Journal of Environmental Monitoring最新文献

An in vitro colon extended physiologically based extraction test (CEPBET) which incorporates human gastrointestinal tract (GIT) parameters (including pH and chemistry, solid-to-fluid ratio, mixing and emptying rates) was applied for the first time to study the bioaccessibility of brominated flame retardants (BFRs) from the 3 main GIT compartments (stomach, small intestine and colon) following ingestion of indoor dust. Results revealed the bioaccessibility of γ-HBCD (72%) was less than that for α- and β-isomers (92% and 80% respectively) which may be attributed to the lower aqueous solubility of the γ-isomer (2 μg L⁻¹) compared to the α- and β-isomers (45 and 15 μg L⁻¹ respectively). No significant change in the enantiomeric fractions of HBCDs was observed in any of the studied samples. However, this does not completely exclude the possibility of in vivo enantioselective absorption of HBCDs, as the GIT cell lining and bacterial flora--which may act enantioselectively--are not included in the current CE-PBET model. While TBBP-A was almost completely (94%) bioaccessible, BDE-209 was the least (14%) bioaccessible of the studied BFRs. Bioaccessibility of tri-hepta BDEs ranged from 32-58%. No decrease in the bioaccessibility with increasing level of bromination was observed in the studied PBDEs.

Cryptosporidium spp. is an obligate, parasitic protozoan that is difficult to detect and causes diarrhea in healthy adults while potentially causing death in the immunocompromised and children. Its treatment options are few and treat the symptoms, not the actual parasite. Current methods of detection are inefficient and rely too heavily upon laboratory sample preparations and technician skill, including differential staining, negative staining, and immunofluorescence methods [especially U.S. Environmental Protection Agency (EPA) Method 1623]. These assays can take from hours to days and require a laboratory environment. In this work, we demonstrated the microbead immunoagglutination assay combined with Mie scatter detection in a microfluidic device to provide a field-deployable and near-real-time alternative to the laboratory-based method (especially EPA Method 1623). Two main challenges were the relatively big diameter of Cryptosporidium oocysts (5-6 μm) and the contaminants in field water samples that negatively affected the immunoagglutination and its scatter detection. We used 4 min sonication to liberate Cryptosporidium oocyst wall proteins (COWP), which was previously used to inactivate Cryptosporidium oocysts. As for the contaminants, we optimized the microbead diameter (920 nm) and the wavelength of incident light (375 nm) to find the angle of scatter detection (45°) where the Mie scatter from immunoagglutinated microbeads was maximum and the background scatter from contaminants was minimum. This enabled the sub-single-oocyst-level detection despite the fact that only a very small volume of water sample (15 μL) was introduced to the microfluidic biosensor. When combined with filtration/concentration, this method is able to detect ≤1 oocyst per large volume of water, comparable to or potentially better than the EPA method 1623, while effectively reducing the time and labor necessary for staining and microscopic analysis. For faster, near-real-time assays, filtration/concentration may not be used, where the detection limit was 1-10 oocysts per mL with the total assay time of 10 min including the 4 min sonication time. The linear range of assay was over 5 orders of magnitude. The final device was compact and had the potential to be used in field situations, and required less technical expertise and/or training compared to the other methods.

Temporal trends of mercury in livers of ringed seals collected from the early 1980s to 2010 from central West, Northwest and central East Greenland were studied. In this period the climate of Greenland warmed and the influences of climate indices such as ice coverage, water temperature and the Atlantic Oscillation Index on mercury concentration were evaluated using multiple regressions and Akaike's Information Criteria (AIC) to determine the most parsimonious models. Biological co-variables such as age, sex and trophic position (as determined by stable isotope analysis) of seals were also evaluated. Increasing levels of mercury in seals were found in Ittoqqortoormiit, central East Greenland, and Avanersuaq, Northwest Greenland, with an annual increase of +10.3 and +2%, respectively. Age was an important co-variable for all three regions and trophic position for two regions. The Atlantic Oscillation Index was also an important explanatory variable for all three regions and was positively associated with mercury concentrations in seals indicating the importance of global climatic processes on ringed seal populations in Greenland.

Particles sampled from the main and auxiliary ship diesel engine exhausts during a measurement campaign aboard a cargo ship are studied by SEM and energy-dispersive X-ray (EDX) microanalysis. Cluster analysis (CA) is applied to characterize the particles by separating them into distinct groups of similar morphology and chemical composition, representative of the particle types in the exhaust from the main and auxiliary engines. Raman microspectroscopy, Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma mass spectrometry and ion chromatography provide the criteria for the clustering of a large data set of individual particles. To identify chemical and morphological features of heavy and distillate fuel oil-derived PM emissions, micromarkers discriminating between the different types of emitted particles are proposed. These micromarkers could enable the classification of multicomponent aerosols according to a source type. This characterization of complex multicomponent aerosols emitted by ship diesel engines improves the quantification of the contribution of shipping to ambient air particulates, and can help to identify a source type in apportionment studies.

Quantitative monitoring of water conditions in a field is a critical ability for environmental science studies. We report the design, fabrication and testing of a low cost, miniaturized and sensitive electrochemical based nitrate sensor for quantitative determination of nitrate concentrations in water samples. We have presented detailed analysis for the nitrate detection results using the miniaturized sensor. We have also demonstrated the integration of the sensor to a wireless network and carried out field water testing using the sensor. We envision that the field implementation of the wireless water sensor network will enable "smart farming" and "smart environmental monitoring".

The River Kennet in southern England has exhibited excessive benthic algal growth and associated ecological problems, such as loss of macrophytes and invertebrates, since the 1980s. These ecological problems were attributed to regular peaks in phosphorus concentration, which were widely attributed to intermittent failures of the Marlborough sewage treatment works (STW). This study deployed high-frequency phosphorus auto-analysers to monitor the total reactive phosphorus (TRP) concentrations of Marlborough STW final effluent and the downstream River Kennet at hourly and 30 minute resolution respectively, between 2008 and 2009. This monitoring confirmed that the Marlborough STW was operating well within its 1000 μg l⁻¹ annual mean total phosphorus consent limit, with mean total P and soluble reactive P concentrations of 675 and 345 μg l⁻¹ respectively. There were two occasions where effluent TRP concentration exceeded 1000 μg l⁻¹, and only one of these resulted in a peak in TRP concentration of over 100 μg l⁻¹ in the River Kennet at Mildenhall. The other nine peaks of over 100 μg l⁻¹ in the River Kennet during the monitoring period were associated with storm events, indicating that diffuse-source inputs and remobilisation of stored within-channel phosphorus were the cause of the peaks in river concentration, rather than Marlborough STW. The value of high-frequency environmental monitoring and the problems associated with using nutrient auto-analysers in the field are discussed. Seasonal phosphorus consents for STWs could provide a useful and cost effective means to improve both water quality and river ecology in the upper River Kennet.

The aim of the present study was to evaluate the effects of metal contamination on the biological responses of 0-group juvenile European flounder and to assess and compare the quality of four estuarine habitats located in the Eastern English Channel. Fish otolith growth and condition indices (RNA : DNA ratio, Fulton's K condition index) were measured and found to be significantly lower in individuals from the Seine estuary compared to those of the Canche, Authie and Somme estuaries. No obvious effects of hydrological condition or food availability on the flounder biological responses were observed. Sediments from the Seine showed the highest metal concentrations, bioavailable proportion and enrichment factors. Higher metal concentrations were observed in fish from the Seine compared to the other ones caught in less polluted estuaries. These results suggest that contaminants may have a negative impact on the early life history stage of flounder.

In stream water xenobiotics usually occur as pulses in connection with floods caused by surface run-off and tile drainage following precipitation events. In streams located in small agricultural catchments we monitored herbicide concentrations during flood events by applying an intensive sampling programme of ½ h intervals for 7 h. In contrast to grab sampling under non-flood conditions, clearly elevated concentrations were recorded during the floods, and pulses varying in occurrence, duration and concentration were recorded. Pulses of recently applied herbicides were the most prominent, but also agricultural herbicides used in previous seasons caused pulses in the streams. Asynchronism of chemographs may be related to the characteristics of the compounds as well as their transport pathways and transformation in compartments between the source and the point of sampling in the stream. Thus, the occurrence of chemographs is difficult to predict, which ought to be taken into account when designing a sampling strategy. Even though the chemographs of herbicides and their transformation products (glyphosate and aminomethylphosphonic acid (AMPA) as well as terbuthylazine and desethylterbuthylazine) seem to be synchronous, their occurrence may still be difficult to predict. It is evident that grab sampling under non-flood conditions yields insufficient information on the dynamics of occurrence of herbicides in stream water, both with respect to environmental effects and the calculation of the load to a recipient. In conclusion, the design of a sampling strategy regarding herbicides in stream waters should adequately consider the aim of the investigation.

Contamination by polycyclic aromatic hydrocarbons (PAHs) of historic wastewater-irrigated agricultural topsoil (0-5 cm) and the contribution of groundwater irrigation and atmospheric deposition to soil PAHs were studied in a typical agricultural region, i.e. Hunpu region, Liaoning, China. Concentrations of total PAHs ranged from 0.43 to 2.64 mg kg⁻¹ in topsoil, being lower than those found in other wastewater-irrigated areas. The levels of PAHs in soil declined as the distance from a water source increased. Concentrations of individual PAHs were generally higher in upland than in paddy topsoils. The calculated nemerow composite index showed that agricultural soil in the region was "polluted" by PAHs. A human health risk assessment based on the total toxic equivalent concentration showed that the presence of elevated concentrations of PAHs in the soil might pose a great threat to the health of local residents. Ratios of pairs of PAHs and principal component analysis (PCA) showed that pyrogenesis, such as coal combustion, was the main source of PAHs, while petroleum, to some extent, also had a strong influence on PAHs contamination in upland soil. The distribution patterns of individual PAHs and composition of PAHs differed between irrigation groundwater and topsoil, but were similar between atmospheric deposition and topsoil. There were significant linear correlations (r = 0.90; p < 0.01) between atmospheric deposition rates and average concentrations of the 16 individual PAHs in soils, while no significant relationships were observed between irrigation groundwater and topsoil in levels of PAHs. These suggested that PAHs in agricultural soils were mainly introduced from atmospheric deposition, rather than from groundwater irrigation after the phasing out of wastewater irrigation in the region since 2002. This study provides a reference to ensure agricultural product safety, pollution control, and proper soil management.

Objectives of this study are to determine if a relationship exists between asthma exacerbations among elementary school children in industrialized countries (with climatic seasons) and exposure to daily air pollution with particulate matter, sulfur dioxide, nitrogen dioxide, nitrogen oxides, carbon monoxide, and ozone, when controlled for potential confounders; and, if so, to derive a statistical model that predicts variation of asthma exacerbations among elementary school children. Using an ecological study design, health records of 168,25 students from elementary schools in 49 Pennsylvania counties employing "Health eTools for Schools" were analyzed. Asthma exacerbations were recorded by nurses as treatment given during clinic visits each day. Daily air pollution measurements were obtained from the EPA's air quality monitoring sites. The distribution of asthmatic grouping for pollen and calendar seasons was developed. A Poisson regression model was used to predict the number of asthma exacerbations. The greatest occurrence of asthma exacerbations was in autumn, followed by summer, spring and winter. If the number of asthma exacerbations on a day is N and the daily mean of asthma exacerbations for the three-year period is 48, the probabilities of N > 48 in tree pollen and grass pollen seasons were 56.5% and 40.8%, respectively (p < 0.001). According to the Poisson regression, the week number and prior day CO, SO₂, NO₂, NOx, PM₂.₅, and O₃ had significant effects on asthma exacerbations among students. Monitoring of air pollutants over time could be a reliable new means for predicting asthma exacerbations among elementary school children. Such predictions could help parents and school nurses implement effective precautionary measures.