2012—2017年海州湾潮间带大型底栖动物群落结构及变化

为了解海州湾潮间带大型底栖动物群落结构,分析人类养殖活动对其影响,于2012-2017年对该区域大型底栖动物进行调查。结果表明：6年间共发现120种大型底栖动物,依据种类组成进行聚类分析可分为4组;调查中总平均丰度为3 495.9 ind./m²,范围为506.7~17 864.0 ind./m²;总平均生物量为197.26 g/m²,范围为1.58~489.17 g/m²。光滑河蓝蛤（Potamocorbula laevis）为第一优势种,其繁殖盛期在每年9-10月。调查期间生物多样性整体呈下降趋势,人类的养殖活动主导着海州湾潮间带大型底栖动物群落结构的变化。     

我国北方农牧交错带生态建设成本体系研究——以吉林省西部为例

北方农牧交错带是我国生态建设的重点地区,对于生态建设成本的研究是生态补偿的科学基础。从科学发展观的视角出发,针对这类地区收入水平低、就业结构单一的特点,认为其成本体系应本着以农民需求为核心、统筹区域内生态建设和发展的关系,并为统筹生态建设区与受益地区发展提供依据的原则进行构建,依此将成本分为营建成本、机会成本和发展成本,并通过在吉林省西部的应用,得出吉林省西部退耕还林、还草、草原抚育的总成本分别为24150、8090、967元h/m₂,远高于国家所提供的补偿标准。因此,除了国家补助外,应本着“受益者支付”的原则,长春、吉林等地应通过就业培训、技术支持等方式支付发展成本。因此,我国在生态建设中应细化补偿标准和实行支付主体多元化,国家和当地政府就营建成本和机会成本方面作出补偿,而受益地区则着重于发展成本的补偿。     

油气田瓦斯隧道开挖掌子面围岩安全厚度研究

为降低油气田区隧道施工风险,以龙泉山隧道为依托,采用数值模拟方法对隧道开挖掌子面前方围岩安全厚度进行分析,并结合现场监测数据对所得结论进行验证。研究结果表明:隧道施工使隧址区围岩应力重分布,且应力变化与围岩距掌子面距离L有关,当L≤0.75D（D为隧道净高）时,围岩处于应力释放区;当0.75D相似文献   

Natural factors and human modifications contributing to marsh loss in Louisiana's Mississippi River Deltaic Plain

Natural factors and human modifications contribute to the estimated annual loss of 10,200 ha of coastal land in the Mississippi River Deltaic Plain Region of south Louisiana. This paper combines information on regional geology and human-induced habitat alterations to evaluate the relative importance of human and natural factors to marsh loss. Data on marsh area and habitat type for 139 7.5-min quadrangles were calculated from maps based on aerial photographs from 1955/56 and 1978, and data on regional geology obtained from published maps were used to construct multivariate model relating initial marsh area, change in urban and agricultural area, change in canal and spoil area, canal area in 1978, depth of sediment overlying the Prairie terrace, and subdelta age to marsh loss. The model indicated that between 25.0% and 39.0% of the marsh loss that occurred during the 23-year period was related to canal and spoil construction, and between 9.5% and 12.7% was related to urban and agricultural development. These are minimal estimates of loss because they do not include many secondary effects (for example, canal orientation, saltwater intrusion, and eutrophication) that can also result in indirect loss. Depth of sediment, initial marsh area, delta lobe age by 1978 canal and spoil area interaction, and indirect effects not included in the model accounted for remaining marsh loss.     

<Emphasis Type="Italic">A Posteriori</Emphasis> Evaluation of Strategies of Management: The Effectiveness of No-Wash Zones in Minimizing the Impacts of Boat-Wash on Macrobenthic Infauna

Wind-driven waves are important in structuring intertidal and shallow subtidal assemblages of macrobenthic infauna. In the sheltered waters of estuaries, boat-generated waves (wash) may play a similar role because they are typically of a similar amplitude or larger than wind-driven waves. However, few studies have attempted to determine the role of wash in structuring assemblages. Consequently, strategies for managing boating focus around minimization of bank erosion. Along the Parramatta River (Sydney, Australia), no-wash zones have been established and mangroves planted to minimize the erosion of riverbanks and collapse of seawalls purportedly caused by 35-m-long RiverCat ferries. Although intended to also reduce the ecological impacts of wash, it is unclear whether these strategies achieve this goal. Unvegetated and vegetated (among the pneumatophores of mangroves) sediments were sampled in wash and no-wash zones along the Parramatta River to assess the effectiveness of no-wash zones and vegetation of river banks in reducing the ecological impacts of wash. Specifically, it was hypothesized that (1) assemblages of intertidal macrobenthic infauna would differ between wash and no-wash zones of the Parramatta River and (2) these differences would be greater in unvegetated than in vegetated habitat. As predicted, assemblages of macrobenthic infauna differed between the wash and no-wash zones. Capitellids, nereids, and spionids were more abundant in the no-wash zone. Contrary to the hypothesis, differences were no greater in the unvegetated habitat than in the vegetated habitat. The results suggest an impact of wash on assemblages of macrobenthic infauana and a role for no-wash zones in minimizing the effects of this disturbance.     

Hydrochemical Buffer Assessment in Agricultural Landscapes: From Local to Catchment Scale

Non-point-source pollution of surface and groundwater is a prominent environmental issue in rural catchments, with major consequences on water supply and aquatic ecosystem quality. Among surface-water protection measures, environmental or landscape management policies support the implementation and the management of buffer zones. Although a great number of studies have focused on buffer zones, quantification of the buffer effect is still a recurring question.The purpose of this article is a critical review of the assessment of buffer-zone functioning. Our objective is to provide land planners and managers with a set of variables to assess the limits and possibilities for quantifying buffer impact at the catchment scale. We first consider the scale of the local landscape feature. The most commonly used empirical method for assessing buffers is to calculate water/nutrient budgets from inflow–outflow monitoring at the level of landscape structures. We show that several other parameters apart from mean depletion of flux can be used to describe buffer functions. Such parameters include variability, with major implication for water management. We develop a theoretical framework to clarify the assessment of the buffer effect and propose a systematic analysis taking account of temporal variability. Second, we review the current assessment of buffer effects at the catchment scale according to the theoretical framework established at the local scale. Finally, we stress the limits of direct empirical assessment at the catchment scale and, in particular, we emphasize the hierarchy in hydrological processes involved at the catchment scale: The landscape feature function is constrained by other factors (climate and geology) that are of importance at a broader spatial and temporal scale.Published on line     

Probabilistic indicators of atmospheric transport for regional monitoring and emergency preparedness systems

In this paper, following a methodology developed within the "Arctic Risk" Project of the Nordic Arctic Research Programme, several probabilistic indicators to evaluate the risk site possible impact on the geographical regions, territories, countries, counties, cities, etc., due to atmospheric transport from the risk site region were suggested. These indicators-maximum possible impact zone, maximum reaching distance, and typical transport time-were constructed by applying statistical methods and using a dataset of isentropic trajectories originated over the selected nuclear risk site (Ignalina nuclear power plant, Lithuania) during 1991-1996. For this site, the areas enclosed by isolines of the maximum possible impact zone and maximum reaching distance indicators are equal to 42 x 10(4) and 703 x 10(4) km(2), respectively. The maximum possible impact zone's boundaries are more extended in the southeast sector from the site and include, in particular, Latvia, Lithuania, Belarus, and several western regions of Russia. The maximum reaching distance's boundaries are twice more extended in the eastern direction from the site (reaching the Caspian Sea) compared with the western direction. The typical transport time to reach the southern territories of Sweden and Finland, northern regions of Ukraine, and northeast of Poland is 1 day. During this time, the atmospheric transport could typically occur over the Baltic States, Belarus, and western border regions of Russia, and central aquatoria of the Baltic Sea. Detailed analysis of temporal patterns for these indicators showed importance of the seasonal variability.     

Riparian Ecosystem Management Model: Sensitivity to Soil,Vegetation, and Weather Input Parameters1

Abstract: The Riparian Ecosystem Management Model (REMM) was developed by the U.S. Department of Agriculture‐Agriculture Research Service (USDA‐ARS) and its cooperators to design and evaluate the efficiency of riparian buffer ecosystems for nonpoint source pollution reduction. REMM requires numerous inputs to simulate water movement, sediment transport, and nutrient cycling in the buffer system. In order to identify critical model inputs and their uncertainties, a univariate sensitivity analysis was conducted for nine REMM output variables. The magnitude of each input parameter was changed from ?50% to +50% from the baseline data in 12 intervals or, in some cases, the complete range of an input was tested. Baseline model inputs for the sensitivity analysis were taken from Gibbs Farm, Georgia, where REMM was tested using a 5‐year field dataset. Results of the sensitivity analysis indicate that REMM responses were most sensitive to weather inputs, with minimum daily temperature having the greatest impact on the nitrogen‐related outputs. For example, the 100% change (?50% to +50%) in minimum daily temperature input values yielded a 164.4% change in total nitrogen (N), a 109.3% change in total nitrate (NO₃), and a 127.1% change in denitrification. REMM was most sensitive to precipitation with regard to total flow leaving the riparian vegetative buffer zone (199.8%) and sediment yield (138.2%). Deep seepage (12.2%), volumetric water content (24.8%), and pore size index (6.5%) in the buffer soil profile were the most influential inputs for the output water movement. Sediment yield was most sensitive to Manning’s coefficient (46.6%), bare soil percent (40.7%), and soil permeability (6.1%). For vegetation, specific leaf area, growing degree day coefficients, and maximum root depth influenced the nitrogen related outputs. Overall results suggest that because of the high sensitivity to weather parameters, on‐site weather data is needed for model calibration and validation. The model’s relatively low sensitivity to vegetation parameters also appears to support the use of regional vegetation datasets that would simplify model implementation without compromising results.     

民窿空区群级联失稳评价

民窿空区群已构成了许多矿山安全生产的极大隐患。针对民窿空区群的特点，运用重整化群方法，从整体的角度对民窿空区群系统的稳定性问题进行了研究，得到了空区群变尺度级联失稳迭代函数。给出了判别空区群系统整体失稳的临界概率，将空区群系统失稳的复杂判别转化为单元失稳概率与临界概率大小的比较问题，同时给出了计算实例，以供参考。所建立的方法可以为大规模民窿空区群范围内的工程施工以及民窿所在矿山空区群整体稳定性评价提供参考，同时也为认识一般空区群系统的失稳机理开辟了一条新的途径。     

Community Perspectives and Conservation Needs for Dugongs (Dugong dugon) Along the Andaman Coast of Thailand

The dugong is classified as vulnerable to extinction by the World Conservation Union on the basis of declines in area or extent of occupancy, habitat quality, and actual or potential levels of exploitation. In Thailand, the largest groups of dugongs are found near islands off the Andaman coast. The authors conducted a 2-year project that included dugong population and habitat assessment as well as interviews with local fishers. The results indicate declining populations of dugongs. The largest threat to dugongs is incidental catch in fishing nets. The numbers of deaths reported place the dugong population along the Andaman Sea in danger of extirpation. Other threats include seagrass destruction both from fishing and coastal development and the use of dugong parts for medicinal purposes. Villagers still show strong ties with dugongs, and the majority favor establishing more large protected areas for the species. These should arise from an integrated national dugong and seagrass conservation strategy formulated by concerned stakeholders from government, nongovernmental organizations, scientists, and local communities. The strategy needs to be both top down and bottom up in its formation to balance existing and potential uses as well as conflicts between artisanal and commercial fishers. The strategy should include the development of educational materials and enforceable regulations, as well as the designation of community-protected seagrass beds and a system of dugong sanctuaries along the Andaman coast. An integrated management plan is needed urgently, with the continued input of concerned scientists, to monitor and increase knowledge of dugong behavior and distribution.