Metal stress and decreased tree growth in response to biosolids application in greenhouse seedlings and in situ Douglas-fir stands

To assess physiological impacts of biosolids on trees, metal contaminants and phytochelatins were measured in Douglas-fir stands amended with biosolids in 1982. A subsequent greenhouse study compared these same soils to soils amended with fresh wastewater treatment plant biosolids. Biosolids-amended field soils had significantly higher organic matter, lower pH, and elevated metals even after 25 years. In the field study, no beneficial growth effects were detected in biosolids-amended stands and in the greenhouse study both fresh and historic biosolids amendments resulted in lower seedling growth rates. Phytochelatins - bioindicators of intracellular metal stress - were elevated in foliage of biosolids-amended stands, and significantly higher in roots of seedlings grown with fresh biosolids. These results demonstrate that biosolids amendments have short- and long-term negative effects that may counteract the expected tree growth benefits.     

Sustainable watershed management: an international multi-watershed case study

Global freshwater resources are being increasingly polluted and depleted, threatening sustainable development and human and ecosystem health. Utilizing case studies from 4 different watersheds in the United States, Japan, Switzerland, and Brazil, this paper identifies the most relevant sustainability deficits and derives general vectors for more sustainable water management. As a consequence of the demographic and economic developments experienced in the last few decades, each watershed has suffered declines in water quality, streamflow and biotic resources. However, the extent and the cultural perception of these water-related problems vary substantially in the different watersheds, leading to specific water-management strategies. In industrialized countries, exemplified by the US, Switzerland, and Japan, these strategies have primarily consisted of finance- and energy-intensive technologies, allowing these countries to meet water requirements while minimizing human health risks. But, from a sustainability point of view, such strategies, relying on limited natural resources, are not long-term solutions. For newly industrialized countries such as Brazil, expensive technologies for water management are often not economically feasible, thus limiting the extent to which newly industrialized and developing countries can utilize the expertise offered by the industrialized world. Sustainable water management has to be achieved by a common learning process involving industrialized, newly industrialized, and developing countries, following general sustainability guidelines as exemplified in this paper.     

流域的可持续管理:国际多个流域的案例研究

全球淡水资源正在不断受到污染和亏耗,威胁着可持续发展及人类和生态系统的健康.本文通过美国、日本、瑞士和巴西四个不同流域的案例研究,阐述了与淡水资源密切相关的可持续发展中的缺陷,指明了水资源可持续管理的总体方向.由于近几十年来人口的增长和经济的发展,每个流域的水质、流量和生物资源量都在下降.但是对于不同的流域来说,与水有关的这些问题的严重程度和文化观念大不相同,因而形成各自独特的水资源管理政策.在工业化国家,例如美国、瑞士和日本,这类政策允许采用资金密集型和能源密集型技术,使得这些国家在满足其水资源需求的同时还能尽量降低人类健康风险.然而,从可持续发展的观点看,以有限的自然资源为基础制定的这类政策,并非长久之计.对于新兴工业化国家(如巴西)来说,昂贵的水资源管理技术在经济上常常行不通,因而限制了新兴工业化国家和发展中国家对发达国家提供的技术的利用程度.要实现水资源的可持续管理,发达国家、新兴工业化国家和发展中国家都需要经历一个学习的过程,同时还需要遵循本文介绍的可持续发展的通用原则.     

用大型底栖动物和ODP系统评价珠江的有机污染

采用大型底栖动物需氧有机体百分率ODP(oxygen demander percentage)法对广州珠江前航道、西航道和流溪河的下游段进行河流有机污染评价.结果显示:底栖动物需氧类群密度在三河段间分布确有显著性差异,并根据其ODP可以判断流溪河水质相对较好,水质级别为中国地表水环境质量标准(EQSSW)Ⅳ级,西航道和前航道水质级别都为Ⅴ级.通过测试,这一方法能成功地应用在珠江及流溪河,且该法可以较好地匹配于EQSSW五级评价系统,初步认为ODP系统可以成为一个较好的河流水质生物监测方法.图3表4参13     

Biomonitoring for metal contamination near two Superfund sites in Woburn, Massachusetts, using phytochelatins

Characterizing the spatial extent of groundwater metal contamination traditionally requires installing sampling wells, an expensive and time-consuming process in urban areas. Moreover, extrapolating biotic effects from metal concentrations alone is problematic, making ecological risk assessment difficult. Our study is the first to examine the use of phytochelatin measurements in tree leaves for delimiting biological metal stress in shallow, metal-contaminated groundwater systems. Three tree species (Rhamnus frangula, Acer platanoides, and Betula populifolia) growing above the shallow groundwater aquifer of the Aberjona River watershed in Woburn, Massachusetts, display a pattern of phytochelatin production consistent with known sources of metal contamination and groundwater flow direction near the Industri-Plex Superfund site. Results also suggest the existence of a second area of contaminated groundwater and elevated metal stress near the Wells G&H Superfund site downstream, in agreement with a recent EPA ecological risk assessment. Possible contamination pathways at this site are discussed.     

Phytoremediation of Atrazine by Poplar Trees: Toxicity,Uptake, and Transformation

Toxicity, uptake, and transformation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] by three species of poplar tree were assessed. Poplar cuttings were grown in sealed flasks with hydrophonic solutions and exposed to various concentrations of atrazine for a period of two weeks. Toxicity effects were evaluated by monitoring transpiration and measuring poplar cutting mass. Exposure to higher atrazine concentrations resulted in decrease of biomass and transpiration accompanied by leaf chlorosis and abscission. However, poplar cuttings exposed to lower concentrations of atrazine grew well and transpired at a constant rate during experiment periods. Poplar cuttings could take up, hydrolyze, and dealkylate atrazine to less toxic metabolites. Metabolism of atrazine occurred in roots, stems, and leaves and became more complete with increased residence time in tissue. These results suggest that phytoremediation is a viable approach to removing atrazine from contaminated water and should be considered for other contaminants.