Assessment of impacts of invasive fishes on the food web structure and ecosystem properties of a tropical reservoir in India

A network model of trophic interactions in a tropical reservoir in India was developed with the objective to quantify matter and energy flows between system components and to study the impact of invasive fishes on the ecosystem. Structure of flows and their distribution within and between trophic levels were analysed by aggregating single flows into combined flows for discrete trophic levels. The trophic flows primarily occurred in the first four trophic level (TL) and the food web structure in this reservoir ecosystem was characterized by the dominance of low TL organisms, with the highest TL of only 3.57 for the top predator. Highest system omnivory index (SOI) was observed for indigenous catfishes (0.422), followed by the exotic fish Mozambique Tilapia (0.402). Nile Tilapia and Pearl spots show the highest niche overlap which suggests high competition for similar resources. The mixed trophic impact routine reveals that an increase in the abundance of the African catfish would negatively impact almost all fish groups such as Indian major carps, Pearl spots, indigenous catfishes and Tilapines. The other invasive fish Mozambique Tilapia adversely affects the indigenous catfishes. The most interesting observation in this study is that the most dominant invasive fish in this reservoir, the Nile Tilapia does not negatively impact any of the fish groups. In fact it positively impacts the Indian major carps. The direct and indirect effects of predation between system components (i.e. fish, invertebrates, phytoplankton and detritus) are quantitatively described and the possible influence and role in the ecosystem's functioning of the invasive fish species are discussed.     

Multicriteria decision support in a technology competition for cleaning polluted soil in Helsinki

Due to expansion of the capital area in Finland, industrial areas are being replanned for residential and commercial use. The soil in these areas is sometimes contaminated, and must therefore be cleaned before building. In spring 1997 the City of Helsinki and the National Technology Agency of Finland declared a contract-based competition for cleaning the polluted soil of the planned Toukolanranta residential area. Nine proposals entered the competition, and the problem was to choose three best candidates for test-cleaning a small part of the region considered. The winner of the test-cleaning phase will get the contract for cleaning the whole area. The proposals were evaluated based on five criteria defined by the competition board consisting of eight experts. The finalists were chosen aided by the SMAA-2 Stochastic Multicriteria Acceptability Analysis technique. SMAA-2 is a method for analysing what kind of preferences favour each alternative. This method is particularly useful in applications, where it is difficult or impossible to obtain accurate preference information. In this application SMAA-2 was observed to suit well for choosing a small set of best alternatives with different strengths and weaknesses.     

滇中城市群环境脆弱性分析及发展对策研究

从水资源短缺、水环境污染、城市环境污染等多方面分析了滇中城市群的环境脆弱性，在此基础上，提出了滇中城市群可持续发展的对策。     

The importance of group‐focused transformational leadership and felt obligation for helping and group performance

Leaders face a challenge to simultaneously motivate workgroups and the individuals within them. Recent criticisms highlight the need to deconstruct broad leadership constructs to offer better theoretical insight into the effects of specific leadership behaviors on groups versus individuals. We address this call by exploring the effects of group‐focused and individual‐focused aspects of transformational leadership. Applying social identity theory, we theorize that group‐focused transformational leadership is key to fostering felt obligation, motivating helping behavior, and enhancing group performance, whereas individual‐focused leadership may only foster helping when individuals also feel a sense of obligation toward their workgroup. In a field study of 260 employees reporting to 36 supervisors in a skilled trade company, we find support for these predictions using multilevel structural equation modeling and multilevel mixed effects modeling. Thus, group‐focused (vs. individual‐focused) transformational leadership and subsequent felt obligation are important antecedents for encouraging helping and, in turn, workgroup performance.     

Influence of Care of Domestic Carnivores on Their Predation on Vertebrates

Abstract: Domestic dogs (Canis familiaris) and cats (Felis catus) are the most abundant mammalian carnivores worldwide. Given that domestic carnivores rely on human‐provided food, their densities are usually independent of prey densities. Nevertheless, underfed pets may need to hunt to meet their energetic and nutritional requirements. We explored the effects of different levels of care (provision of food) of dogs and cats on their predation rates on wild vertebrates in 2 areas of southern Chile. We interviewed cat and dog owners and analyzed prey remains in scats of pets to examine how domestic dogs and cats were managed and to gather information on the wild vertebrates killed and harassed by pets. We used logistic regression to examine the association between pet care and the frequency of wild vertebrate remains in scats. The probability of a dog preying on vertebrates was higher for poorly fed than for adequately fed dogs (odds ratio = 3.7) and for poorly fed than for adequately fed cats (odds ratio = 4.7). Domestic dogs and cats preyed on most endemic and threatened mammals present in the study sites. Our results provide support for the hypothesis that the less care domestic animals receive from owners the higher the probability those animals will prey on wild vertebrates.     

基于ArcGIS的校园景观水体水质特征研究与评价

为了解校园景观水体的水质污染特征及规律,结合富营养化常规监测指标,运用单因子指数法、内梅罗指数法、综合营养状态指数法及基于Arc GIS的空间叠加分析法对重庆某大学校园景观水体(静湖)冬季枯水期的水质状况进行了分析与评价。结果表明,叶绿素a和高锰酸钾指数超标点位为83%和17%;而总氮和总磷能满足地表水环境质量标准中的Ⅳ类与Ⅴ类;叶绿素a与总氮、总磷存在一定的线性关系,且各因子对富营养化的贡献大小为叶绿素a总磷透明度、高锰酸钾指数总氮;该人工湖冬季枯水期综合水质已呈现中度富营养化状态,水质有待改善。     

元谋干热河谷植物功能性状组合的海拔梯度响应

植物功能性状能够显示对环境变化的响应,不同的适应对策呈现出不同的功能性状组合。干热河谷地区水分是最主要的限制性环境因子,之前的大部分研究都是集中关注于干热河谷局部地段,对于从垂直海拔上来研究不同植物在环境梯度下的变化的研究较少。干热河谷地区由于梵风效应,水分胁迫沿海拔梯度发生变化,一般表现为随海拔高度升高,气温降低,湿度和降水量增加,而蒸发量减小,辐射增强。以云南元谋干热河谷4个海拔梯度（1491.33、1730.20、1850.00、1925.57 m）中的植物为研究对象,选取叶片干物质含量（LDMC）、叶面积（LA）、比叶面积（SLA）、叶片厚度（LT）和叶密度（LD）5个功能性状,研究它们的相互关系,比较了海拔间的差异。结果表明：1）5个功能性状在不同海拔间均呈现出一定差异,变异系数由高到低为LD>LA>SLA>LT>LDMC（分别是101%、64%、56%、41%和19%）;方差分析结果也表明,5个功能性状在不同海拔之间差异显著（F=56.218,P<0.01;F=7.829,P<0.01;F=11.21,P<0.01;F=7.429,P<0.01;F=19.213,P<0.01）,尤其是在最低（1491.33 mm）和最高（1927.57 mm）海拔之间,各性状均具有极显著的差异;2）性状之间存在组合关系, LD与其他性状间相关性最为明显,除LDMC以外,LD与LA、SLA、LT均呈现出极显著负相关关系;LDMC与LA和LT呈极显著负相关;SLA与LA和LT呈正相关,而与LDMC显著负相关;LT与SLA显著正相关,与LA之间相关性不显著;3）在不同的海拔梯度之间,性状组合存在非同步变化现象。研究显示,元谋干热河谷地区,植物对水分环境的海拔梯度变化产生功能性状组合的响应,低海拔和高海拔物种对所处环境的适应策略不同,使得植物在海拔梯度上出现叶片功能性状组合的分化和差异。     

湖库富营养化状态的快速评价

介绍了实现富营养化评价的EXCEL自定义函数的代码编写、模块保存与导入、函数使用等。以富营养化评价的实例,说明使用自定义函数求解含多参数的复杂计算是很方便的。     

ATR-FTIR investigation of the role of phenolic groups in the interaction of some NOM model compounds with aluminum hydroxide

The role of phenolic groups in the interaction of natural organic matter (NOM) with metal hydroxides was investigated with ATR-FTIR spectroscopy and adsorption tests by employing a series of dihydroxybenzoic acids (DHBAs) as the NOM surrogates and aluminum hydroxide as the adsorbent. All DHBAs examined in this study were found to be adsorbed on aluminum hydroxide by forming inner-sphere complexes. Carboxylic groups governed the complexation of DHBAs with aluminum hydroxide at low pH or in cases when the two hydroxyl groups were not adjacent to each other and neither of them was ortho to the carboxylic group. The involvement of the phenolic groups, ortho to another phenolic group or ortho to the carboxylic groups, in the complexation increased with increasing pH as the deprotonation of phenolic groups was easier at higher pH. The presence of phenolic groups increased the electron density of the carboxylic groups and facilitated the inner-sphere complexation of the carboxylic groups with metal hydroxide. The correlation between the pK_a values and the amount of organic acid adsorbed on the aluminum hydroxide revealed that the adsorption of DHBAs at acidic pH was largely dependent on the surface chelate formation rather than on the electronic effect.     

盐城湿地大米草-芦苇群落对生活污水净化效果的实验研究

大米草、芦苇群落对COD、N、P和NH4-N等污染物有着明显的净化作用,这对潮间带水质稳定起着积极的作用.研究发现在同一淹水深度下,随着群落盖度的增加,芦苇与大米草对有机物、N,P的净化能力也随之增强;而随着淹水深度的增加,大米草对COD的去除率在淹水深度为30 cm时效果最佳;而芦苇群落对COD去除率随淹水深度的增加呈缓慢下降的趋势.光照能够促进湿地植物群落对污染物的净化,但受植物群落垂直结构与淹水深度的影响很大.在群落盖度大于60%、淹水深度为30 cm与当前水质条件下,大米草、芦苇二者联合净化作用在一个潮周期内对有机物、N、P和NH4-N分别可达33.6、24.9、20.8和27.6%以上.