The biotic ligand model (BLM) is a theoretical, potentially mechanistic approach to assess metal bioavailability in soil and aquatic systems. In a BLM, toxicity is linked to the fraction of biotic ligand occupied, which in turn, depends on the various components of the solution, including activity of the metal. Bioavailability is a key factor in determining toxicity and uptake of metals in organisms. In this study, the present status of BLM development for soil and aquatic organisms is summarized. For all species and all metals, toxicity was correlated with the conditional biotic ligand binding constants. For almost all organisms, values for Ag, Cu, and Cd were higher than those for Zn and Ni. The constants derived for aquatic systems seem to be equally valid for soil organisms, but in the case of soils, bioavailability from the soil solution is greatly influenced by the presence of the soil solid phase.

The aim of this study was to gain an understanding of the transport of C4–10 perfluoroalkyl carboxylic acids (PFCAs) and C4,6,8 perfluoroalkyl sulfonic acids (PFSAs) in a water-saturated sediment column representing a riverbank filtration scenario under near-natural conditions. Short-chain PFCAs and PFSAs with up to six C-atoms showed complete tracer-like breakthrough. Longer chain ones were retarded due to sorption to the sediment or due to other processes in the aqueous phase. The study reports the first column derived sediment–water partition coefficients ranging from 0.01 cm3 g−1 to 0.41 cm3 g−1 for C4,6 PFSAs and from 0.0 cm3 g−1 to 6.5 cm3 g−1 for C4,5,6,8,9 PFCAs. The results clearly indicate that short-chain PFCAs and PFSAs may pose a problem if contaminated surface waters are used for drinking water production via riverbank filtration.

Titanium dioxide (TiO2) nanoparticles are widely used in water treatments, yet their influences on other contaminants in the water are not well studied. In this study, the aqueous uptake, assimilation efficiency, and toxicity of two ionic metals (cadmium-Cd, and zinc-Zn) in a freshwater zooplankton, Daphnia magna, were investigated following 2 days pre-exposure to nano-TiO2. Pre-exposure to 1 mg/L nano-TiO2 resulted in a significant increase in Cd and Zn uptake from the dissolved phase. After the nano-TiO2 in the guts were cleared, the uptake rates immediately recovered to the normal levels. Concurrent measurements of reactive oxygen species (ROS) and metallothioneins (MTs) suggested that the increased metal uptake was mainly due to the increased number of binding sites provided by nano-TiO2 presented in the guts. Consistently, pre-exposure to nano-TiO2 increased the toxicity of aqueous Cd and Zn due to enhanced uptake. Our study provides the evidence that nano-TiO2 in the guts of animals could increase the uptake and toxicity of other contaminants.

The climate sensitivity of carbon (δ13C), oxygen (δ18O) and hydrogen (δ2H) isotope signatures in tree-ring cellulose of Abies alba Mill. from a marginally industrialized area of Franconia (Germany) was analysed for the last 130 years. All isotopes preserve climatic signals up to c. 1950 AD. After 1950 we observe a clear reduction in climate sensitivity of δ13C and δ2H while δ18O – climate relations remain well pronounced. Nevertheless statistical tests implied that SO2 background emissions of West Germany had influenced isotope signatures long before 1950. The relationships between isotope values and concentrations of SO2, dust, O3 and NO2 at the regional level during the period 1979–2006 indicate that δ13C and δ18O were influenced primarily by SO2. The impact of SO2 on δ2H was negligible, but the observed reduction of climate sensitivity may be caused by synergic influences. The results have significant implications if isotope signatures from tree-rings from anthropogenic influenced regions are used to reconstruct past climate.

High-technology industries have grown continuously in Taiwan and elsewhere in the world. Volatile organic compounds (VOCs) comprise the highest percentage of emissions in these industries. The objectives of this study were to identify VOC sources and to apportion their contributions by using a three-step approach. These included estimating concentration distributions, performing principal component analysis (PCA), and mapping concentration contours. The results showed that the dominant compound groups were aromatic and aliphatic compounds. The PCA resolved four emission sources: vehicular traffic, industrial solvents, waste water plants, and cleaning/degreasing agents. Spatial distributions showed that concentrations of vehicular traffic-related compounds (benzene and isooctane) were highest at the entrances to the science park, and strongly related to traffic volume, and that the emissions of industry-related compounds (xylene and ethylbenzene) were closest to the associated sources. This study provided an accurate, practical and efficient method of characterizing emission sources in an industrial complex.

In the 1950s and 60s, discharges from a DDT manufacturing plant contaminated a tributary system of the Tennessee River near Huntsville, Alabama, USA. Regulatory action resulted in declaring the area a Superfund site which required remediation and extensive monitoring. Monitoring data collected from 1988, after remediation, through 2011 showed annual decreases approximating first-order decay in concentrations of total DDT and its six principal congeners (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE and o,p'-DDE) in filets from three species of fish. As of 2013, these concentrations met the regulatory requirements of 5 mg/kg or less total DDT for each fish tested. The enantiomer fractions (EF) of chiral o,p'-DDD in smallmouth buffalo and channel catfish were always below 0.5, indicating preferential decay of the (+)-enantiomer of this congener; this EF did not change significantly over 15 years. The often-neglected DDT metabolite p,p'-DDA was found at a concentration of about 20 μg/l in the ecosystem water.

POP bioaccumulation pathways in the clam Tapes philippinarum were examined for two years from juveniles to adult size. Two polluted sites, one with sandy sediment, the other muddy were compared with a reference site characterized by low contamination levels. Juvenile clams coming from a hatchery were reared both on the sediment and in nets suspended at 30 cm from the bottom. POP changes in clam tissue were related to the concentrations recorded in sediments and in the particulate matter during the entire fattening period. Results provided interesting data on the relationships between environmental contamination and bioaccumulation. Contrary to studies on the decontamination times of the clams collected in polluted areas, this work investigates the preferential clam bioaccumulation pathways during growth under different environmental conditions. In general POP bioaccumulation resulted to be correlated to concentrations in SPM rather than in sediments and was higher in S-clams rather than in B-clams.

The impact of in vivo and in vitro exposure to anticancer drug 5-Fluorouracil (5-FU) on the level of DNA damage was evaluated using comet assay on haemocytes of freshwater mussels Unio pictorum and Unio tumidus. For the in vivo experiment, the groups of 5 mussels per concentration were exposed for 72 h to 5-FU (0.04, 0.4, 4, 40 and 100 μM) with 0.4 μM being the lowest concentration to induce significant DNA damage. For the in vitro experiment, the primary cultures of haemocytes were treated with 0.04, 0.4, 4 and 40 μM 5-FU for 22 h and the treatment with CdCl2 was used as a positive control. In contrast to in vivo exposure, 5-FU did not induce significant increase of DNA damage in vitro, possibly because of the absence of haemocytes proliferation in primary cultures.

Transformation of ring-14C-labelled tetrabromobisphenol-A (TBBPA) was studied in an oxic soil slurry with and without amendment with Sphingomonas sp. strain TTNP3, a bacterium degrading bisphenol-A. TBBPA degradation was accompanied by mineralization and formation of metabolites and bound-residues. The biotransformation was stimulated in the slurry bio-augmented with strain TTNP3, via a mechanism of metabolic compensation, although this strain did not grow on TBBPA. In the absence and presence of strain TTNP3, six and nine metabolites, respectively, were identified. The initial O-methylation metabolite (TBBPA-monomethyl ether) and hydroxytribromobisphenol-A were detected only when strain TTNP3 was present. Four primary metabolic pathways of TBBPA in the slurries are proposed: oxidative skeletal rearrangements, O-methylation, ipso-substitution, and reductive debromination. Our study provides for the first time the information about the complex metabolism of TBBPA in oxic soil and suggests that type II ipso-substitution could play a significant role in the fate of alkylphenol derivatives in the environment.