Global-scale environmental transport of persistent organic pollutants

In order to realistically simulate both chemistry and transport of atmospheric organic pollutants, it is indispensable that the applied models explicitly include coupling between different components of the global environment such as atmosphere, hydrosphere, cryosphere and soil system. A model with such properties is presented.

The atmospheric part of the model is based on the equations in a general contravariant form which permits easy changes of the coordinate system by redefining the metric tensor of a specifically employed coordinate system. Considering a need to include explicitly the terrain effects, the terrain following spherical coordinate system is chosen from among many possible coordinate systems. This particular system is a combination of the Gal-Chen coordinates, commonly employed in mesoscale meteorological models, and the spherical coordinates, typical for global atmospheric models.

In addition to atmospheric transport, the model also simulates the exchange between air and different types of underlying surfaces such as water, soil, snow, and ice. This approach permits a realistic representation of absorption and delayed re-emission of pollutants from the surface to the atmosphere and, consequently, allows to capture hysteresis-like effects of the exchange between the atmosphere and the other components of the system. In this model, the most comprehensive numerical representation of the exchange is that for soil. In particular, the model includes a realistic soil module which simulates both diffusion and convection of a tracer driven by evaporation from the soil, precipitation, and gravity.

The model is applied to a long-term simulation of the transport of pesticides (hexachlorocyclohexanes in particular). Emission fluxes from the soil are rigorously computed on the basis of the realistic data of the agricultural application. All four modelled systems, i.e. atmosphere, soil, hydrosphere and cryosphere, are driven by objectively analysed meteorological data supplemented, when necessary, by climatological information. Therefore, the verification against the observed data is possible. The comparison of the model results and the observations taken at remote stations in the Arctic indicates that the presented global modelling system is able to capture both trends and short-term components in the observed time series of the concentrations, and therefore, provides a useful tool for the evaluation of the source–receptor relationships.     

Differentiation in low molecular weight organic acids exudation into rhizosphere and their creation in Ulmus laevis Pall organs treated by As – pot experiment

Two-year old Ulmus laevis Pall (U. laevis) seedlings were cultivated in a three-month hydroponic experiment with inorganic (aresenite – As(III) and arsenate – As(V)) and organic (dimethylarsenic acid – DMA(V)) arsenic forms, at 0.06 and/or 0.6?mM concentrations. Further, the profile and content of total low molecular weight organic acids (LMWOAs) were investigated in the rhizosphere, roots and leaves of U. laevis. Obtained results showed that the addition of As(III) or As(V) individually or in a mixture led to increased LMWOAs concentration in the rhizosphere, especially of oxalic and malonic acids, in comparison to the control, while in roots the overall content of the profiled LMWOAs decreased. In both rhizosphere and roots, addition of the DMA(V) form resulted in the inhibition of LMWOAs exudation into the rhizosphere and their creation in plant roots. Leaves were characterised by a higher content of LMWOAs than in the rhizosphere and roots for all experimental systems, where the profile and content of LMWOAs was strictly correlated with the analysed As forms. Our study indicated that creation of LMWOAs in U. laevis organs and their exudation to the rhizosphere could be responsible for the As toxicity tolerance of the plants.     

Residues of fluoroquinolones in marine aquaculture environment of the Pearl River Delta, South China

Concentrations and distributions of selected fluoroquinolones (norfloxacin, ciprofloxacin and enrofloxacin) in water, sediments and nine kinds of fish species collected from 6 sites in two marine aquaculture regions of the Pearl River Delta, China, were analyzed by using high-performance liquid chromatography with fluorescence detector (HPLC). The results showed that the concentrations of ciprofloxacin and enrofloxacin were below the limits of quantification (LOQ) in all water samples except for norfloxacin. Norfloxacin and ciprofloxacin concentrations ranged from 1.88 to 11.20 ng g⁻¹ dry wt, 0.76–2.42 ng g⁻¹ dry wt in sediments collected from the Dapeng’ao region (sites 1–3) and ranged from 2.31 to 4.75 ng g⁻¹ dry wt, 1.26–1.76 ng g⁻¹ dry wt in sediments collected from the Hailing Island region (sites 4–6), respectively. However, no enrofloxacin was found in all sediment samples. The three fluoroquinolones (FQs) were detected in all fish samples, and the concentrations were higher in liver tissues than those in muscle tissues. The levels of norfloxacin were higher than ciprofloxacin and enrofloxacin in both liver and muscle tissues. Among the nine marine fish species, Siganus fuscescens from Hailing Island had a significantly high level of norfloxacin in liver tissue (254.58 ng g⁻¹ wet wt), followed by Sparus macrocephalus (133.15 ng g⁻¹ wet wt) from Dapeng’ao, and the lowest value was Lutianus argentimaculatus (5.18 ng g⁻¹ wet wt) from Hailing Island. The obtained results of FQs in present study do not represent a risk to the human health in Guangdong coastal area, based on the maximum residue limits (MRLs) established by Chinese Government and the acceptable daily intake (ADI) recommended by the Food and Agriculture Organization and World Health Organization (FAO/WHO).     

Shaving of axillary hair has only a transient effect on perceived body odor pleasantness

In contrast to other apes, humans have relatively greater amounts of armpit hair, which is thought to retain signaling molecules. Although armpit shaving is widespread cross-culturally, its effect on body odor has been little investigated. In four experiments, we tested the effect of shaving and the subsequent regrowth of axillary hair. Armpit odors were collected from men who regularly shaved (group S) or who had never shaved (group N) their armpits before. The samples were subsequently rated by women for intensity, pleasantness, and attractiveness. In Experiments I, II (group N) and III, subjects firstly shaved one armpit and then let the hair regrow over 6 or 10 weeks. In Experiments I, II (group S) and IV, subjects shaved both armpits before the sampling and subsequently shaved one armpit during the same period, leaving the second armpit unshaved. Odors of the shaved armpits were rated more pleasant, attractive, and less intense compared to the unshaved armpits (Experiment I (group N)). However, no significant differences found in Experiments II and III (group N) suggest the effect of shaving is relatively minor. Moreover, there were no significant differences in odor comparing unshaved armpits with armpits after 1 week of regrowth (Experiments I, II (group N) and III) or comparing regularly shaved armpits with armpits after 1 or 3 weeks of regrowth (Experiments I, II (group S) and IV). The odor of shaved armpits was rated significantly more attractive compared to the armpits where hair had been regrowing for 6 or 10 weeks.     

Life-history correlates of extinction risk and recovery potential

Extinction risk is inversely associated with maximum per capita population growth rate (r(max)). However, this parameter is not known for most threatened species, underscoring the value in identifying correlates of r(max) that, in the absence of demographic data, would indirectly allow one to identify species and populations at elevated risk of extinction and their associated recovery potential. We undertook a comparative life-history analysis of 199 species from three taxonomic classes: Chondrichthyes (e.g., sharks; n = 82), Actinopterygii (teleost or bony fishes; n = 47), and Mammalia (n = 70, including 16 marine species). Median r(max) was highest for (and similar between) terrestrial mammals (0.71) and teleosts (0.43), significantly lower among chondrichthyans (0.26), and lower still in marine mammals (0.07). Age at maturity was the primary (and negative) correlate of r(max). In contrast, although body size was negatively correlated with r(max) in chondrichthyans and mammals, evidence of an association in teleosts was equivocal, and fecundity was not related to r(max) in fishes, despite recurring assertions to the contrary. Our analyses suggest that age at maturity can serve as a universal predictor of extinction risk in fishes and mammals when r(max) itself is unknown. Moreover, in contrast to what is generally expected, the recovery potential of teleost fishes does not differ from that of terrestrial mammals. Our findings are supportive of the application of extinction-risk criteria that are based on generation time and that are independent of taxonomic affinity.     

Acknowledging the spatial heterogeneity in modelling/reconstructing carbon dioxide exchange in a northern aapa mire

Chamber method is commonly used to measure the CO₂ exchange from plant communities. Due to low time resolution, actual measurements reflect only momentary CO₂ exchange rates. Therefore, a common way to derive seasonal or annual estimates is to establish models describing the response of CO₂ exchange to environmental variables, and then to reconstruct the CO₂ exchange over the desired time period. There are several alternative ways to obtain the CO₂ balance for the entire mire: models can be parameterized by individual sample plots, plant communities or the entire site. Similarly, the CO₂ balance can be reconstructed by plots, plant communities or the entire site. We tested how the choice of the modelling and reconstruction approach influences the CO₂ exchange estimates for the entire mire and for individual sample plots and plant communities. We measured the CO₂ exchange in a spatially heterogeneous sedge-dominated northern aapa mire for two growing seasons. We observed high spatial variation in CO₂ balance between the plant communities. We noticed that when the CO₂ balances of individual sample plots or plant communities are of interest, using a model appropriate for the entire site may result in biased estimates. In worst case the different modelling approaches may turn the CO₂ balance of an individual sample plot from positive to negative. Further, while using the whole ecosystem approach in modelling, the superior ability of chamber method in acknowledging spatial variation is lost. While the modelled growing season CO₂ balance of the mire ranged from 232 to 625 g CO₂ m⁻² depending on the chosen modelling and reconstruction approach, the average estimates still remained within the uncertainty range of one another. Acknowledgement of the spatial variation in plant community level makes the areal estimate more robust to varying weather conditions. Further, the reliability of estimates is improved by explicit formulation of the choices behind the modelling and reconstruction units reflecting the study objectives.     

Antipredator strategies of house finches: are urban habitats safe spots from predators even when humans are around?

Urbanization decreases species diversity, but it increases the abundance of certain species with high tolerance to human activities. The safe-habitat hypothesis explains this pattern through a decrease in the abundance of native predators, which reduces predation risk in urban habitats. However, this hypothesis does not consider the potential negative effects of human-associated disturbance (e.g., pedestrians, dogs, cats). Our goal was to assess the degree of perceived predation risk in house finches (Carpodacus mexicanus) through field studies and semi-natural experiments in areas with different levels of urbanization using multiple indicators of risk (flock size, flight initiation distance, vigilance, and foraging behavior). Field studies showed that house finches in more urbanized habitats had a greater tendency to flock with an increase in population density and flushed at larger distances than in less urbanized habitats. In the semi-natural experiment, we found that individuals spent a greater proportion of time in the refuge patch and increased the instantaneous pecking rate in the more urbanized habitat with pedestrians probably to compensate for the lower amount of foraging time. Vigilance parameters were influenced in different ways depending on habitat type and distance to flock mates. Our results suggest that house finches may perceive highly urbanized habitats as more dangerous, despite the lower number of native predators. This could be due to the presence of human activities, which could increase risk or modify the ability to detect predators. House finches seem to adapt to the urban environment through different behavioral strategies that minimize risk.     

Combined chemical and biological treatment of oil contaminated soil

Combined chemical (Fenton-like and ozonation) and biological treatment for the remediation of shale oil and transformer oil contaminated soil has been under study. Chemical treatment of shale oil and transformer oil adsorbed in peat resulted in lower contaminants' removal and required higher addition of chemicals than chemical treatment of contaminants in sand matrix. The acidic pH (3.0) conditions favoured Fenton-like oxidation of oil in soil. Nevertheless, it was concluded that remediation of contaminated soil using in situ Fenton-like treatment will be more feasible at natural soil pH. Both investigated chemical processes (Fenton-like and ozonation) allowed improving the subsequent biodegradability of oil. Moderate doses of chemical oxidants (hydrogen peroxide, ozone) should be applied in combination of chemical treatment (both, Fenton-like or ozonation) and biotreatment. For remediation of transformer oil and shale oil contaminated soil Fenton-like pre-treatment followed by biodegradation was found to be the most efficient.     

Bioavailability assessment and environmental fate of polycyclic aromatic hydrocarbons in biostimulated creosote-contaminated soil

When hydrocarbon-contaminated soil is subjected to bioremediation technology, hydrocarbon depletion is typically marked by an initially rapid reduction rate. This rate decreases over time and frequently a residual concentration remains in the soil. This kinetic has been attributed primarily to the enrichment of more recalcitrant fractions, as well as to the lack of resting hydrocarbon bioavailability. Thus, at the end of the bioremediation process, a part of the residual hydrocarbon soil concentration represents the non-bioavailable fraction, which is difficult to degrade by microbial populations and which poses a minor hazard. Therefore, determination of the bioavailable fraction in a bioremediation project represents both an estimation of the maximum level of achievable biodegradation, as well as an additional indication of the environmental health hazard. In the present study, aged creosote-contaminated soil was subjected to biostimulation processes, and the bioavailable fraction for several target polycyclic aromatic hydrocarbons (PAHs) was calculated using a mild extraction with cyclodextrines. The amount of PAH extracted corresponded to the desorbing fraction and can be regarded as the bioavailable fraction. The non-desorbing fraction data obtained from this procedure were compared to the remaining PAH concentrations following bioremediation treatment of soil microcosms. These results permitted the establishment of a theoretical biodegradation limit based on the desorbing fraction. In addition, neither accumulation of intermediate metabolites, nor the formation of bound-residues or reduced acute toxicity was observed.     

Urban atmospheric pollution: personal exposure versus fixed monitoring station measurements

We initiated the PETER (pedestrian environmental traffic pollutant exposure research) project to investigate pedestrians' exposure to traffic related atmospheric pollutants, based on data obtained with the collaboration of selected categories of pedestrian urban workers. We investigated relations between roadside personal exposure levels of volatile aromatic hydrocarbons (including benzene) and particulate matter <10 microm (PM10) among traffic police (n = 126) and parking wardens (n = 50) working in downtown Bologna, Italy. Data were collected from workshifts throughout four 1-week periods in different seasons of 2000-2001. For benzene and PM10, comparisons were made with measurements by fixed monitoring stations, and influence of localized traffic intensity and meteorological parameters was examined. Roadside personal exposure to benzene correlated more strongly with other volatile aromatic hydrocarbons (toluene, xylenes and ethylbenzene) than with PM10. Benzene and PM10 personal exposure levels were higher than fixed monitoring station values (both p<0.0001). At multivariate analysis, benzene and PM10 data from fixed monitoring stations both correlated with meteorological variables, and were also influenced by localized traffic intensity. Plausibly because of the downtown canyon-like streets, weather conditions (during a period of drought) only marginally affected benzene personal exposure, and moderately affected PM10 personal exposure. These findings reinforce the concept that urban atmospheric pollution data from fixed air monitoring stations cannot automatically be taken as indications of roadside exposures.