The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. Terrestrial ecotoxicological effects of antibiotics are related to their sorption and degradation behavior in soil.

River sediment at a disused lead-zinc mine was analysed to provide an understanding of the chemical nature of the source term for contaminated sediment exported from the site. Changes in concentration and geochemical associations of Pb and Zn were measured using aqua regia digestion and the BCR sequential extraction procedure. Sediment in the immediate vicinity of the mine was highly contaminated with Pb (max. c. 11,000 mg kg⁻¹) and Zn (max. c. 30,000 mg kg⁻¹), but these values declined rapidly within 1 km of the mine due to dilution and hydraulic sorting. Lead fractionation changed from being predominantly in the reducible fraction to being in the acetic acid-extractable fraction, whereas Zn was predominantly in the residual fraction. This material is transported as fine sediment in the river system. Metal concentrations and fractionation have defined the source characteristics of Pb and Zn dispersed from a disused mine and transported by fluvial processes.

Plants react to O3 threat by setting up a variety of defensive strategies involving the co-ordinated modulation of stress perception, signalling and metabolic responses. Although stomata largely controls O3 uptake, differences in O3 tolerance cannot always be ascribed to changes in stomatal conductance but cell protective and repair processes should be taken into account. O3-driven ROS production in the apoplast induces a secondary, active, self-propagating generation of ROS, whose levels must be finely tuned, by many enzymatic and non-enzymatic antioxidant systems, to induce gene activation without determining uncontrolled cell death. Additional signalling molecules, as ethylene, jasmonic and salicylic acid are also crucial to determine the spreading and the containment of leaf lesions. The main recent results obtained on O3 sensing, signal transduction, ROS formation and detoxification mechanisms are here discussed. A dissection of the complex network of interacting mechanisms which determine the cell fate under ozone stress.

To determine background values of the 252 chemical compounds listed in Dutch legislation, a survey was designed with the aim of estimating percentiles of the cumulative frequency distributions and areal fractions exceeding the former, legislative reference values. Sampling locations were selected by probability sampling, so that in estimating the target quantities no model assumptions on the spatial variation were required, and valid estimates could be obtained by design-based inference. Strata in random sampling were formed by overlaying an aggregated soil map and land use map. For most of the heavy metals the areal fraction with concentrations in the topsoil (0-10 cm) exceeding the reference value was smaller than the allowable maximum of 5%. For these compounds a background value was determined smaller than the reference value. Exceptions were V, Co, Ba and Cu, for which a background value was defined (slightly) larger than the reference value. Legislative background values can be best derived by probability sampling and design-based estimation.

Concentrations of organic contaminants in common productive soils based on the total soil mass give a misleading account of actual contamination effects. This is attributed to the fact that productive soils are essentially water-saturated, with the result that the soil uptake of organic compounds occurs principally by partition into the soil organic matter (SOM). This report illustrates that the soil contamination intensity of a compound is governed by the concentration in the SOM (Com) rather than by the concentration in whole soil (Cs). Supporting data consist of the measured levels and toxicities of many pesticides in soils of widely differing SOM contents and the related levels in in-situ crops that defy explanation by the Cs values. This SOM-based index is timely needed for evaluating the contamination effects of food crops grown in different soils and for establishing a dependable priority ranking for intended remediation of numerous contamination sites. The concentration of an organic compound in soil based on the entire soil mass is not a proper measure of its contamination intensity.

Aniline and 2,4,6-trinitrotoluene (TNT) were equilibrated with particulate (POM) and dissolved organic matter (DOM) from an organic soil at different compositions of adsorbed major cations (Na, Al) and pH (aniline: 3.7-5.1, TNT: 4.8-5.0). After separation of POM, concentrations of ¹⁴C-labelled aniline and TNT* (including TNT degradation products) were determined in DOM size fractions using size-exclusion chromatography (SEC) and UV-detection. Concentrations in the <3.5 kDa size fraction were 2.8-6.0 and 8.5-9.5 times higher for aniline and TNT*, respectively, as compared to the >40 kDa fraction. Thus, both aniline and TNT* were preferentially associated to the smallest DOM size fraction. The significant binding to DOM (similar extent as to POM) and the fact that the <3.5 kDa DOM fraction was less susceptible to flocculation by major metals suggests that the mobility of aniline and TNT is highly affected by the solubility of soil organic matter. Concentrations of aniline and TNT associated with dissolved organic matter (DOM) was shown to increase with decreasing apparent molecular mass of DOM.

In this study, we report that silver ions (Ag+) from the oxidative dissolution of silver engineered nanoparticles (Ag-ENs) determined the EN toxicity to the marine diatom Thalassiosira weissflogii. Most of the Ag-ENs formed non-toxic aggregates (>0.22 μm) in seawater. When the free Ag+ concentration ([Ag+]F) was greatly reduced by diafiltration or thiol complexation, no toxicity was observed, even though the Ag-ENs were better dispersed in the presence of thiols with up to 1.08 x 10⁻⁵ M Ag-ENs found in the <0.22 μm fraction, which are orders of magnitude higher than predicted for the natural aquatic environment. The secretion of polysaccharide-rich algal exopolymeric substances (EPS) significantly increased at increasing [Ag+]F. Both dissolved and particulate polysaccharide concentrations were higher for nutrient-limited cells, coinciding with their higher Ag+ tolerance, suggesting that EPS may be involved in Ag+ detoxification. Ag-ENs were found to only have indirect toxic effects on marine phytoplankton as a result of their rapid Ag+ release.

Chlorinated paraffins (CPs) are toxic, bioaccumulative, persistent, and ubiquitously present in the environment. CPs were analyzed in humus and needle samples, which were taken within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) at sampling sites of 7 different altitude profiles in the Alps. Gas chromatography combined with electron ionization tandem mass spectrometry (EI-MS/MS) was used for the determination of total CPs (sum of short, medium and long chain CPs). CPs were found in all samples; the concentrations varied between 7 and 199 ng g−1 dry weight (dw) and within 26 and 460 ng g−1 dw in humus and needle samples, respectively. A clear vertical tendency within the individual altitude profiles could not be ascertained. Within all altitude profiles, elevated concentrations were observed in humus samples taken between 700 and 900 m and between 1300 and 1500 m. In the needle samples no similar correlation could be observed due to higher variation of the data. For the first time, CP levels of humus and spruce needle samples from the Alps (MONARPOP) were presented including the evaluation of altitude profiles.

A dynamic flux model for lakes taking into account the interactions between atmospheric depositional and biogeochemical processes (BIODEP model) was used to assess the importance of internal cycling and biogeochemical processes with respect to accumulation of four different polychlorinated biphenyls (PCBs) (congeners 28, 52, 101 and 153) in Lake Redo, a high-altitude lake in the Spanish Pyrenees. To investigate the effect of temperature on sediment accumulation, the model was run at different temperatures and corresponding sediment inventories were plotted vs. reciprocal temperature. In line with measurements from a previous study looking at sediment inventories of 19 European high-altitude lakes (MOLAR study), we found a stronger temperature dependence of lake sediment concentrations for the less volatile/less soluble PCBs. Seasonal and annual mass balances were investigated and highlighted the importance of internal lake processes controlling the differences in sediment accumulation for the different PCB congeners. For example, the higher temperature dependence of sediment inventories for the high chlorinated congeners is due to the fast dynamics of water-to-sediment transport in comparison to atmospheric deposition processes. A dynamic flux model was used to assess the importance of internal lake processes in controlling sediment accumulation for different PCB congeners.

In the present study, we aim to investigate the extent of soil contamination by Hg, particularly by anthropogenic Hg, and tentatively estimate the total Hg (HgT) accumulation in topsoils (0-15 cm) in Fuyang, Zhejiang Province--a secondary Cu smelter of China. The results show that the levels of soil Hg in the vicinity of the smelters have been substantially elevated following local smelting activities. The spatial distribution of soil Hg in this area reveals a rapid decrease as the distance from the smelter reaches 1.5 km, which is probably due to the quick deposition process of particulate Hg and reactive gaseous Hg emitted from the smelters. The total accumulation of HgT in the topsoils of the study area of 10.9 km² is approximately 365-561 kg and of which 346-543 kg might be contributed by anthropogenic emission alone with an annual emission of 17.3-27.2 kg Hg to the topsoils. Secondary copper smelters in Fuyang release a considerable amount of mercury into topsoils.