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71.
Computer-based landscape evolution models offer the ability to evaluate landscape stability over the short (annual), medium
(decades to hundreds of years) and long-term (thousands of years). Modeling has advantages in that design ideas can be tested,
different surface material properties can be evaluated and risk analysis carried out. Landscape evolution models allow landscape
surface change through time. These models also offer the advantage that the landscape can be evaluated visually as it develops
through time, which is not possible with other types of models. Landscape evolution models can be used for not only soil loss
assessment (i.e. tonnes/hectare/year), but also to evaluate the method of soil loss (i.e. rill or interrill erosion). This
study examines a range of waste rock dump designs for the Minera Alumbrera Ltd. copper mine, Argentina. An erosion assessment
using the SIBERIA erosion model over a 1000-year simulation period demonstrates waste rock dump designs using a conventional
stepped design of backsloping benches and caps with angle of repose slopes provide the lowest average erosion rates and depths
of incision than do other designs. Caution should be applied in interpreting these results as the SIBERIA erosion model is
sensitive to parameter input and in this case was calibrated and run using a generic set of parameters that are not site specific.
Nevertheless, the results provide a guide as to the strengths and weaknesses of different rehabilitation designs and demonstrate
the insights that modeling studies can provide. 相似文献
72.
Methodologies are presented for minimization of risk in a river water quality management problem. A risk minimization model is developed to minimize the risk of low water quality along a river in the face of conflict among various stake holders. The model consists of three parts: a water quality simulation model, a risk evaluation model with uncertainty analysis and an optimization model. Sensitivity analysis, First Order Reliability Analysis (FORA) and Monte–Carlo simulations are performed to evaluate the fuzzy risk of low water quality. Fuzzy multiobjective programming is used to formulate the multiobjective model. Probabilistic Global Search Laussane (PGSL), a global search algorithm developed recently, is used for solving the resulting non-linear optimization problem. The algorithm is based on the assumption that better sets of points are more likely to be found in the neighborhood of good sets of points, therefore intensifying the search in the regions that contain good solutions. Another model is developed for risk minimization, which deals with only the moments of the generated probability density functions of the water quality indicators. Suitable skewness values of water quality indicators, which lead to low fuzzy risk are identified. Results of the models are compared with the results of a deterministic fuzzy waste load allocation model (FWLAM), when methodologies are applied to the case study of Tunga–Bhadra river system in southern India, with a steady state BOD–DO model. The fractional removal levels resulting from the risk minimization model are slightly higher, but result in a significant reduction in risk of low water quality. 相似文献
73.
本文通过对陕西华县金堆城钼矿区西川河流经废石堆的入口处和出口处采取的水样进行了常量组分、微量组分的测定,分析其污染特征,确定出金堆城钼矿废石堆对水环境的污染指标. 相似文献
74.
Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial
for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental
Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some
operational difficulties for the use of this model in Germany, which has been developed for the United States. The model results
are tested against field data of the water balance, measured on test fields on the Georgswerder landfill in Hamburg. Theoretically,
HELP considers gravitational forces as driving forces of water flow only. Therefore capillary barriers cannot be simulated.
Furthermore, the formation of and the flow through macropores are not considered, a main critical process that the diminishes
the effectiveness of compacted soil liners. In the output comparison, the matching of measured and simulated data is quite
good for lateral drainage, but failed for surface runoff and liner leakage through compacted soil liners. A further validation
study is planned for HELP version 3 using a broader range of test field data.
Received: 10 January 1995 · Accepted: 14 November 1995 相似文献
75.
The dynamic leaching behaviour of environmentally relevant heavy metals makes it difficult to fix a suitable elution time of leaching tests. With ten different solid materials which were characterized by wavelength-dispersive X-ray fluorescence analysis and by the determination of aqua regia soluble amounts of heavy metals we performed 24 h and long-term leaching tests using the pHstat procedure at pH 4 to be able to compare the resulting acid neutralization capacities (ANC) and heavy metal mobilization. This comparison demonstrates firstly the limitations in predicting the extent of heavy metal release after a longer (geological) time period only from the leached amounts after 24 hours and the ratio of the ANC values measured in the 24 h test and in a long-term experiment, respectively. Secondly, the effect of elution time on the leachability is not uniform but element specific and matrix dependent. Hence, the pHstat leaching test performed in the usual manner does not seem to be suitable particularly for assessing long-term mobilization of heavy metals under acidic conditions. Additional experiments under variation of shaking frequency and time clearly demonstrate the dominant influence of the first parameter on the resulting ANC and support the necessity of further studies to optimize the pHstat leaching procedure before the test can be recommended in regulations for environmental protection. 相似文献
76.
Massive amounts of land are being reclaimed to build airports, new cities, ports, and highways. Hundreds of kilometers are added each year, as coastlines are extended further out to the sea. In this paper, this urbanization approach is monitored by Persistent Scatterer Interferometry (PSI) technique with Sentinel-1 SAR data. The study aims to explore this technology in order to support local authorities to detect and evaluate subtle terrain displacements. For this purpose, a large 3-years Sentinel-1 stack composed by 92 images acquired between 07/01/2015 to 27/01/2018 is employed and stacking techniques are chosen to assess ground motion. The test site of this study, Rize, Turkey, has been declared at high risk of collapse and radical solutions such as the relocation of the entire city in another area are been taken into consideration. A media fact-checking approach, i.e. evaluating national and international press releases on the test site, is considered for the paper and this work presents many findings in different areas of the city. For instance, alerts are confirmed by inspecting several buildings reported by the press. Critical infrastructures are monitored as well. Portions of the harbor show high displacement rates, up to 1 cm/year, proving reported warnings. Rural villages belonging to the same municipality are also investigated and a mountainous village affected by landslide is considered in the study. Sentinel-1 is demonstrated to be a suitable system to detect and monitor small changes or buildings and infrastructures for these scenarios. These changes may be highly indicative of imminent damage which can lead to the loss of the structural integrity and subsequent failure of the structure in the long-term. In Rize, only a few known motion-critical structures are monitored daily with in-situ technologies. SAR interferometry can assist to save expensive inspection and monitoring services, especially in highly critical cases such as the one studied in this paper. 相似文献
77.
Mineralogical constraints on the determination of neutralization potential and prediction of acid mine drainage 总被引:4,自引:1,他引:3
A. D. Paktunc 《Environmental Geology》1999,39(2):103-112
Acid-base accounting tests, commonly used as a screening tool in acid mine drainage (AMD) predictions, have limitations in
(1) measuring with confidence the amount of neutralizers present in samples and (2) affording an interpretation of what the
test results mean in terms of predicting the occurrence of acid mine drainage. Aside from the analytical difficulties inherent
to the conventional methods, a potential source of error in neutralization potential (NP) measurements is the contribution
from the dissolution of non-carbonate minerals. Non-carbonate alkalinity measured during static tests may or may not be available
to neutralize acidity produced in the field. In order to assess the value-added of extending the NP with the knowledge of
mineralogical composition and evaluate potential sources of errors in NP measurements, a suite of samples were examined and
characterized in terms of their mineralogical and chemical compositions. The results indicate that although the acid-base
accounting tests work well for simple compositions, the tests may result in overestimation or underestimation of NP values
for field samples. Mineralogical constraint diagrams relating NP determinations to Ca, Mg and CO2 concentrations were developed with the purpose to serve as supplementary guides to conventional static tests in identifying
possible NP contributions from non-carbonate minerals and checking the quality of the chemical testing results. Mineralogical
NP makes it possible to interpret the meaning of NP results and to assess the behaviour of samples over time by predicting
the onset of AMD and calculating NP values for individual size fractions.
Received: 1 June 1998 · Accepted: 6 October 1998 相似文献
78.
A field survey and modelling of the oxidation and carbonate buffering reactions inside the alum-shale-containing waste rock
dumps located in Maardu, Estonia, was accomplished. In the slope areas, the shale has been altered at high temperatures due
to the spontaneous combustion and the pyritic acidity has been eliminated through migration of SOx gases out from the dump. In the central parts of the waste rock plateaus, low temperature pyrite oxidation fronts develop
towards the dump depth and towards the centres of individual shale lumps. The main secondary phases precipitating in the weathering
profile are gypsum, ferric oxyhydroxide, K-jarosite and smectite. The respective field data made it possible to calibrate
the two-stage oxygen diffusion model and the characteristic pyrite oxidation rate 0.06–0.08 mol of pyrite reacted per kg of
available water (pyrox/H2O value) was estimated to describe the first tens of years of dump performance. The model is capable to compare different
shale disposal strategies that are illustrated with two case scenarios. The buffering of sulphuric acid by Mg-calcite appears
to be an incongruent reaction with gypsum precipitating that leads to the build-up of the high Mg/Ca ratio in the leachate.
Application of the Mg/Ca method estimates the pyrox/H2O value in the range of 0.05–0.14 mol/kg.
Received: 26 January 1999 · Accepted: 23. February 1999 相似文献
79.
E. M. Frempong 《Environmental Geology》1999,37(3):255-260
An engineering geological investigation has been undertaken of a proposed landfill site in coastal southwestern Ghana which
is characterized by torrential rains, high relative humidity, shallow groundwater conditions and almost surrounded by a ridge.
The study shows that the site has some desirable characteristics such as availability of suitable soils for the construction
of the capping and bottom liners of the landfill, a large tract of land for landfilling operation and its location close to
a major highway. However, the groundwater table was shallow and there was a high potential for leachate intrusion into and
consequent contamination of nearby groundwater abstraction wells and surface potable water sources thereby constituting serious
threat to life. Construction costs could be prohibitive as extensive dewatering and backfilling of vast portions of the project
site would be required to enable the provision of a separation between the shallow water table and the bottom of the landfill.
Received: 20 January 1998 · Accepted: 26 May 1998 相似文献
80.
Assessing pollutions of soil and plant by municipal waste dump 总被引:1,自引:0,他引:1
Changli Liu Yun Zhang Feng’e Zhang Sheng Zhang Miying Yin Hao Ye Hongbing Hou Hua Dong Ming Zhang Jianmei Jiang Lixin Pei 《Environmental Geology》2007,52(4):641-651
Research is few in the literature regarding the investigation and assessment of pollutions of soil and plant by municipal
waste dumps. Based upon previous work in seven waste dumping sites (nonsanitary landfills) in Beijing, Shanghai and Shijiazhuang,
this study expounds the investigation and assessment method and report major pollutants. Using relative background values,
this study assesses soil pollution degree in the seven dumping sites. Preliminary conclusions are: (1) pollution degrees are
moderate or heavy; (2) pollution distance by domestic waste that is dumped on a plane ground is 85 m; (3) the horizontal transport
distance of pollutants might be up to 120 m if waste leachates are directly connected with water in saturated soils; (4) vertical
transport depth is about 3 m in unsaturated silty clayey soils. Furthermore, using relative background values and hygiene
standards of food and vegetable this study assesses the pollutions of different parts of reed, sorghum, watermelon and sweet-melon.
It is found: (1) in comparison with the relative background values in a large distance to the waste dumping sites, domestic
wastes have polluted the roots and stems of reed and sorghum, whereas fine coal ash has polluted the leaves, rattans and fruits
of watermelon and sweet-melon; (2) domestic wastes and fine coal ash have heavily polluted the edible parts of sorghum, water
melon and sweet-melon. As, Hg, Pb and F have far exceeded standard values, e.g., Hg has exceeded the standard value by up
to 650–1,700 times and Cd by 120–275 times, and the comprehensive pollution index is up to 192.9–369.7; (3) the polluted sorghum,
watermelon and sweet-melon are inedible. 相似文献