Estimation of efficiency of processing soil samples for pesticide residues analysis

The efficiency of four sample processing methods was tested with eight different types of soils representing the major proportion of cultivated soils. The principle of sampling constant was applied for characterizing the efficiency of the procedures and testing the well-mixed status of the prepared soil. The test material was 14C-labeled atrazine that enabled keeping the random error of analyses 相似文献   

Experience-dependent choices ensure species-specific fragrance accumulation in male orchid bees

Male neotropical orchid bees (Euglossini) collect volatile chemicals from orchid flowers and other sources and store them in hind leg cavities. The accumulated fragrance bouquets are later emitted at mating sites. Although most other insects synthesize pheromone blends de novo, specific euglossine perfumes are derived from active choices in a changing fragrance market. Male bees of three species of Euglossa possessed distinctive fragrance phenotypes showing little variation by locality and habitat in mainland Central America. In cage experiments, fragrance choice by male Euglossa imperialis was influenced markedly by a bee's collection history. Collection of a given chemical strongly reduced its attractiveness on subsequent occasions, an effect that was retained over days. Experimentally adding the chemicals directly to bee hind legs produced no effect. We conclude that bees learn and remember chemicals they collect. Innate odor preferences, memory and the avoidance of overcollecting by negative feedback may be the primary mechanisms that ensure unique blends of pheromone analogs in these tropical forest bees.Supplementary material is available in the online version of this article at and is accessible for authorized users.An erratum to this article can be found at     

Water management strategies against toxic Microcystis blooms in the Dutch delta.

To prevent flooding of the Dutch delta, former estuaries have been impounded by the building of dams and sluices. Some of these water bodies, however, experience major ecological problems. One of the problem areas is the former Volkerak estuary that was turned into a freshwater lake in 1987. From the early 1990s onward, toxic Microcystis blooms dominate the phytoplankton of the lake every summer. Two management strategies have been suggested to suppress these harmful algal blooms: flushing the lake with fresh water or reintroducing saline water into the lake. This study aims at an advance assessment of these strategies through the development of a mechanistic model of the population dynamics of Microcystis. To calibrate the model, we monitored the benthic and pelagic Microcystis populations in the lake during two years. Field samples of Microcystis were incubated in the laboratory to estimate growth and mortality rates as functions of light, temperature, and salinity. Recruitment and sedimentation rates were measured in the lake, using traps, to quantify benthic-pelagic coupling of the Microcystis populations. The model predicts that flushing with fresh water will suppress Microcystis blooms when the current flushing rate is sufficiently increased. Furthermore, the inlet of saline water will suppress Microcystis blooms for salinities exceeding 14 g/L. Both management options are technically feasible. Our study illustrates that quantitative ecological knowledge can be a helpful tool guiding large-scale water management.     

New tools and strategies for the inspection of the psychosocial working environment: The experience of the Danish Working Environment Authority

In 2007 the Danish Working Environment Authority launched a new strategy to strengthen and qualify primary prevention of work related stress. Part of the strategy consists of increased inspections of the psychosocial working environment as well as the development and implementation of a new inspection tool, namely the “guidance tool”.Twenty-four sector specific guidance tools have been developed to help WEA inspectors assess psychosocial working environment problems in all Danish enterprises. Based on recent research, the guidance tools consist, in each sector, of the three to five most important risk factors (for example quantitative demands, emotional demands, and work related violence), as well as the most important preventive factors, e.g. quality of management, influence/control and training.During the first years of the strategy, an increasing number of inspectors have issued improvement notices regarding work related stress and violence, and there has been an increasing number of notices issued on several risk factors. For some aspects, the tools have helped increase the clarity and comprehensibility of the improvement notices and reduce the WEA’s time consumption per enterprise.The guidance tools seem to be a suitable and efficient way of assessing several health and safety risks concerning work related stress and violence thereby allowing the WEA to detect more of the existing problems. Future challenges projected for the strategy include continuously training all WEA inspectors in the proper use of the tools and continuously refining the tools – or developing new tools – based on further research and experiences from practice.     

Drivers of illegal resource extraction: An analysis of Bardia National Park,Nepal

While park-people conflicts have received worldwide attention, the extent of illegal resource extraction and the relationship with communities’ livelihoods has gained little attention in the literature. Thus this paper investigates the impact of socio-economic factors involved in illegal fuel wood and fodder extraction at Bardia National Park in Nepal. Household questionnaires, key-informant interviews and focus groups were conducted to identify different plant species used by households and explore the causes and mode of resource extraction in three buffer zone villages in the park. Altogether 50 different plants were identified by villagers that were used regularly for different livelihood purposes. Almost half of the respondents met their needs by illegally and regularly extracting resources from the park. Incentive schemes in the form of development projects were important but not sufficient in meeting the basic needs of households’ especially for such daily items such as fuel wood and fodder. The results described in this paper showed that proximity and access to resources either in the national park, the buffer zone community forest or the government forest, and impact on the livelihoods significantly influenced the likelihood of illegal resource extraction activities. Villages that differed in terms of their location to the resource base, the provision of alternative resources and influence of these on their livelihoods showed significant differences in terms of their patterns of resource extraction and use of these resources. As resource use options, resource interest, and resource extraction patterns were different between villages and dependent on circumstances specific to villages, site-specific management strategies were necessary and more influential than the enforcement of ‘one-size fits all’ policies. It is suggested that park management plans should be flexible and adaptive enough to meet site-specific contexts and to endear wider support from local communities.