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441.
Asogan N. Gounden Sreekanth B. Jonnalagadda 《Environmental monitoring and assessment》2013,185(10):8227-8237
The ozone-initiated oxidation of 2-chloroethanol was followed by monitoring the consumption of the halogenated organic substrate. Gas chromatographic analysis of the ozonated products showed an increase in conversion from about 1 % after 3 h of ozone treatment to about 22 % after 12 h. The yields of major ozonated products identified and quantified namely acetaldehyde, acetic acid, and chloride ion increased proportionately as a function of ozone treatment time. The percent conversion of 2-chloroethanol in the presence of acetic acid or ethyl acetate were found to be higher than those under solvent-free conditions with similar products obtained. The use of activated charcoal during the ozonolyis of 2-chloroethanol showed a significant increase in the percent conversion of the substrate compared to solvent free ozonation. Based on the experimental findings, the overall mechanism for the reaction between 2-chloroethanol and ozone is described. 相似文献
442.
济南市环境空气VOCs污染特征及来源识别 总被引:4,自引:4,他引:0
对济南市2010年6月至2012年5月环境空气中56种挥发性有机污染物(VOCs)进行在线气相色谱监测,研究其污染特征并识别其主要来源。结果表明,该期间总挥发性有机化合物(TVOCs)变化规律基本一致,其平均浓度水平夏季冬季秋季春季;TVOCs浓度的日变化趋势呈双峰分布,与早晚交通高峰相吻合;济南市城区环境空气中VOCs的主要物种是C3~C5的烷烃、丙烯、顺-2-丁烯、甲苯和间、对二甲苯等;不同季节环境空气中VOCs的主要物种基本一致,夏季烯烃所占比重高于其他季节;烷烃、烯烃与TVOCs的浓度日变化趋势相似,呈明显的双峰状,而芳香烃浓度日变化规律双峰特征不明显。济南市城区VOCs的主要来源为汽车尾气、工业源、燃烧源。 相似文献
443.
444.
Fernandes CE Das A Nath BN Faria DG Loka Bharathi PA 《Environmental monitoring and assessment》2012,184(5):2677-2689
We investigated the influence on bacterial community and biochemical variables through mechanical disturbance of sediment-akin
to small-scale mining in Kalbadevi beach, Ratnagiri, a placer-rich beach ecosystem which is a potential mining site. Changes
were investigated by comparing three periods, namely phase I before disturbance, phase II just after disturbance, and phase
III 24 h after disturbance as the bacterial generation time is ≤7 h. Cores from dune, berm, high-, mid-, and low-tide were
examined for changes in distribution of total bacterial abundance, total direct viability (counts under aerobic and anaerobic
conditions), culturability and biochemical parameters up to 40 cm depth. Results showed that bacterial abundance decreased
by an order from 106 cells g − 1 sediment, while, viability reduced marginally. Culturability on different-strength nutrient broth increased by 155% during
phase II. Changes in sedimentary proteins, carbohydrates, and lipids were marked at berm and dune and masked at other levels
by tidal influence. Sedimentary ATP reduced drastically. During phase III, Pearson’s correlation between these variables evolved
from non-significant to significant level. Thus, simulated disturbance had a mixed effect on bacterial and biochemical variables
of the sediments. It had a negative impact on bacterial abundance, viability and ATP but positive impact on culturability.
Viability, culturability, and ATP could act as important indicators reflecting the disturbance in the system at short time
intervals. Culturability, which improved by an order, could perhaps be a fraction that contributes to restoration of the system
at bacterial level. This baseline information about the potential mining site could help in developing rational approach towards
sustainable harnessing of resources with minimum damage to the ecosystem. 相似文献
445.
Langston WJ O'Hara S Pope ND Davey M Shortridge E Imamura M Harino H Kim A Vane CH 《Environmental monitoring and assessment》2012,184(1):289-311
Biomonitoring of contaminants (metals, organotins, polyaromatic hydrocarbons (PAHs), PCBs) was undertaken in Milford Haven
Waterway (MHW) and a reference site in the Tywi Estuary (St Ishmael/Ferryside) during 2007–2008. Bioindicator species encompassed
various uptake routes—Fucus vesiculosus (dissolved contaminants); Littorina littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and Hediste (=Nereis) diversicolor (sediments). Differences in feeding and habitat preference have subtle implications for bioaccumulation trends though, with
few exceptions, contaminant burdens in MHW were higher than the Tywi reference site, reflecting inputs. Elevated metal concentrations
were observed at some MHW sites, whilst As and Se (molluscs and seaweed) were consistently at the higher end of the UK range.
However, for most metals, distributions in MH biota were not exceptional. Several metal-species combinations indicated increases
in bioavailability upstream, which may reflect the influence of geogenic/land-based sources—perhaps enhanced by lower salinity.
TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi were close to zero. Phenyltins were not accumulated
appreciably in M. edulis, whereas some H. diversicolor populations appear subjected to localized (historical) sources. PAHs in H. diversicolor were distributed evenly across most of MHW, although acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and chrysene were highest at one site near the mouth; naphthalenes in H. diversicolor were enriched in the mid-upper Haven (a pattern seen in M. edulis for most PAHs). Whilst PAH (and PCB) concentrations in MH mussels were mostly above reference and OSPAR backgrounds, they
are unlikely to exceed ecotoxicological thresholds. Bivalve Condition indices (CI) were highest at the Tywi reference site
and at the seaward end of MH, decreasing upstream—giving rise to several significant (negative) relationships between CI and
body burdens. Despite the possible influence of salinity gradient as a complicating factor, multivariate analysis indicated
that a combination of contaminants could influence the pattern in condition (and the biomarkers metallothionein and TOSC).
Integrating bioaccumulation data with biological and biochemical endpoints is seen as a useful way to discriminate environmental
quality of moderately contaminated areas such as MHW and to prioritise cause and effect investigations. 相似文献
446.
de Andrade Brito I Arruda Freire C Yamamoto FY Silva de Assis HC Rodrigues Souza-Bastos L Cestari MM de Castilhos Ghisi N Prodocimo V Filipak Neto F de Oliveira Ribeiro CA 《Journal of environmental monitoring : JEM》2012,14(2):615-625
Paraíba do Sul River is located at a very densely inhabited region of Brazil crossing the three most industrialized states of the country (S?o Paulo, Minas Gerais and Rio de Janeiro states). As a result, industrial and farming residues as well as urban sewage are frequently disposed without appropriate treatment. The current study aimed at investigating the water quality in three reservoirs along the Paraíba do Sul River (Ilha dos Pombos, Santa Cecília and Santa Branca), through physiological, morphological, biochemical, and genetic biomarkers. The bioindicator chosen was the catfish Pimelodus maculatus, sampled during the dry (June 2008) and rainy (February 2009) seasons. Also, some water physicochemical parameters were analyzed from the sampling sites, but displayed no alterations according to the Brazilian Agency for Water Quality Legislation. Branchial carbonic anhydrase activity was inhibited in the dry season, while renal carbonic anhydrase activity was inhibited in the rainy season in the Santa Branca reservoir, indicating disturbance of osmoregulatory and acid-base regulation processes. Histopathological alterations were observed in the gills (neoplasic and tissue hyperplasia processes) and liver (necrosis), indicating serious damage to the functional integrity of these organs. A high incidence of melanomacrophage centers was observed in the liver, suggesting an intense immune response in all reservoirs. Acetylcholinesterase and catalase activity showed also differences corroborating some morphological results. Likewise, the induction of the micronucleus and DNA damage indicate genotoxicity, but mainly in the Santa Branca reservoir. Thus, the health status of P. maculatus warrants caution in the use of the water from the 3 reservoirs for direct human consumption, particularly after the accidental spill of endosulfan in November 2008, three months before the rainy season sampling. 相似文献
447.
Michael G. Hutchins Amelie Deflandre-Vlandas Paulette E. Posen Helen N. Davies Colin Neal 《Environmental Modeling and Assessment》2010,15(2):93-109
A combined semi-distributed hydrological model (CASCADE/QUESTOR) is used to evaluate the steady-state that may be achieved
after changes in land-use or management and to explore what additional factors need to be considered in representing catchment
processes. Two rural headwater catchments of the River Derwent (North Yorkshire, UK) were studied where significant change
in land-use occurred in the 1990s and the early 2000s. Much larger increases in mean nitrate concentration (55%) were observed
in the catchment with significant groundwater influence (Pickering Beck) compared with the surface water-dominated catchment
(13% increase). The increases in Pickering Beck were considerably greater than could be explained by the model in terms of
land-use change. Consequently, the study serves to focus attention on the long-term increases in nitrate concentration reported
in major UK aquifers and the ongoing and chronic impact this trend is likely to be having on surface water concentrations.
For river environments, where groundwater is a source, such trends will mask the impact of measures proposed to reduce the
risk of nitrate leaching from agricultural land. Model estimates of within-channel losses account for 15–40% of nitrate entering
rivers. 相似文献
448.
T. R. Gireeshkumar P. M. Deepulal N. Chandramohanakumar 《Environmental monitoring and assessment》2013,185(3):2535-2552
Sequential chemical extraction using chelating agents were used to study the P dynamics and its bioavailability along the surface sediments of the Cochin estuary (southwest coast of India). Sediments were analyzed for major P species (iron bound P, calcium bound P, acid soluble organic P, alkali soluble organic P and residual organic P), Fe, Ca, total carbon, organic carbon, total nitrogen and total sulfur contents. An abrupt increase in the concentration of dissolved inorganic P with increasing salinity was observed in the study region. Iron-bound P exhibited a distinct seasonal pattern with maximum values in the monsoon season when fresh water condition was prevailed in the estuary. As salinity increased, the percentage of iron-bound P decreased, while that of calcium-bound P and total sedimentary sulfur increased. C/P and N/P ratios were low which indicate that large amounts of organic matter enriched with P tend to accumulate in surface sediments. The high organic P contribution in the sedimentary P pool may indicate high organic matter load with incomplete mineralization, as well as comparatively greater percentage of humic substance and resistant organic compounds. Principal component analysis is employed to find the possible processes influencing the speciation of P in the study region and indicate the following processes: (1) the spatial and seasonal variations of calcium bound P and acid soluble organic P was mainly controlled by sediment texture and organic carbon content, (2) sediment redox conditions control the distribution of iron bound P and (3) the terrigenous input of organic P is a significant processes controlling total P content in surface sediments. The bioavailable P was very high in the surface sediments which on an average accounts for 59 % in the pre-monsoon, 65 % in the monsoon and 53 % in the post-monsoon seasons. The surface sediments act as a potential internal source of P in the Cochin estuary. 相似文献
449.
C. Kesavachandran B. S. Pangtey V. Bihari M. Fareed M. K. Pathak A. K. Srivastava N. Mathur 《Environmental monitoring and assessment》2013,185(2):1265-1272
The World Health Organization has estimated that air pollution is responsible for 1.4 % of all deaths and 0.8 % of disability-adjusted life years. NOIDA, located at the National Capital Region, India, was declared as one of the critically air-polluted areas by the Central Pollution Control Board of the Government of India. Studies on the relationship of reduction in lung functions of residents living in areas with higher concentrations of particulate matter (PM) in ambient air were inconclusive since the subjects of most of the studies are hospital admission cases. Very few studies, including one from India, have shown the relationship of PM concentration and its effects of lung functions in the same location. Hence, a cross-sectional study was undertaken to study the effect of particulate matter concentration in ambient air on the lung functions of residents living in a critically air-polluted area in India. PM concentrations in ambient air (PM1, PM2.5) were monitored at residential locations and identified locations with higher (NOIDA) and lower concentrations (Gurgaon). Lung function tests (FEV1, PEFR) were conducted using a spirometer in 757 residents. Both air monitoring and lung function tests were conducted on the same day. Significant negative linear relationship exists between higher concentrations of PM1 with reduced FEV1 and increased concentrations of PM2.5 with reduced PEFR and FEV1. The study shows that reductions in lung functions (PEFR and FEV1) can be attributed to higher particulate matter concentrations in ambient air. Decline in airflow obstruction in subjects exposed to high PM concentrations can be attributed to the fibrogenic response and associated airway wall remodeling. The study suggests the intervention of policy makers and stake holders to take necessary steps to reduce the emissions of PM concentrations, especially PM1, PM2.5, which can lead to serious respiratory health concerns in residents. 相似文献
450.
Nédia de Castilhos Ghisi Marta Margarete Cestari 《Environmental monitoring and assessment》2013,185(4):3201-3207
The glyphosate-based herbicide, Roundup®, is one of the most used pesticides worldwide. In concert with the advent of transgenic crops resistant to glyphosate, the use of this pesticide has led to an increase in agricultural yields. The objective of this study was to evaluate the genotoxic effect that the herbicide Roundup® (at a concentration of 6.67 μg/L, corresponding to 3.20 μg/L glyphosate) can have on the fish Corydoras paleatus. Treatment groups were exposed for 3, 6, and 9 days, and effects were analyzed using the piscine micronucleus test (PMT) and comet assay. A group subjected to filtered water only was used as a negative control. The PMT did not show differences between the control and exposed groups for any of the treatment times. In contrast, the comet assay showed a high rate of DNA damage in group exposed to Roundup® for all treatment times, both for blood and hepatic cells. We conclude that for the low concentration used in this research, the herbicide shows potential genotoxic effects. Future research will be important in evaluating the effects of this substance, whose presence in the environment is ever-increasing. 相似文献