连续曝气下河水水质及睡莲生理响应的季节变化

采取现场实验方法,在春、夏、秋三季测定了6个睡莲(Nymphaea tetragona L.)植物净化槽(曝气、非曝气)中睡莲的叶绿素(Chl)、可溶性蛋白(SP)含量与过氧化物酶(POD)、过氧化氢酶(CAT)活性,氮磷积累、生物量、根长、茎高、叶长、分蘖数、根密度等生物学指标及对应的水质常规理化指标,探讨了连续曝气下睡莲的生理响应及河水水质的季节变化。结果表明,连续曝气明显影响了睡莲的生理特性,导致净化槽中水质发生相应变化,且影响程度与睡莲生长状况的季节变化相关。曝气槽中睡莲植物的根长、茎高、叶长较短,叶片Chl-a、Chl-b、SP含量下降,而根组织POD、CAT活性升高,氮磷积累、生物量下降,分蘖数、根密度下降;春、夏季曝气对睡莲的影响相对较小,曝气槽中TN、NH4+-N浓度低于非曝气槽,而TP、溶解性P浓度明显升高;秋季曝气对睡莲的影响较严重,曝气槽中TN、NH4+-N、TP、溶解性P浓度均高于非曝气槽。研究结论为在污染河道生态修复工程实践中,针对水生植物生长状况的季节变化而进行曝气方式调节提供理论依据。     

响应面法优化O_3/H_2O_2/UV工艺降解1,2,4-三氯苯

研究了O3/H2O2/UV臭氧光催化工艺对水中TCB的降解效果,考察了TCB初始浓度、O3转化率、H2O2投加量及pH值对TCB降解效果的影响及其动力学分析,并通过响应面分析法对实验条件进行了优化组合.结果表明,O3/H2O2/UV对TCB的降解均遵循准一级反应动力学,其中条件优化组合后的反应动力学方程为y=0.0219x-0.0127,准一级反应速率常数为0.0219 min-1,所得线性相关系数为0.983.响应面分析结果表明,在TCB初始浓度0.3 mg.L-1、pH=10.1、H2O2投加量0.33 mmol.L-1、O3转化率99.75%的最优工艺组合条件下,TCB的3次平均去除率为94.2%,与预测值95.0%吻合度较高.     

近35a西藏那曲地区湖泊动态遥感与气候因素关联度分析

利用1976、1990、2000和2010年4期遥感影像对西藏那曲地区面积大于1 km2湖泊的动态变化进行信息提取,并结合1966—2010年研究区9个站点的气象数据,探讨其对气候变化的响应。结果表明,2010年那曲地区大于1 km2湖泊的总面积为16 841.93 km2,湖泊总数为469。近35 a那曲地区大于1 km2湖泊面积共增加3 505.12km2,增幅为26.28%,其中以2000—2010年增长速度最快,达18.18%;近35 a湖泊数量增加96,增幅为25.73%,其中以1990—2000年增幅最大,达13.38%。色林错面积从1976年的1 648.61 km2增加到2010年的2 332.55km2,超过纳木错成为西藏第一大咸水湖。1966年以来,那曲地区年平均温度、年平均最高温度、年平均最低温度、年平均相对湿度和年平均降水量总体呈上升趋势,年平均蒸发量呈下降趋势,气候朝暖湿方向发展,其中温度变化最明显,线性气温倾向率为0.51℃.(10 a)-1。湖泊动态变化与气象因子的灰度关联分析表明,气温升高引起冰雪融水增加、降水量增加、相对湿度增加和蒸发量减少,是近35 a来那曲地区湖泊面积和数量不断增加的主要原因。气象要素与湖泊面积间的回归方程表明,两者具有显著线性相关关系。     

生物样品体外致突变高通量检测方法研究进展

评述了几种常用的体外致突变检测方法及其用于生物样品检测的可行性,有些方法经改进可用于高通量检测生物样品体外致突变性.经典Ames实验受生物样品中组氨酸的影响,易产生假阳性结果,尽管经过修正可以排除组氨酸的干扰,但操作繁琐,不适合高通量检测.基于SOS反应的检测体系避开了组氨酸的影响,且简单易行,适合高通量检测:以β-半乳糖苷酶基因(lacZ)作为报告基因的检测体系灵敏度高,且经过离心洗涤或后培养的方式可降低样品颜色的影响;以绿色荧光蛋白(GFP)基因作为报告基因的检测体系避开了颜色的干扰,但这类方法灵敏度普遍不高,可以寻找信号更强的荧光蛋白以替代GFP;荧光素酶(lux)基因集lacZ和GFP的优点于一身,但检测时需要额外添加辅助因子,限制了其应用.也对单细胞凝胶电泳、tk基因突变实验、染色体损伤检测等方法进行了分析,有些适合生物样品高通量检测,但由于缺少国际通用的标准,很难推广使用.     

Origins and scales of hypoxia on the Louisiana shelf: Importance of seasonal plankton dynamics and river nutrients and discharge

Management plans for the Mississippi River Basin call for reductions in nutrient concentrations up to 40% or more to reduce hypoxia in the Gulf of Mexico (GOM), while at the same time the government is considering new farm subsidies to promote development of biofuels from corn. Thus there are possibilities of both increasing and decreasing river nutrients depending on national priorities. River flow rates which also influence the extent of hypoxia on the shelf may be altered by global climate change. We have therefore developed a series of simulations to forecast ecosystem response to alterations in nutrient loading and river flow. We simulate ecosystem response and hypoxia events using a linked model consisting of multiple phytoplankton groups competing for nitrogen, phosphorus and light, zooplankton grazing that is influenced by prey edibility and stoichiometry, sub-pycnocline water-column metabolism that is influenced by sinking fecal pellets and algal cells, and multi-element sediment diagenesis. This model formulation depicts four areas of increasing salinity moving westward away from the Mississippi River point of discharge, where the surface mixed layer, four bottom layers and underlying sediments are represented in each area. The model supports the contention that a 40% decrease in river nutrient will substantially reduce the duration and areal extent of hypoxia on the shelf. But it also suggests that in low and middle salinity areas the hypoxia response is saturated with respect to nutrients, and that in high salinity regions small increases in nutrient and river flow will have disproportionally large effects on GOM hypoxia. The model simulations also suggest that river discharge is a stronger factor influencing hypoxia than river nutrients in the Mississippi River plume. Finally, the model simulations suggest that primary production in the low salinity regions is light limited while primary production in the higher salinity zones is phosphate limited during the May to October period when hypoxia is prevalent in the Mississippi River plume.     

Modeling the refuge effect of submerged macrophytes in ecological dynamics of shallow lakes: A new model of fish functional response

Submerged macrophytes often provide refuge for zooplankton from fish predation in temperate and subtropical shallow lakes. However, since the relationship between submerged macrophyte abundance and its refuge effect has not been well established, the refuge effect is difficult to be simulated. In this paper, we constructed mathematical models to describe the refuge effect of submerged macrophytes on fish foraging activities and ecological dynamics of shallow lakes based on the previous studies. We clarified the underlying behavioral mechanisms of the observed functional responses through analyses of the fish foraging behavior, extracted the affected variables related to the refuge effect, formulized the relationship between the affected variables and submerged vegetation density, and determined parameter values with a compensative procedure. Calibration and validation results indicated that the new functional response model was successful to simulate the refuge effect on interfering with fish foraging behavior. Moreover, the model was cooperated into a minimal ecological model for shallow lakes. Modeling results showed that the model was able to simulate the refuge effect in ecological dynamics, and made the ecological model produce significantly different results from those with the existing functional response models.     

稻秸秆制备微生物絮凝剂及改善污泥脱水性能的研究

采用水稻秸秆制备微生物絮凝剂,研究了微生物絮凝剂对污泥脱水性能的影响,并通过响应面分析法优化了微生物絮凝剂与聚合氯化铝（Polyaluminum chloride,PAC）复配改善污泥脱水性能的过程.结果表明,制备微生物絮凝剂的最佳条件为：800mL蒸馏水、200mL水稻秸秆酸解液、4g K₂HPO₄、2g KH₂PO₄、0.2g MgSO₄、0.1g NaCl、2g尿素,在此条件下,微生物絮凝剂产量达0.96g/L.保持原污泥pH值,当微生物絮凝剂投加量为12mg/L,干污泥量（DS）较原污泥提高了59.5%,污泥比阻（SRF）降低了53.6%,表明经微生物絮凝剂絮凝处理,污泥脱水性能显著改善.保持原污泥pH值,当PAC投加量为3g/L,干污泥量（DS）为16.4%,高于原污泥的13.2%,污泥比阻为（SRF）5.4×10¹²m/kg,低于原污泥的11.3×10¹²m/kg,说明PAC对污泥脱水性能有着明显的改善作用.响应面分析结果显示,污泥脱水最佳条件为微生物絮凝剂8.1mg/L、PAC 1.9g/L、pH值8.0,相应DS和SRF分别为24.1%和3.0×10¹²m/kg.实际污泥脱水工程中,污泥pH往往不进行调节,保持原污泥pH=6.4条件下,DS和SRF分别为23.6%和3.2×10¹²m/kg,均优于单独采用微生物絮凝剂和PAC时的污泥脱水效果.     

Water and sediment toxicity assessment by use of behavioural responses of medicinal leeches

Behaviour has been shown to be a sensitive indicator of chemically induced stress and pathology in aquatic organisms. However, ecotoxicological investigations on medicinal leech are restricted because of scarce leech resources in natural waters. We used artificially bred medicinal leech (Hirudo medicinalis L.) of two different ages: young (1-2 weeks old) and adult leeches (1 year old). Animals were exposed to: (1) waters of Lake Drukshiai-the cooler of Ignalina Nuclear Power Plant, (2) sediments of the river Nemunas and (3) solution of heavy metal model mixture (HMMM). The following behavioural responses of leech were investigated: mobility (number of moving individuals within certain periods of time), avoidance response (number of individuals escaping the tested water or sediments) changes in body shape (contractions of some muscles, abnormal position of suckers) and feeding activity (longevity of attachment process, interruptions of feeding bouts, size of blood meal). Mobility of young leeches was increased in the tested waters of Lake Drukshiai, whereas adult leeches showed no changes of this index. Avoidance response as well as impaired feeding activity (prolonged attachment process or completely suppressed attachment reflex, decreased size of blood meal) was observed in young leeches exposed to the waters from Lake Drukshiai and in adult animals exposed to all three kind of trials mentioned above. Avoidance response and changes in mobility were recorded during the first hour of exposure to tested samples; therefore, these responses can be used as an express method for water and sediment pollution assessment. Impaired feeding activity was recorded after 1-3-week exposure: this response may be used in assessing a chronic toxicity of pollution. Medicinal leech, due to its sensitivity, simplicity of measured indices and ease of laboratory maintenance, can be used as a test organism in ecotoxicity studies.     

Visitor Response to Management Regulations—A Study Among Recreationists in Southern Norway

/ The objectives of nature area management are often twofold: To protect the natural environment and to facilitate recreational use. In order to maintain the natural setting, it is sometimes necessary to regulate the recreational use of an area. In deciding on a management action, one problem can be the lack of knowledge about the effects of management actions on visitors. In order to enhance the knowledge base for future management practices, this study empirically evaluates the effects of management regulations in a Norwegian nature area. In this area camping outside commercial campgrounds was restricted in 1992. The management regulations seems to have influenced the use of Sjodalen for camping in several ways. The number of campers using the area has decreased. The user composition seems to have changed, with new campers in the area after the regulation being more tolerant of human influence on the natural environment than the campers before the regulations. In addition, a considerable proportion of the existing users ceased to stay overnight in Sjodalen, totally or partly due to the regulations. The behavioral response among existing users is related both to environmental preferences and place attachment. Implications for management and future research studies on impact assessment in general, and displacement specifically, are discussed.KEY WORDS: Outdoor recreation; Management regulations; Behavioral response; Displacement, Place attachment     

农业生产潜力指数评价方法的研究

本文提出了农业生产潜力指数评价的基本理论和方法，并利用这一评价方法对内江市主要家业作物的生产潜力的进行了评价分析。