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701.
Groundwater pollution due to discharge of industrial effluents in Venkatapuram area, Visakhapatnam, Andhra Pradesh, India 总被引:1,自引:0,他引:1
Hindustan Polymers Limited was established in the Venkatapuram area in the northwestern part of Visakhapatnam urban agglomeration.
Untreated industrial effluent from the plant is discharged with total dissolved solids concentrations reaching up to 6500 mg/l.
The groundwater pollution was identified as early as 1981 and a hydrogeologic and water-quality database is available from
1981. The groundwater quality in the plant environs is found to be in the range of 3500–4500 mg/l. Major chemical constituents
of industrial-waste waters consist of Na, Cl, and SO4. Some characteristic parameters of the aquifer were estimated. The available hydrogeologic and hydrologic data was analyzed
to conceptualize the groundwater regime. A mathematical groundwater flow model was constructed to compute the hydraulic head
at the center of finite-difference grid. The computed head distribution and effective porosity of the formations were used
to calculate the groundwater flow velocity. The computed velocity field was ultimately used to prognose the pollutant migration
in groundwater accounting for the advection and dispersion processes in the mass transport model and for determining the time-dependent
pathlines of pollutant. Areal migration of pollutants from the source was predicted up to year 2002.
Received: 23 December 1996 · Accepted: 9 September 1997 相似文献
702.
We use beaver-pond deposits and geomorphic characteristics of small streams to assess long-term effects of beavers and climate change on Holocene fluvial activity in northern Yellowstone National Park. Although beaver damming has been considered a viable mechanism for major aggradation of mountain stream valleys, this has not been previously tested with stratigraphic and geochronologic data. Thirty-nine radiocarbon ages on beaver-pond deposits fall primarily within the last 4000 yr, but gaps in dated beaver occupation from ~ 2200–1800 and 950–750 cal yr BP correspond with severe droughts that likely caused low to ephemeral discharges in smaller streams, as in modern severe drought. Maximum channel gradient for reaches with Holocene beaver-pond deposits decreases with increasing basin area, implying that stream power limits beaver damming and pond sediment preservation. In northern Yellowstone, the patchy distribution and cumulative thickness of mostly < 2 m of beaver-pond deposits indicate that net aggradation forced by beaver damming is small, but beaver-enhanced aggradation in some glacial scour depressions is greater. Although 20th-century beaver loss and dam abandonment caused significant local channel incision, most downcutting along alluvial reaches of the study streams is unrelated to beaver dam abandonment or predates historic beaver extirpation. 相似文献
703.
The combined geothermal discharge from over 10,000 features in Yellowstone National Park (YNP) can be can be estimated from the Cl flux in the Madison, Yellowstone, Falls, and Snake Rivers. Over the last 30 years, the Cl flux in YNP Rivers has been calculated using discharge measurements and Cl concentrations determined in discrete water samples and it has been determined that approximately 12% of the Cl flux exiting YNP is from the Snake River. The relationship between electrical conductivity and concentrations of Cl and other geothermal solutes was quantified at a monitoring site located downstream from the thermal inputs in the Snake River. Beginning in 2012, continuous (15 min) electrical conductivity measurements have been made at the monitoring site. Combining continuous electrical conductivity and discharge data, the Cl and other geothermal solute fluxes were determined. The 2013–2015 Cl fluxes (5.3–5.8 kt/yr) determined using electrical conductivity are comparable to historical data. In addition, synoptic water samples and discharge data were obtained from sites along the Snake River under low-flow conditions of September 2014. The synoptic water study extended 17 km upstream from the monitoring site. Surface inflows were sampled to identify sources and to quantify solute loading. The Lewis River was the primary source of Cl, Na, K, Cl, SiO2, Rb, and As loads (50–80%) in the Snake River. The largest source of SO4 was from the upper Snake River (50%). Most of the Ca and Mg (50–55%) originate from the Snake Hot Springs. Chloride, Ca, Mg, Na, K, SiO2, F, HCO3, SO4, B, Li, Rb, and As behave conservatively in the Snake River, and therefore correlate well with conductivity (R2 ≥ 0.97). 相似文献
704.
705.
706.
707.
苏州城市游憩场点系统空间结构分形 总被引:5,自引:2,他引:5
城市游憩场点系统是和谐城市规划建设的核心对象,也是一种结构复杂的自然-人文复合系统.本文选取随机聚集维数、空间关联维数、网格维数三项指标.以苏州市区为例,对新时期我国城市游憩场点系统的空间结构分形及优化进行了系统论证与解析.研究发现:①城市游憩场点系统的空间结构是具有分形特性的;②各分维指标能够准确地刻画城市游憩场点系统的空间结构及其分异,也为环城游憩带理论及城乡二元游憩结构分异现象等提供了分形解释依据;③苏州游憩场点系统的空间结构呈现出一种核心松散-外围紧致、白组织能力离心化现象比较严重的结构递变趋势,这种结构模式与游憩需求的空间分布结构基本吻合,它准确反映了成熟型游憩场点系统的空间发展态势,也说明加强对游憩场点系统的自组织能力的引导和提升,是和谐城市规划建设中的一项不可或缺的重要工作;④与以往研究结论相对比,发现游憩场点系统与旅游景区(点)系统在空间结构上存在合理的分形差异. 相似文献
708.
《Singapore journal of tropical geography》2018,39(2):281-299
This paper examines spatial and temporal patterns of large to medium‐sized fires across the Indonesian Archipelago using remote sensing, particularly the MODIS fire products, over a 14 years period (2000–13 inclusive) in conjunction with climatic and land data in a GIS. Results showed fires (burned area and number of fires) were detected the most in year 2002 and least in 2010. The extent of burning was correlated with the annual Southern Oscillation Index with most burning occurring during times of sustained negative SOI values, which generally means drier conditions across the region. Most of the detected fires occurred in the middle of the dry season and in drier eastern Indonesia. Across Indonesia, approximately 1.5 per cent of available open vegetation area burned, whereas only 0.5 per cent of forest area burned. Most open vegetation burning was detected in the savanna with an area equivalent to 11.1 per cent of its extent being burned over the 14 years. On Sumba Island, where the pronounced dry season extends for at least four months, open vegetation is the most common land cover type, of which 99 per cent burned by area over the study period making it the island with the most burned areas in the Indonesian Archipelago. 相似文献
709.
The retreating snowfields and glaciers of Glacier National Park, Montana, USA, present alpine plants with changes in habitat and hydrology. The adjacent and relic periglacial patterned ground consists of solifluction terraces of green, vegetation-rich stripes alternating with sparsely vegetated brown stripes. We established georeferenced transects on striped periglacial patterned ground for long-term monitoring and data collection on species distribution and plant functional traits at Siyeh Pass and at Piegan Pass at Glacier National Park. We documented species distribution and calculated the relative percent cover(RPC) of qualitative functional traits and used 16 S rRNA from soil samples to characterize microbial distribution on green and brown stripes. Plant species distribution varied significantly and there were key differences in microbial distribution between the green and brown stripes. The rare arctic-alpine plants Draba macounii, Papaver pygmaeum, and Sagina nivalis were restricted to brown stripes, where the RPC of xeromorphic taprooted species was significantly higher at the leading edge of the Siyeh Pass snowfield. Brown stripes had a higher percentage of the thermophilic bacteria Thermacetogenium and Thermoflavimicrobium. Green stripes were co-dominated by the adventitiously-rooted dwarf shrubs Salix arctica and the possibly N-fixing Dryas octopetala. Green stripes were inhabited by Krummholz and seedlings of Abies lasiocarpa and Pinus albicaulus. Prosthecobacter, a hydrophilic bacterial genus, was more abundant on the green stripes, which had 6,524 bacterial sequences in comparison to the 1,183 sequences from the brown stripes. While further research can determine which functional traits are critical for these plants, knowledge of the current distribution of plant species and their functional traits can be used in predictive models of the responses of alpine plants to disappearing snowfields and glaciers. This research is important in conservation of rare arctic-alpine species on periglacial patterned ground. 相似文献
710.
产业转移背景下区域工业碳排放时空格局演变——以泛长三角为例 总被引:1,自引:0,他引:1
产业转移背景下区域能源消费、碳排放格局时空格局变化是近期研究者关注的热点。以处于产业转移期的泛长三角地区为例,以工业能源消费为对象,分析了1990,1995,2000,2005和2010年5个年份碳排放的空间格局和演变规律,探索了产业转移对碳排放格局演变的影响。结果表明,1990年以来工业碳排放稳步增长,高值区集中于长三角核心区;碳排放增长的区域差异较大,热点区域由长三角核心区向外围区转移;碳排放格局发生变化,排放重心呈现先东南向、后西北向移动的态势;工业重心和碳排放重心空间分离,但移动过程类似。研究认为,产业转移所引起的各地区工业产值、产品结构和碳排放强度的变化,与碳排放格局变化具有较大关联性,是影响区域碳排放格局变化的重要因素。 相似文献