不同抗生素种类及浓度对麻疯树培养的影响

以麻疯树(jatropha ctrcas)的子叶、真叶、根及其对应的愈伤组织作为实验材料,研究各种抗生素对其生长的影响;在MS培养基中添加不同浓度和不同种类的抗生素,比较其对麻疯树不同外植体及对应愈伤组织生长的影响.方差分析和总体观察的结果表明,用于筛选转化植株的最佳抗生素是卡那霉素,其最佳抗性筛选浓度范围为10～25mg/L.表9参10     

13株真菌对聚β-羟基丁酸酯膜的降解特性

从不同来源的活性污泥中分离筛选出13株可降解聚β—羟基丁酸酯(PHB)的真菌，分别编号为DS9701、DS9702、DS9703、DS9704、DS9705、DS9706、DS9707、DS9708、DS9709、DS9710、DS9711、DS9712、DS9713．对DS97系列真菌降解PHB膜的特性进行了研究．结果表明，各菌株平均降解PHB膜速率之间的差异均达到极显著水平；13个菌株对PHB膜的降解可分为四种类型，即缓慢降解—快速降解—缓慢降解；缓慢降解—快速降解；缓慢降解—等速降解；缓慢降解—中速降解—快速降解。     

袁河流域不同土地利用方式下河流浮游细菌群落结构特征

于2018年8月采集袁河上游至下游的16个采样点表层水样,基于高通量测序技术分析土地利用方式下河流浮游细菌群落特征并对比土地利用与水化学指标对浮游细菌群落的影响差异.结果表明：①袁河优势浮游细菌群落为变形菌门（Proteobacteria,35.17%）,放线菌门（Actinobacteria,33.99%）和拟杆菌门（Bacteroidetes,17.59%）,其中Bacteroidetes丰度随流向显著降低;②受农田和建设用地增加的影响,袁河上、下游河段细菌群落多样性均随流向呈升高趋势;中游河段浮游细菌群落多样性由于湖库滞留作用明显下降;③水域和林地是土地利用方式中最佳组合因子,土地利用方式显著影响浮游细菌群落,两者相关系数为0.4797,土地利用方式对浮游细菌群落的方差解释量为31.3%;④土地利用方式对浮游细菌群落的影响大小与水化学指标相近,同时存在土地利用方式与水化学的交叉影响（方差解释量为10.9%）,表明在袁河浮游细菌群落的形成中,质量效应与物种分选机制并存.本研究表明,在河流浮游细菌研究中要重视流域土地利用方式造成的外源细菌输入差异,以及土地利用方式输入的不同水化学成分对浮游细菌的分选作用.     

Positives and pathologies of natural resource management on private land‐conservation areas

In managed natural resource systems, such as fisheries and rangelands, there is a recognized trade‐off between managing for short‐term benefits and managing for longer term resilience. Management actions that stabilize ecological attributes or processes can improve productivity in the supply of ecosystem goods and services in the short term but erode system resilience at longer time scales. For example, fire suppression in rangelands can increase grass biomass initially but ultimately result in an undesirable, shrub‐dominated system. Analyses of this phenomenon have focused largely on how management actions influence slow‐changing biophysical system attributes (such as vegetation composition). Data on the frequency of management actions that reduce natural ecological variation on 66 private land‐conservation areas (PLCAs) in South Africa were used to investigate how management actions are influenced by manager decision‐making approaches, a largely ignored part of the problem. The pathology of natural resource management was evident on some PLCAs: increased focus on revenue‐generation in decision making resulted in an increased frequency of actions to stabilize short‐term variation in large mammal populations, which led to increased revenues from ecotourism or hunting. On many PLCAs, these management actions corresponded with a reduced focus on ecological monitoring and an increase in overstocking of game (i.e., ungulate species) and stocking of extralimitals (i.e., game species outside their historical range). Positives in natural resource management also existed. Some managers monitored slower changing ecological attributes, which resulted in less‐intensive management, fewer extralimital species, and lower stocking rates. Our unique, empirical investigation of monitoring‐management relationships illustrates that management decisions informed by revenue monitoring versus ecological monitoring can have opposing consequences for natural resource productivity and sustainability. Promoting management actions that maintain resilience in natural resource systems therefore requires cognizance of why managers act the way they do and how these actions can gradually shift managers toward unsustainable strategies.     

Chilean Blue Whales as a Case Study to Illustrate Methods to Estimate Abundance and Evaluate Conservation Status of Rare Species

Abstract: Often abundance of rare species cannot be estimated with conventional design‐based methods, so we illustrate with a population of blue whales (Balaenoptera musculus) a spatial model‐based method to estimate abundance. We analyzed data from line‐transect surveys of blue whales off the coast of Chile, where the population was hunted to low levels. Field protocols allowed deviation from planned track lines to collect identification photographs and tissue samples for genetic analyses, which resulted in an ad hoc sampling design with increased effort in areas of higher densities. Thus, we used spatial modeling methods to estimate abundance. Spatial models are increasingly being used to analyze data from surveys of marine, aquatic, and terrestrial species, but estimation of uncertainty from such models is often problematic. We developed a new, broadly applicable variance estimator that showed there were likely 303 whales (95% CI 176–625) in the study area. The survey did not span the whales' entire range, so this is a minimum estimate. We estimated current minimum abundance relative to pre‐exploitation abundance (i.e., status) with a population dynamics model that incorporated our minimum abundance estimate, likely population growth rates from a meta‐analysis of rates of increase in large baleen whales, and two alternative assumptions about historic catches. From this model, we estimated that the population was at a minimum of 9.5% (95% CI 4.9–18.0%) of pre‐exploitation levels in 1998 under one catch assumption and 7.2% (CI 3.7–13.7%) of pre‐exploitation levels under the other. Thus, although Chilean blue whales are probably still at a small fraction of pre‐exploitation abundance, even these minimum abundance estimates demonstrate that their status is better than that of Antarctic blue whales, which are still <1% of pre‐exploitation population size. We anticipate our methods will be broadly applicable in aquatic and terrestrial surveys for rarely encountered species, especially when the surveys are intended to maximize encounter rates and estimate abundance.     

ESTIMATING MEAN AND VARIANCE FOR ENVIRONMENTAL SAMPLES WITH BELOW DETECTION LIMIT OBSERVATIONS1

ABSTRACT: Left-censoring of data sets complicates subsequent statistical analyses. Generally, substitution or deletion methods provide poor estimates of the mean and variance of censored samples. These substitution and deletion methods include the use of values above the detection limit (DL) only, or substitution of 0, DL/2 or the DL for the below DL values during the calculation of mean and variance. A variety of statistical methods provides better estimators for different types of distributions and censoring. Maximum likelihood and order statistics methods compare favorably to the substitution or deletion methods. Selected statistical methods applicable to left-censoring of environmental data sets are reviewed with the purpose of demonstrating the use of these statistical methods for coping with Type I (and Type II) left-censoring of normally and log-normally distributed environmental data sets. A PC program (UNCENSOR) is presented that implements these statistical methods. Problems associated with data sets with multiple DLs are discussed relative to censoring methods for life and fatigue tests as recently applied to water quality data sets.     

降雨径流污染风险等级识别与优化方法

径流污染控制是当前城市水环境保护的难题,识别径流污染物入河风险是提高污染控制效率的关键.将景观格局与过程相结合,借助景观指数和最小阻力模型,提出了降雨径流污染风险识别和治理方法.计算得到研究区主要河段的降雨径流污染格局、过程和综合风险指数;并计算出以耕地、城镇建设用地和交通工矿用地为"源"产生的风险路径分别为256、1...     

基于Newmark模型的地震诱发滑坡易发性分析方法的研究

以芦山地震诱发滑坡数据为研究对象,开展Newmark模型在区域性地震诱发滑坡空间易发性分析中的应用研究.首先采用网格形式进行数据处理,完成地形坡度、地震参数等数据的统一化,重点利用地层岩性数据对Newmark模型内参数开展区域定量化赋值,在此基础上根据Newmark模型及地震参数相关公式分别计算了安全系数、临界加速度和...     

Development of a New Approach to Cumulative Effects Assessment: A Northern River Ecosystem Example

If sustainable development of Canadian waters is to be achieved, a realistic and manageable framework is required for assessing cumulative effects. The objective of this paper is to describe an approach for aquatic cumulative effects assessment that was developed under the Northern Rivers Ecosystem Initiative. The approach is based on a review of existing monitoring practices in Canada and the presence of existing thresholds for aquatic ecosystem health assessments. It suggests that a sustainable framework is possible for cumulative effects assessment of Canadian waters that would result in integration of national indicators of aquatic health, integration of national initiatives (e.g., water quality index, environmental effects monitoring), and provide an avenue where long-term monitoring programs could be integrated with baseline and follow-up monitoring conducted under the environmental assessment process.     

沈阳环境空气臭氧浓度及累积速率时序曲线模拟研究

为了解环境空气臭氧累积规律,利用2017年沈阳市环境空气臭氧浓度数据,统计分析臭氧累积速率,并利用回归方法拟合并优化臭氧浓度及其累积速率的时间序列模型,同时结合气温、风力、臭氧前体物等时序变化情况分析臭氧浓度的影响因素。研究发现:沈阳市臭氧月均浓度年变化、日均浓度年变化以及小时浓度日变化时序曲线均呈现单峰形态;年变化中,6月的臭氧浓度最大,4月臭氧累积速率达到最大值;日变化中,14:00臭氧浓度达到最大值,09:00—11:00臭氧累积速率最大,19:00—20:00臭氧迅速消减。温度、风速同臭氧浓度之间均有较好的正相关性。臭氧前体物二氧化氮、挥发性有机物与臭氧浓度之间均呈明显的负相关性。