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881.
传统概念的地气测量是指地下上升到地表并扩散到大气空间的天然状态气体 ,如CO2 、CH4 、Rn、Hg、H2 等。近十多年的研究证实地气还包含着新的内涵 ,即地壳岩石以及地表土壤中还存着痕量的金属与非金属气体 ,通过捕集这些气体 ,可以获得更多的深部地质构造、矿床信息。据报导 ,国内外的研究主要是在已知矿床上做的正演研究。本文是在已知隐伏断层构造上方地表 ,试验金属与非金属地气存在的可能性。 相似文献
882.
Zhang B Hong M Zhang B Zhang XL Zhao YS 《Environmental monitoring and assessment》2007,133(1-3):379-386
Endemic fluorosis was investigated and studied in the west region of the Songnen plain, Northeast China in 2001–2002. The
results showed that the fluorine distribution in aquatic environment was that the fluorine concentrations in the lake water
and unconfined ground water were higher than that in the river water and confined ground water. The lake water (Alkali lake)
is connected with unconfined ground water. In unconfined ground water, from the east and southeast areas to the west and the
northwest areas of the plain, fluorine concentration fluctuated with high and low alternatively. The fluorine in the water
comes from the weathering of rocks and minerals in the mountains and hills around the Songnen Plain. The main influence factors
of the fluorine distribution in aquatic environment are discussed. Unconfined ground water containing high fluorine is used
as drinking water. In this region, the fluorine concentration in drinking water is evidently correlated to the morbidity of
dental and skeletal fluorosis. High fluorine concentration in drinking water has endangered human health. 相似文献
883.
The present paper describes an effort for developing the total maximum daily load (TMDL) for phosphorus and a load reduction
strategy for the Feitsui Reservoir in Northern Taiwan. BASINS model was employed to estimate watershed pollutant loads from
nonpoint sources (NPS) in the Feitsui Reservoir watershed. The BASINS model was calibrated using field data collected during
a 2-year sampling period and then used to compute watershed pollutant loadings into the Feitsui Reservoir. The simulated results
indicate that the average annual total phosphorus (TP) loading into the reservoir is 18,910 kg/year, which consists of non-point
source loading of 16,003 kg/year, and point source loading of 2,907 kg/year. The Vollenweider mass balance model was used
next to determine the degree of eutrophication under current pollutant loading and the load reduction needed to keep the reservoir
from being eutrophic. It was estimated that Feitsui Reservoir can becoming of the oligotrophic state if the average annual
TP loading is reduced by 37% or more. The results provide the basis on which an integrated control action plan for both point
and nonpoint sources of pollution in the watershed can be developed. 相似文献
884.
Use of USLE/GIS Methodology for Predicting Soil Loss in a Semiarid Agricultural Watershed 总被引:1,自引:0,他引:1
The Universal Soil Loss Equation (USLE) is an erosion model to estimate average soil loss that would generally result from
splash, sheet, and rill erosion from agricultural plots. Recently, use of USLE has been extended as a useful tool predicting
soil losses and planning control practices in agricultural watersheds by the effective integration of the GIS-based procedures
to estimate the factor values in a grid cell basis. This study was performed in the Kazan Watershed located in the central
Anatolia, Turkey, to predict soil erosion risk by the USLE/GIS methodology for planning conservation measures in the site.
Rain erosivity (R), soil erodibility (K), and cover management factor (C) values of the model were calculated from erosivity
map, soil map, and land use map of Turkey, respectively. R values were site-specifically corrected using DEM and climatic
data. The topographical and hydrological effects on the soil loss were characterized by LS factor evaluated by the flow accumulation
tool using DEM and watershed delineation techniques. From resulting soil loss map of the watershed, the magnitude of the soil
erosion was estimated in terms of the different soil units and land uses and the most erosion-prone areas where irreversible
soil losses occurred were reasonably located in the Kazan watershed. This could be very useful for deciding restoration practices
to control the soil erosion of the sites to be severely influenced. 相似文献
885.
Pedrosa P 《Environmental monitoring and assessment》2007,129(1-3):137-150
This study investigates the inherent optical properties (IOP) of a Brazilian river during a non-natural, anthropogenically
mediated, toxic spill of a wood-pulping factory (the ‘Cataguazes accident’). The results indicated an outstanding transformation
in the river water chromophoric dissolved organic matter (CDOM) pools. For instance, increases in CDOM absorption coefficients,
a
CDOM
(λ), which were averaged at specific spectral intervals, , ranged from 58-fold at the UV-B and UV-A ranges to 95-fold at the PAR range. As a result, the water color expressed as CDOM
absorption at 440 nm, a
CDOM
(440), varied from 4.16 to 365.03 m-1. For S-coefficient, the variations ranged from ∼1.1 to 5.6-fold, respectively, at the 300–650 nm and UV-B range. The variability
of S as a proxy of dissolved chromophores was thus clearly influenced by the spectral range used. Optical proportions were also
investigated through the use of and S ratios at the UV-B, UV-A, and PAR ranges and, in the case of , also at the NIR range. This approach also showed clear variations between the water samples, likely reflecting changes in
the composition of optically active substances in the river system. As a whole, the findings obtained here indicated that
both the quantity and quality of the chromophoric material dissolved in the river water were greatly altered by the toxic
spill. The changes in the optical properties of the river water, although extreme and likely with no parallel in the literature,
were quite rapid as indicated by the optical resilience of the system. Overall, this study indicates that IOP might be thought,
and possibly used, as a metric tool for monitoring the state of waters and aquatic ecosystems. 相似文献
886.
Demirak A 《Environmental monitoring and assessment》2007,129(1-3):189-196
In this study, the chemical composition of the rainwater in Yatağan, which is a region surrounding a coal power plant was
investigated from February to April 2002. Rainwater samples were obtained from Yatağan, located northwest of Muğla City in
Turkey. pH values and concentrations of major ions (Ca2+, Na+, K+, , , ) in the rainwater samples were analyzed. The pH varied from 5.1 to 7.9 with an average of 6.7 which was in alkaline range
considering 5.6 as the neutral pH of cloud water in equilibrium with atmospheric CO2. In the total of 30 rain events, only three events were observed with water in the acidic range (<5.6), which occurred after
continuous rains. The equivalent concentration of components followed the order: Ca2+ > > Na+ > > > K+ > H+. The anion and cation concentrations in the rainwater samples showed a high sulphate concentration (131 μEq/l), as well as
high sodium (40 μEq/l) and calcium (298 μEq/l) concentrations. These values indicate that one probable source of the high
sodium concentration is fly ash, after the coal burning process and the power plant can be effective on level concentrations in rainwater. In addition, the dust-rich local and surrounding limestone environment might have caused the
high concentration of Ca2+ in rainwater of the Yatağan Basin. Due to a large contribution of these cations to the sulphate neutralization action, the
rainwater of this region displays only a moderate acidity, which does not cause significant environmental impact. 相似文献
887.
Wen-Cheng Liu Jan-Tai Kuo Chih-Chieh Young Ming-Ching Wu 《Environmental Modeling and Assessment》2007,12(3):201-211
Numerical models are often used to evaluate the potential impact of human alternation of natural water bodies and to help
the design of the alternation to mitigate its impacts. In the past decade, three-dimensional hydrodynamic and reactive transport
modeling has matured from a research subject to a practical analysis technology. This paper presents a practical study in
which a three-dimensional hydrodynamic and water quality model [hydrodynamic eutrophication model (HEM-3D)] was applied to
determine the optimal location for treated wastewater discharged from marine outfall system in the Keelung harbor and the
adjacent coastal sea. First, model validation was conducted with respect to surface elevation, current, and water quality
variables measured in the Keelung harbor station and its coastal sea. The overall performance of the model was in qualitative
agreement with the available field data. The model was then used to evaluate several scenarios of the locations from marine
outfall system. Based on model simulation results, a location at the northeast of Ho-Ping Island was recommended for adoption
because the environmental impact is smaller than any other alternative.
相似文献
Wen-Cheng LiuEmail: |
888.
889.
Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et~al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or
chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary
objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic
from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination
of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168~hours. Results
showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution.
Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in
the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO4/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic
present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting
in elevated levels at the consumer's tap. 相似文献
890.
Budziak D Richard L Beltrame E Carasek E 《Environmental monitoring and assessment》2007,127(1-3):435-444
Formation of trihalomethanes (THM) was monitored at the Laboratório de Camarões Marinhos (LCM) from the Universidade Federal de Santa Catarina. THM could be present because chlorinated effluents from disinfection are discharged from the different hatchery rooms. THM quantification was done through an analytical methodology using Purge&;Trap coupled with a gas chromatograph equipped with an electron capture detector. Relative standard deviation (RSD), limit of detection (LOD) and limit of quantification (LOQ) for the methodology corresponded to the ranges of 8–17%; 0.01–0.03 μg L?1 and 0.03–0.08 μg L?1, respectively. Linear working range was of 0.1–8.0 μg L?1 for all compounds. Enrichment and recovery method was applied to evaluate possible matrix effects and the results varied from 71.2% to 107.9%. LCM was monitored between August and December, 2004. This study showed that THM did not increase with the increase in postlarvae production and also that the aquatic life and the surrounding environment were not affected. 相似文献