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571.
Mercury mining was a large and thriving industry during the last century in Asturias (NW Spain). At Bra?alamosa, mining activity introduced significant quantities of wastes in spoil heaps located close to the mining operations. In these mining wastes, in addition to mercury, high concentrations of other potentially dangerous elements like As have been found. As a consequence, pollution and dereliction of the local environment occurred. This paper focuses on the environmental impact of these old mining operations and describes a preliminary assessment of the extent of contamination. This includes analytical data from systematic sampling of soils, stream sediments, wastes from spoil heaps, water and herbaceous plants in areas affected by mining activities. The potential risk that spoil materials imply for human health and the environment is documented on the basis of the application of EPA Risk Assessment methodology. 相似文献
572.
Can machines recognise stress in plants? 总被引:2,自引:0,他引:2
Ronald?Maldonado-RodriguezEmail author Stancho?Pavlov Alberto?Gonzalez Abdallah?Oukarroum Reto?J.?Strasser 《Environmental Chemistry Letters》2003,1(3):201-205
In this paper we show that chlorophyll a fluorescence signals analysed with the self-organizing map (SOM) can be used as a routine tool for the monitoring and classification of pea varieties (Pisum sativum) according to their degree of resistance against drought stress. Fluorescence kinetics measurements were obtained from non-stressed plants. The aim of this study is to evaluate the applicability of artificial intelligence techniques in eco-physiological research. Our goal is to provide a fast tool that will contribute to the knowledge needed to develop strategies that would help to decrease the impact of environmental stress in agriculture and forestry. 相似文献
573.
Total mercury content was evaluated in water and suspended sediment samples of the Moji-Gua?u river and in water and bottom sediment of its 3 marginal lagoons (Catingueiro, Barrinha, and Rio das Pedras), located downstream of the sampling point in the main channel. In all situations, low Hg concentrations were found in suspended and bottom sediments. Aluminum was used as a geochemical tracer to normalize the Hg concentrations in the sediment cores from the Rio das Pedras lagoon (r = 0.92). It was estimated that the Moji-Gua?u river transports up to 19 kg Hg yr(-1), 65% in the dissolved form and 35% adsorbed onto particulate matter. Following an acute toxic stage observed in the years 1970-1980, the basin has been restored to its original conditions mainly by natural recovery and a general reduction in Hg input to the ecosystem. 相似文献
574.
M. Masud K. Khan Carlos J. Hilado Sushant Agarwal Rakesh K. Gupta 《Journal of Polymers and the Environment》2007,15(3):188-194
Acrylonitrile–Butadiene–Styrene (ABS), Polycarbonate (PC) and their alloys are widely used in automotive industry, computer
and equipment housings. With increasing disposal of end-of-life electronic equipment, there is also an increased demand for
recycling of these materials so that they do not pose environmental challenge as solid waste. One of the recycling approaches
is mechanical recycling of these thermoplastics where recycled plastic is melt blended with virgin materials to obtain a high
quality product. Besides obtaining desirable mechanical properties, such blends should also conform to fire safety standards.
In this work, a series of blends were prepared using PC and ABS recovered from discarded computers and virgin materials using
a twin-screw extruder. Their flammability properties were evaluated using burner flammability tests and Ohio State University
(OSU) release rate tests. It was found that the extinguishing time, burning extent and weight loss appears to progressively
decrease with the addition of both virgin or recycled PC to virgin or recycled ABS. It was also seen that the addition of
the 70% of PC, virgin or recycled, to ABS virgin or recycled, appears to significantly decrease heat release and smoke evolution.
The results of this study indicate that recycled polycarbonate can be used as an additive for virgin or recycled ABS, as a
means of giving flame resistance to ABS in high-value applications. This result is significant when related to the result
obtained by a separate study indicating that up to 25% of recycled material can be used without degradation of mechanical
properties in the presence of 15% short glass fiber reinforcement. 相似文献
575.
Using the hedonic pricing approach, this paper investigates how the information released on public registries of contaminated and potentially contaminated sites affects nearby commercial and industrial properties in Baltimore, Maryland. The study found that industrial properties are virtually unaffected by proximity to a site with a history of contamination, while commercial properties do suffer an external cost due to the proximity to a contaminated site. This external cost is not cleared once the site has been cleaned up or has been pronounced to be harmless. It also found that the impacts of urban economic development policies, such as Empowerment Zones and Enterprise Zones, have had positive effects on industrial property values, but less so on commercial properties. In sum, brownfield properties in Baltimore are not particularly attractive investments for developers, and there is little potential for self-sustaining clean-up based on appropriate fiscal incentives, such as Tax Increment Financing. It is doubtful that ‘one size fits all’ measures to encourage the clean-up of contaminated sites can be successful in this context. 相似文献
576.
Plants against the global epidemic of arsenic poisoning 总被引:3,自引:0,他引:3
Due to the growing current trend around the world of drinking water from underground sources, in an attempt to replace heavily polluted surface water supplies, arsenic is causing a global epidemic of poisoning with hundreds of millions of people now being thought at serious risk in many countries. Phytoremediation (bioremediation mediated by plants) has been proposed as an effective tool in arsenic cleanup. Actually, some plants (most notably, the Chinese brake fern Pteris vittata) have been reported to be suitable for arsenic phytoremediation. In this respect, transgenic plants are being developed to improve their capacity to accumulate arsenic. Most interestingly, rhizofiltration (use of plants to absorb or adsorb pollutants from water) is being considered for the ex situ and in situ remediation of arsenic-contaminated water. Similarly, some plants show great potential to remove arsenic from polluted soil. 相似文献
577.
Mercury in sediments and vegetation in a moderately contaminated salt marsh
(Tagus Estuary, Portugal) 总被引:1,自引:1,他引:0
Jo?ao Can′ario Carlos Vale Laurier Poissant Marta Nogueir Martin Pilote Vasco Branco 《环境科学学报(英文版)》2010,22(8):1151-1157
Depth variations of total mercury (Hg) and methylmercury (MeHg) concentrations were studied in cores from non-colonized
sediments, sediments colonized by Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima and belowground biomass,
in a moderately contaminated salt marsh (Tagus Estuary, Portugal). Concentrations in belowground biomass exceeded up to 3 (Hg) and
15 (MeHg) times the levels in sediments, and up to 198 (Hg) and 308 (MeHg) times those found in aboveground parts. Methylmercury
in colonized sediments reached 3% of the total Hg, 50 times above the maximum values found in non-colonized sediments. The absence
of correlations between total Hg concentrations in sediments and the corresponding MeHg levels suggested that methylation was only
dependent on the environmental and microbiological factors. The analysis of belowground biomass at high-depth resolution (2 cm)
provided evidence that Hg and MeHg were actively absorbed from sediments, with higher enrichment factors at layers where higher
microbial activity was probably occurring. The results obtained in this study indicated that the biotransformation of Hg to the toxic
MeHg could increase the toxicity of plant-colonized sediments. 相似文献
578.
Gerd Sparovek Alberto Barretto Goran Berndes Sergio Martins Rodrigo Maule 《Mitigation and Adaptation Strategies for Global Change》2009,14(3):285-298
Governments are promoting biofuels and the resulting changes in land use and crop reallocation to biofuels production have
raised concerns about impacts on environment and food security. The promotion of biofuels has also been questioned based on
suggested marginal contribution to greenhouse gas emissions reduction, partly due to induced land use change causing greenhouse
gas emissions. This study reports how the expansion of sugarcane in Brazil during 1996–2006 affected indicators for environment,
land use and economy. The results indicate that sugarcane expansion did not in general contribute to direct deforestation
in the traditional agricultural region where most of the expansion took place. The amount of forests on farmland in this area
is below the minimum stated in law and the situation did not change over the studied period. Sugarcane expansion resulted
in a significant reduction of pastures and cattle heads and higher economic growth than in neighboring areas. It could not
be established to what extent the discontinuation of cattle production induced expansion of pastures in other areas, possibly
leading to indirect deforestation. However, the results indicate that a possible migration of the cattle production reached
further than the neighboring of expansion regions. Occurring at much smaller rates, expansion of sugarcane in regions such
as the Amazon and the Northeast region was related to direct deforestation and competition with food crops, and appear not
to have induced economic growth. These regions are not expected to experience substantial increases of sugarcane in the near
future, but mitigating measures are warranted. 相似文献
579.
580.
Hugo D. Silva Marco T. A. García-Zapata Carlos E. Anunciação 《Food and environmental virology》2011,3(3-4):138-140
Adenovirus is the virus that contains the highest amount of features favorable to its use as a virologic marker for water quality. Those pathogens are resistant on the environment, abundant, easily detected by molecular methods and are of great importance in public health. 相似文献