石油污染土壤微生物联合修复技术研究进展

石油是一种具有生物毒性的复杂有机物,土壤中石油烃的过量积累会给生态环境和人类健康造成严重威胁。微生物联合修复技术因处理成本低、环境影响小、无二次污染等优点,且较微生物修复或植物修复效率更高,耗时更短,成为当前的研究热点。文章介绍了植物-微生物联合修复、电动-微生物联合修复、氧化-微生物联合修复和表面活性剂强化微生物修复四种联合修复技术,简要阐述了修复机理、适用范围和工艺参数,为生物修复技术的选择提供了参考,并对以后生物修复的研究重点进行了展望。     

国家海洋公园建设的制度经验与优化

我国正逐步完善以国家公园为主体的自然保护地体系的顶层设计,将国家公园定义为具有国家代表性的"陆域或海域"。但与国外相比,我国现有海洋类自然保护地单个及总体面积都不大,管理上也存在碎块化的问题,没有地域广阔、覆盖更完整生物链的国家海洋公园,离实现海洋生态系统性保护的目标尚有距离。而事实上,我国已经具备相关制度供给,既拥有国际规范支撑,也积累了本国海洋类自然保护地建设的法治成果,只是仍存在一些制度障碍需要克服,需进一步优化、整合原有的海洋类自然保护地体系以匹配新体制。建议明确国家海洋公园的国家公园属性,调整国家公园的监管主体,统筹陆海不同的功能分区,构建中国特色的国家海洋公园管理体制。     

Food exploitation by a winter flock of greylag geese: behavioral dynamics,competition and social status

Summary To investigate the dynamics of the winter flock patch exploitation, feeding experiments were performed with 140 semi-tame, free-roaming greylag geese (Anser anser). Three different initial densities of barley were offered on a 50-m² patch: low (1600 grains/m²), intermediate (3300/m²) and high (I 1500/m²). Goose numbers on the patch, peck rates, and frequencies of agonistic encounters and of alert postures were observed by scanning the flock and in focal individuals. At low and intermediate initial food densities, peck rates decreased with food density, whereas at high food density, peck rates decreased only slightly over the feeding bout. Agonistic interactions increased as food decreased. A switch from exploitation to interference competition occurred at a threshold of approximately 900 remaining grains per square meter. With high initial food density, agonistic encounters began to increase gradually after 20–30 min. The same general patterns were observed for frequency of alertness. Family members occupied the patch for the longest time periods. The family female and the offspring fed most intensely. The family gander however, fed significantly less but was more aggressive and vigilant than all other social categories. Solitary geese spent their time on the patch doing little else but feeding and were the first to leave. It seems that high-ranking families and low-ranking singles adopt different competitive strategies, the former being superior interference competitors whereas the latter are forced scramble competitors.This study is dedicated to the memory of Konrad Lorenz Correspondence to: K. Kotrschal     

Triangulation theory applied to conflict over hormone herbicide drift in Natal,South Africa

Policies that arise out of conflict or collaboration between specific interest groups and government agencies are often explained by theoretical constructs that fall under the umbrella of group theory. Triangulation theory is one of these constructs and serves to explain the mutuality of interests that exist between government agencies and interest groups expressed as points linking geometric forms. Conflict tends to occur when competing interest groups are excluded from the linkage, in this case between the opponents and proponents of hormone herbicides in the Tala area in Natal, South Africa. In opposition to the use of hormone herbicides were vegetable farmers and their supporters: in linked support were agricultural interest groups who used hormone herbicides, the manufacturers of the herbicides, and the government agency responsible for agriculture. Because of the influence exerted through mutual support by the proponents of hormone herbicides, the formulation of policy decisions directed towards the resolution of the conflict was delayed. When the minister of agriculture finally intervened, the policy decisions were designed to secure the support of those opposing the use of hormone herbicides by introducing issues that cut across those maintaining the discord.     

Utilising the Synergy between Plants and Rhizosphere Microorganisms to Enhance Breakdown of Organic Pollutants in the Environment (15 pp)

Background Phytoremediation is a promising technology for the cleanup of polluted environments. The technology has so far been used mainly to remove toxic heavy metals from contaminated soil, but there is a growing interest in broadening its applications to remove/degrade organic pollutants in the environment. Both plants and soil microorganisms have certain limitations with respect to their individual abilities to remove/breakdown organic compounds. A synergistic action by both rhizosphere microorganisms that leads to increased availability of hydrophobic compounds, and plants that leads to their removal and/or degradation, may overcome many of the limitations, and thus provide a useful basis for enhancing remediation of contaminated environments.Main Features The review of literature presented in this article provides an insight to the nature of plant-microbial interactions in the rhizosphere, with a focus on those processes that are relevant to the breakdown and/or removal of organic pollutants. Due consideration has been given to identify opportunities for utilising the plant-microbial synergy in the rhizosphere to enhance remediation of contaminated environments.Results and Discussion The literature review has highlighted the existence of a synergistic interaction between plants and microbial communities in the rhizosphere. This interaction benefits both microorganisms through provision of nutrients by root exudates, and plants through enhanced nutrient uptake and reduced toxicity of soil contaminants. The ability of the plant-microbial interaction to tackle some of the most recalcitrant organic chemicals is of particular interest with regard to enhancing and extending the scope of remediation technologies.Conclusions Plant-microbial interactions in the rhizosphere offer very useful means for remediating environments contaminated with recalcitrant organic compounds.Outlook A better knowledge of plant-microbial interactions will provide a basis for improving the efficacy of biological remediations. Further research is, however, needed to investigate different feedback mechanisms that select and regulate microbial activity in the rhizosphere.     

Spillover of Agriculturally Subsidized Predators as a Potential Threat to Native Insect Herbivores in Fragmented Landscapes

Abstract:  Habitat loss and fragmentation can have strong negative impacts on populations of some native species. Spillover of generalist natural enemies from the surrounding landscape matrix is one mechanism potentially generating such effects, yet this has been rarely studied in insects. We examined the influence of habitat conversion to agriculture on the abundance and potential effects of predatory coccinellid beetles on native insect herbivores within 12 grassland remnants in central Nebraska (U.S.A.). Results of sweep sampling revealed that coccinellids were three to six times more abundant at native grassland sites embedded within cropland-dominated landscapes compared with control sites in grassland-dominated landscapes over the 3 years of the study. Exclusion experiments further demonstrated that predation intensity was strongly related to coccinellid abundances across sites and that coccinellids can dramatically reduce densities of a native aphid herbivore. In contrast to studies of specialized insect parasitoids, which have generally found reduced enemy pressure in fragmented landscapes, our results suggest that native herbivores may in some cases experience increased consumer pressure in landscapes with increasing habitat loss because of spillover of generalist predators from surrounding cropland habitats.     

Local and systemic induced responses to cabbage root fly larvae (Delia radicum) in Brassica nigra and B. oleracea

Summary. Feeding by belowground herbivores may induce systemic changes in shoot defence levels that affect the performance of above ground herbivores and higher trophic levels. In this paper two wild Brassica species, B. nigra and B. oleracea were experimentally infested with 10 larvae of the cabbage root fly, Delia radicum. Plant dry masses and glucosinolate levels in shoots, main roots, and fine roots were determined at 3, 7, 12 and 14 days after infestation and compared to those of control plants. The systemic response in the leaves differed between plant species. In B. nigra shoot glucosinolate levels in D. radicum infested plants steadily increased with time until they were almost twice those of controls 14 days after infestation. B. oleracea plants infested with D. radicum did not show significant changes in shoot glucosinolate levels within 14 days, which may be due to the unexpected poorer performance of D. radicum on this species. Both plant species showed a local increase in indole glucosinolates in the main roots, which are the preferred feeding site of D. radicum larvae. B. oleracea plants however showed a stronger (1.9 – 4.7 times) increase in indole glucosinolate levels than B. nigra (1.5 – 2.6 times). The increase in indole glucosinolates in B. nigra main roots, was counterbalanced by a significant decrease in aromatic glucosinolate levels. These differences in local responses to D. radicum feeding between the two species may have contributed to the slower growth rates of the larvae on B. oleracea. D. radicum feeding did not result in altered glucosinolate levels in the fine roots in either plant species. The differences in glucosinolate induction patterns between the summer annual B. nigra and the perennial B. oleracea are discussed in the light of their different life histories.     

Chaos and pattern formation in a spatial tritrophic food chain

The model of Hastings and Powell describes a tritrophic food chain that exhibits chaotic dynamics. The model assumes that the populations are homogeneously mixed, so that the probability that any two individuals interact is uniform and space can be ignored. In this paper we propose a spatial version of the Hastings and Powell model in which predators seek their preys only in a finite neighborhood of their home location, breaking the mixing hypothesis. Treating both space and time as discrete variables we derive a set of coupled equations that describe the evolution of the populations at each site of the spatial domain. We show that the introduction of local predator–prey interactions result in qualitatively distinct dynamics of predator and prey populations. The evolution equations for the predators involve averages over the local density of preys, whereas the equations for the preys involve double averages, where the local density of both preys and predators appear. Our numerical simulations show that local predation also leads to spontaneous pattern formation and to qualitative changes in the global dynamics of the system. In particular, depending on the size of the predation neighborhoods, the chaotic strange attractor present in the original model of Hastings and Powell can be replaced by a stable fixed point or by an attractor of simpler topology.     

Impact of heavy metal pollution on plants and leaf-miners

Large-scale effects of diffuse heavy metals pollution on terrestrial ecosystems are still underestimated. We studied the relation between the biodiversity of vascular plants and the feeding Lepidoptera, in our case leaf-miners and pollinating adult butterflies, in a Dutch nature reserve over a period of five years. We found that 5% of the 56 plants species which provide food and habitat to Microlepidoptera during their larval stage were affected by heavy metal pollution. Furthermore, the numerical abundance of leaf-mining larvae remained rather constant, despite of significant increases of the concentrations of Cd, Cu, Ni and Zn pollutants in leaves and litter.