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611.
S. Kim 《国际发展与全球生态学杂志》2019,26(2):141-153
The impact of large-scale urban development on land resources has long been debated by urban planners and designers. This study investigated the extent to which different urban characteristics are associated with land-cover change. The Yangtze River Delta region in China, forming one of the largest sprawling urban landscapes among the regions around the world, was chosen for the study area. Spatial analysis and multiple regression methods were applied to empirically investigate the pattern of resource sites lost to urban development in the area between the 1950s and 2017. The results showed that contrary to the widespread notion that large-sized cities are predominantly responsible for a region’s environmental degradation, city size was not a significant factor in determining the rate of resource loss. Large-sized cities gained their populations with far lesser impacts on land than small-sized cities and towns if normalized to the same number of populations. One explanation for the diminishing effect of city size on land-cover change relates to the degree of spatial dispersion of urban development and local differences in social valuation of diversified lands by cities. 相似文献
612.
Jiajun Liu Long Wang Yun Zhu Che-Jen Lin Carey Jang Shuxiao Wang Jia Xing Bin Yu Hui Xu Yuzhou Pan 《Frontiers of Environmental Science & Engineering》2019,13(1):2
613.
珠江流域土壤中碳库的存量与通量 总被引:3,自引:1,他引:3
通过对珠江流域各主要环境介质中不同形态碳含量的分析和计算,得出该流域0~1.0m范围内土壤碳库的存量为1.36×1013kg,占中国陆地碳库总量的9.51%,全球碳库总量的0.907%;流域净碳输入量为4.141×1010kg/a,碳通量912.74kg/(hm2·a),初步计算表明珠江流域可能是陆地生态系统的一个碳汇区。另一方面,人类活动造成流域内有机碳的大量流失,其中,水土流失损失的碳8.01×109kg/a,植物收割及森林砍伐从土壤-植物系统中携带出的有机碳高达6.26×1011kg/a,这将造成土壤有机质含量的降低,因此促进陆地生态系统有机碳存储是提高本流域土地质量的关键。 相似文献
614.
珠江三角洲经济区耕地锐减,水资源分布不均,工业和农业污染严重,农业生态环境日趋恶化。经济发展不平衡,农业趋于萎缩状态,本文针对这些问题,提出了珠江三角洲农业生态环境治理的指导思想、发展目标和基本措施。 相似文献
615.
珠江三角洲淡水养殖沉积物及鱼体中DDTs和PAHs的残留与风险分析 总被引:4,自引:0,他引:4
采用GC-ECD和GC-MS分析了珠江三角洲淡水养殖鱼塘沉积物及鱼体中DDTs、PAHs的质量分数。结果表明,珠江三角洲地区鱼塘积物中DDTs质量分数范围为2.87~8.25ng·g-1,PAHs质量分数分布在61.76~196.05ng·g-1(干物质量)之间;鳙鱼、草鱼等5种鱼肌肉样品中DDTs质量分数为5.47~125.27ng·g-(1湿质量),PAHs质量分数为30.94~410.06ng·g-1(湿质量),5个品种鱼体内DDTs质量分数均未超过国家食用卫生标准。部分鱼塘中含有o,p’-DDT和p,p'-DDT,表明近期曾受到DDT污染。生态风险分析表明,珠江三角洲部分地区DDTs污染生态风险较高。 相似文献
616.
长江口柱状沉积物中有机质C/N比的研究 总被引:14,自引:0,他引:14
对长江口四个站位沉积物中有机质的C/N比在垂向上的分布进行了研究,在影响沉积物中有机质C/N比的环境因素中,上覆水体的水深、盐度、密度以及浊度对其有一定的影响.在研究沉积物中有机质C/N比的分布及其影响因素的基础上,进一步估算了陆源输入和海洋自生有机碳在这四个站位沉积物有机碳中所占的比例,结果表明,海洋自生组分占沉积物总有机碳的比例分别为:53.57%(8号站位)、20.34%(11号站位),12.28%(17号站位)和32.73%(26号站位). 相似文献
617.
Abstract: Anadromous salmonids have been particularly successful at establishing wild populations in southern Patagonia, in contrast to their limited success elsewhere outside their native ranges. The most recent such discovery is a spawning population of Chinook salmon in the Santa Cruz River, which flows into the Atlantic Ocean from Argentina. We used mitochondrial DNA analysis to discriminate between alternative potential sources of this population and were able to discard in situ introductions of fish imported directly from California in the early twentieth century. Our results showed that the fish most likely came from Puget Sound, Washington, imported into southern Chile for salmon-ranching experiments in the 1980s. This finding provides concrete evidence of colonization of Atlantic rivers from Pacific locations. The southern Pacific and Atlantic oceans provide a favorable marine environment for the success of invading salmon. In particular, the waters associated with fjords, southern channels, and the inshore portion of the Patagonian shelf provide a rather bounded, continuous waterway for exotic anadromous salmonids, rich in diverse forage species. 相似文献
618.
Arsenic in groundwaters of the Lower Mekong 总被引:1,自引:0,他引:1
Stanger G Truong TV Ngoc KS Luyen TV Thanh TT 《Environmental geochemistry and health》2005,27(4):341-357
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible
arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to
provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general
natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at
typical concentrations of between 8 and 16 ppm; (dry weight). Industrial and agricultural arsenic is localised and relatively
unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 μg L−1, although scattered anomalous areas of 10 to 30 μg L−1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 μg L−1, are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water
level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters
result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under
reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper
aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards,
and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture.
An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction
in the future, will require continuing caution in water resources development throughout the region. 相似文献
619.
黄河三角洲及珠江三角洲生态足迹分析 总被引:3,自引:0,他引:3
利用遥感解译数据,分析了解珠江三角洲及黄河三角洲自然资本的供需状况,通过分析两大三角洲地区的生态足迹,探讨在经济发展程度不同的情况下,人类对生态环境的影响程度。并借鉴珠江三角洲经济发展过程中出现的问题,对黄河三角洲今后发展可能出现的问题提出预防措施,以减少对资源的不合理需求,提出正确的功能定位,制定正确的发展方向。研究结果表明,(1)黄河三角洲和珠江三角洲的生态足迹需求均高于全国0.8hm2/人的平均水平,珠江三角洲地区生态足迹需求为1.5403hm2/人;黄河三角洲地区生态足迹需求为1.3514hm2/人。(2)化石燃料的供需状况是影响两大三角洲地区生态赤字的关键因素,珠江三角洲地区对化石燃料的需求占总生态足迹需求的72.67%,位居全国第一位;黄河三角洲地区对化石燃料的需求占总生态足迹需求的49.85%。(3)珠江三角洲除林地尚有少量生态盈余外,其他生态足迹需求均存在明显的生态赤字。受城市化及工业化进程的影响,黄河三角洲化石燃料用地和耕地资源已出现生态赤字。(4)与西方一些发达国家相比,两大三角洲的生态足迹均呈现“低需求,低供给”的特点。 相似文献
620.
Conventional mathematical programming methods, such as linear programming, non linear programming, dynamic programming and
integer programming have been used to solve the cost optimization problem for regional wastewater treatment systems. In this
study, a river water quality management model was developed through the integration of a genetic algorithm (GA). This model
was applied to a river system contaminated by three determined discharge sources to achieve the water quality goals and wastewater
treatment cost optimization in the river basin. The genetic algorithm solution, described the treatment plant efficiency,
such that the cost of wastewater treatment for the entire river basin is minimized while the water quality constraints in
each reach are satisfied. This study showed that genetic algorithm can be applied for river water quality modeling studies
as an alternative to the present methods. 相似文献