Rapid incorporation and short-term distribution of a nonylphenol isomer and the herbicide MCPA in soil-derived organo-clay complexes

Organo-clay complexes in soil are a major sink for xenobiotics and, thus, often enhance their persistence dramatically. However, the knowledge on environmental processes of non-extractable residue formation on a short time scale is very restricted. Therefore, this study examined the distribution of 4-(3,5-dimethylhept-3-yl)phenol (NP) and 4-chloro-2-methylphenoxyacetic acid (MCPA) in soil over a short time period of 48 h and in different soil sub-fractions. The overall proportion of organo-clay-associated bound residues was not only abundant but also in the same range for both substances (MCPA: 8%; NP: 11% of applied ¹⁴C-radioactivity). However, a more detailed view revealed two different distribution patterns: a higher proportion of clay-associated NP was accompanied by a lower content of bound residues, whereas a smaller fraction of clay-associated MCPA was characterized by a higher proportion of non-extractable residues. Further on, a selective accumulation of bound residues among clay-associated humic fractions was observed. NP residues were linked predominantly to humic acids, whereas MCPA residues tended to be incorporated more into fulvic acids. It was evident that the overall distribution was influenced primarily by the physico-chemical properties of the contaminants. This study demonstrates in detail a rapid initial incorporation accompanied by a specific distribution into soil sub-fractions for selected xenobiotics in soil and points to a complex interaction of clay-associated organic matter with low molecular weight compounds.     

Nestmate recognition in social wasps: manipulation of hydrocarbon profiles induces aggression in the European hornet

The influence of individual cuticular hydrocarbons on nestmate recognition in the European hornet, Vespa crabro L., was investigated. We observed the behavioural response of workers towards differently treated dead conspecifics in a bioassay. Dummies were extracted with dichloromethane and extracts were spiked with microgram amounts of synthetic hydrocarbons naturally occurring on the cuticle of V. crabro. These modified extracts were reapplied to extracted workers that were subsequently tested in the bioassay. Non-spiked nestmate dummies (negative control) and untreated non-nestmate dummies (positive control) were tested in control experiments. The addition of only heneicosane or a mixture of heneicosane, tricosane, and (Z)-9-tricosene to the extracts led to a significant increase of agonistic behaviour in workers leaving the nest for foraging flights. Returning workers reacted much less aggressively than those leaving. This is one of the first behavioural proofs that manipulation of cuticular hydrocarbon profiles can be perceived by a social insect species. The results support the hypothesis that colony-specific cuticular hydrocarbon profiles are involved in the phenomenon of nestmate recognition among social insects.     

Partitioning behavior of polychlorinated biphenyls

Partitioning of polychlorinated biphenyls (PCBs) among several idealized environmental compartments was investigated using equilibrium conditions. Simulations with single equilibrations suggested that PCB mixtures do not weather significantly. However, simulations with multiple equilibrations of a selected phase with renewed phases suggested that PCB mixtures have the potential to weather. These simulations were strongly influenced by temperature; both the compositions and total amount of the PCBs in each phase at equilibrium changed significantly with temperature. These simulations lend support to the hypothesis that lower and higher chlorinated PCBs behave differently in the environment.     

Synthesis of branched para-nonylphenol isomers: occurrence and quantification in two commercial mixtures

Eight tertiary nonanols were synthesized via Grignard reaction and coupled by Friedel–Crafts alkylation with phenol to the corresponding nonylphenols. Six branched para-nonylphenols (NP) were obtained: 4-(3′-methyl-3′-octyl)phenol (33NP), 4-(2′-methyl-2′-octyl)phenol (22NP), 4-(2′,5′-dimethyl-2′-heptyl)phenol (252NP), 4-(2′,5′,5′-trimethyl-2′-hexyl)phenol (2552NP), 4-(2′,4′-dimethyl-2′-heptyl)phenol (242NP) and 4-(4′-ethyl-2′-methyl-2′-hexyl)phenol (4E22NP). Their structures were confirmed by GC–MS and NMR spectroscopy. These six isomers as well as the earlier synthesized 4-(3′,5′-dimethyl-3′-heptyl)phenol (353NP), 4-(3′,6′-dimethyl-3′-heptyl)phenol (363NP) and 4-(2′,6′-dimethyl-2′-heptyl)phenol (262NP) were compared with commercial NP mixtures purchased from Acros and Fluka by GC–MS (equipped with a 100 m polysiloxane column). The analyses revealed that all obtained isomers are occurring in different quantities in both commercial NP mixtures.     

Terrestrial snails as quantitative indicators of environmental metal pollution

Concentrations of cadmium, lead, copper and zinc were measured in individuals of Arianta arbustorum from different urban sampling sites. In comparison to snails from a reference site, the animals collected in the city showed higher concentrations of cadmium, lead, and copper, indicating elevated levels of metal pollution. The most pronounced difference in tissue concentrations between control animals and contaminated snails was observed for lead. Within the city, metal levels in snails differed significantly, even between adjacent populations. Arianta arbustorum is a suitable species for biomonitoring, because it is widespread, resident and easy to collect; it has a high capacity for metal accumulation and shows different concentrations depending on metal contamination of the sampling area. An interspecific comparison of metal concentrations in terrestrial gastropods was conducted to define background levels and classes of burden. Three pollution levels are distinguished on the basis of the snails' metal burden: no pollution (class 1: reference sites), moderate (class 2: traffic and other human activities in urban areas), and high pollution (class 3: mining and heavy industry).     

Ecological risk as a tool for evaluating the effects of offshore wind farm construction in the North Sea

Offshore wind power generation represents a chance to supply energy in a more sustainable way; however, the ecological risks associated with the construction and operation of offshore wind farms are still largely unknown. This paper uses the concept of ecological risk for analysing ecological changes during construction of offshore wind farms. “Ecological risk” is defined as the potentially reduced ability of providing ecosystem services. The ERSEM ecosystem model allows assessing ecological risk based on a number of selected variables (integrity indicators) and under the assumption that increased suspended matter concentration during construction of wind farms affects ecosystem functioning. We conclude that ecological risk is adequate to describe the effects of wind farm constructions, although the computation procedure still needs to be refined and the choice of indicators further optimised. In this context, the choice of indicators available in modelling as well as in monitoring time-series may offer the way forward.     

Comparison of microbial pyrene and benzo[a]pyrene mineralization in liquid medium, soil slurry, and soil

The microbial degradation of 14C-pyrene and 14C-benzo[a]pyrene by a bacterial mixed culture was studied within a mixture of the PAHs phenanthrene, anthracene, pyrene, fluoranthene, and benzo[a]pyrene as sole carbon source in the different culture systems: (i) liquid medium, (ii) soil slurry (surface and grinding influence), and (iii) soil. The fate of these two labeled compounds was followed in these systems with an emphasis on mineralization to carbon dioxide, extractability, and adsorption to humic materials and formation of unextractable residual. Mineralization showed the most obvious differences: soil slurries achieved the best results both concerning the extent of mineralization and the time required. The highest extent of pyrene mineralization (54% within 21 days) was observed in soil slurries; in liquid media, pyrene mineralization was slower, but reached approximately the same extent (54% in 150 days); in soils, mineralization reached only 36% of added pyrene after 160 days. Benzo[a]pyrene was mineralized in a mixture of PAHs in soil slurries to an extent of 34% within 70 days, whereas mineralization in liquid medium and soil occurred in the range of 5% (70 days). Mineralization of benzo[a]pyrene in sand slurries was lower compared to soil slurries (19% in sand slurries vs. 32% in soil slurries within 50 days).