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361.
从含油废水中筛选分离到1株原油降解菌XD-1,鉴定为假单胞菌(Pseuomonas sp.).初步实验表明菌XD-1具有较强的产表面活性剂乳化原油的作用,对该菌的产表面活性剂性能进行了研究.实验证明,菌XD-1所产表面活性剂为脂肽类物质,菌在生长对数期产表面活性剂,表面活性剂的产生为生长相关型;充足的碳源是产表面活性剂的必需条件,菌利用原油为碳源时能持续大量地产表面活性剂;原油和尿素为产表面活性剂的最适碳源和氮源,菌XD-1产表面活性剂的最佳营养培养基组成为葡萄糖10 g,尿素4 g,磷酸二氢钾1 g,微量元素液4 mL,水1 L,pH 8.0.  相似文献   
362.
颗粒物中重金属元素可对人体健康造成不利影响,粒径越小危害越大.利用在线重金属观测仪于2021年1月7~25日在郑州市连续测定PM1中Al、 Si、 K、 Ca、 V、 Cr、 Mn、 Fe、 Ni、 Cu、 Zn、 As、 Se、 Ba、 Pb和Cd共16种重金属元素.结果表明,观测期间ρ(K)的浓度最高(0.62μg·m-3).根据污染物浓度和气象特征,将观测期间划分为清洁日、沙尘日和霾日.大气PM1中重金属污染特征和健康风险评价在不同污染过程下的贡献不同.利用美国EPA健康风险评价法评估重金属的健康风险,采用富集因子法和正定矩阵因子模型(PMF)解析重金属来源,并利用浓度权重轨迹分析法(CWT)和后向轨迹法对传输的影响进行评估.结果表明在不同污染过程下Zn、 As、 Se、 Pb和Cd的富集因子超过100,均受人类活动影响较大.在观测期间重金属主要来源为工业源、燃煤/生物质源、机动车源和扬尘源.将健康风险结果代入PMF分析发现,在清洁日、沙尘日和霾日期间工业源是致癌与非致癌健康风险的主要贡献源,且本地区PM...  相似文献   
363.
采用问卷调查、信效度分析和因子分析等方法,研究玻璃行业不安全行为影响因素,研究结果表明:玻璃行业员工不安全行为主要包括车间照明、PPE佩戴等18个影响因素指标;根据方差分析结果将影响因素归结为工作环境与行为要求(F1)、安全教育与培训(F2)、群体与组织行为影响(F3)和激励沟通与奖惩(F4)等4个主因子,其方差解释率分别为32%、12%、10%、10%,权重分别为0.51、0.19、0.15、0.15;根据分析结果针对性提出“4+1”安全管理模式,为玻璃行业降低不安全行为几率、保障安全生产提供理论依据。  相似文献   
364.
The Potential for Species Conservation in Tropical Secondary Forests   总被引:3,自引:0,他引:3  
Abstract: In the wake of widespread loss of old‐growth forests throughout the tropics, secondary forests will likely play a growing role in the conservation of forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary forests. Beyond the characteristics of local forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary forests. Prospects for conservation of old‐growth species in secondary forests are maximized in regions where the ratio of secondary to old‐growth forest area is relatively low, older secondary forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed‐dispersing fauna are present, and old‐growth forests are close to abandoned sites. The conservation value of a secondary forest is expected to increase over time, as species arriving from remaining old‐growth forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of old‐growth species present in secondary forests. Older secondary forests are not often studied and few long‐term studies are conducted in secondary forests. Available data indicate that both old‐growth and second‐growth forests are important to the persistence of forest species in tropical, human‐modified landscapes.  相似文献   
365.
The chemical composition of the defensive secretions of 52 species from 15 genera of the tenebrionid subtribe Stizopina was analyzed. The secretions of all species contained 1,4-benzoquinones, 1-alkenes, and monoterpene hydrocarbons, only one species was lacking the latter. Methyl- and ethyl-1,4-benzoquinone were ubiquitous, mostly accompanied by smaller amounts of 1,4-benzoquinone as well as isopropyl- and propyl-1,4-benzoquinone. 1-Alkenes were dominated by 1-undecene with varying admixtures of other 1-alkenes. The monoterpene hydrocarbons always consisted of a mixture of α-pinene, camphene, β-pinene and limonene, but also p-cymene, α-terpinene or α-phellandrene were found in some species. Furthermore, some species synthesized additional compounds such as phenols, ketones, 2,5-dihydroxy-6-methylbenzoate, 2-hydroxy-4-methoxyacetophenone and naphthoquinones. Bioassays showed that the defensive secretion co-functioned as an aggregation pheromone in the subtribe Stizopina. All nine tested species from six genera were attracted to defensive secretion of Stizopina species, but they did not distinguish between defensive secretions of different Stizopina species. This lack of discrimination might be the initial step for the formation of interspecific aggregations and the evolution of cleptoparasitism within the Stizopina.  相似文献   
366.
ABSTRACT: Unrelenting pressure on limited surface water supplies requires increasingly sophisticated water management approaches. Climate forecasts of seasonal precipitation and temperature are potentially useful, but the operational water management community currently underutilizes them. However, some agencies in Arizona took unprecedented advantage of forecasts for a potentially wet winter during the 1997–1998 El Niño event. This study investigates use of this information through a series of semi‐structured in‐depth interviews with key personnel from agencies responsible for emergency management and water supply; their jurisdictions ranged from urban to rural and local to regional. Interviews investigated information acquisition, interpretation, and incorporation into specific decisions and actions. While unprecedented actions were taken by some water management agencies and no agencies implemented inappropriate measures, some missed opportunities for more effective response, primarily through inaction. This study reveals a variety of technical factors and institutional characteristics affecting forecast use. Study findings emphasize the need for: (a) closer ongoing relationships between forecast producers and users, (b) increased institutional flexibility to exploit the increasing skill of seasonal climate forecasts, (c) demonstration projects of effective forecast use, and (d) a regional forum to facilitate information transfer between the hydro‐climatic research community and operational water managers.  相似文献   
367.
The Lagoon Olho d'Água in Pernambuco State, Northeast Brazil has received increasing environmental concern due to significant stress from pollution in the catchment. The existing environmental problems are the result of great pressure from a broad range of human activities, especially in the last 10 years. Serious pollution exists mainly from some industrial and urban activities, which increased intensively after the eighties. There is a strong social and economical pressure for housing and construction near the lagoon, due to the available land nearby beaches and estuarine zone, and recently by growing tourism activities. Uncontrolled land use by low-income communities and the pressure for construction by developers have led to landfilling and to deterioration of water quality in the lagoon catchment. Improvement of the environmental conditions in the catchment needs integrated measures. Guidelines and some specific actions involving several institutions have been established and refer to sanitation and urban infrastructure as the main priorities. A main target is the construction of low-cost sewage system with smaller and decentralised treatment plants.  相似文献   
368.
用离子交换法从β盐母液中分离1-萘磺酸钠的研究   总被引:3,自引:2,他引:1  
比较了D290、D296、D301、D370、D372、D380 6种树脂对β盐母液中1-萘磺酸的静态交换性能,筛选出D296用以回收β盐母液中的1-萘磺酸钠,进行了PH、接触时间、交换温度等影响因素的条件试验及树脂再生试验,得到1-萘磺酸钠收率80%以上。  相似文献   
369.
Abstract: The natterjack toad (Bufo calamita) is endangered in several parts of its distribution, including Belgium, where it occurs mainly in artificial habitats. We parameterized a general model for natterjack population viability analysis (PVA) and tested its sensitivity to changes in the values of basic parameters. Then we assessed the relative efficiency of various conservation measures in 2 situations: a small isolated population and a system of 4 populations connected by rare dispersal movements. We based the population viability analysis on a stage‐structured model of natterjack population dynamics. We parameterized the model in the RAMAS GIS platform with vital rates obtained from our own field experience and from published studies. Simulated natterjack populations were highly sensitive to habitat quality (particularly pond drying), to dispersal from surrounding local populations, and to a lesser extent to values of fecundity and survival of terrestrial stages. Population trajectories were nearly insensitive to initial abundances, carrying capacities, and the frequency of extreme climatic conditions. The simulations showed that in habitats with highly ephemeral ponds, where premetamorphosis mortality was high, natterjack populations nearly always had a very high extinction risk. We also illustrated how low dispersal rates (<1 dispersing individual/generation) efficiently rescued declining local populations. Such source‐sink dynamics demonstrate that the identification and management of source populations should be a high priority.  相似文献   
370.
The Future of Scattered Trees in Agricultural Landscapes   总被引:1,自引:0,他引:1  
Abstract: Mature trees scattered throughout agricultural landscapes are critical habitat for some biota and provide a range of ecosystem services. These trees are declining in intensively managed agricultural landscapes globally. We developed a simulation model to predict the rates at which these trees are declining, identified the key variables that can be manipulated to mitigate this decline, and compared alternative management proposals. We used the initial numbers of trees in the stand, the predicted ages of these trees, their rate of growth, the number of recruits established, the frequency of recruitment, and the rate of tree mortality to simulate the dynamics of scattered trees in agricultural landscapes. We applied this simulation model to case studies from Spain, United States, Australia, and Costa Rica. We predicted that mature trees would be lost from these landscapes in 90–180 years under current management. Existing management recommendations for these landscapes—which focus on increasing recruitment—would not reverse this trend. The loss of scattered mature trees was most sensitive to tree mortality, stand age, number of recruits, and frequency of recruitment. We predicted that perpetuating mature trees in agricultural landscapes at or above existing densities requires a strategy that keeps mortality among established trees below around 0.5% per year, recruits new trees at a rate that is higher than the number of existing trees, and recruits new trees at a frequency in years equivalent to around 15% of the maximum life expectancy of trees. Numbers of mature trees in landscapes represented by the case studies will decline before they increase, even if strategies of this type are implemented immediately. This decline will be greater if a management response is delayed.  相似文献   
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