Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 4. The influence of salt speciation, soil type, and sewage sludge on toxicity using the collembolan Folsomia fimetaria and the earthworm Aporrectodea caliginosa as test organisms.

Sewage sludge applied to agricultural soils often contains linear alkylbenzene sulfonates (LAS) in the range of 1 to 10 g/kg dry weight, and their toxicity to relevant soil organisms should, therefore, be assessed to ensure safe use of sewage sludge as a fertilizer. Studies of LAS toxicity to soil organisms are few, and to our knowledge, factors that may influence the toxicity in the field have not been studied in detail. In this paper, we report on the influence of speciation of LAS in the test solution added to soil (soluble Na-LAS vs poorly soluble Ca-LAS or Mg-LAS), the influence of soil type, and the modifying effects of sludge amendment on the toxicity of LAS. These issues were investigated using reproduction of Collembola and growth of juvenile earthworms as test parameters. Speciation of the LAS added to test soil did not have any influence on toxicity for any of the test species. Likewise, in three different agricultural soils (sand, loam, and clay), we found almost equal toxicities. The LAS added to test soil in a sludge-water suspension was equally toxic as when it was added in an aqueous solution. However, anaerobic incubation for 7 and 14 d of the LAS-sludge suspension (with no decay of LAS) caused the toxicity to increase almost threefold in both collembolan and earthworm. The relationships between soil constituents, bioavailability, and toxicity are also discussed.

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 5. Probabilistic risk assessment of linear alkylbenzene sulfonates in sludge-amended soils.

Linear alkylbenzene sulfonates (LAS) can be found in high concentrations in sewage sludge and, hence, may enter the soil compartment as a result of sludge application. Here, LAS may pose a risk for soil-dwelling organisms. In the present probabilistic risk assessment, statistical extrapolation has been used to assess the risk of LAS to soil ecosystems. By use of a log-normal distribution model, the predicted no-effect concentration (PNEC) was estimated for soil fauna, plants, and a combination of these. Due to the heterogeneous endpoints for microorganisms, including functional as well as structural parameters, the use of sensitivity distributions is not considered to be applicable to this group of organisms, and a direct, expert evaluation of toxicity data was used instead. The soil concentration after sludge application was predicted for a number of scenarios and used as the predicted environmental concentration (PEC) in the risk characterization and calculation of risk quotients (RQ = PEC/PNEC). A LAS concentration of 4.6 mg/kg was used as the current best estimate of PNEC in all RQ calculations. Three levels of LAS contamination (530, 2,600, and 16,100 mg/kg), three half-lives (10, 25, and 40 d), and five different sludge loads (2, 4, 6, 8, and 10 t/ha) were included in the risk scenarios. In Denmark, the initial risk ratio would reach 1.5 in a realistic worst-case consideration. For countries not having similar sludge regulations, the estimated risk ratio may initially be considerably higher. However, even in the most extreme scenarios, the level of LAS is expected to be well beyond the estimated PNEC one year after application. The present risk assessment, therefore, concludes that LAS does not pose a significant risk to fauna, plants, and essential functions of agricultural soils as a result of normal sewage sludge amendment. However, risks have been identified in worst-case scenarios.

Picein and piceol concentrations in Norway spruce.

The concentrations of the glucoside picein and its aglucone piceol (4-hydroxy acetophenone) in the needles of Norway spruce (Picea abies (L.) Karsten) are considered indicators of plant stress. By use of two clones and a natural population of Norway spruce it was shown that the picein concentration was dependent on the site and the provenance of the trees. No effects were observed by normal treatment with the herbicides atrazine, glyphosate, and hexazinone, or by drought. The significance of different environmental factors is discussed.

PCDDs, PCDFs, and metals in selected Danish soils.

Topsoil samples from five locations in Denmark were collected and analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and selected heavy metals. The upper soil layers contained elevated concentrations of PCDDs, PCDFs, Pb, Zn, and Cu compared to the lower layers. The soil contents of PCDDs plus PCDFs were closely related to Pb contents. Higher concentrations were found near urban areas relative to strictly rural locations. From the presented data the provisional Danish background content of PCDDs plus PCDFs is estimated to be 4-7 micrograms m-2 in the topsoil of coniferous forests.

Ecoepidemiology--a casuistic discipline describing ecological disturbances and damages in relation to their specific causes: exemplified by chlorinated phenols and chlorophenoxy acids.

Ecoepidemiology is a new concept created in analogy to human epidemiology, and aims at the study of ecotoxicological effects at the levels of ecosystems, biological communities, and populations in relation to causative environmental exposures, mostly by chemicals. By way of example, ecoepidemiology is described by presenting an example of unintentional dissipation and possible discharges of chlorophenols and phenoxy acids into the terrestrial environment and--as a more specific case--a marine, aquatic area, viz., the Køge Bay immediately to the south of Copenhagen, Denmark. The examples are illustrative of the complex situation which characterizes most ecoepidemiological cases. Difficulties with which the ecoepidemiologist are confronted are not only the identification of possible causative and confounding chemicals, and the description of ecoepidemiological effects per se, but also the assessment of critical pathways of multimedium pollutants. Biomonitoring, computer-based handling of data from natural localities, and determination of a variety of anthropogenic impact factors are necessary elements of ecoepidemiological studies.

Sorption of selected organic pollutants in Danish soils.

The sorption of benzoic acid, nitrobenzene, 4-nitrophenol, 2,4-dichlorophenoxyacetic acid (2,4-D), and naphthalene was determined for 10 Danish soils in laboratory studies. Measured equilibrium isotherms were of nonlinear Freundlich type for nearly all combinations of soil-test compounds. Adsorption was significantly correlated with the organic carbon content of the soils tested. No significant correlations with pH and cation-exchange capacity were observed. The adsorption of benzoic acid was found to be reversible and the sorption of naphthalene was reversible in 4 of 10 soils. A desorption-resistant fraction of adsorbed 2,4-D was estimated from interdependent adsorption and desorption isotherms.

Effects of 2,4-dichlorophenoxyacetic acid in artificial acid rain on Brassica napus and Sinapis alba.

The effect of 2,4-dichlorophenoxyacetic (2,4-D) acid in artificial rain at pH 3.3 was examined for young plants of rape (Brassica napus L.) and white mustard (Sinapis alba L.). Plants were treated in a closed simulation chamber system with varying CO2 supply (198-418 ppm). Single or daily showers were applied for 20-30 min at varying 2,4-D concentrations (0, 0.03, 0.1, 0.5, and 2.5 mg liter-1). The plants were sampled 5 days after the last treatment. Epinasty was observed for Brassica at 0.5 mg liter-1 and for Sinapis at 0.1 mg liter-1 2,4-D. Leaf to stem dry weight ratios increased with increasing CO2 concentrations in the air and decreased following single treatments with 0.5 or 2.5 mg liter-1 2,4-D in the rain. Dose-effect relationships are proposed for both plant species. Leaf dry matter weights per area unit decreased with increasing CO2 concentrations, but were not significantly affected by the 2,4-D treatments.

Uptake of 2,4-D in higher plants from artificial rain.

Sinapis alba L., Lapsana communis L., Achillea millefolium L., Brassica napus L., Lactuca sativa L., and Lycopersicum esculentum L. were exposed to 2,4-dichlorophenoxy [2-14C]acetic acid (2,4-D) at 10 micrograms liter-1 in artificial rain, pH 6.5 and 3.3. The 2,4-D was absorbed in all species tested. Concentrations of parent 2,4-D appeared at the highest level in Achillea (0.1 mg kg-1 dry wt), and at zero level in Lycopersicum. Twenty-one daily treatments at pH 6.5 for 30-min periods increased dry-matter concentrations (P less than or equal to 0.05) in the leaves of Achillea and decreased those in Brassica. No change in dry-matter concentration was observed in the leaves of Brassica by seven daily treatments for 30-min periods at pH 3.3.

Analysis of free and bound chlorophenoxy acids in cereals.

Extraction of the chlorophenoxy acids 2,4-D and dichlorprop in cereals has been examined by analyzing barley from spraying experiments. A procedure has been set up by combination of acid hydrolysis and enzymatic degradation followed by extraction and clean up on either silica gel or basic aluminum oxide. The final determination is based on reaction with diazomethane and subsequently GLC with ECD. This procedure was compared with two different extraction procedures previously described in the literature. The one comparative procedure uses a mixture of 50% diethyl ether/hexane in presence of sulphuric acid and resulted in residues up to ten times lower than found after the combined acid hydrolysis/enzymatic degradation procedure. In the second comparison a direct extraction was made with a mixture of 65% (v/v) acetonitrile in water. No differences were found between this and the combined acid hydrolysis/enzymatic degradation procedure.