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41.
Sepulveda A Schuller P Walling DE Castillo A 《Journal of environmental radioactivity》2008,99(1):35-49
Intensification and expansion of agricultural production since the 1970s have increased soil erosion problems in south-central Chile. Quantitative information on soil loss is needed for erosion risk assessment and to establish the effectiveness of improved land management practices. Since information from traditional sources, such as erosion plots, is limited, attention has been directed to the use of environmental radionuclides for documenting erosion rates. Cs-137 has been successfully utilised for this purpose, but only provides information on medium-term erosion rates. There is also a need to document event-related soil erosion. This paper outlines the basis for using (7)Be measurements to document short-term erosion and reports its successful use for quantifying the erosion that occurred within an arable field, as a result of a period of heavy rainfall (400mm in 27 days) occurring in May 2005. The study field had been under a no-till, no-burning system for 18 years, but immediately prior to the period of heavy rainfall the harvest residues were burnt. The erosion recorded therefore reflected both the extreme nature of the rainfall and the effects of the burning in increasing surface runoff and erosion. The sampled area corresponded to that used previously by the authors to document the medium-term erosion rates associated with both conventional tillage and the subsequent switch to a no-till system. Comparisons between the erosion documented for the period of heavy rainfall in 2005 with these medium-term erosion rates permits some tentative conclusions regarding the importance of extreme events and the impact of burning in increasing the erosion associated with the no-till system. 相似文献
42.
Stakeholder Management for Conservation Projects: A Case Study of Ream National Park, Cambodia1 总被引:2,自引:0,他引:2
THANAKVARO THYL DE LOPEZ 《Environmental management》2001,28(1):47-60
The paper gives an account of the development and implementation of a stakeholder management framework at Ream National Park, Cambodia. Firstly, the concept of stakeholder is reviewed in management and in conservation literatures. Secondly, the context in which the stakeholder framework was implemented is described. Thirdly, a five-step methodological framework is suggested: (1) stakeholder analysis, (2) stakeholder mapping, (3) development of generic strategies and workplan, (4) presentation of the workplan to stakeholders, and (5) implementation of the workplan. This framework classifies stakeholders according to their level of influence on the project and their potential for the conservation of natural resources. In a situation characterized by conflicting claims on natural resources, park authorities were able to successfully develop specific strategies for the management of stakeholders. The conclusion discusses the implications of the Ream experience and the generalization of the framework to other protected areas. 相似文献
43.
RUDOLF S. DE GROOT JAMES BLIGNAUT SANDER VAN DER PLOEG JAMES ARONSON THOMAS ELMQVIST JOSHUA FARLEY 《Conservation biology》2013,27(6):1286-1293
Measures aimed at conservation or restoration of ecosystems are often seen as net‐cost projects by governments and businesses because they are based on incomplete and often faulty cost‐benefit analyses. After screening over 200 studies, we examined the costs (94 studies) and benefits (225 studies) of ecosystem restoration projects that had sufficient reliable data in 9 different biomes ranging from coral reefs to tropical forests. Costs included capital investment and maintenance of the restoration project, and benefits were based on the monetary value of the total bundle of ecosystem services provided by the restored ecosystem. Assuming restoration is always imperfect and benefits attain only 75% of the maximum value of the reference systems over 20 years, we calculated the net present value at the social discount rates of 2% and 8%. We also conducted 2 threshold cum sensitivity analyses. Benefit‐cost ratios ranged from about 0.05:1 (coral reefs and coastal systems, worst‐case scenario) to as much as 35:1 (grasslands, best‐case scenario). Our results provide only partial estimates of benefits at one point in time and reflect the lower limit of the welfare benefits of ecosystem restoration because both scarcity of and demand for ecosystem services is increasing and new benefits of natural ecosystems and biological diversity are being discovered. Nonetheless, when accounting for even the incomplete range of known benefits through the use of static estimates that fail to capture rising values, the majority of the restoration projects we analyzed provided net benefits and should be considered not only as profitable but also as high‐yielding investments. Beneficios de Invertir en la Restauración de Ecosistemas 相似文献
44.
硅藻砷甲基化和氧化过程在淡水生态系统砷生物地球化学循环中发挥重要作用,并且硅藻的重金属抗性与营养元素硅酸盐有效性紧密相关。然而,不同硅藻对无机砷的转化能力和砷抗性差异,硅酸盐对硅藻砷转化的影响机制尚不清楚。选取2种淡水硅藻,即针状菱形藻(Nitzschia acicularis)和谷皮菱形藻(Nitzschia palea),作为研究对象,探究其砷甲基化和氧化作用,以及硅酸盐影响下砷转化和此过程中的相关基因转录活性。结果表明,硅藻暴露于As(Ⅲ)的10 d培养期内主要产生二甲基砷,针状菱形藻的二甲基砷转化率为5.54%,高于谷皮菱形藻的转化率(0.80%)。谷皮菱形藻的As(Ⅲ)氧化作用比针状菱形藻强,前者和后者的氧化率分别为90.1%和3.2%。2种硅藻砷甲基化和氧化能力的差异表明不同硅藻As(Ⅲ)胁迫下的主要砷抗性策略不同。针状菱形藻在As(Ⅲ)胁迫下显著上调砷甲基转移功能基因(arsM)表达,并显著下调硅酸盐转运基因(sit)表达。这表明硅藻驱动胞内砷甲基化反应和减少硅/砷转运活性,从而有助于胞内砷解毒和减少As(Ⅲ)吸收。硅酸盐添加对针状菱形藻的arsM基因表达没有明显影响,但上调了线粒体核糖体RNA 12S基因表达,同时促进As(Ⅲ)向As(Ⅴ)转化,这表明硅酸盐可促进硅藻砷氧化和呼吸产能活性,有助于增加硅藻对砷的抗性。本研究证实了硅藻间砷甲基化和氧化能力差异,并且硅酸盐是影响其砷转化的重要因素,可为硅藻应用于砷污染水体修复提供参考。 相似文献
45.
SOLANGE PAPINI TOMAZ LANGENBACH LUIZ C. LUCHINI MARA M. DE ANDRÉA 《Journal of environmental science and health. Part. B》2013,48(5):523-530
Contamination of soil with pesticides can be evaluated using toxicity tests with worms because their ecological niche makes them good bioindicators. Bioaccumulation in compost worms of [methyl- 14C] paraquat (1,1′-dimethyl-4,4′-bipyridinium dichloride) was measured after three-month exposure in two substrates with differing physicochemical characteristics, in particular their organic matter and clay contents. The treatments were 1.2, 12, and 120 μg paraquat g?1 substrate. The action of the worms did not influence the loss of 14C from the substrates, as the 14C-recovered was essentially quantitative at the end of the study in both the presence and absence of the worms. The organic matter and clay contents of the substrates determined the extent of the paraquat uptake by the worms; worms from the substrate with smaller amounts of clay and organic matter had the higher values of the bioconcentration factor (BCF), these being about 5 (fresh-weight basis) and independent of the application rate. The BCF values in the substrate containing more organic matter and clay were smaller but increased from 1.1 to 3.8 with the increasing rates of application. However, in both substrates the amounts of paraquat bioaccumulated in the worms was always less than 1% of that applied, indicating the very strong binding of paraquat to the substrates and hence low availability to the worms. 相似文献
46.
There is increasing awareness of the damage caused to valuable and often unique sensitive habitats by people pressure as degradation causes a loss of plant species, disturbance to wildlife, on-site and off-site impacts of soil movement and loss, and visual destruction of pristine environments. This research developed a new perspective on the problem of recreational induced environmental degradation by assessing the physical aspects of soil erosion using the fallout radionuclide caesium-137 (137Cs). Temporal sampling problems have not successfully been overcome by traditional research methods monitoring footpath erosion and, to date, the 137Cs technique has not been used to estimate longer-term soil erosion in regard to sensitive recreational habitats. The research was based on-sites within Dartmoor National Park (DNP) and the South West Coast Path (SWCP) in south-west England. 137Cs inventories were reduced on the paths relative to the reference inventory (control), indicating loss of soil from the path areas. The Profile Distribution Model estimated longer-term erosion rates (ca. 40 years) based on the 137Cs data and showed that the combined mean soil loss for all the sites on ‘paths’ was 1.41 kg m?2 yr?1 whereas the combined ‘off path’ soil loss was 0.79 kg m?2 yr?1, where natural (non-recreational) soil redistribution processes occur. Recreational pressure was shown to increase erosion in the long-term, as greater soil erosion occurred on the paths, especially where there was higher visitor pressure. 相似文献
47.
R. M. LOEWY L. G. CARVAJAL M. NOVELLI A. M. PECHEN DE D'ANGELO 《Journal of environmental science and health. Part. B》2013,48(6):869-881
Groundwater samples were collected from monitoring wells along an area of intensive fruit production. Different types of correlations were investigated between soil physicochemical characteristics, depths and agricultural practices with pesticide detection frequency. In the three analyzed periods azinphos methyl, S-(3,4-diydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl)-O,O-dimethyl phosphorodithioate, showed a definite seasonal behavior related to the application pattern, increasing its concentration in the aquifer from October to November-December and then decreasing towards March. Samples obtained during the non-spraying season showed that azinphos methyl residues were lower than detection limit (LOD). An inverse correlation was observed between azinphos methyl concentration and the time elapsed since the last pesticide application. Seasonal events such as rain and irrigation influence the chemical concentration in the well, while no correlation was obtained between soil characteristics and azinphos methyl concentration. The soil attenuation capacity was not enough to prevent the presence of azinphos methyl in the aquifer during the application season. 相似文献
48.
Deborah J. Ballantine Desmond E. Walling Adrian L. Collins Graham J. L. Leeks 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):371-380
Deposition and storage of fine sediment on channel beds represents an important component of a catchment’s sediment budget
and can have important implications for sediment-associated P fluxes, due to storage and remobilisation, and for P concentrations
through water–sediment interactions. Spatial and temporal variations in P content and storage in fine bed sediment have been
studied in two UK lowland catchments, the Rivers Frome and Piddle in Dorset. Fine bed sediment was sampled in representative
reaches on a bi-monthly basis using a re-suspension cylinder, and the resulting samples were analysed for total P, a range
of P fractions and particle size. The results demonstrate significant spatial and temporal variability in PP concentrations
and storage, with maximum and minimum P concentrations and storage occurring in late summer and winter, respectively. Temporal
variations in concentrations reflect residence times of the sediment and ambient P concentrations, while variations in storage
are mainly due to hydrological regimes. Spatial variations reflect catchment characteristics, the location of inputs and local
variations in hydrological and channel bed conditions. 相似文献
49.
RODOLFO JAFFÉ VINCENT DIETEMANN MIKE H. ALLSOPP CECILIA COSTA ROBIN M. CREWE RAFFAELE DALL’OLIO PILAR DE LA RÚA MOGBEL A. A. EL‐NIWEIRI INGEMAR FRIES NIKOLA KEZIC MICHAEL S. MEUSEL ROBERT J. PAXTON TAHER SHAIBI ECKART STOLLE ROBIN F.A. MORITZ 《Conservation biology》2010,24(2):583-593
Abstract: Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad picture of the current status of honeybees across their natural range, we used microsatellite genetic markers to estimate colony densities and genetic diversity at different locations in Europe, Africa, and central Asia that had different patterns of land use. Genetic diversity and colony densities were highest in South Africa and lowest in Northern Europe and were correlated with mean annual temperature. Confounding factors not related to climate, however, are also likely to influence genetic diversity and colony densities in honeybee populations. Land use showed a significantly negative influence over genetic diversity and the density of honeybee colonies over all sampling locations. In Europe honeybees sampled in nature reserves had genetic diversity and colony densities similar to those sampled in agricultural landscapes, which suggests that the former are not wild but may have come from managed hives. Other results also support this idea: putative wild bees were rare in our European samples, and the mean estimated density of honeybee colonies on the continent closely resembled the reported mean number of managed hives. Current densities of European honeybee populations are in the same range as those found in the adverse climatic conditions of the Kalahari and Saharan deserts, which suggests that beekeeping activities do not compensate for the loss of wild colonies. Our findings highlight the importance of reconsidering the conservation status of honeybees in Europe and of regarding beekeeping not only as a profitable business for producing honey, but also as an essential component of biodiversity conservation. 相似文献
50.
Using Fallout Lead-210 Measurements to Estimate Soil Erosion in Three Small Catchments in Southern Italy 总被引:1,自引:0,他引:1
Paolo Porto Des E. Walling Giovanni Callegari Francesco Catona 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):657-667
Soil erosion and associated off-site environmental impacts have attracted increasing attention in recent decades, and there
is a growing need for reliable information on rates of soil loss. The potential for using 137Cs fallout to quantify rates and patterns of soil redistribution over medium-term timescales (ca. 45 years) has been successfully
demonstrated in a wide range of environments around the world. The similar behaviour of fallout 210Pb in soils offers potential for its use as an alternative to 137Cs, in areas where 137Cs inventories are low or are complicated by additional fallout from the Chernobyl accident. There have, however, to date
been few attempts to validate the use of fallout 210Pb measurements for assessing erosion rates. This paper reports an attempt to explore the use of fallout 210Pb to estimate rates of water-induced soil erosion on uncultivated land. It focuses on three small forest/rangeland catchments
located in Calabria, southern Italy, for which measurements of sediment output are available. Comparison of the estimates
of net soil loss from the catchments derived from 210Pb measurements with the measured sediment output, confirmed the validity of the 210Pb approach. The soil redistribution rates estimated using 210Pb measurements were also consistent with equivalent estimates obtained for the same study catchments using 137Cs measurements. 相似文献