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321.
N. Aarab D.M. Pampanin A. Nvdal K.B.
ysd L. Gastaldi R.K. Bechmann 《Marine pollution bulletin》2008,57(6-12):569
Histopathological characteristics of specific organs express condition, and represent time-integrated impacts on the organism stemming from alterations at lower levels of biological organisation. As integrative parameters, histochemical investigations have proved to be sensitive tools to detect effects of chemical compounds.The objective of this study was to determine changes in the tissues of mussels collected at a PAH contaminated site compared to a reference site using histopathological and histochemical parameters: lipofuscin (LF) accumulation in mussel digestive gland, and lysosomal membrane stability (LMS), and using additional information provided by body burden analysis to compare the sensitivity of these parameters.The histochemical measurements for both LF and LMS gave a clear indication of a high level of stress in animals from the PAH contaminated site. This LF accumulation in lysosomes is the result of peroxidation of autophagocytosed proteins associated with protein aggregates and oxidatively damaged organelles. These measurements were able to detect the effects of PAHs, and showed a strong relationship with the body burden results. 相似文献
322.
Rehan Sadiq Solomon Tesfamariam 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(4):495-505
Environmental indices (EI) constitute a common communication tool that is often used to describe the overall status of environmental
systems (air, water and soil). EI development entails the use of mathematical operators to aggregate various non-commensurate
input parameters in a logical manner. The ordered weighted averaging (OWA) operator is a general mean type operator that provides
flexibility in the aggregation process such that the aggregated value is bounded between minimum and maximum values of the
input parameters. This flexibility of the OWA operator is realized through the concept of orness, which is a surrogate for
decision maker’s attitude. The type of input parameters also affects the choice of aggregation operators. If the input parameters
are linguistic or fuzzy, the aggregation through OWA operators is not possible, and the use of fuzzy arithmetic is warranted.
The concept of fuzzy number OWA (FN-OWA) operators is explored to handle situations in which one or more input parameter has
fuzzy (or linguistic) values. The proposed approach is demonstrated using data provided in an earlier study by Swamee and
Tyagi (ASCE J Environ Eng 126(5):451–455, 2000) for establishing water quality indices. Multiple hypothetical scenarios are also generated to highlight the utility and
sensitivity of the proposed approach. 相似文献
323.
324.
The construction of multiple dams and barrages in many Indian River basins over the last few decades significantly reduced river flow to the sea and affected the sediment regime. More reservoir construction is planned through the proposed National River Linking Project (NRLP), which will transfer massive amounts of water from the North to the South of India. The impacts of these developments on fertile and ecologically sensitive deltaic environments are poorly understood and quantified at present. In this paper an attempt is made to identify, locate and quantify coastal erosion and deposition processes in one of the major river basins in India—the Krishna—using a time series of Landsat images for 1977, 1990 and 2001 with a spatial resolution ranging from 57.0 m to 28.5 m. The dynamics of these processes are analyzed together with the time series of river flow, sediment discharge and sediment storage in the basin. Comparisons are made with similar processes identified and quantified earlier in the delta of a neighboring similarly large river basin—the Godavari. The results suggest that coastal erosion in the Krishna Delta progressed over the last 25 years at the average rate of 77.6 ha yr− 1, dominating the entire delta coastline and exceeding the deposition rate threefold. The retreat of the Krishna Delta may be explained primarily by the reduced river inflow to the delta (which is three times less at present than 50 years ago) and the associated reduction of sediment load. Both are invariably related to upstream reservoir storage development. 相似文献
325.
This paper raises fundamental questions about the sole use of paleolimnological techniques to identify sediment sources and
develop catchment management plans. The concept of an integrated lake: catchment framework was established 30 years ago, yet
paleolimnologists occasionally fail to appreciate the dynamics of the contributing catchment. This is especially critical
when the predominant source of sediment accumulating in a lake is allochthonous. In this paper we argue that a detailed appraisal
of catchment sources and investigation of historical documentary evidence is needed to identify and evaluate the relative
significance of sediment sources. We used such an approach at Aqualate Mere, Shropshire, UK. Mineral magnetic and radionculide
signatures of potential catchment sources and accumulating lake sediments were compared in an attempt to match the sources
to sediments deposited in the Mere. Dated lake sediments indicate there has been an increase in sedimentation rate and the
relative amount of minerogenic material delivered to the Mere over the last 200 years. In contrast to a previous study at
the same site, there is no evidence to attribute this increase to an overspill from a nearby canal. Other catchment disturbances
include landscaping in parkland surrounding the Mere in the early nineteenth century and drainage systems installed to improve
catchment agriculture over the last ca. 150 years. Both activities may explain the change in sedimentation rates and types,
independent of the hypothesized canal origin. Although our results exclude the canal as a major sediment source, identifying
the contribution of other potential catchment sources remains problematic. 137Cs inventories for the lake are similar to those recorded at a local reference site, suggesting little influx of 137Cs-bearing topsoil, yet 137Cs activities remain high in the upper 20–30 cm of the lake sediment profile, indicating a topsoil origin. Combined radionuclide
and mineral magnetic signatures proved to be relatively poor discriminators of potential sources, and the high atmospheric
pollution load from the West Midland conurbation has probably altered recent lake sediment signatures. Although further research
is required to identify the origins of recent (last ca. 200 years) minerogenic sediment inputs to the Mere, we suggest that
the combined lake: catchment approach offers a more rigorous method for understanding the impact of catchment disturbance
than analysis of the paleolimnological record alone. 相似文献
326.
327.
Environmental decision-making under uncertainty using intuitionistic fuzzy analytic hierarchy process (IF-AHP) 总被引:1,自引:0,他引:1
Rehan Sadiq Solomon Tesfamariam 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(1):75-91
Analytic hierarchy process (AHP) is a utility theory based decision-making technique, which works on a premise that the decision-making
of complex problems can be handled by structuring them into simple and comprehensible hierarchical structures. However, AHP
involves human subjective evaluation, which introduces vagueness that necessitates the use of decision-making under uncertainty. The vagueness is commonly handled through fuzzy sets theory, by assigning degree of membership. But, the environmental decision-making
problem becomes more involved if there is an uncertainty in assigning the membership function (or degree of belief) to fuzzy pairwise comparisons, which is referred to as ambiguity (non-specificity). In this paper, the concept of intuitionistic fuzzy set is applied to AHP, called IF-AHP to handle both vagueness and ambiguity
related uncertainties in the environmental decision-making process. The proposed IF-AHP methodology is demonstrated with an
illustrative example to select best drilling fluid (mud) for drilling operations under multiple environmental criteria. 相似文献
328.
Deriving hillslope sediment budgets in wildfire-affected forests using fallout radionuclide tracers 总被引:3,自引:1,他引:2
W.H. Blake P.J. Wallbrink S.N. Wilkinson G.S. Humphreys S.H. Doerr R.A. Shakesby K.M. Tomkins 《Geomorphology》2009,104(3-4):105-116
Information on post-fire sediment and nutrient redistribution is required to underpin post-fire catchment management decisions. Fallout radionuclide budgets (210Pbxs, 137Cs and 7Be) were derived to quantify soil redistribution and sediment yield in forested terrain following a moderately severe wildfire in a small (89 ha) water supply catchment in SE Australia. Application of these techniques in burnt terrain requires careful consideration of the partitioning of radionuclides between organic and mineral soil components. Beryllium-7 and 210Pbxs were shown to be closely associated with ash, litter and soil organic matter whereas 137Cs was more closely associated with subsurface coarse mineral soil. Comparison of the three tracer budgets indicated that the dominant sediment source areas were ridgetops and steep valley sideslopes, from which burnt surface material was conveyed to the stream network via pre-existing gullies. Erosion was predominantly driven by sheetwash, enhanced by soil water repellency, and modified by bioturbation which both supplies subsurface sediment and provides sinks for erosive overland flow. Footslope and riparian zones were not important sediment source areas. The estimated event-based (wildfire and subsequent rainfall) sediment yield is 58 ± 25 t km− 2, based on fallout 7Be measurements. The upper estimate of total particulate phosphorus yield (0.70 kg ha− 1) is more than 10 times that at equivalent unburnt sites. This illustrates that, soon after fire, burnt eucalypt forest can produce nutrient loads similar to those of agricultural catchments. The tracer budgets indicate that wildfire is an important control on sediment and phosphorus inputs to the stream network over the decadal timeframe and the pulsed nature of this release is an important concern for water quality management. 相似文献
329.
基于钻孔数据的含断层地质体三维建模方法 总被引:16,自引:1,他引:15
提出了一种构建含断层地质体三维模型的新方法。该方法以广义三棱柱作为建模的基本体元,根据钻孔数据的特点和知识推理规则,进行断层等复杂地质构造的推理和自动建模,避免了不必要的人为干预,扩展了钻孔数据建模的适用范围和表现能力。最后,通过研究实例展示该方法的实际建模效果。 相似文献
330.
苏北王港近岸表层沉积物元素地球化学特征与环境意义 总被引:1,自引:0,他引:1
对王港河河道及河口附近潮滩典型地貌部位表层沉积物粒度、常量和微量元素进行分析,结果表明:潮滩和河道近岸沉积物为粘土质粉砂,粒度分布频率曲线在平均高潮线附近的沉积物为双峰态外,其余为单峰态。互花米草滩沉积物中常量和微量元素(Al2O3,TiO2,CaO,Fe2O3,K2O,MgO,MnO和Cu,Rb,Pb,As,Zn)均表现出相对富积的特征,盐蒿滩次之,反映海岸带互花米草在削浪促淤的过程中,对重金属污染有效吸附作用比盐蒿潮滩滩大。SiO2化学性质比较稳定,对沉积地貌动力的响应比较显著,近岸高潮线附近和河道中主洪道沉积物SiO2含量明显偏高。河闸上游河道沉积物中烧失量、磷(P2O5)、硫(稳定态SO3)的含量最高,反映流域营养盐在水闸以上河段沉积物中富积,重金属元素Rb,Pb,As,Ba在河道沉积物中与地壳风度相比表现为富集。王港附近潮滩表层沉积物物质组成不仅与王港河、黄河及长江的物质来源有关,而且与古潮滩沉积再搬运、再沉积以及人类围垦及排放污染活动有关。As,S是该区主要的污染元素。 相似文献