厌氧混合培养条件下六氯苯生物降解的外加碳源必要性

采用标准血清瓶实验探讨了厌氧污泥对六氯苯(HCB)的降解活性以及各种环境因素的影响.结果表明,经过14d的HCB驯化,厌氧污泥具备了较好的降解HCB能力;反应温度对HCB的降解速率有很大影响,适宜温度为35℃左右;葡萄糖、甲酸、乙酸、丙酸和丁酸等有机碳源的存在明显促进了HCB的厌氧降解,其中甲酸和乙酸的加入极其重要;根据实验结果推测出,产甲烷过程对HCB的生物降解发挥了重要作用.     

Genetic biomonitoring of an urban population exposed to mutagenic airborne pollutants

Biomonitoring studies have increased as a consequence of risks and effects to human health on exposure to environmental contaminants, mainly air pollutants. Genetic biomarkers are useful tools for the early assessment of exposure to occupational and environmental pollution. The objective of the present study was to investigate genotoxic effects on people residing and/or working downwind from an oil refinery in southern Brazil and the mutagenic activity of airborne particulate matter (PM10). Samples of peripheral blood and buccal mucosa cells were evaluated using the single-cell gel electrophoresis assay (comet assay) and the micronucleus (MN) assay, respectively. PM10 samples were collected in the target site and the organic matter extraced with dichloromethane was assessed for mutagenic activity in the Salmonella/microsome assay. The exposed group (n = 37) was compared to a reference group (n = 37) of subjects living in an urban area with limited traffic and industrial influence, located far from the main industrial areas. All PM10 organic extracts showed mutagenic positive responses and the effect decreased in the presence of S9 mix indicating that the predominant compounds present were direct-acting mutagens. The responses of YGs strains are consistent with aromatic amines and nitroarenes being present in the PM10 extracts. The group in the area under the influence of the oil refinery (exposed group) showed significantly higher DNA damage in lymphocytes than the reference group. The MN frequencies in buccal mucosa were very low for both groups and no difference between groups was observed. No association was found between age and tobacco smoking habit and level of DNA damages measured by the comet assay. The results indicate that the comet assay was a sensitive tool to detect DNA damage in subjects under the influence of an oil refinery, with marked genotoxic activity in the atmospheric environment.     

Atrazine leaching through surface and subsurface of a tropical Oxisol

The fate of ¹⁴C atrazine was investigated using microcosms and an undisturbed Red-Yellow Latossol (Oxisol) under simulated rainfall conditions of 200 mm water month^?1. Experiments were carried out using microcosm cores, the first with an uncovered surface soil; the second set with uncovered subsurface soil; the third with subsurface soil covered with 3 cm of cow manure and the last with subsurface soil covered with 5 cm of grass straw. Average values for the amount of atrazine leached after 60 days were as follows: surface soil 1.6%; subsurface 47.3%; subsurface plus manure 17.3% and subsurface plus straw 24.8%. In the surface soil, 53% of the ¹⁴C atrazine remained within the upper 1 cm, while in the subsurface microcosms the atrazine was more evenly distributed. The authors report that surface soil was retained atrazine and its metabolites for 60 days. The addition of a straw or manure covering to exposed subsoil helped to retard atrazine leaching.     

基于环境监测的矿井通风三维仿真辅助决策系统设计

为优化金属矿山矿井通风系统及辅助决策设计,弥补常用矿井通风仿真解算软件在环境监测、实时解算和辅助决策方面的不足,基于矿井通风理论、环境监测、计算机与通信技术开发矿井通风三维仿真辅助决策系统。提出通过利用实时监测到的井下通风环境参数（风量、风速等）和已存储在系统数据库里的巷道参数,实现对矿井通风网络实时解算,并将其应用到山金阿尔哈达矿井通风系统中。结果表明:矿井通风三维仿真辅助决策系统同步实现了山金阿尔哈达矿井通风系统的环境监测、风网实时解算和三维仿真模拟,提高了其矿井通风管理水平,为矿井通风系统改造优化设计和矿井向深部中段延伸时的通风系统设计提供辅助决策依据。     

Impact of Urban Growth and High Residential Irrigation on Streamflow and Groundwater Levels in a Peri‐Urban Semiarid Catchment

The impact of urbanization on groundwater is not simple to understand, as it depends on a variety of factors such as climate, hydrogeology, water management practices, and infrastructure. In semiarid landscapes, the urbanization processes can involve high water consumptions and irrigation increases, which in turn may contribute to groundwater recharge. We assessed the hydrological impacts of urbanization and irrigation rates in an Andean peri‐urban catchment located in Chile, in a semiarid climate. For this purpose, we built and validated a coupled surface–groundwater model that allows the verification of a strong stream–aquifer interaction in areas with shallow groundwater, higher than some sewers and portions of the stream. Moreover, we also identified a significant local recharge associated with pipe leaks and inefficient urban irrigation. From the evaluation of different future scenarios, we found a sustainable water conservation scenario will decrease the current groundwater levels, while the median flow reduces from 408 to 389 L/s, and the low flow (Q_95%) from 43 to 22L/s. Overall, our results show the relevance of integrating the modeling of surface and subsurface water resources at different spatial and temporal scales, when assessing the effect of urban development and the suitability of urban water practices.     

环境因素对六氯苯厌氧降解活性的影响

在厌氧污泥具备了较好的六氯苯（HCB）降解能力的基础上,采用标准血清瓶实验方法考察了反应温度、初始pH、摇床转速和营养元素等环境因素对厌氧污泥降解HCB活性的影响。实验设计的反应温度为25、30、35和40℃;初始pH为5.0、6.0、7.0和8.0;摇床转速为0和150r·min-1;营养元素有葡萄糖和维生素b12。用HCB浓度随时间的减少来表征微生物对其的降解活性。结果表明,反应温度对HCB的降解速率有很大影响,适宜温度为35℃左右。初始pH对HCB降解活性没有显著影响,但显示出有随初始pH增大而HCB降解活性增加的趋势。与静置条件相比,一定的混合作用有利于提高HCB的降解活性。有葡萄糖存在条件下,维生素b12对HCB的降解活性有明显的促进作用。温度及外加碳源（葡萄糖）是影响HCB厌氧降解活性的重要因素,并推测葡萄糖在HCB降解过程中提供电子供体方面发挥了重要作用。     

Phytoplankton food quality determines time windows for successful zooplankton reproductive pulses

Recruitment success at the early life stages is a critical process for zooplankton demography. Copepods often dominate the zooplankton in marine coastal zones and are prey of the majority of fish larvae. Hypotheses interpreting variations of copepod recruitment are based on the concepts of "naupliar predation," "nutritional deficiency," and "toxic effect" of diatom diets. Contradictory laboratory and field studies have reached opposite conclusions on the effects of diatoms on copepod reproductive success, blurring our view of marine food-web energy flow from diatoms to higher consumers by means of copepods. Here we report estimates of copepod feeding selectivity and reproduction in response to seasonally changing phytoplankton characteristics measured in a highly productive coastal upwelling area off the coast of central Chile. The variable phytoplankton diversity and changing food quality had a strong and highly significant impact on the feeding selectivity, reproduction, and larval survival of three indigenous copepod species. Seasonal changes in copepod feeding behavior were related to the alternating protozoan-diatom diets, mostly based on dinoflagellates and ciliates during winter and autumn (low highly unsaturated fatty acids [HUFA]/polyunsaturated fatty acids [PUFA] availability), but switched to a diet of centric and chain-forming diatoms (high HUFA/PUFA availability) during the spring/summer upwelling period. Ingestion of diatom cells induced a positive effect on egg production. However, a negative relationship was found between egg hatching success, naupliar survival, and diatom ingestion. Depending on the phytoplankton species, diets had different effects on copepod reproduction and recruitment. In consequence, it seems that the classical marine food web model does not apply to some coastal upwelling systems.     

自适应神经网络在确定落煤残存瓦斯量中的应用

落煤残存瓦斯量的确定是采掘工作面瓦斯涌出量预测的重要环节，它直接影响着采掘工作面瓦斯涌出量预测的精度，并与煤的变质程度、落煤粒度，原始瓦斯含量、暴露时间等影响因素呈非线性关系，人工神经网络具有表示任意非线性关系和学习的能力，是解决复杂非线性，不确定性和时变性问题的新思想和新方法，基于此，作提出自适应神经网络的落煤残丰瓦斯量预测模型，并结合不同矿井落煤残存瓦斯量的实际测定结果进行验证研究，结果表明，自适应调整权值的变步长BP神经网络模型预测精度高，收敛速度快，该预测模型的应用可为采掘工作面瓦斯涌出量的动态预测提供可靠的基础数据，为采掘工作面落煤残存瓦斯量的确定提出了一种全新的方法和思路。     

Obtaining Environmental Favourability Functions from Logistic Regression

Logistic regression is a statistical tool widely used for predicting species’ potential distributions starting from presence/absence data and a set of independent variables. However, logistic regression equations compute probability values based not only on the values of the predictor variables but also on the relative proportion of presences and absences in the dataset, which does not adequately describe the environmental favourability for or against species presence. A few strategies have been used to circumvent this, but they usually imply an alteration of the original data or the discarding of potentially valuable information. We propose a way to obtain from logistic regression an environmental favourability function whose results are not affected by an uneven proportion of presences and absences. We tested the method on the distribution of virtual species in an imaginary territory. The favourability models yielded similar values regardless of the variation in the presence/absence ratio. We also illustrate with the example of the Pyrenean desman’s (Galemys pyrenaicus) distribution in Spain. The favourability model yielded more realistic potential distribution maps than the logistic regression model. Favourability values can be regarded as the degree of membership of the fuzzy set of sites whose environmental conditions are favourable to the species, which enables applying the rules of fuzzy logic to distribution modelling. They also allow for direct comparisons between models for species with different presence/absence ratios in the study area. This makes them more useful to estimate the conservation value of areas, to design ecological corridors, or to select appropriate areas for species reintroductions. Received: June 2005 / Revised: July 2005