Arsenic and other trace element concentrations were determined for tube-well water collected in the Lao PDR provinces of Attapeu, Bolikhamxai, Champasak, Savannakhet, Saravane, and Vientiane. Water samples, especially from floodplain areas of central and southern Laos, were significantly contaminated not only with As, but with B, Ba, Mn, U, and Fe as well. Total As concentrations ranged from <0.5μgL⁻¹ to 278μgL⁻¹, with over half exceeding the WHO guideline of 10μgL⁻¹. 46% of samples, notably, were dominated by As(III). Samples from Vientiane, further north, were all acceptable except on pH, which was below drinking water limits. A principal component analysis found associations between general water characteristics, As, and other trace elements. Causes of elevated As concentrations in Lao tube wells were considered similar to those in other Mekong River countries, particularly Cambodia and Vietnam, where young alluvial aquifers give rise to reducing conditions.

Membrane filtration is commonly performed for solid–liquid separation of aqueous solutions prior to trace metal analysis and when assessing “dissolved” metal fractions. Potential artifacts induced by filtration such as contamination and/or adsorption of metals within the membrane have been investigated for different membrane materials, metals, applied pressures and pre-cleaning steps. Measurements have been conducted on aqueous solutions including well-defined metal standards, ultrapure water, and on runoff water from corroded samples. Filtration using both non-cleaned and pre-cleaned filters revealed contamination and adsorption effects, in particular pronounced for zinc, evident for copper but non-significant for nickel. The results clearly show these artifacts to be non-systematic both for non-cleaned and pre-cleaned membranes. The applied pressure was of minor importance. Measurements of the labile fraction by means of stripping voltammetry clearly elucidate that membrane filtration followed by total metal analysis cannot accurately assess the labile or the dissolved metal fraction.

We tested the resistance of five different fullerenes (C₆₀, C₇₀, C₇₆/₇₈ mix, and C₈₄) to chemothermal oxidation at 375 °C (CTO-375), a method that has been used and tested for quantifying black carbon (BC) and CNTs in soils and sediments. C₆₀ survived CTO-375 the most (50%), while C₇₀ was the fullerene with the lowest survival rate (<1%). Standard additions of C₆₀ to soil and sediment reference materials yielded recoveries between 18 and 36%. Although lower than recoveries previously observed for soot and CNTs, these results demonstrate the capability of CTO-375 to partially isolate C₆₀ from solid environmental matrices. Standard additions of C₇₀, C₇₆/₇₈, and C₈₄ yielded slightly higher survival rates when added to soil and sediment than in their pure form. These results indicate that the mineral matrices of these samples probably had a catalytic effect towards C₆₀ and a protective effect towards C₇₀, C₇₆/₇₈, and C₈₄ during CTO-375.

An OECD initiative for the development of mollusc-based toxicity tests for endocrine disrupters and other chemicals has recommended three test species with respective test designs for further standardisation. Preparing a subsequent pre-validation study we performed a reproduction test with Potamopyrgus antipodarum, determining the concentration range of the selected test substances, bisphenol A (BPA) and cadmium (Cd). At 16 °C, the recommended test temperature, the number of embryos in the brood pouch was increased by BPA and decreased by Cd (NOEC: 20 μg BPA/L and 1 μg Cd/L). Coinstantaneous BPA tests at 7 °C and 25 °C demonstrated a temperature dependency of the response, resulting in lower NOECs (5 μg/L respectively). As expected, reproduction in control groups significantly varied depending on temperature. Additional observations of the brood stock showed seasonal fluctuations in reproduction under constant laboratory conditions. The recommended temperature range and test conditions have to be further investigated.

The environmental risks of antibiotics have attracted lots of research attention, but their environmental behavior is not clear yet. Functionalized carbon nanotubes (CNTs) were used as model adsorbents and sulfamethoxazole (SMX) was used as a model antibiotic to investigate the effect of both cations (Ca²⁺, Cs⁺) and anions (phosphate) on antibiotics adsorption. Various mechanisms (such as electrostatic interaction, hydrophobic interaction, π–π and hydrogen bonds) play roles in SMX adsorption. Cations and anions could “wedge into” these mechanisms and thus alter SMX adsorption. This study emphasized that both increased and decreased SMX adsorption could be observed with the addition of cations/anions, depending on environmental conditions (such as pH in this current study). The net effect is the balance between the increased and decreased effects. The contribution of different mechanisms to the overall antibiotic adsorption on solid particles should be identified to accurately predict the apparent effect by cations and anions.

Facing the concern of the population to its environment and to climatic change, city planners are now considering the urban climate in their choices of planning. The use of climatic maps, such Urban Climate Zone‑UCZ, is adapted for this kind of application. The objective of this paper is to demonstrate that the UCZ classification, integrated in the World Meteorological Organization guidelines, first can be automatically determined for sample areas and second is meaningful according to climatic variables. The analysis presented is applied on Toulouse urban area (France). Results show first that UCZ differentiate according to air and surface temperature. It has been possible to determine the membership of sample areas to an UCZ using landscape descriptors automatically computed with GIS and remote sensed data. It also emphasizes that climate behavior and magnitude of UCZ may vary from winter to summer. Finally we discuss the influence of climate data and scale of observation on UCZ mapping and climate characterization.

Soils and agricultural products from the Red River basin in Northern Vietnam were reported to be contaminated by agrichemicals. To assess potential exposure of local farmers and consumers to these contaminants, pesticide use and management practices of local farmers were surveyed and residue concentrations were determined for recently used as well as for banned pesticides in water, soil, vegetables, and fish samples in two communes of Northern Vietnam. DDTs, HCHs, and Drin compounds still persist at relatively high concentrations in soil and occur in vegetable and fish samples. Recently used pesticides, such as fenobucarb, trichlorfon, cyfluthrin, and cypermethrin were detected in vegetable and fish samples. Thresholds for acceptable daily intake levels (ADI) were frequently reached in the analyzed food products pointing to the fact that current pesticide management practices do not only result in a pollution of the environment but also pose threats to human health.

Receptor-oriented approaches can assess the individual-specific exposure to air pollution. In such an individual-based model we analyse the impact of human mobility to the personal exposure that is perceived by individuals simulated in an exemplified urban area. The mobility models comprise random walk (reference point mobility, RPM), truncated Lévy flights (TLF), and agenda-based walk (RPMA). We describe and review the general concepts and provide an inter-comparison of these concepts. Stationary and ergodic behaviour are explained and applied as well as performance criteria for a comparative evaluation of the investigated algorithms. We find that none of the studied algorithm results in purely random trajectories. TLF and RPMA prove to be suitable for human mobility modelling, because they provide conditions for very individual-specific trajectories and exposure. Suggesting these models we demonstrate the plausibility of their results for exposure to air-borne benzene and the combined exposure to benzene and nonane.

As part of a field campaign that studied the impact of Mexico City pollution plume at the local, sub-regional and regional levels, we studied transport-related changes in PM₁₀ composition, oxidative potential and in vitro toxicological patterns (hemolysis, DNA degradation). We collected PM₁₀ in Mexico City (T₀) and at a suburban-receptor site (T₁), pooled according to two observed ventilation patterns (T₀ → T₁ influence and non-influence). T₀ samples contained more Cu, Zn, and carbon whereas; T₁ samples contained more of Al, Si, P, S, and K (p < 0.05). Only SO₄ ⁻² increased in T₁ during the influence periods. Oxidative potential correlated with Cu/Zn content (r = 0.74; p < 0.05) but not with biological effects. T₁ PM₁₀ induced greater hemolysis and T₀ PM₁₀ induced greater DNA degradation. Influence/non-influence did not affect oxidative potential nor biological effects. Results indicate that ventilation patterns had little effect on intrinsic PM₁₀ composition and toxicological potential, which suggests a significant involvement of local sources.

Monitoring campaigns from different locations have recently shown how air concentrations of persistent semivolatile contaminants such as polychlorinated biphenyls (PCBs) often exhibit short-term (less than 24 h) variations. The observed patterns have been ascribed to different factors, such as temperature-mediated air–surface exchange and variability of planetary boundary layer (PBL) height and dynamics. Here, we present a new modeling approach developed in order to investigate the short-term variability in air concentrations of organic pollutants at a local scale. A new dynamic multimedia box model is supplied by a meteorological preprocessor (AERMET) with hourly values of air compartment height and wind speed. The resulting model is tested against an existing dataset of PCB air concentrations measured in Zurich, Switzerland. Results show the importance of such modeling approach in elucidating the short- and long-term behavior of semivolatile contaminants in the air/soil system.