Regulation of decomposer community structure and decomposition processes in herbicide stressed humus soil
Abstract Regulation of soil decomposer community structure and ecosystem processes, such as nutrient cycling, under herbicide stress was studied in a microcosm experiment. For the experiment, coniferous forest soil was defaunated and put into the microcosms. In the microcosms two different food webs including microbes, nematodes, tardigrades and oribatid mites, either with or without predatory mesostigmatid mites, were reconstructed. Half of the microcosms were stressed with a herbicide (active ingredient was terbuthylazine). During the 57 weeks incubation community structure of decomposers and nitrogen mineralisation were studied at five destructive samplings and two water irrigations. Soi…
Effects of pentachlorophenol in forest soil: a microcosm experiment for testing ecosystem responses to anthropogenic stress
Changes in the structure and function of a soil decomposer community and growth of birch (Betula pendula) due to chemical contamination were studied in laboratory microcosms. Sodium pentachlorophenate (PCP) was added to the humus layer of a simulated forest soil at three nominal concentrations (0, 50 and 500 mg kg-1 dry mass). After two growing periods (48 weeks), there were more small soft-bodied mites, but less collembolans and microbial biomass, in the higher PCP concentration treatment than in the other treatments. Number of enchytraeids were significantly reduced and fungal-feeding nematodes became extinct in the soil with the higher PCP concentration. Soil respiration did not change d…
Effects of Terbuthylazine on Soil Fauna and Decomposition Processes
Abstract Acute lethal and sublethal effects of terbuthylazine and the commercial herbicide preparation Gardoprim [terbuthylazine is the active ingredient (a.i.)] on soil organisms (microbes, oppioid mites, two gamasid mite species, enchytraeids, and nematodes) were studied. In the humus soil terbuthylazine had no toxic effects on soil animals tested. However, the herbicide preparation had acute toxic effects on enchytraeids [no-observed-effect level (NOEL) 1.0 g a.i./m 2 ] and both gamasid mites (NOEL 2.4 and 5.0 g a.i./m 2 ). According to filter paper test, the LC 50 value for oppioid mites was 14.5 g a.i./m 2 . In the humus soil the commercial preparation caused no dose-related mortality …
Bioaccumulation of organochlorine compounds in earthworms
Abstract Bioaccumulation of chlorophenolic wood preservatives 2,3,4,6-tetrachlorophenol (2346-TeCP) and pentachlorophenol (PeCP) and their metabolites in earthworms were studied in the laboratory, and by taking worm samples from the contaminated soil of a sawmill which was abandoned 28 yr ago. In two laboratory experiments 2346-TeCP (containing PeCP as impurity) was added into the soil, and samples were taken at certain intervals both from the soil and the earthworms ( Lumbricus rubellus in experiment 1 and Aporrectodea caliginosa tuberculata in experiment 2). Considerable amounts of chlorophenols were found in field samples. Soil concentrations ranged from 157 to 338 μg 2346-TeCP g −1 dry …
Polychlorinated phenols and their metabolites in soil and earthworms of sawmill environment
Abstract Topsoil and earthworm samples collected from three Finnish sawmill environments were analysed for polychlorinated phenols, 2,3,4,6-tetrachloro- and pentachlorophenol, and their metabolites. Analyses were carried out by gas chromatography/mass spectrometry using a selected ion monitoring technique and by dual-channel gas chromatography using quartz capillary columns and two electron capture detectors. The total chlorophenol concentrations ranged from ca. 260 to 480 μg/g (dry weight) in soil and from ca. 140 to 3500 μg/g fat in earthworms. The most important metabolites in soil were chlorinated dihydroxy-benzenes (also at ppm level); only traces of chlorinated anisoles were detected …
Chloroanisoles in soils and earthworms
One important group of metabolites of chlorophenols in Finnish soils is their methylation products, i.e. chloroanisoles. Bioaccumulation of chloroanisoles into the biomass of earthworms was studied both in laboratory and by taking earthworm samples from contaminated soils. Concentrations of these compounds in the soils were also analysed. In the laboratory experiment, concentrations of 2,3,4,6-tetrachloroanisole (2346-TeCA) and pentachloroanisole (PeCA) were high in earthworms 1 week after introduction (approx. 50 μ/g fat). Later on, the concentrations decreased to a low level at a considerable rate, bcth in soil and in earthworms. The higher the concentration of chloroanisoles in the soil …
Effects of Pentachlorophenol and Biotic Interactions on Soil Fauna and Decomposition in Humus Soil
In a laboratory experiment, effects of chemical stress (pentachlorophenol, PCP, at concentrations of 0, 50, and 500 mg/kg) and biotic interactions (nematodes in the presence or absence of collembolas and enchytraeids) on the community structure of soil animals and decomposition processes were studied. PCP was strongly adsorbed to humus that contained 65% organic matter. Numbers of fungal-feeding nematodes decreased significantly at the highest PCP concentration, while no effects were found in bacterial feeders. There were differences in the numbers of nematodes between different animal combinations, but at the highest PCP concentration, collembolas and enchytraeids had no effect on them. Nu…
Responses of microbial activity and decomposer organisms to contamination in microcosms containing coniferous forest soil.
Soil respiration from microcosms contaminated with pentachlorophenol, 2-ethanolhexanoate, creosote, CuSO4, and benomyl was measured in order to evaluate usefulness of soil microcosms and microbial respiration rate monitoring as a toxicity test in soils with high organic matter content. Coniferous forest soil and its organisms were used as test objects. In addition, how a short-term low temperature period including frost affects respiration dynamics in stressed soils was studied, i.e., whether contaminants reduce resistance of the community to other (also natural) stresses. In addition, at the end of the experiment, effects of contaminants on faunal and microbial community structures were an…
Horizontal distribution of copper, nickel and enchytraeid worms in polluted soil
We studied the horizontal distribution of Cu, Ni and enchytraeid worms (Cognettia sphagnetorum, Vejdovsky, Oligochaeta, Enchytraeidae) in forest soil near a Cu–Ni smelter in SW Finland. Soil samples were taken from a polluted site (2 km from the smelter) and a reference area (8 km from the smelter). We used a hierarchical sampling design in the polluted area for studying possible scale-dependent variability in parameters measured, distance between the samples (different scales) being 5, 50 and 500 cm. Distribution of metals was moderately heterogeneous in the polluted soil; coefficient of variances (CV), 26% for Cu and 32% for Ni. Instead, distribution of enchytraeids in the area was highly…
Distribution of soil animals in patchily contaminated soil
Abstract Distribution of soil animals with respect to patchy chemical contamination was studied in microcosms containing reconstituted coniferous forest floor. Soil materials were defaunated and soil organisms were reinoculated into a mesh basket in the centre of each microcosm. Part of the humus layer was contaminated with three concentrations of sodiumpentachlorophenate (0, 50 or 500 mg PCP kg −1 of dry humus) and put into mesh baskets (two per concentration) around the central patch. No differences in dispersion ability from the reinoculated patch were found between microarthropod species. PCP decreased microbial biomass in the humus. Numbers of collembolans were significantly lower in t…
Methylation products of chlorophenols, catechols and hydroquinones in soil and earthworms of sawmill environments
Abstract Soil samples and earthworms collected from one noncleaned and two cleaned sawmill environments were analysed for their content of chlorinated anisoles (methoxybenzenes), veratroles (1,2-dimethoxybenzenes) and 1,4-dimethoxybenzenes. 2,3,4,6-tetrachloroanisole and pentachloroanisole were observed in all soil samples studied, in maximum combined amount about 1.5 μg/g dry soil. Small amounts (ca. 1–110 ng/g dry mass) of 3,4,5-trichloroveratrole, tetrachloroveratrole and tetrachloro-1,4-dimethoxybenzene were found in the most polluted soil samples. Only 2,3,4,6-tetrachloroanisole and pentachloroanisole were found in earthworms, where concentrations of each were ca. 0.1–20 μg/g fat. In g…
Decomposer communities in contaminated soil: Is altered community regulation a proper tool in ecological risk assessment of toxicants?
Abstract Effects of patchy soil contamination on decomposer organisms, their community regulation and nutrient mineralization were studied in a microcosm experiment. Coniferous forest soil was patchily contaminated with three concentrations of sodiumpentachlorophenate PCP (0, 50 and 500 mg PCP kg−1 of dry soil). Abundance of microbes, enchytraeids, nematodes, small oribatids and predatory mites were reduced by the PCP. Direct toxicity of PCP and lowered microbial biomass seemed to affect animal community composition in the most contaminated patches. Some large oribatids which seemed to be tolerant to PCP increased their numbers in the most contaminated patches. Although predatory mites suff…
Life history and spatial distribution of the enchytraeid wormCognettia sphagnetorum(Oligochaeta) in metal-polluted soil: Below-ground sink-source population dynamics?
We studied the life history, metal-avoidance behavior, spatial distribution, and population growth of enchytraeid worms (Cognettia sphagnetorum [Oligochaeta]) originating from two sites: one uncontaminated, and another patchily polluted by heavy metals. Effects of patchy soil contamination on populations were studied in microcosms. In uncontaminated soil, worms from the polluted site had lower viability and reduced growth rate as juveniles but higher growth rate as adults compared to worms from the unpolluted site. They were also smaller in size at fragmentation (reproduction). Worms from the polluted site reached a larger population size than worms from the unpolluted site. Hence, worms fr…