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191.
Cadmium and lead were determined simultaneously in seawater by differential pulse stripping voltammetry (DPSV) preceded by
adsoptive collection of complexes with 8-hydroxyquinoline (oxine) on to a hanging mercury drop electrode (HMDE). In preliminary
experiments the optimal analytical condition for oxine concentration was found to be 2.10−5 M, at pH 7.7, the accumulation potential was −1.1 V, and the initial scannig potential was −0.8 V. The peak potentials were
found −0.652 V for Cd and −0.463 V for Pb At the 60 s accumalation time. The limit of detection (LOD) and limit of quantitatification
(LOQ) were found to be by voltammetry as 0.588 and 1.959 μg l−1 (RSD, 5.50%) for Cd and 0.931 and 3.104 μg l−1 (RSD, 4.10%) for Pb at 60 s stirred accumulation time respectively. In these conditions the most of the seawater samples
are amenable for direct voltammetric determination of cadmium and lead using a HMDE. An adsorptive stripping mechanism of
the electrode reaction was proposed. For the comparison, seawater samples were also analysed by ICP-atomic emission spectrometry
method (ICP-AES). The applied voltammetric technique was validated and good recoveries were obtained. 相似文献
192.
The microbiological contamination of waterways by pathogenic microbes has been, and is still, a persistent public safety concern
in the United States and in most countries of the world. As most enteric pathogens are transmitted through the fecal–oral
route, fecal pollution is generally regarded as the major contributor of pathogens to waterways. Fecal pollution of waterways
can originate from wastewater treatment facilities, septic tanks, domestic- and wild-animal feces, and pets. Because enteric
pathogens are derived from human or animal sources, techniques capable of identifying and apportioning fecal sources have
been intensively investigated for use in remediation efforts and to satisfy regulatory concerns. Pollution of human origin
is of the most concern, since human feces is more likely to contain human-specific enteric pathogens. Fecal indicator bacteria
have been used successfully as the primary tool for microbiologically based risk assessment. However measurement of fecal
indicator bacteria does not define what pathogens are present, or define the sources of these bacteria. Microbial source tracking
(MST) methods that have the ability to differentiate among sources of fecal pollution are currently under development. These
methods will ultimately be useful for risk assessment purposes and to aid regulatory agencies in developing strategies to
remediate microbiologically impaired waterways. 相似文献
193.
The methodology of materials accounting is presented and applied to developing nutrient balance (nitrogen and phosphorus)
in a river basin. The method is based on the balance principle: inputs and outputs of each nitrogen and phosphorus related
sub-systems were balanced. The application of the methodology strategies was illustrated by means of a case study of the Krka
river, Slovenia. Different pathways of emission to surface waters were taken into account: WWTP discharges, direct discharges,
erosion/runoff and baseflow. Total annual emission into the river Krka was estimated to be 362 tonnes N/year and 73.3 tonnes
P/year. The main sources of nitrogen are diffuse sources, emitted via baseflow (52%). Other important sources are effluents
from WWTP, which account for 36% of total emissions. Other sources like erosion and direct discharges to surface water (animal
manure, industry, households) are of lower magnitude. Erosion is main source of phosphorus emission (55% of total emission),
WWTP effluents account for 37% of total emission, while other sources are less important. Besides reduction of point sources
by means of wastewater collection and implementation of nutrient removal technology, managing agricultural nitrogen and phosphorus
to protect water quality should become a major challenge in the Krka river basin. 相似文献
194.
Eutrophication conditions and ecological status in typical bays of Lake Taihu in China 总被引:4,自引:0,他引:4
Sampling was conducted at three site groups, group E (in East Taihu Bay), G (in Gonghu Bay) and M (in Meiliang Bay) in Lake
Taihu. TN and TP concentrations among site groups was in the increasing order of E < G < M. TP level at G sites is at the
critical threshold for loss of submersed macrophytes. Mean values of DO and Transparence showed different trend, i.e., E >
G > M. The mean phytoplankton fresh-weight biomass at M sites was 5.81 mg/l, higher than that at E sites (4.96 mg/l) and G
sites (5.18 mg/l). Mean zooplankton fresh-weight biomass was in the decreasing order of M (6.4 mg/l) > G (4.9 mg/l) > E (2.7 mg/l).
However, Rotifera density was in the sequence of E > G > M. Both zooplankton biomass and phytoplankton biomass increased with the rise of TN
and TP concentrations. Relationships between zooplankton biomass and phytoplankton biomass showed that zooplankton played
a limited role in the control of algae in eutrophic lakes. Nutrient availability is much more important than zooplankton grazing
pressure in controlling phytoplankton growth in lakes. For most sites in Lake Taihu, reduction of nutrient loading, as well
as macrophyte conservation, zappears to be especially important in maintaining high water quality and regulating lake biological
structure, but for M sites, it’s urgent to control nutrient inputs rather than to restore macrophyte community. 相似文献
195.
196.
Passy SI 《Environmental monitoring and assessment》2007,127(1-3):409-417
Diatom assemblages from 83 epilithic samples taken from the Mesta River, Bulgaria, were regressed against three sets of predictor
variables, i.e. environmental, spatial, and temporal. Redundancy analysis (RDA) of species and environmental data explained
36% of the diatom variance and extracted several important gradients of species distribution, associated with a downstream
increase in nutrient levels, pH, temperature, and organic pollution. The inclusion of spatial and temporal variables in the
RDA model captured additional 24% of the diatom variance and revealed three more gradients, a spatial gradient represented
by higher order polynomial terms of latitude and longitude, and two temporal gradients of annual and seasonal variation. Partial
RDAs demonstrated that the unique contribution of each predictor set to the explained diatom variance was the highest in the
spatial dataset (16%), followed by the environmental (9%), and the temporal (7%) datasets. The remaining 28% of the variance
was explained by the covariance of the predictor sets. This suggests that in biomonitoring of single stream basins, the cheap
and simple account of space and time would explain most of the variance in assemblage composition obviating the necessity
of expensive and time-consuming environmental assessments. The nature of the underlying environmental mechanisms can be easily
inferred from the diatom composition itself. 相似文献
197.
Almeida CA Quintar S González P Mallea MA 《Environmental monitoring and assessment》2007,133(1-3):459-465
A study of the water quality of the Potrero de los Funes River (San Luis – Argentina) was carried out in order to evaluate
the possible effect of the anthropogenic activities on the river developed in the homonymous town. Samples were collected
during the period March 2000–November 2005 at three selected sampling sites (RP1, RP2 and RP3). Different physicochemical and bacteriological parameters (turbidity, pH, conductivity, suspended solids, alkalinity, potassium,
sodium, calcium, magnesium, chlorides, nitrates, phosphates, sulphates, chemical oxygen demand (COD), 5-day biological oxygen
demand (BOD5), dissolved oxygen, total coliforms, Escherichia coli and total heterotrophic bacteria) were analysed according to the Standard Method for the Examination of Water and Wastewater.
When comparing the values of total coliforms, E. coli, total heterotrophic bacteria, COD, BOD5 and phosphates from the zone without anthropogenic influence (RP1) and the urban zones (RP2 and RP3) an important variation in the parameters was observed. These results indicate that the urban activity produces a serious
and negative effect on the water quality, thus constituting a sanitary risk and may have a major impact on the trophic status
of the Potrero de los Funes dam. As case study, we report on the use of General Quality Index (GQI) to evaluate spatial and
seasonal changes in the water quality of Potrero de los Funes River. Results revealed a significant degradation of the water
quality at RP2 and RP3. 相似文献
198.
Sustainable development planning must be based on environmental and biophysical baseline indices that effectively define comparative development potential and environmental constraints. As such, indices must define the comparative advantage of the natural resource base and measure the fundamental capacity to sustain production rates of natural resource goods and services used to create societal well being. Complex biophysical and socioeconomic characteristics affect the identification and selection of sustainable development strategies. When derived from effective baseline indicators, indices may be used to define the spatial and temporal distribution of economically viable production opportunities and may be expressed in derived indices that realistically describe basic production opportunities and guide the selection of feasible, long-term development strategies. Specifically, representative indices are critical in the identification of development goals and realistic objectives and can be used to evaluate, select and implement sustainable development strategies and plans. It is stressed that the relevancy and effectiveness of public policies depend on the identification of representative evaluation models and baseline indices to define development strategies that are both environmentally sustainable and economically viable. In this context, the role of baseline indicators that define natural resource production capacities is discussed. This includes potential resource uses, derived benefits and their economic and environmental impacts. Key thematic indicators are suggested that may be especially useful in identifying development alternatives and impacts. This suggested that clearly defined environmental pollution limits or impact standards be used to define public risk tolerance limits and carrying capacity constraints. It is argued that these measures may be more effective in directing policy choices than economic valuation of non market goods and services that represent environmental externalities associated with resource exploitation options and economic development strategies. To this end, examples of thematic indicators and derived indices are introduced that may prove effective in resource assessment, economic evaluation and strategic development planning. 相似文献
199.
介绍了瑞典的水环境保护法规政策、水环境保护机构、污水处理体系及其在水环境保护方面的特色做法。结合目前我国水环境管理所处的阶段,从顶层设计、宣传教育、项目管理、污染防治等方面,总结了瑞典经验对我国水环境保护工作的启示。 相似文献
200.
综述了微生物絮凝剂产生菌筛选和培育方面的研究进展,介绍了微生物絮凝剂在给水和饮用水、乳化液的油水分离、污水处理等领域的应用,以及廉价培养基的探索实践。提出针对影响微生物絮凝剂产生菌生长代谢的环境条件开展深入研究,同时寻找或设计廉价培养基,降低生产成本,推动其工业化应用。 相似文献