Division of labour in a crisis: task allocation during colony emigration in the ant Leptothorax unifasciatus (Latr.)

Division of labour during colony emigration is widespread in ants. An important problem is how tasks are allocated during colony movement from one nest site to another. The generally favoured view is that emigrations are organised by a minority group of individuals, which either work unusually hard at tasks (elites) or have the exclusive task of carrying out the emigration (moving specialists). Five consecutive emigrations of a Leptothorax unifasciatus (Latr.) colony showed that the number of transporters, i.e. the individuals that took an active part in the emigration by transporting brood and ants, was smaller than it would have been if allocation of this task was random during each emigration. However, single emigrations of another three colonies, for which the spatial distribution and behaviour of the workers had been observed for a week prior to the emigration, demonstrated that the transporters did not form a homogeneous group. They differed in their spatial positions and tasks before the emigration. There was also no evidence that transporters worked harder or less hard than their nestmates before the emigration. Therefore, the individuals which carry out emigrations in L. unifasciatus colonies appear to be neither moving specialists nor elites. We propose that task allocation during emigrations of L. unifasciatus colonies is based on a feedback mechanism that involves learning.     

Does interaction between bumblebees (Bombus ignitus) reduce their foraging area?: bee-removal experiments in a net cage

To examine whether the interaction between bumblebees, Bombus ignitus, reduces their foraging area, we conducted bee-removal experiments in a net cage. In the cage, we set potted Salvia farinacea plants, allowed bumblebees to forage freely on those plants, and followed their plant-to-plant movements to identify a bee with a relatively small foraging area. We then removed all the other foraging bees, except for the bee with a small foraging area, and observed the change of the foraging area of the focal bee under conditions of no interaction with other bees. After the removal of the other bees, all five bees tested enlarged their foraging areas, suggesting that the interaction between bees is an important determinant of their foraging areas. The result also means that bumblebees are able to adjust their foraging areas in response to other foragers, indicating the necessity for future studies to clarify what cues bees use to interact with other bees. Moreover, after the removal treatments, all five bees showed temporary increases in the number of flower probes per plant. This can be explained by their optimal foraging according to the old average intake rate for the plant population and by the delayed changes in response to the new high average energy intake rate after the bee-removal treatments.Communicated by M. Giurfa     

Spatial variability of ammonium and nitrate in soils near a poultry farm

This paper assesses the distribution of ammonium (NH4+) and nitrate (NO3-) nitrogen deposition in native bushland soil adjacent to an open ventilated poultry farm. The farm is located in Thirlmere 150 km south west of Sydney, Australia. A total of 104 geographically referenced soil cores were obtained from the study area. Soil pH, electrical conductivity (EC), NH4(+) - and NO3(-)-nitrogen concentrations were analysed for variable trends at three depths, i.e. 0-30, 30-60, and 60-90 cm. Significantly higher concentrations of the two nitrogen forms and EC were observed nearer to the farm in the surface soil samples (0-30 cm). The distribution of NH4+, NO3- and EC were all correlated in surface samples throughout the study area. There was no indication of NH4+ and NO3- leaching within soil profile sampled and it appears that weeds and native vegetation had utilised the accumulated nitrogen. The level of N deposition adjacent to the poultry farm decreased downwind due to dispersion of plume and to the buffering effects from the bushland.     

Bayesian entropy for spatial sampling design of environmental data

We develop a spatial statistical methodology to design national air pollution monitoring networks with good predictive capabilities while minimizing the cost of monitoring. The underlying complexity of atmospheric processes and the urgent need to give credible assessments of environmental risk create problems requiring new statistical methodologies to meet these challenges. In this work, we present a new method of ranking various subnetworks taking both the environmental cost and the statistical information into account. A Bayesian algorithm is introduced to obtain an optimal subnetwork using an entropy framework. The final network and accuracy of the spatial predictions is heavily dependent on the underlying model of spatial correlation. Usually the simplifying assumption of stationarity, in the sense that the spatial dependency structure does not change location, is made for spatial prediction. However, it is not uncommon to find spatial data that show strong signs of nonstationary behavior. We build upon an existing approach that creates a nonstationary covariance by a mixture of a family of stationary processes, and we propose a Bayesian method of estimating the associated parameters using the technique of Reversible Jump Markov Chain Monte Carlo. We apply these methods for spatial prediction and network design to ambient ozone data from a monitoring network in the eastern US.     

环境监理在海洋环境保护中的作用

阐述了开展海洋环境监理工作意义，论述了海洋环境监理的任务介绍了本地区开展海洋环境监理工作的经验。     

噪声功能区划中一类,二类混合区域的划定方法研究

根据灰色系统理论,通过灰色聚类的方法判定噪声功能区中的一类、二类混合区。判定结果与实际情况具有较高吻合度。     

A hybrid modeling approach to resolve pollutant concentrations in an urban area

A modeling tool that can resolve contributions from individual sources to the urban environment is critical for air-toxics exposure assessments. Air toxics are often chemically reactive and may have background concentrations originated from distant sources. Grid models are the best-suited tools to handle the regional features of these chemicals. However, these models are not designed to resolve pollutant concentrations on local scales. Moreover, for many species of interest, having reaction time scales that are longer than the travel time across an urban area, chemical reactions can be ignored in describing local dispersion from strong individual sources making Lagrangian and plume-dispersion models practical. In this study, we test the feasibility of developing an urban hybrid simulation system. In this combination, the Community Multi-scale Air Quality model (CMAQ) provides the regional background concentrations and urban-scale photochemistry, and local models such as Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT) and AMS/EPA Regulatory Model (AERMOD) provide the more spatially resolved concentrations due to local emission sources. In the initial application, the HYSPLIT, AERMOD, and CMAQ models are used in combination to calculate high-resolution benzene concentrations in the Houston area. The study period is from 18 August to 4 September of 2000. The Mesoscale Model 5 (MM5) is used to create meteorological fields with a horizontal resolution of 1×1 km². In another variation to this approach, multiple HYSPLIT simulations are used to create a concentration ensemble to estimate the contribution to the concentration variability from point sources. HYSPLIT simulations are used to model two sources of concentration variability; one due to variability created by different particle trajectory pathways in the turbulent atmosphere and the other due to different flow regimes that might be introduced when using gridded data to represent meteorological data fields. The ensemble mean concentrations determined by HYSPLIT plus the concentrations estimated by AERMOD are added to the CMAQ calculated background to estimate the total mean benzene concentration. These estimated hourly mean concentrations are also compared with available field measurements.     

Population dynamics and the physical and financial impacts to cereal crops of the Egyptian Goose Alopochen aegyptiacus on the Agulhas Plain, Western Cape, South Africa

Cereal crop farmers in the Western Cape province of South Africa regard the Egyptian Goose as a serious pest. The Agulhas Plain, in particular, attracts thousands of geese annually primarily because of the abundance and availability of nutritious crops such as wheat Triticum spp. and barley Hordeum spp. for food and permanent water bodies for roosting, moulting and breeding. Therefore, this paper investigates the population dynamics and physical and financial impacts to cereal crops of the Egyptian Goose on the Agulhas Plain, Western Cape. Egyptian Geese inflict damage during three main periods, viz. soon after sowing (surface seeds); young, developing plants (growing plants); and cut plants stacked in windrows (long, linear piles) to dry. The largest numbers of geese were recorded during June and July when they foraged on growing plants less than 25 cm tall. Overall, the mean yield loss was 65.6% in 1997 and 63.5% in 1998. Fields suffering greatest yield loss in 1997 and 1998 were generally those within 600 m of the roosting sites and had about 300 geese grazing on them on areas of around 2 ha in size for about 2 months. By August, geese moved from croplands on to pastures. During October and November, geese once again fed primarily on barley seeds in harvested crops stacked in windrows. Damage by geese to farmers was estimated to be >2.5 and 7% of annual revenue received from barley and wheat farming, in 1997 and 1998, respectively. There are many variables that need to be considered when attempting to quantify and explain damage to cereal crops by Egyptian Geese.     

南水北调东线水源地的生态补偿问题探究

生态补偿机制及其建立是目前生态经济学领域研究的热点,尤其是流域生态补偿机制的建立更为重要。本文以南水北调东线水源地生态功能保护区建设为例,探讨了跨流域调水所涉及的生态补偿问题,并根据多种计算方法的加和,提出了建立南水北调水源地生态功能保护区建设流域生态补偿机制的思路和建议。     

江苏省排污申报登记管理信息系统的研制

排污申报登记信息系统的研制和推广，对江苏省环境管理和规划的现代化、环境信息系统建设的进程具有很大的推动作用；环境管理不断面临新的问题、产生新的需求，促使申报系统更加完善，功能更加丰富。详细介绍申报系统的开发背景、开发环境及主要功能。