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621.
Fecal source tracking by antibiotic resistance analysis on a watershed exhibiting low resistance 总被引:2,自引:0,他引:2
The ongoing development of microbial source tracking has made it possible to identify contamination sources with varying accuracy,
depending on the method used. The purpose of this study was to test the efficiency of the antibiotic resistance analysis (ARA)
method under low resistance by tracking the fecal sources at Turkey Creek, Oklahoma exhibiting this condition. The resistance
patterns of 772 water-isolates, tested with nine antibiotics, were analyzed by discriminant analysis (DA) utilizing a five-source
library containing 2250 isolates. The library passed various representativeness tests; however, two of the pulled-sample tests
suggested insufficient sampling. The resubstitution test of the library individual sources showed significant isolate misclassification
with an average rate of correct classification (ARCC) of 58%. These misclassifications were explained by low antibiotic resistance
(Wilcoxon test P < 0.0001). Seasonal DA of stream E. coli isolates for the pooled sources human/livestock/deer indicated that in fall, the human source dominated (P < 0.0001) at a rate of 56%, and that human and livestock respective contributions in winter (35 and 39%), spring (43 and
40%), and summer (37 and 35%) were similar. Deer scored lower (17–28%) than human and livestock at every season. The DA was
revised using results from a misclassification analysis to provide a perspective of the effect caused by low antibiotic resistance
and a more realistic determination of the fecal source rates at Turkey Creek. The revision increased livestock rates by 13–14%
(0.04 ≤ P ≤ 0.06), and decreased human and deer by 6–7%. Negative misclassification into livestock was significant (0.04 ≤ P ≤ 0.06). Low antibiotic resistance showed the greatest effect in this category. 相似文献
622.
Modelling vegetation greenness responses to climate variability in a Mediterranean terrestrial ecosystem 总被引:2,自引:0,他引:2
Accurate knowledge of the quality and environmental impact of the highway runoff in Pear River Delta, South China is required
to assess this important non-point pollution source. This paper presents the quality characterization and environmental impact
assessment of rainfall runoff from highways in urban and rural area of Guangzhou, the largest city of Pear River Delta over
1 year’s investigation. Multiple regression and Pearson correlation analysis were used to determine influence of the rainfall
characteristics on water quality and correlations among the constituents in highway runoff. The results and analysis indicates
that the runoff water is nearly neutral with low biodegradability. Oil and grease (O&G), suspended solids (SS) and heavy metals
are the dominant pollutants in contrast to the low level of nutrient constituents in runoff. Quality of highway runoff at
rural site is better than that of at urban site for most constituents. Depth and antecedent dry period are the main rainfall
factors influencing quality of highway runoff. The correlation patterns among constituents in highway runoff at urban site
are consistent with their dominant phases in water. Strong correlations (r ≥ 0.80) are found among chemical oxygen demand (COD), total phosphorus, Cu and Zn as well as conductivity, nitrate nitrogen
and total nitrogen. O&G, COD, SS and Pb in highway runoff at urban site substantially exceed their concentrations in receiving
water of Pear River. The soil directly discharged by highway runoff at rural site has contaminated seriously by heavy metals
in surface layer accompanying with pH conversion from original acidic to alkaline at present. 相似文献
623.
R. Janikowski R. Kucharski A. Sas-Nowosielska 《Environmental monitoring and assessment》2000,60(1):89-102
Errors in environmental resource management over the years have created pollution problems in some areas which are difficult to handle, regardless of the development of knowledge and technologies. This is particularly true in the case of soil pollution. The negative effects of persistent pollutants have been observed for a long time. For instance, lead and cadmium remain in the soil for centuries, during which time they are absorbed by plants and simultaneously cause secondary air pollution. The authors made an attempt to describe and assess the possible options of dealing with the problem of contaminated land in Katowice District. Considering the necessity of a multilateral approach, a pairwise comparison technique has been chosen as the most suitable to show the complexity of the problem. The different variants of actions aimed at preventing the pollutants from getting into the food chain were analyzed against a set of criteria, consisting of the following issues: time, cost, effectiveness, social acceptance, feasibility. The relative importance of actions were judged by the team of experts using the Saaty method. Also, a two-perspective assessment (the two different stakeholders), which involves considering the perspective of an owner of a piece of contaminated land and an ecologist has been performed. The results of comparative, multicriteria and multi-perspective assessment indicate the following:- the best method for contaminated agricultural land management is willful and controlled cultivation,- other recommended actions are deep ploughing and phytoremediation,- there is not much acceptance for the other methods. 相似文献
624.
回顾了原子吸收光谱分析在我国环境、医学卫生和食品分析方面的应用概况。 相似文献
625.
水和废水中黄磷的测定 总被引:1,自引:0,他引:1
试验了黄磷在紫外光区的吸收光谱,建立了紫外分光光度法测定水和废水中黄磷的方法.该方法不需酸化、氧化,可在萃取后直接比色测定.当样品中含有石油类干扰物质时,可用含氧化剂的酸性水溶液对萃取液进行反萃取即能将其排除.该方法灵敏,具有测定范围宽、准确度高、精密度好、操作简便等特点. 相似文献
626.
Adomako D Nyarko BJ Dampare SB Serfor-Armah Y Osae S Fianko JR Akaho EH 《Environmental monitoring and assessment》2008,141(1-3):165-175
Waters and sediments of Subin River, which flows through the industrial and commercial areas of Kumasi in the Ashanti region
of Ghana, were geochemically investigated to ascertain heavy metal pollution levels due to anthropogenic activities. The study
shows preoccupying pollution levels that constitute a threat to public and ecological systems. The waters of Subin River are
neutral to slightly basic, inferred from pH values of 6.89–7.65). Electric conductivity (EC) of the waters ranges from 822
to 1,821 μs/cm and the range of total dissolved solids (TDS) is from 409 to 913 mg/l. Toxic elements contents of sediments
and waters from 10 sites along the river were analysed by instrumental neutron activation analysis (INAA), and Al, As, Cd,
Cr, Cu and Zn were determined. The concentrations of Al, As, Cd, Cr, Cu and Zn in the waters range between 4.02–15.18, 0.007–0.16,
0.002–0.05, 0.001–0.019, 1.32–7.04 and 4.28–10.2 mg/l, respectively. The contamination factors (CF) computed for the elements
indicate that with the exception of sampling site S10, the sediments are polluted with Cd. Chromium contamination in the sediments
is observed at S6 and S7, where the CF values were 1.39 and 1.52, respectively. The pollution load indices (PLI) were low
(<1) and ranged from 0.14 to 0.75, suggesting that the overall sediment column of the river is not polluted. 相似文献
627.
Balachandran KK Jayalakshmy KV Laluraj CM Nair M Joseph T Sheeba P 《Environmental monitoring and assessment》2008,139(1-3):217-226
The interaction effects of abiotic processes in the production of phytoplankton in a coastal marine region off Cochin are
evaluated using multiple regression models. The study shows that chlorophyll production is not limited by nutrients, but their
physiological regulations (responses to nutrients, pH, temperature and salinity) are mainly responsible for the increased
biological production. The model explaining 77% of variability for chlorophyll a production is indicative of preconditioning of the coastal waters. The phytoplankton production is found to be sensitive
to the environment, which varies seasonally. Further, the study suggests that supply of organic matter and grazing of zooplankton
(not included) would improve the model efficiency. Despite this, the good agreement in the computed and measured chlorophyll
a values shows that step-up multiple regression model is a useful tool to understand the influence of environmental variables
on the production of phytoplankton in these coastal waters. 相似文献
628.
629.
Nabil Semmar Maurice Jay Muhammad Farman Maurice Roux 《Environmental Modeling and Assessment》2008,13(1):17-33
The quantitative assessment of plant diversity and its monitoring with time represent a key environmental issue for management
and conservation of natural resources. Assessment of plant diversity could be based on chemical analyses of secondary metabolites
(e.g. flavonoids, terpenoids), because of the substantial quantitative and qualitative between-individual variability in such
compounds. At a geographical scale, the plant populations become widely dispersed, and their monitoring from numerous routine
individual analyses could become restricting. To overcome such constraint, this study develops a multivariate calibration
model giving the relative frequency of a particular taxon from a simple high-performance liquid chromatography (HPLC) analysis
of a plant mixture. The model was built from a complete set of mixtures combining different taxons, according to an experimental
design (Scheffé’s matrix). For each mixture, a reference HPLC pattern was simulated by averaging the individual HPLC profiles
of the constitutive taxons. The calibration models, based on Bayesian discriminant analysis (BDA), gave statistical relationships
between the contributions of each taxon in mixtures and reference HPLC patterns of these mixtures. Finally, these models were
validated on new mixtures by using outside plants. This new biodiversity survey approach is illustrated on four chemical taxons
(four chemotypes) of Astragalus caprinus (Fabaceae). The more differentiated the taxon, the better predicted its contributions (in mixtures) were by BDA calibration
model. This new approach could be very useful for a global routine survey of plant diversity. 相似文献
630.
环境气体标准样品量值的计算及不确定度分析 总被引:1,自引:1,他引:0
依据《气体分析校准气体混合物的制备重量法》(1SO6142—2001)和《气体分析气体标准样品组成的测定和校验比较法》(ISO6143—2001),阐述了环境气体标准样品不同定值方法的量值计算及不确定度来源,并比较了同一气体标准样品采用不同定值方法得到的不同量值结果及不确定度: 相似文献