Prediction of SVOC vegetation and atmospheric concentrations using calculated deposition velocities

A simple modeling concept was previously applied to study air-foliage exchange of both polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) using field measurements. In this paper, the predictive capabilities of this framework were tested using an independent set of data collected at the same sampling location for a different time period. Firstly, atmospheric (particle-bound and gaseous phase) PBDE and PAH concentrations were used to predict their accumulation in spruce needles. Conversely, we used PBDE and PAH concentrations in vegetation to predict their atmospheric concentrations. In both cases, calculated and measured values showed good agreement, providing evidence that the developed framework and our derived deposition velocities can be used as a predictive tool for these two different classes of semi-volatile organic compounds.     

Concentrations of polybrominated diphenyl ethers (PBDEs) in matched samples of human milk,dust and indoor air

Polybrominated diphenyl ethers (PBDEs) are lipophilic, persistent pollutants found worldwide in environmental and human samples. Exposure pathways for PBDEs remain unclear but may include food, air and dust. The aim of this study was to conduct an integrated assessment of PBDE exposure and human body burden using 10 matched samples of human milk, indoor air and dust collected in 2007–2008 in Brisbane, Australia. In addition, temporal analysis was investigated comparing the results of the current study with PBDE concentrations in human milk collected in 2002–2003 from the same region.PBDEs were detected in all matrices and the median concentrations of BDEs -47 and -209 in human milk, air and dust were: 4.2 and 0.3 ng/g lipid; 25 and 7.8 pg/m³; and 56 and 291 ng/g dust, respectively. Significant correlations were observed between the concentrations of BDE-99 in air and human milk (r = 0.661, p = 0.038) and BDE-153 in dust and BDE-183 in human milk (r = 0.697, p = 0.025). These correlations do not suggest causal relationships — there is no hypothesis that can be offered to explain why BDE-153 in dust and BDE-183 in milk are correlated. The fact that so few correlations were found in the data could be a function of the small sample size, or because additional factors, such as sources of exposure not considered or measured in the study, might be important in explaining exposure to PBDEs. There was a slight decrease in PBDE concentrations from 2002–2003 to 2007–2008 but this may be due to sampling and analytical differences. Overall, average PBDE concentrations from these individual samples were similar to results from pooled human milk collected in Brisbane in 2002–2003 indicating that pooling may be an efficient, cost-effective strategy of assessing PBDE concentrations on a population basis.The results of this study were used to estimate an infant's daily PBDE intake via inhalation, dust ingestion and human milk consumption. Differences in PBDE intake of individual congeners from the different matrices were observed. Specifically, as the level of bromination increased, the contribution of PBDE intake decreased via human milk and increased via dust. As the impacts of the ban of the lower brominated (penta- and octa-BDE) products become evident, an increased use of the higher brominated deca-BDE product may result in dust making a greater contribution to infant exposure than it does currently.To better understand human body burden, further research is required into the sources and exposure pathways of PBDEs and metabolic differences influencing an individual's response to exposure. In addition, temporal trend analysis is necessary with continued monitoring of PBDEs in the human population as well as in the suggested exposure matrices of food, dust and air.     

Ra–Po–Pb isotope systematics in waters of Sambhar Salt Lake,Rajasthan (India): geochemical characterization and particulate reactivity

The Sambhar Salt Lake hydrological system, including river waters, groundwaters, evaporating pans and sub-surface brines, has been analyzed for the salt content (TDS) and naturally occurring radionuclides (²¹⁰Po, ²¹⁰Pb and ^226,228Ra). The abundance of these radionuclides and their activity ratios show a wide variation in different hydrological regimes, which helps to geochemically characterize the lake system. A significantly lower Ra to total dissolved solids (TDS) ratio in the brines (by two to three orders of magnitude), when compared to the groundwaters and river waters, suggests removal of dissolved Ra by co-precipitation with Ca–Mg minerals at an early stage of the brine evolution. The concentration of Ra in evaporating lake/pan waters saturates at a value of about 35 Bq L⁻¹ over the salinity range of 100–370 g L⁻¹; attributable to its equilibration with the clay minerals. The two distinct regimes, saline lake system (lake water, evaporating pans and sub-surface brines) and groundwaters have been identified based on their differences in the distribution of ^226,228Ra isotopes. This observation points to the conclusion that the groundwaters and the lake brines are not intimately coupled in terms of their origin and evolution. The abundances of ²¹⁰Po and ²¹⁰Pb along with their activity ratios (²¹⁰Po/²¹⁰Pb) are markedly different among the surface lake waters/evaporating pans, sub-surface lake brines and groundwaters. These differences are explained in terms of different geochemical behaviour of these nuclides in presence of algae and organic matter present in these water regimes.     

Spatial distribution of uranium and thorium in the surface soil around proposed uranium mining site at Lambapur and its vertical profile in the Nagarjuna Sagar Dam

The understanding and evaluation of the possible interactions of various naturally occurring radionuclides in the world's third largest man-made dam, Nagarjuna Sagar located in Andhra Pradesh, India and built on river Krishna assumed significance with the finding of uranium deposits in locations near the dam. For the present work, surface soil samples from the mineralized area of Lambapur, Mallapuram, Peddagattu and sediment core samples from the Nagarjuna Sagar dam were analyzed for naturally occurring radionuclides namely uranium and thorium using gamma spectrometric technique. Also toxic elements lead and chromium were analysed by the Energy Dispersive X-ray Fluorescence Spectrometer (EDXRF) technique. Surface soil samples show a variation from 25 to 291 Bq/kg (2.02–23.5 mg/kg) for ²³⁸U and 32–311 Bq/kg (7.9–76.9 mg/kg) for ²³²Th. U/Th concentration ratio in surface soil samples ranged from 0.19 to 0.31 and was found comparable with the nation wise average of 0.26. The study of sediment core samples reflected higher U/Th concentration ratio of 0.30–0.33 in the bottom section of the core as compared to 0.22–0.25 in the upper section. The concentration ratio in the upper section of the core was similar to the ratio 0.23 found in the western Deccan Basalt region through which the river originates. A higher concentration of lead and chromium was observed in the upper section of the core compared to bottom section indicating the impact of river input on the geochemical character of dam sediment.     

Reproductive parameters and disturbances of embryonic development in the fieldfare (<Emphasis Type="Italic">Turdus pilaris</Emphasis> L.) in the zone of impact from the nuclear fuel industry

The impact of emissions from the Siberian Chemical Plant (Tomsk oblast) on reproduction and embryonic development of the fieldfare was studied. Bird abundance, clutch size, and egg volume in the impact and background (control) zones were similar, but partial brood mortality in the impact zone proved to be significantly higher, and the frequency of embryonic pathologies (including developmental abnormalities) was also several times higher than in the control.     

Remote effect of nuclear polyhedrosis virus on the gypsy moth (<Emphasis Type="Italic">Lymantria dispar</Emphasis> L.) in its natural environment

The remote effect of the nuclear polyhedrosis virus on the gypsy moth was studied for the first time under natural conditions. In the generation that developed from infected eggs, the weight of pupae was reduced, sex ratio was altered, and female fecundity and egg fertility were lower than in control individuals. The F₁ progeny of these moths were characterized by an increased rate of latent virus carriage and high mortality caused by the combined effect of polyhedrosis and insect parasites.     

Biodegradation potential of MTBE in a fractured chalk aquifer under aerobic conditions in long-term uncontaminated and contaminated aquifer microcosms

The potential for aerobic biodegradation of MTBE in a fractured chalk aquifer is assessed in microcosm experiments over 450 days, under in situ conditions for a groundwater temperature of 10 °C, MTBE concentration between 0.1 and 1.0 mg/L and dissolved O₂ concentration between 2 and 10 mg/L. Following a lag period of up to 120 days, MTBE was biodegraded in uncontaminated aquifer microcosms at concentrations up to 1.2 mg/L, demonstrating that the aquifer has an intrinsic potential to biodegrade MTBE aerobically. The MTBE biodegradation rate increased three-fold from a mean of 6.6 ± 1.6 μg/L/day in uncontaminated aquifer microcosms for subsequent additions of MTBE, suggesting an increasing biodegradation capability, due to microbial cell growth and increased biomass after repeated exposure to MTBE. In contaminated aquifer microcosms which also contained TAME, MTBE biodegradation occurred after a shorter lag of 15 or 33 days and MTBE biodegradation rates were higher (max. 27.5 μg/L/day), probably resulting from an acclimated microbial population due to previous exposure to MTBE in situ. The initial MTBE concentration did not affect the lag period but the biodegradation rate increased with the initial MTBE concentration, indicating that there was no inhibition of MTBE biodegradation related to MTBE concentration up to 1.2 mg/L. No minimum substrate concentration for MTBE biodegradation was observed, indicating that in the presence of dissolved O₂ (and absence of inhibitory factors) MTBE biodegradation would occur in the aquifer at MTBE concentrations (ca. 0.1 mg/L) found at the front of the ether oxygenate plume. MTBE biodegradation occurred with concomitant O₂ consumption but no other electron acceptor utilisation, indicating biodegradation by aerobic processes only. However, O₂ consumption was less than the stoichiometric requirement for complete MTBE mineralization, suggesting that only partial biodegradation of MTBE to intermediate organic metabolites occurred. The availability of dissolved O₂ did not affect MTBE biodegradation significantly, with similar MTBE biodegradation behaviour and rates down to ca. 0.7 mg/L dissolved O₂ concentration. The results indicate that aerobic MTBE biodegradation could be significant in the plume fringe, during mixing of the contaminant plume and uncontaminated groundwater and that, relative to the plume migration, aerobic biodegradation is important for MTBE attenuation. Moreover, should the groundwater dissolved O₂ concentration fall to zero such that MTBE biodegradation was inhibited, an engineered approach to enhance in situ bioremediation could supply O₂ at relatively low levels (e.g. 2–3 mg/L) to effectively stimulate MTBE biodegradation, which has significant practical advantages. The study shows that aerobic MTBE biodegradation can occur at environmentally significant rates in this aquifer, and that long-term microcosm experiments (100s days) may be necessary to correctly interpret contaminant biodegradation potential in aquifers to support site management decisions.     

Occurrence and congener specific profiles of polybrominated diphenyl ethers and their hydroxylated and methoxylated derivatives in breast milk from Catalonia

The presence of polybrominated diphenyl ethers (PBDEs) from mono to hepta brominated and 11 hydroxylated (OH-) and methoxylated (MeO-) PBDEs was examined in 37 breast milk samples collected from 11 mothers living in Barcelona. An extraction method based on accelerated solvent extraction followed by gas chromatography coupled to high resolution mass spectrometry was used to inequivocally identify all target compounds at the low pg g(-1) lw level. Data obtained were examined for absolute and relative concentrations and specific PBDE, OH- and MeO-PBDE congener patterns. Sigma PBDE concentration ranged between 1,161 and 1,372,797 pg g(-1) lw and BDEs 47, 99, 100, 153 and 183 accounted for more than 80% of the total PBDEs. All tri and tetra OH- and MeO-PBDEs compounds were detected at levels between 6 and 14,984 pg g(-1)lw. The median ratio OH/PBDE and MeO-PBDEs/PBDEs was from 2.9% to 1.6%, respectively, suggesting either that PBDE metabolism to OH- and MeO- derivatives is not an important degradation route in humans or either OH- and MeO-PBDEs are rapidly excreted. No significant correlation was observed between PBDEs and OH- and MeO-PBDE, although OH- and OMe-PBDEs co-occurred in mothers' milk (R(2)=0.5349). According to the daily intake of PBDEs and OH- and MeO-PBDEs, which was between 0.47 and 363 ng d(-1) (excluding a smoking donor), potential health risks associated with these compounds are assessed.     

A detailed field-based evaluation of naphthenic acid mobility in groundwater

An anaerobic plume of process-affected groundwater was characterized in a shallow sand aquifer adjacent to an oil sands tailings impoundment. Based on biological oxygen demand measurements, the reductive capacity of the plume is considered minimal. Major dissolved components associated with the plume include HCO₃, Na, Cl, SO₄, and naphthenic acids (NAs). Quantitative and qualitative NA analyses were performed on groundwater samples to investigate NA fate and transport in the subsurface. Despite subsurface residence times exceeding 20 years, significant attenuation of NAs by biodegradation was not observed based on screening techniques developed at the time of the investigation. Relative to conservative tracers (i.e., Cl), overall NA attenuation in the subsurface is limited, which is consistent with batch sorption and microcosm studies performed by other authors. Insignificant biological oxygen demand and low concentrations of dissolved As (< 10 µg L^− 1) in the plume suggest that the potential for secondary trace metal release, specifically As, via reductive dissolution reactions driven by ingress of process-affected water is minimal. It is also possible that readily leachable As is not present in significant quantities within the sediments of the study area. Thus, for similar plumes of process-affected groundwater in shallow sand aquifers which may occur as oil sands mining expands, a reasonable expectation is for NA persistence, but minimal trace metal mobilization.