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401.
Health effects of ambient air pollution were studied in three groups of schoolchildren living in areas (suburban, urban and urban-traffic) with different air pollution levels in Eski?ehir, Turkey. This study involved 1,880 students aged between 9 and 13 years from 16 public primary schools. This two-season study was conducted from January 2008 through March 2009. Symptoms of asthma, rhinitis and eczema were determined by the International Study of Asthma and Allergies in Childhood questionnaire in 2008. Two lung function tests were performed by each child for summer and winter seasons with simultaneous ambient air measurements of ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2) by passive sampling. Effects of air pollution on impaired lung function and symptoms in schoolchildren were estimated by multivariate logistic regression analyses. Girls with impaired lung function (only for the summer season evaluation) were more observed in suburban and urban areas when compared to urban-traffic area ([odds ratio (OR)?=?1.49; 95 % confidence interval (CI) 1.04–2.14] and [OR?=?1.69 (95 % CI 1.06–2.71)] for suburban vs. urban-traffic and urban vs. urban-traffic, respectively). Significant association between ambient ozone concentrations and impaired lung function (for an increase of 10 μg m?3) was found only for girls for the summer season evaluation [OR?=?1.11 (95 % CI 1.03–1.19)]. No association was found for boys and for the winter season evaluation. No association was found between any of the measured air pollutants and symptoms of current wheeze, current rhinoconjunctivitis and current itchy rash. The results of this study showed that increasing ozone concentrations may cause a sub-acute impairment in lung function of school aged children.  相似文献   
402.
Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd2+ ions by nZVI through adsorption. Cd2+ adsorption decreased in the presence of competitive cations in the order: Zn2+?>?Co2+?>?Mg2+?>?Mn2+?=?Cu2+?>?Ca2+?>?Na2+?=?K+. Higher concentrations of Cl? significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd2+ adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI–Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions.  相似文献   
403.
The Tarland Catchment Initiative is a partnership venture between researchers, land managers, regulators, and the local community. Its aims are to improve water quality, promote biodiversity, and increase awareness of catchment management. In this study, the effects of buffer strip installations and remediation of a large septic tank effluent were appraised by water physico-chemistry (suspended solids, NO, NH, soluble reactive P) and stream macroinvertebrate indices used by the Scottish Environmental Protection Agency. It was done during before and after interventions over an 8-yr period using a paired catchment approach. Because macroinvertebrate indices were previously shown to respond negatively to suspended solid concentrations in the study area, the installation of buffer strips along the headwaters was expected to improve macroinvertebrate scores. Although water quality (soluble reactive P, NH) improved downstream of the septic tank effluent after remediation, there was no detectable change in macroinvertebrate scores. Buffer strip installations in the headwaters had no measurable effects (beyond possible weak trends) on water quality or macroinvertebrate scores. Either the buffer strips have so far been ineffective or ineffectiveness of assessment methods and sampling frequency and time lags in recovery prevent us detecting reliable effects. To explain and appreciate these constraints on measuring stream recovery, continuous capacity building with land managers and other stakeholders is essential; otherwise, the feasibility of undertaking sufficient management interventions is likely to be compromised and projects deemed unsuccessful.  相似文献   
404.
An inventory survey conducted to determine pesticide usage in a sub-catchment of the Nzoia sugarcane belt found a variety of pesticides used in the sub-catchment, which are reported in this paper. Analysis of soil samples from seven fallow experimental field plots left uncultivated for various periods from 3 to 96?months after cultivation with pesticide application indicated persistence of high concentrations of pesticide residues in the soil, with estimated soil half-lives (in years) ranging from 0.72 to 57.75 for organochlorines and from 1.13 to 8.25 for herbicides. The mean water concentrations (in ??g/L) of the pesticide residues in River Kuywa, which flows through the Nzoia Nucleus Estate sugarcane farms, ranged from 0.12 (lindane) to 1.36 (p,p??-DDT) for organochlorines and from 0.14 (atrazine) to 1.75 (diuron) for herbicides during the heavy rains period in August 2008 while the mean sediment concentrations (in ??g/g) ranged from 0.28 (lindane) to 1.87 (endrin) for organochlorines and 0.39 (hexazinone) to 4.61 (alachlor) for herbicides. The mean concentrations of residues in water during the light rain period in December 2008 ranged from 0.17 (p,p??-DDT) to 0.71 (aldrin) for organochlorines and 0.01 (atrazine) to 1.74 (alachlor) for herbicides while the sediment concentrations ranged from 0.38 (p,p??-DDT) to 1.145 (aldrin) for organochlorines and 0.74 (atrazine) to 1.98 (alachlor) for herbicides. Although DDT, aldrin, dieldrin, and endrin were not reported in the survey, their presence in the fallow experimental field plot soils and in River Kuywa water and sediment could indicate previous application, lack of recorded data or illegal usage since 1997 when they were banned. Notably, the concentrations of alachlor, diuron, cypermethrin, and hexazinone in the water column were substantial indicating their extensive usage and residual persistence in the sub-catchment, with subsequent wash-off and leaching into River Kuywa. The concentration levels of some of the individual pesticides exceeded the EU limit requirements for drinking water and indicated potential risk to humans and cattle if the water is used without treatment.  相似文献   
405.
This study examined what factors best predict residents’ concerns about neighborhood safety. One-hundred and twenty-two participants were selected from a large, Midwestern metropolitan area. All participants lived in high crime areas. Participants completed a 22-item questionnaire that assessed their perceptions of neighborhood safety and vigilance. These items were clustered as: 1) Community care and vigilance, 2) neighborhood safety concerns, 3) physical incivilities, and 4) social incivilities. Police crime data were also used in the analyses. Our findings suggest that aspects of the broken window theory, collective efficacy, and place attachments/territoriality play a role in affecting residents’ concerns about neighborhood safety.  相似文献   
406.
Biostimulation, bioaugmentation and dual-bioaugmentation strategies were investigated in this study for efficient bioremediation of water co-contaminated with 1,2-dichloroethane (1,2-DCA) and heavy metals, in a microcosm set-up. 1,2-DCA concentration was periodically measured in the microcosms by gas chromatographic analysis of the headspace samples, while bacterial population and diversity were determined by standard plate count technique and Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR–DGGE) analysis, respectively. Dual-bioaugmentation, proved to be most effective exhibiting 22.43%, 26.54%, 19.58% and 30.49% increase in 1,2-DCA degradation in microcosms co-contaminated with As3+, Cd2+, Hg2+ and Pb2+, respectively, followed by bioaugmentation and biostimulation. Dual-bioaugmented microcosms also exhibited the highest increase in the biodegradation rate constant (k1) resulting in 1.76-, 2-, 1.7- and 2.1-fold increase in As3+, Cd2+, Hg2+ and Pb2+ co-contaminated microcosms respectively, compared to the untreated microcosms. Dominant bacterial strains obtained from the co-contaminated microcosms were found to belong to the genera Burkholderia, Pseudomonas, Bacillus, Enterobacter and Bradyrhizobium, previously reported for 1,2-DCA and other chlorinated compounds degradation. PCR–DGGE analysis revealed variation in microbial diversity over time in the different co-contaminated microcosms. Results obtained in this study have significant implications for developing innovative bioremediation strategies for treating water co-contaminated with chlorinated organics and heavy metals.  相似文献   
407.
Organochlorine contamination in the Mediterranean coastal environment of Egypt was assessed based on 26 surface sediments samples collected from several locations on the Egyptian coast, including harbors, coastal lakes, bays, and estuaries. The distribution and potential ecological risk of contaminants is described. Organochlorine compounds (OCs) were widely distributed in the coastal environment of Egypt. Concentrations of PCBs, DDTs, and chloropyrifos ranged from 0.29 to 377 ng g−1 dw, 0.07 to 81.5 ng g−1 dw, and below the detection limit (DL) to 288 ng g−1 dw, respectively. Other organochlorinated pesticides (OCP) studied were 1–2 orders of magnitude lower. OCP and PCBs had higher concentrations at Burullus Lake, Abu Qir Bay, Alexandria Eastern Harbor, and El Max Bay compared to other sites. OCP and PCB contamination is higher in the vicinity of possible input sources such as shipping, industrial activities and urban areas. PCB congener profiles indicated they were derived from more than one commercially available mixture. The ratios of commercial chlordane and heptachlor metabolites indicate historical usage; however, DDT and HCHs inputs at several locations appear to be from recent usage. The concentrations of PCBs and DDTs are similar to those observed in sediments from coastal areas of the Mediterranean Sea. Ecotoxicological risk from DDTs and PCBs is greatest in Abu Qir Bay, Alexandria Harbor, and El-Max Bay.  相似文献   
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410.
To date, many water quality monitoring networks for surface freshwaters have been rather haphazardly designed without a consistent or logical design strategy. Moreover, design practices in recent years indicate a need for cost-effective and logistically adaptable network design approaches. There are many variables that need to be included in a comprehensive yet practical monitoring network: a holistic appraisal of the monitoring objectives, representative sampling locations, suitable sampling frequencies, water quality variable selection, and budgetary and logistical constraints are examples. In order to investigate the factors which affect the development of an effective water quality monitoring network design methodology, a review of past and current approaches is presented.  相似文献   
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