Toxicity of Hg2+ was determined in two strains of Euglena gracilis var. bacillaris: the wild-type (B) and a streptomycin-resistant strain (Smr). Cells were cultured under 12-h dark/12-h light regime or under continuous darkness. In the dark/light cultures, cellular growth was severely diminished in the B strain by Hg2+, whereas only a slight decrease was attained in the Smr strain; Hg2+ also affected the photosynthetic and respiratory activities of the B strain, but not those of Smr strain. Under continuous darkness, cellular growth of both strains was lower than under dark/light cycles, but it was inhibited by Hg2+ to a much lesser extent. Cell culture by 5 days under continuous dark or by 8 days of dark/light cycles resulted in a higher intracellular content of mercury in B strain than in Smr strain. In contrast, in both culture conditions, the fraction of mercury removed from medium by B strain was lower than that attained by Smr strain, whereas the ability to bio-transform (reduce) Hg2+ was two times higher in the mutant strain. The results suggested that Smr strain cells acquired an ability to remove Hg2+ from the medium, which was not associated to accumulation and which conferred protection against mercury.

The disruption of endocrine systems due to environmental contaminants potentially impacts on the developmental, behavioural, regulatory and reproductive systems of animals. A major source of exposure of animals (terrestrial and aquatic) to endocrine-disrupting compounds is through contact with contaminated surface waters contaminated with sewage effluent and/or stormwater discharge. We studied the response to endocrine-disrupting compounds of Gambusia holbrooki mosquito fish resident of wetlands that were used for the storage of either treated sewage effluent or stormwater runoff. We found that fish from wetlands that received polluted waters directly from the source (treated sewage effluent or stormwater runoff) demonstrated a morphological response consistent with endocrine disruption. In contrast, fish in the second in the series of wetlands that housed treated sewage effluent did not show evidence of such response. However, those from the second in the series of stormwater receiving wetlands did display a morphological response, although it could be considered milder than was observed in fish from the first in this effluent stream. Fish were also smaller in the wetland that received sewage effluent directly from the sewage treatment plant than elsewhere. Although the differences were not statistically significant, the average size of fish in the first in the series of stormwater wetlands were also small and second only to those in the first sewage effluent wetland.

Daily mass concentrations of PM1, PM2.5, and PM10 were measured along with meteorological parameters from October 2008 to October 2009 in the city of Elche, close to the southeastern Spanish Mediterranean coast. Annual mean levels of 9.2, 13.2, and 26.2 μg m−3 were obtained for PM1, PM2.5, and PM10, respectively. PM2.5 and PM10 concentrations were lower than those previously measured at the same location due to unusual weather conditions that occurred during winter 2009, specially the decrease in the number of high atmospheric stability episodes. The contribution of road traffic to the levels of submicron (PM1), fine (PM2.5–1), and coarse (PM10–2.5) particles was studied by correlating PM concentrations with NO2. The results showed a higher relative contribution in winter (0.45 < r < 0.65) than in summer (−0.26 < r < 0.05). However, the scarce variability in traffic intensity (in terms of number of vehicles per day) was unable to explain daily and seasonal variations in PM levels. Rather, these variations were associated to seasonal changes in other PM sources and meteorological conditions. The three size fractions showed good negative correlations with wind speed during winter, suggesting that the main effect of cold season winds was the dilution of atmospheric aerosols. For the coarse fraction, good correlation coefficients were obtained with temperature and solar radiation (0.60 and 0.70, respectively) due to identical seasonal behavior of coarse PM and these parameters during the study period.

The 137Cs and 40K activities and transfer factors from soil to vegetables, grass, and milk from villages located around Tarapur Atomic Power Station (TAPS) were determined using high-resolution gamma spectrometry. A total of 32 soil, 21 vegetable, 23 dry paddy grass, and 23 milk samples were collected from 23 different agricultural farms from various villages around TAPS to determine transfer factors for natural environment. The mean concentration values for 137Cs and 40K in soil, grass, and milk were 2.39 ±â€‰0.86 Bq kg−1, 0.31 ±â€‰0.23 Bq kg−1, and 12.4 ±â€‰5.7 mBq L−1 and 179 ±â€‰31 Bq kg−1, 412 ±â€‰138 Bq kg−1, and 37.6 ±â€‰9.3 Bq L−1, respectively, for soil–grass–milk pathway. In the soil–vegetation pathway, the mean concentrations values for 137Cs and 40K were 2.15 ±â€‰1.04 Bq kg−1, 16.5 ±â€‰7.5 mBq kg−1, and 185 ±â€‰24, 89 ±â€‰50 Bq kg−1, respectively. The evaluated mean transfer factors from soil–grass, grass–milk, and soil–vegetation for 137Cs were 0.14, 0.0044, and 0.0073 and that of 40K were 2.42, 0.0053, and 0.49, respectively. Only 15 out of total 44 milk and vegetable samples were detected positive for 137Cs, indicating a very low level of bioavailability.

Source-oriented models are ideally suited to examine the impact of terrain and meteorology and source factors such as stack height when evaluating exposures to air pollutants. A source-oriented, Gaussian plume air pollution dispersion model AERMOD was used to estimate the spatial distribution of elemental mercury (Hg0) from a typical coal-fired boiler emitting 0.001 g Hg0/s. Hg0 was chosen because of its health impact related to potential neurological and reproductive effects which may be especially important for high-risk populations. Results from four simulations using meteorological data from 2004 were compared for flat and hilly terrain from 20- and 55-m stacks at a distance of 1,350 m from the source. Variations within a quadrant were affected primarily by topography. For the 20-m stack, the average annual ambient concentration for individuals living within the northeast (NE) quadrant was significantly lower at 2.5 ng Hg0/m3 (P < 0.001; confidence interval (CI), 2.4–2.6) in flat terrain versus 3.3 ng Hg0/m3 in hilly (P < 0.001; CI, 1.2–1.3). NE concentrations of the source showed high spatial variability attributed to topography with 1-h maximums of 4.0 ng Hg0/m3 flat versus 7.1 ng Hg0/m3 hilly. Not unexpectedly, average annual concentrations were considerably lower for the 55-m stack although topography remained a significant variable with 0.1 ng Hg0/m3 in flat terrain (p < 0.001; CI, 0.11–0.13) and double that exposure at 0.2 ng Hg0/m3 in hilly terrain (p < 0.001; CI, 0.16–0.18). Annual average mercury concentrations due to emissions from the 20-m stack were ~20 times higher than ambient concentrations associated with the 55-m stack. A sensitivity analysis was performed for meteorological effects, using meteorological data from years 2001–2005. Varying the roughness factor had no significant effect on the results. For all simulations, the highest concentrations were located in the NE quadrant. During 2001–2005, the highest average annual ambient Hg concentration ranged from 6.2 to 7.0 ng Hg0/m3 for the 20-m stack and 0.3–0.5 ng Hg0/m3 for the 55-m stack. Thus, this model is robust. These results demonstrate the usefulness of a source-oriented model such as AERMOD for incorporating multiple factors for estimating air pollution exposures for communities near point sources. The importance of considering topography, meteorology, and source characteristics when placing air samplers to measure air quality and when using buffer zones to estimate ambient residential exposures is also illustrated. Residential communities in hilly terrain near industrial point sources may have between two to three times the exposures as those in flat terrain. Exposures will vary depending on the stack height of the point source.

The vertical distribution of mercury along a weathering profile derived from a diabase was compared to the main geochemical and mineralogical characteristics of the soil and its parental rock. The sampling site was in a metropolitan area, nearby to an active quarry and relatively close to an industrial park. The samples of a 6-m-deep fresh exposure of the soil profile and also of fresh rock were collected during the dry season. Kaolinite, goethite, hematite, and residual primary minerals were identified in the soil samples. Typically, the concentrations of Hg in the soil are low. Whole samples contained between 1 (rock) and 37 μg kg−1 Hg, while the < 63-μm soil fraction had up to 52 μg kg−1 Hg. The higher values of Hg corresponded to the upper layers of A (0–10 cm) and B (200–220 cm) soil horizons. Elemental gains and losses calculated against Zr resulted in the following order: Hg>>Pb > Zr > LREE > Nb > HREE > Al > Ti > Fe > Cr. Total organic carbon in soil samples varied between 0.2 and 5.1 g dm−3, and correlation with Hg concentrations was moderate. The acid pH (4.2–5.5) of the soil samples favors the sorption Hg species by predominant secondary phases like goethite and kaolinite. The Hg concentration of the rock is insufficient to explain the large enrichment of Hg along the soil profile, indicating that exogenic Hg, via atmospheric deposition, contributed to the measured Hg concentrations of the soil.

The complexation of heavy metals, present in their dissolved state at relevant trace levels, with new humic acids (HAs) isolated from Yakouren forest (YHA) and Sahara (Tamenrasset: THA) soils has been studied by differential pulse anodic stripping voltammetry (DPASV) at a hanging mercury drop electrode and conductimetry methods. After extraction and purification, humic acids were characterized by elemental analyses, atomic absorption spectroscopy, FT-IR, and solution state 13C-NMR. Taking Zn(II) and Cd(II) as examples, the aim of this study was to gain direct information on the general level of importance of humic acids for the speciation of certain heavy metals in soil to determine the complexing capacities of AHs and stability constant of the complexes formed with these metal ions and to compare the complexation capacity of forest and Sahara soils with the commercial humic acid and other published AHs. The results determined by conductimetry method are interpreted using an excess function (∆k) which related the conductivity of the mixture and of the separated components. A positive value of this function is obtained. It indicates the complexation of humic acids with metallic ions. The DPASV method was used for determining metal ion complexing capacities and stability constants of metal ion complexes of HAs in solution at pH 7. In both types of soils, the commercial humic acid (CHA) is less efficient in complexing Zn(II) and Cd(II) than THA and YHA and the complexing capacity (CCM) decreases in the order: THA > YHA > CHA. In general, the results of complexing capacity for all humic acids and stability constants of Zn(II) and Cd(II) complexes found by DPASV method showed good correlation with those of conductimetry method. CCM of THA and YHA calculated by DPASV were higher than those of CHA and the other natural HAs published in the literature at pH 7 basing on these results.

Radon concentration and gamma activity concentration of naturally occurring radionuclides were determined and presented for two tourist caves (Karaca and Çal caves) in this study. These caves are reported to receive about 77,000 visitors during the summer season in 2007. It was seen that mean radon activity concentrations for the winter and summer seasons for the Karaca cave is 1,023 and 823 Bq/m³ and for the Çal cave is 264 and 473 Bq/m³. Mean ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations are found to be 43, 19, and 262 Bq/kg for the Karaca cave and 31, 27, and 460 Bq/kg for the Çal cave. Doses received by the cave guides due to radon were estimated to be 2.9 mSv/year for the winter season and 2.3 mSv/year for the summer season for the Karaca cave. Same values were estimated for the Çal cave, and the results were found to be 0.6 mSv/year for the winter season and 1.1 mSv/year for the summer season. Annual effective doses received by the visitors in both caves were estimated to be in the order of μSv/year because of the short exposure time comparing the cave guides. Although the reported values are below the recommended values, both groups are exposed to possible radiological risk during their stay inside the cave, since prolonged exposure to high radon concentration has been linked to lung cancer.

Comamonas sp. UVS was able to decolorize Reactive Blue HERD (RBHERD) dye (50 mg L−1) within 6 h under static condition. The maximum dye concentration degraded was 1,200 mg L−1 within 210 h. A numerical simulation with the model gives an optimal value of 35.71 ±â€‰0.696 mg dye g−1 cell h−1 for maximum rate (Vmax) and 112.35 ±â€‰0.34 mg L−1 for the Michaelis constant (Km). Comamonas sp. UVS has capability of decolorization of RBHERD in the presence of Mg2+, Ca2+, Cd2+, and Zn2+, whereas decolorization was completely inhibited by Cu2+. Metal ions also affected the levels of biotransformation enzymes during decolorization of RBHERD. Comamonas sp. UVS was also able to decolorize textile effluent with significant reduction in COD. The biodegradation of RBHERD dye was monitored by UV–vis spectroscopy, FTIR spectroscopy, and HPLC.

We combined stream chemistry and hydrology data from surveys of 436 tributary stream sites and 447 great river sites in the Upper Mississippi, Missouri and Ohio River basins to provide a regional snapshot of baseflow total nitrogen (TN) and total phosphorus (TP) concentrations, and to investigate the relationships between land use and stream chemistry. Catchments in the Upper Mississippi River basin had more land in agricultural uses (51%) than the Missouri or Ohio River basin catchments (25% and 29%, respectively). The difference in agriculture is reflected in the TN concentrations in tributary streams and the great rivers: 5,431 and 2,112 μg L−1 for the Upper Mississippi, 1,751 and 978 μg L−1 for the Missouri, and 1,074 and 1,152 μg L−1 for the Ohio River basins. This agricultural effect was not as evident for tributary stream or great river TP concentrations: 165 and 181 μg L−1 in the Upper Mississippi, 177 and 171 μg L−1 in the Missouri, and 67 and 53 μg L−1 in the Ohio River basins. We set reference thresholds based on the 75th percentile TN and TP concentrations at our least disturbed sites. The TN threshold was exceeded for 50–63% of the tributary stream and 16–55% of great river lengths, with the greatest proportion in the Upper Mississippi River basin. The TP threshold was exceeded in 32–48% of tributary stream and 12–41% of great river lengths. Tributary stream N/P ranged from 67:1 (Ohio) to 210:1 (Upper Mississippi); river N/P ranged from 20:1 (Missouri) to 60:1 (Ohio). N/P indicated that potential N-limitation occurred in 10–21% of total tributary stream length and in 0–46% of great river length; potential P-limitation ranged from 60–83% of cumulative tributary stream length and from 21–98% of cumulative great river length. Total N flux (concentration × discharge) was highest in the Upper Mississippi River basin; TP flux was lowest in the Ohio River basin. River TN yields and TP yields for both tributary streams and great rivers, was not significantly different between the sub-basins. Our study empirically links catchment land use and stream chemistry, and demonstrates using monitoring data for estimating nutrient yields at a large regional scale.