loading may increase uptake of persistent pollutants in stream biota.
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| 6. |
- Berglund, Olof, et al.
(author)
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Influence of trophic status on PCB distribution in lake sediments and biota
- 2001
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In: Environmental Pollution. - 0269-7491. ; 113:2, s. 199-210
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Journal article (peer-reviewed)abstract
- We investigated the relationship between trophic status and polychlorinated biphenyl (PCB) distribution in 19 Swedish lakes. We analyzed PCB in water, phytoplankton, zooplankton, fish and sediment during two sampling periods, in spring and summer. The mass of Sigma PCB in the lake sediments was positively related to lake trophy, i.e. more PCBs were accumulated and buried in the sediment of eutrophic lakes than in oligotrophic lakes. In the oligotrophic lakes a greater fraction of the total PCB load was dissolved in water. We conclude that this is a result of higher sedimentation rates in eutrophic lakes and relatively lower turnover of organic carbon in the water column of the shallow, eutrophic lakes. In the stratified lakes, the amount of PCB per cubic meter in the epilimnion decreased from spring to summer. We suggest that sedimentation of plankton beneath the thermocline during stratification act as a sink process of PCBs from the epilimnion
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| 7. |
- Berglund, Olof, et al.
(author)
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The effect of lake trophy on lipid content and PCB concentrations in planktonic food webs
- 2001
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In: Ecology. - 0012-9658. ; 82:4, s. 1078-1088
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Journal article (peer-reviewed)abstract
- We investigated the influence of trophic status on the lipid content and polychlorinated biphenyl (PCB) concentrations in planktonic food webs from 19 lakes in southern Sweden. The lipid content in phytoplankton (10-45 mum), microzooplankton (45-150 mum) and large macrozooplankton (>500 mum) was negatively related to the total phosphorus (Tot-P) concentration in lakes. The lipid content in macrozooplankton (>150 Gem) and young-of-the-year roach (Rutilus rutilus) was not related to Tot-P in lakes. On a dry mass basis (ng/g dry mass), the sum of PCB concentrations in phytoplankton and microzooplankton was negatively related to Tot-P in lakes. Thus, the PCB concentrations in phytoplankton and microzooplankton were explained by the decreasing lipid content of these fractions with increasing trophic status of lakes; and when normalized to lipid content (ng/g extractable lipid) we found no differences in PCB concentrations among lakes. We conclude that the lipid content of phytoplankton increased with increased nutrient stress, explaining the negative relationship between lake trophy and phytoplankton organochlorine (OC) concentrations on a dry mass basis. The relationship found between lipids and lake trophy in producers was not transferred in the food chain.
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| 8. |
- Bremle, Gudrun, et al.
(author)
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PCB in water and sediment of a lake after remediation of contaminated sediment
- 1998
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In: Ambio: a Journal of Human Environment. - 0044-7447. ; 27:5, s. 398-403
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Journal article (peer-reviewed)abstract
- PCB concentration in river water at the outlet of a lake was monitored far two years following the completed remediation of the PCB contaminated sediment of the lake. The remediation resulted in lowered PCB concentration in the sediment, from 5 mu g g(-1) (d.w.) to 0.060 mu g g(-1) (d.w.). PCB concentration in the water decreased over the two years, but varied seasonally. Highest PCB concentrations were recorded in summer. PCB concentration was positively correlated to temperature. Spring and winter values of PCB concentration were positively correlated to water discharge and to suspended matter probably originating from resedimented particles during remediation, PCA analysis of congener patterns in the water supported this conclusion. The seasonality in PCB concentration and congener distribution seemed to gradually become similar to a location upstream of the contaminated lake.
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| 9. |
- Bremle, Gudrun, et al.
(author)
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Uptake of PCBs in fish in a contaminated river system: Bioconcentration factors measured in the field
- 1995
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 29, s. 2010-2015
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Journal article (peer-reviewed)abstract
- We have studied PCB concentration and domain (one to three congeners) distribution in water and fish along a gradient of a contaminated river system. The river was contaminated by a small lake that contains about 400 kg of PCB in the sediment. The PCB concentration in water in the outlet from the lake was 8.6 ng/L, which was 12 times higher than upstream. PCB concentration in fish from the lake was about 20 times higher than the concentration in fish from upstream lakes. The polluted lake considerably influenced domain distribution in both water and fish. The fish bioconcentration factors (BCFs) for low to highly chlorinated domains showed a bell-shaped curve. BCFs for low chlorinated PCBs were less than for more highly chlorinated ones, but for the largest molecules the BCFs were reduced. The bell-shaped curve remained also when domain numbers were transformed into corresponding log K-OW values. BCFs for the same domains were shown to vary between stations.
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| 10. |
- Ewald, Göran, et al.
(author)
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Biotransport of organic pollutants to an inland Alaska Lake by migrating Sockeye Salmon (Oncorhynchus nerka)
- 1998
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In: Arctic. - 0004-0843. ; 51:1, s. 40-47
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Journal article (peer-reviewed)abstract
- Persistent organic pollutants such as polychlorinated biphenyls (PCBs) and the pesticide DDT, known to harm wildlife, have been shown to reach pristine Subarctic and Arctic areas by global atmospheric transport. Another transport route for pollutant entry into these ecosystems is provided by migrating salmon. Pollutant transport was studied in a population of sockeye salmon (Oncorhynchus nerka) in the Copper River, Alaska during their 410 km spawning migration. Pollutants accumulated by the salmon during their ocean life stage were not eliminated during migration, but were transported to the spawning lakes and accumulated in the freshwater food web there. The influence of the biotransported pollutants was investigated by comparing pollutant levels and compositions in atmospheric deposition as well as in two different populations of arctic grayling (Thymallus arcticus). One grayling population was in the salmon spawning lake and the other in a nearby lake not hosting anadromous fish, but receiving pollutants only via atmospheric deposition. The grayling in the salmon spawning lake were found to have concentrations of organic pollutants more than two times higher than those of the grayling in the salmon-free lake, and the pollutant composition resembled that found in salmon. Thus, in the studied Alaska river system, biotransport was found to have a far greater influence than atmospheric input on the PCB and DDT levels in lake biota.
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| 11. |
- Jonsson, I., et al.
(author)
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Photography and temperature measurements from a remotely piloted vehicle
- 1980
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In: Oikos. - : JSTOR. - 1600-0706 .- 0030-1299. ; 35:1, s. 120-125
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Journal article (peer-reviewed)abstract
- Radio-controlled model planes are useful when carrying out photography, especially from low altitudes, and meteorological soundings (air temperatures in boundary layers). Soundings were carried out with a system which stored the measured data on board the plane pending evaluation after the flight. The payload of the plane was a camera and equipment for measuring temperature and air pressure (altitude). Data were stored so that the signals from the temperature and pressure sensors (thermistor and micro aneroid respectively) lit a combination of light-emitting diodes (BCD code) that corresponded to the actual temperature and pressure (altitude). At the instant of measurement, this combination was photographed togther with the ground surface. the camera manoeuvred by means of servo-function. The position of the plane at the instant of measurement was determined on the basis of pressure values and air photographs. Photography from model planes is not a new method. However, previous results have in general been inadequate because, for safety's sake, cheap and consequently less advanced cameras were used. The determination of temperature and other soundings from such aircraft has been little tried hitherto. Photography and sounding from model planes can be of interest in ecological, physical-geographical and meteorological contexts. The method lends itself best to a rapid and handy documentation from the air of a water or land area, e.g. a severely polluted area, or a wind-eroded ground surface, or to the sounding or sampling of aif qualities such as pollution in the smoke plumes of stacks and other types of discharge, of radioactivity in the air over leaking plants, of temperature and humidity conditions in urban boundary layers and of eolian dust in the air over wind-exposed erosion surfaces in arid areas. Radio-controlled model planes could possibly also be used for dissemination of e.g. silver iodide in order to artificially release precipitation and for pollination of forest.
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| 12. |
- Larsson, Per, et al.
(author)
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An attempt to measure the flow of chlorinated hydrocarbons, such as PCBs, from water to air in the field
- 1987
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In: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 44:3, s. 219-225
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Journal article (peer-reviewed)abstract
- A field sampling device to study the transport of aromatic, persistent chlorinated hydrocarbons from water to air was constructed. It was tested in large, outdoor artificial ponds contaminated with polychlorinated biphenyls (PCBs). The PCB compounds volatilised to air at a rate of 0·9 to 9·6 ng m−2 h−1 depending on levels of PCBs in the water and water temperature.
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| 13. |
- Larsson, Per, et al.
(author)
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Atmospheric transport of chlorinated hydrocarbons to Sweden 1985 compared to 1973
- 1989
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 23:8, s. 1699-1711
-
Journal article (peer-reviewed)abstract
- The atmospheric fallout of DDT and DDE (ΣDDT) over Sweden has decreased during the last decade. Today long-range transport from southern sources outside the country dominates the inflow. This was reflected in a decreasing south-to-north gradient of the compounds in atmospheric deposition and in the lower atomosphere. The fallout of PCBs was similar in 1984–1985 and 1972–1973, and today local contamination by combustion is more prominent than it was 10 years ago, even though PCB restrictions have been in force during the interim. Since PCB deposition is higher in the coastal areas than in the inland regions, other sources, such as volatilization from the seas and long-range transport also contribute to PCBs in fallout. The levels of PCB and ΣDDT in the lower atmosphere were positively correlated with temperature. Consequently, the compounds tended to be in the gas phase during the warmer summer period whereas during winter they were more liable to be adsorbed to particles, partition to airborne water and contribute in fallout. From each sampling station a chromatographic 'fingerprint' of pollutants in airborne fallout and in the lower atmosphere was obtained. The fingerprint was the combined result of the station's location and climate. The results show that considerable amounts of chlorinated pollutants are being transported to and within Sweden via the atmosphere.
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| 14. |
- Larsson, Per, et al.
(author)
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Atmospheric transport of persistent pollutants governs uptake by Holarctic biota
- 1990
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 24:10, s. 1599-1601
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Journal article (peer-reviewed)abstract
- The atmospheric deposition of PCBs, DDT, and lindane,governed uptake in terrestrial biota in the Scandinavianpenninsula. Mammalian herbivores and predators as wellas predatory insects contained higher levels of pollutantsat locations where the fallout load was high than at stationswhere atmospheric deposition was lower, and the twovariables were significantly correlated.
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| 15. |
- Larsson, Per, et al.
(author)
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Contaminated sediment as a source of PCBs in a river system
- 1990
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In: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 47:4, s. 746-754
-
Journal article (peer-reviewed)abstract
- The transport of PCBs (Aroclor 1242) in a river system in southern Sweden was governed by outflow from sediment in a 26-ha contaminated lake. Experiments in the lake revealed that 14 g PCBs/d escaped from the sediment, while sedimentation was 3 g PCB/d. Volatilization of PCBs from the lake surface was 0.02 g/d, which was considerably higher than the atmospheric fallout . The majority of the sediment-desorbed compounds (80%) remained at the river mouth, 60 km downstream, and entered the Baltic Sea. Desorption increased the ratio of tetrachlorobiphenyls to pentachlorobiphenyls in the water. Transport across the water/air interface was higher for trichlorobiphenyls, while atmospheric deposition was dominated by penta- and hexachlorobiphenyls. Therefore, the sediment of the lake acted as a source of PCBs entering the river system as well as the atmosphere.
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| 16. |
- Larsson, Per, et al.
(author)
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Factors determining the uptake of persistent pollutants in an eel population (Anguilla anguilla L.) of a eutrophic lake
- 1991
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In: Environmental Pollution. - 0269-7491 .- 1873-6424. ; 69:1, s. 39-50
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Journal article (peer-reviewed)abstract
- The distribution of persistent pollutants in an eel population from a eutrophic lake of southern Scandinavia was examined. The origin of PCBs, DDT, DDE and lindane found in the fish was most likely the atmosphere. The most important factors for uptake of the chlorinated hydrocarbons was age (exposure time), growth rate and fat content. The life cycle of the eel is unique with a stage in freshwater when energy reserves (fat stored in muscular tissue) and lipophilic pollutants are accumulated. This stage is followed by a long migration to the spawning areas in the Sargasso Sea when pollutants are released from the fat deposits. These two stages followed by a once-in-a-lifetime spawning behaviour, makes the eel especially vulnerable to persistent pollutants. The effects of persistent pollutants combined with the eel's unusual life cycle may explain the decline in the eel population in northern Europe in recent decades.
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| 17. |
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| 18. |
- Larsson, Per, et al.
(author)
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Lake productivity and water chemistry as governors of the uptake of persistent pollutants in fish
- 1992
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 26:2, s. 346-352
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Journal article (peer-reviewed)abstract
- Factors influencing uptake and levels of persistent pollutants (PCBs, p,p'-DDE) were investigated in 341 northern pike from 61 lakes in southern Scandinavia. Although the inflow of pollutants from the atmosphere was similar throughout the area studied, large differences in levels of PCBs and DDE in predatory fish were found between lakes. The factors primarily responsible for this variation appeared to be lake trophic status and content of humic substances. Levels of persistent pollutants in the fish decreased as productivity increased. Contents of total phosphorus and chlorophyll alpha and lake water transparency (mainly influenced by phytoplankton biomass) were used as productivity indicators. The reasons for the lower levels of pollutants in fish in lakes of increasing productivity were higher growth rate of pike and higher turnover time and sedimentation of particles (phytoplankton) to which the pollutants are adsorbed. Levels of persistent pollutants decreased as the amount of humic substances (water color) increased, apparently because humus adsorbs persistent pollutants, rendering them less available for uptake in fish. The results show that it should be possible to predict levels of persistent pollutants in fish, based on the productivity and chemical properties of the lake.
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| 19. |
- Larsson, Per, et al.
(author)
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Microbial degradation of xenobiotic, aromatic pollutants in humic water
- 1988
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In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 54:7, s. 1864-1867
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Journal article (peer-reviewed)abstract
- The microbial degradation of a number of 14C-labeled, recalcitrant,aromatic pollutants, including trichloroguaiacol and di-, tri-,and pentachlorophenol, was investigated in aquatic model systemsin the laboratory. Natural, mixed cultures of microorganismsin the water from a brown-water lake with a high content ofhumic compounds mineralized all of the tested substances toa higher degree than did microorganisms in the water from aclear-water lake. Dichlorophenol was the most rapidly degradedpollutant.
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| 20. |
- Larsson, Per, et al.
(author)
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Persistent pollutants in a salmon population (Salmo salar) of the southern Baltic Sea
- 1996
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 53:1, s. 62-69
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Journal article (peer-reviewed)abstract
- Persistent pollutants in an Atlantic salmon (Salmo salar) population spawning in a river of southern Sweden were investigated. The population was characterized by a high growth rate. Some males reached 20-30 kg after 3 to 4 years in the sea. The fat content of migrating salmon varied by one order of magnitude and was the most significant correlate of pollutant concentrations. No relationships were recorded between fat content and gender, age (weight, length), year at sea, or different measures of condition. The reasons for this may be the varied evolutionary strategies for maximizing reproductive output; male salmon may enter the spawning river as small grilse and spawn opportunely, or migrate at a larger size, when they can hold spawning territories in the river. Females have a greater and more uniform size, and spend more energy on gonadal products. The varying fat content of individual fish may also be attributed to foraging in different areas of the Baltic and thereby to migration distances as well as foraging strategies. When pollutant levels were normalized for fat content, other factors such as age (weight, length) were shown to be important for uptake; older fish had higher levels of pollutants than younger ones
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| 21. |
- Larsson, Per, et al.
(author)
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Reproductive status and lipid content as factors in PCB, DDT and HCH contamination of a pike population (Esox lucius L.)
- 1993
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In: Environmental Toxicology and Chemistry. - 0730-7268. ; 12:5, s. 855-861
-
Journal article (peer-reviewed)abstract
- Levels of persistent pollutants, including PCBs, SIGMADDT, and gamma-hexachlorocyclohexane, were examined in a pike population inhabiting a eutrophic lake in southern Scandinavia. For females, levels of persistent pollutants decreased linearly with age, weight, or length. This decline was ascribed to the seasonal elimination of the lipophilic pollutants in roe, which contained up to 10 times higher fat levels compared to muscle and over 10 times the amounts of pollutants. Male pike contained higher levels of pollutants than females, probably due to the lower elimination via gonadal products, as germinal tissue constitutes only 2% of the male total body weight and has a lower fat content than ovaries. Female germinal tissue can account for as much as 15% of the body weight. No major fat deposits other than those in germinal tissue were found in pike, which also had a low muscle fat content, suggesting that the importance of roe elimination in removing pollutants may be greater in pike than in salmonids. Uptake of persistent pollutants can vary greatly within a species, owing to differences in sex, age, and so forth, as well as between species, owing to differences in fat deposition strategies.
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| 22. |
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| 23. |
- Larsson, Per, et al.
(author)
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Turnover of polychlorinated biphenyls in an eutrophic and an oligotrophic lake in relation to internal lake processes and atmospheric fallout
- 1998
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 55:8, s. 1926-1937
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Journal article (peer-reviewed)abstract
- The atmospheric deposition of PCB within the catchment areas of an oligotrophic lake and an eutrophic lake in southern Sweden resulted in a flow of about 1 mg PCB.m(-2).year(-1) to the lakes. The sedimentation of the pollutants in the lakes (measured by sediment traps) was 110 and 52 mg PCB.m(-2).year(-1) for the oligotrophic and eutrophic lakes, respectively. The concentration of pollutants in plankton (separated in fractions of >150, 45-150, and 10-45 mu m) was lower than that found in the sedimenting material. This indicated that the degradation of lipid and organic carbon was higher than the release of persistent pollutants from settling particles. Higher concentrations of PCB were recorded in the phytoplankton of the oligotrophic than of the eutrophic lake and attributed to higher lipid content. The higher lipid content and the higher pollutant amounts found in the primary producers suggest a mechanism that leads to zooplankton and fish displaying high pollutant concentrations in oligotrophic ecosystems. No biomagnification for phytoplankton to zooplankton was detected. The results indicate that the major part of the persistent pollutants cycling in the lakes is due to internal lake processes.
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| 24. |
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| 25. |
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| 26. |
- Okla, Lennart, et al.
(author)
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Day-night differences in volatilization rates of polychlorinated biphenyls from water to to air
- 1987
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In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 6:9, s. 659-662
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Journal article (peer-reviewed)abstract
- The transport rate of polychlorinated biphenyls (PCBs) from water to air was followed in a large (50-m3) artificial pond. The transport rate across the water/air interface during the day exceeded the rate at night and was positively correlated to air temperature. Volatilization is probably responsible for the PCB transfer.
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| 27. |
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| 28. |
- Tranvik, Lars, et al.
(author)
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In-situ mineralization of chlorinated phenols by pelagic bacteria in lakes of differing humic content
- 1991
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In: Environmental Toxicology and Chemistry. - 0730-7268. ; 10:2, s. 195-200
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Journal article (peer-reviewed)abstract
- The microbial mineralization of phenol and three chlorinated phenols (3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the water column of 23 pristine, oligotrophic lakes of different humic content was investigated. During short-term (approximately 2 d) in situ incubations of water samples amended with C-14-labeled phenolic compounds, the fraction of the added pollutant mineralized to (CO2)-C-14 was positively correlated with water color (an estimate of humic content) and the total organic carbon concentration of the water. The rate of mineralization per bacterial cell was not correlated with humic content, due to increased bacterial abundance with increasing humic content. Hence, the higher mineralization rate in humic lakes than in clear-water lakes was probably a result of higher bacterial abundance rather than being an effect of bacterial cells having a higher potential for the degradation of such compounds.
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| 29. |
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