Mercury biomethylation assessment in the estuary of Bilbao (North of Spain)

The relationship between the microbial methylation of mercury and the microbial activities in sediments and water collected from the estuary of Bilbao (North of Spain) was studied in three different sampling points and in two different seasons. Three different cultures were prepared with a sediment slurry to distinguish between biotic and abiotic methylation pathways and the variations of the methylmercury concentration and the variations of the population of total number of bacteria (TDC), anaerobic heterotrophic bacteria (AHB), sulphate-reducing bacteria (SRB) and Desulfovibrio were measured. From this work, it can be concluded that the variation of MeHg concentrations is a result of the methylation/demethylation processes in the sediments, and that the abiotic processes have a negligible contribution to those processes. According to the statistical analysis of the results (partial least squares analysis) a significant statistical correlation was established between methylmercury and the SRB counts.     

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test.     

Characterizing ammonia emissions from swine farms in eastern North Carolina: part 1--conventional lagoon and spray technology for waste treatment

Ammonia (NH3) fluxes from waste treatment lagoons and barns at two conventional swine farms in eastern North Carolina were measured. The waste treatment lagoon data were analyzed to elucidate the temporal (seasonal and diurnal) variability and to derive regression relationships between NH3 flux and lagoon temperature, pH and ammonium content of the lagoon, and the most relevant meteorological parameters. NH3 fluxes were measured at various sampling locations on the lagoons by a flowthrough dynamic chamber system interfaced to an environmentally controlled mobile laboratory. Two sets of open-path Fourier transform infrared (FTIR) spectrometers were also used to measure NH3 concentrations for estimating NH3 emissions from the animal housing units (barns) at the lagoon and spray technology (LST) sites. Two different types of ventilation systems were used at the two farms. Moore farm used fan ventilation, and Stokes farm used natural ventilation. The early fall and winter season intensive measurement campaigns were conducted during September 9 to October 11, 2002 (lagoon temperature ranged from 21.2 to 33.6 degrees C) and January 6 to February 2, 2003 (lagoon temperature ranged from 1.7 to 12 degrees C), respectively. Significant differences in seasonal NH3 fluxes from the waste treatment lagoons were found at both farms. Typical diurnal variation of NH3 flux with its maximum value in the afternoon was observed during both experimental periods. Exponentially increasing flux with increasing surface lagoon temperature was observed, and a linear regression relationship between logarithm of NH3 flux and lagoon surface temperature (T1) was obtained. Correlations between lagoon NH3 flux and chemical parameters, such as pH, total Kjeldahl nitrogen (TKN), and total ammoniacal nitrogen (TAN) were found to be statistically insignificant or weak. In addition to lagoon surface temperature, the difference (D) between air temperature and the lagoon surface temperature was also found to influence the NH3 flux, especially when D > 0 (i.e., air hotter than lagoon). This hot-air effect is included in the statistical-observational model obtained in this study, which was used further in the companion study (Part II), to compare the emissions from potential environmental superior technologies to evaluate the effectiveness of each technology.     

Ecorisk evaluation and treatability potential of soils contaminated with petroleum hydrocarbon-based fuels

We used a series of toxicity tests to monitor oil degradation in the Kuwaiti oil lakes. Three soils from different locations with a history of hydrocarbon contamination were treated in bench-scale microcosms with controlled nutrient amendments, moisture content, and temperature that had promoted mineralization of total hydrocarbon and oil and grease in a preliminary study. Two hundred days of bioremediation treatment lowered hydrocarbon concentration to below 2 and 5 mg g(-1) for soils A and B, respectively, while in soil C hydrocarbon concentration remained at 12 mg g(-1). Although 85% of the total petroleum hydrocarbons (TPHs) in soil A were reduced 50d after treatment, results of the seed germination and Microtox tests suggested an initial increase in toxicity, indicating that toxic intermediary metabolites may have formed during biodegradation. Also, the significant decrease of TPHs and corresponding high toxicity levels were noted in soil B 200d after bioremediation. Clearly, toxicity values, and not just hydrocarbon concentration, are a key factor in assessing the effectiveness of bioremediation techniques. Field chemistry data showed a significant reduction in hydrocarbon levels after the biological treatment. We concluded that the toxicity assessment of the contaminated soil with a battery of toxicity bioassays could provide meaningful information regarding a characterization procedure in ecological risk assessment.     

Sorption of fenamiphos to different soils: the influence of soil properties

Fenamiphos (0-ethyl-0(3-methyl-4-methylthiophenyl)-isopropylamido-phosphate) is a widely used nematicide and insecticide in bowling greens and agriculture, but information on its sorption including its metabolites is limited. Hence, the sorption of fenamiphos (nematicide) and its major degradation products fenamiphos sulfoxide (FSO) and fenamiphos sulfone (FSO2) were determined in thirteen contrasting soils collected from Australia and Ecuador. The sorption coefficients (Kd) exhibited a wide range of variation from 2.48 to 14.94 L/Kg for fenamiphos; from 0 to 7.42 L/Kg for FSO and from 0 to 9.49 L/Kg for FSO2. The sorption affinity of the three compounds for all soils tested was as follows: fenamiphos > fenamiphos sulfone > fenamiphos sulfoxide. The results showed that the sorption of fenamiphos and its metabolites in some soils is very low, and in one case is nonexistant for the metabolites. This is of particular concern as due to its low sorption coefficient, the compound could easily migrate and contaminate water bodies. Fenamiphos and its oxidation products have been reported to be highly toxic to aquatic invertebrates and therefore, the information generated in this study assumes great importance in the risk assessment of fenamiphos and its metabolites in the environment.     

Cadmium stress alters gene expression of DNA mismatch repair related genes in Arabidopsis seedlings

Cadmium (Cd) is a non essential element, and is a widespread environmental pollutant. Exposure to Cd can result in a variety of adverse health effects in plant and humans. In the current study, Arabidopsis seedlings were used as a bio-indicator of Cd pollution. Seedlings were grown on MS media containing 0-6.0 mg L(-1) Cd for 18 days, and the gene expression patterns were used to link increased Cd exposure with progressive biological effects. Reduction of total soluble protein content in shoots of the Arabidopsis seedlings occurred with increase in Cd concentrations. For the gene expression patterns, seven genes known to be involved in cell division and DNA mismatch repair (MMR) system were investigated by semi-quantitative RT-PCR, and normalized using 18S rRNA gene expression. Expression of the proliferating cell nuclear antigen 2 (atPCNA 2), MutS 3 homolog (atMSH 3) and MutL1 homolog (atMLH1) genes in shoots of Arabidopsis was strongly induced by exposure to 0.75 mg L(-1) Cd, but were repressed by other Cd concentrations whereas exposure to 0.75-6 mg L(-1) of Cd resulted in a decreased expression of atPCNA1, atMSH 2, 6 and 7 genes independently of any observable biological effects, including survival, fresh weight and chlorophyll level of shoots. This work demonstrated that specific gene expression changes could serve as useful molecular biomarkers indicative of Cd exposure and related biological effects.     

Dioxins in adipose tissue of women in Southern Spain

Seventeen polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were quantified in adipose tissue samples of non-occupationally exposed women living in Southern Spain. Geometric mean levels of sum of congeners and WHO(PCDD/F)-TEQ(2005) were 410 and 17.9pgg(-1) fat, respectively. Among PCDDs, octachlorodibenzo-p-dioxin (OCDD) showed the highest concentration with a mean value of 265pgg(-1) fat, followed by 1,2,3,6,7,8-HxCDD (49.3pgg(-1) fat) and 1,2,3,4,6,7,8-HpCDD (45.2pgg(-1) fat). These three congeners were responsible for around 90% of the sum of all PCDD/F congeners in adipose tissue. The geometric mean 2,3,7,8-TCDD value was 1.87pgg(-1) fat. 2,3,4,7,8-PeCDF (8.43pgg(-1) fat) showed the highest concentration among the PCDFs, followed by 1,2,3,4,7,8-HxCDF (4.17pgg(-1) fat) and 1,2,3,6,7,8-HxCDF (3.28pgg(-1) fat), and these three congeners were responsible for 4% of the sum of all studied PCDD/F congeners in adipose tissue and 76% of the sum of ten PCDFs. 1,2,3,7,8,9-HxCDF was the only congener not quantified in any sample, while 1,2,3,4,7,8,9-HpCDF, 1,2,3,7,8-PeCDF, OCDF and 2,3,7,8-TCDF were found in 5, 16, 16 and 19 samples, respectively. All other congeners were quantifiable in all 20 samples. Congeners contributing most to the WHO(PCDD/F)-TEQ(2005) were 1,2,3,7,8-PeCDD (31.6%), 1,2,3,6,7,8-HxCDD (28.3%) and 2,3,4,7,8-PeCDF (14.6%). The body burden of log-transformed WHO(PCDD/F)-TEQ(2005) levels increased with age (B=0.02; 95% CI=0.01, 0.03; p=0.02). Although these adipose tissue PCDD/F levels are similar to previously published findings in Spain and other European countries, further research is needed to determine trends in the exposure of women to these chemical residues.     

Hepatic monooxygenase (CYP1A and CYP3A) and UDPGT enzymatic activities as biomarkers for long-term carbofuran exposure in tench (Tinca tinca L)

The effect of a long-term exposure of tenchs to different concentrations (10 and 100 micro g/L) of the pesticide carbofuran has been evaluated. Microsomal hepatic cytochrome P450 subfamily 1A (CYP1A) and 3A (CYP3A) activities, as well as the phase II enzyme uridine diphospho-glucuronosyltransferase (UDPGT) activity were evaluated as adequate biomarkers of fish exposure to environmentally relevant concentrations of the pesticide carbofuran in freshwater ecosystems. A clear time-dependent inhibition of both CYP1A and UDPGT activities was observed in fish exposed to the highest dose of carbofuran with respect to controls, whereas in the case of CYP3A activity, values of exposed animals did not show a clear pattern of alteration during the experiment. The results of the present study demonstrated that hepatic CYP1A and UDPGT activities from tench could be considered as sensitive biomarkers for carbamate pesticides in polluted water, thus allowing future and ecologically relevant biomonitoring studies with this species.