Can Warmwater Streams Be Rehabilitated Using Watershed-Scale Standard Erosion Control Measures Alone?

Degradation of warmwater streams in agricultural landscapes is a pervasive problem, and reports of restoration effectiveness based on monitoring data are rare. Described is the outcome of rehabilitation of two deeply incised, unstable sand-and-gravel-bed streams. Channel networks of both watersheds were treated using standard erosion control measures, and aquatic habitats within 1-km-long reaches of each stream were further treated by addition of instream structures and planting woody vegetation on banks (“habitat rehabilitation”). Fish and their habitats were sampled semiannually during 1–2 years before rehabilitation, 3–4 years after rehabilitation, and 10–11 years after rehabilitation. Reaches with only erosion control measures located upstream from the habitat measure reaches and in similar streams in adjacent watersheds were sampled concurrently. Sediment concentrations declined steeply throughout both watersheds, with means ≥40% lower during the post-rehabilitation period than before. Physical effects of habitat rehabilitation were persistent through time, with pool habitat availability much higher in rehabilitated reaches than elsewhere. Fish community structure responded with major shifts in relative species abundance: as pool habitats increased after rehabilitation, small-bodied generalists and opportunists declined as certain piscivores and larger-bodied species such as centrarchids and catostomids increased. Reaches without habitat rehabilitation were significantly shallower, and fish populations there were similar to the rehabilitated reaches prior to treatment. These findings are applicable to incised, warmwater streams draining agricultural watersheds similar to those we studied. Rehabilitation of warmwater stream ecosystems is possible with current knowledge, but a major shift in stream corridor management strategies will be needed to reverse ongoing degradation trends. Apparently, conventional channel erosion controls without instream habitat measures are ineffective tools for ecosystem restoration in incised, warmwater streams of the Southeastern U.S., even if applied at the watershed scale and accompanied by significant reductions in suspended sediment concentration.     

珠江三角洲光化学活跃期甲醛及其前体物的源解析研究

选取珠江三角洲大气超级站的三个代表性超级站点（东莞东城城市超级站、深圳莲花山城市超级站和鹤山花果山区域超级站）,同步在线监测和分析了2021年5~10月大气光化学活跃期甲醛（HCHO）及其前体物挥发性有机物（VOCs）组分的时空变化特征,利用多元线性回归法对HCHO来源进行解析,识别出了关键VOCs前体物及其贡献,并对比了三个点位来源及前体物的差异.结果表明：三个站点的HCHO体积浓度存在明显差异,鹤山区域站浓度最高达5.82×10^-9,与历史研究数据相比浓度升高,而城市超级站东城与莲花山浓度水平降低.臭氧浓度与甲醛浓度存在一定相关性,各站点臭氧浓度最高的9月,HCHO的平均浓度水平也高;臭氧超标日的HCHO浓度显著高于臭氧非超标日.利用多元线性回归法,选择甲苯、异戊二烯和O₃作为源示踪剂,结果表明二次源对HCHO来源贡献占比最多,范围为43.5%~54.9%,其中区域站点二次源占比高于其它两个城市站点.基于生成产率法得到各站点二次转化生成HCHO的前体物主要为烯烃,其中贡献最大的是异戊二烯,其次为乙烯和丙烯.综合对比,HCHO的一次人为源的下降导致城市站点HCHO浓度降低,较高的二次转化导致了区域站点HCHO浓度升高,需重点关注甲醛的人为源直接排放和异戊二烯、苯乙烯、乙烯等前体物.     

Nomadic pastoralists adopt subsistence strategies that maximise long-term household survival

Summary Optimality approaches have been used to investigate the adaptiveness of human subsistence strategies mainly in hunter-gatherer societies. However the static optimality models used are not suitable for investigating the long-term costs and benefits of decisions, especially in societies where wealth is accumulated and hence resources gained in one year have an influence on future years. Here I use dynamic optimality modelling to investigate the adaptiveness of a subsistence strategy in the Gabbra, a nomadic pastoralist group. I show that herders forego short-term gain in favour of long-term household survival. This is done by herders sometimes manipulating the life histories of their sheep. In herds where the breeding rate has been slowed, by restricting ewes access to males, females have greater longevity, but fewer offspring per year, than in unmanipulated herds. Models maximising offtake from the herd predict that herd breeding-rate should never be slowed. Models maximising short-term household survival predict herd-breeding rate should always be slowed. Models of long-term household survival predict that herd-breeding rate should be slowed only by relatively wealthy households. This is the behaviour observed. Poor and wealthy house-holds adopt different behaviours, yet all are following optimal strategies for their own level of wealth, that maximise their long-term survival. This is the behaviour that would be predicted on the basis of evolutionary theory, given that a family takes many years to be raised. Correspondence to: R. Mace     

1999年辽宁省重点工业污染源监测及废水达标排放状况分析

通过对辽宁省重点污染源的监测和对污水排放情况的分析，及时掌握和了解污染源排放状况，为环境管理提供依据。     

Design sensitivity of reactive absorption units for improved dynamic performance and cleaner production: the NOx removal process

The dynamic characteristics of reactive absorption processes are of great importance for the smooth operation of the unit and the overall performance of the implemented control system under the influence of process disturbances and the presence of tight environmental and safety constraints. In the present study, the effect of the major design parameters and column configurations on the dynamic behaviour of the environmentally sensitive NO_x removal processes, through the use of rigorous rate-based dynamic models, is investigated. Static and dynamic disturbance rejection properties are evaluated for the screening and assessment of alternative design decisions.     

赤潮研究现状与动向

综述了赤潮研究现状，分析了发生原因，危害，总结了防治措施，监测预报技术，展望了今后的研制动向。     

南水北调东线水源区的生态监测

分析了南水北调东线水源区近期的生态监测工作重点、生态类型划分、监测指标确定及监测报告的编制，提出水源区近期生态监测应以监测区域生态质量状况和地面监测各生态系统信息指标为主，水源区的湿地生态系统、农村生态系统、农田生态系统、森林生态系统4种生态类型应按照综合性、独立性、可测性、数据可获得性和长期性的原则，分别确定其监测指标和监测频次。对生态监测报告的形式、内容提出了具体要求。     

Developing a National Indicator of Soil Quality on U.S Forestlands: Methods and Initial Results

The Montreal Process was formed in 1994 to develop an internationally agreed upon set of criteria and indicators for the conservation and sustainable management of temperate and boreal forests. In response to this initiative, the Forest Inventory and Analysis (FIA) and Forest Health Monitoring (FHM) programs of the United States Department of Agriculture Forest Service have implemented soil measurements as part of a national monitoring program to address specific questions related to the conservation of soil and water resources. Integration of soil assessments into the national FIA program provides for systematic monitoring of soil properties across all forested regions of the U.S. using standardized collection, laboratory, and statistical procedures that are compatible with existing forest inventory data. The resulting information will provide quantitative benchmarks for regional, national, and international reporting on sustainable forest management and enhance our understanding of management effects on soil quality. This paper presents an overview of the FIA soil monitoring program, outlines the field and laboratory protocols as currently implemented, and provides examples of how these data may be used to assess indicators of sustainable management as defined by the Montreal Process.     

模糊聚类分析法对哈密地下水监测网的优化研究

试用模糊聚类分析法将哈密地下水监测网点从原来的８个点优化为６个点．经研究较符合实际情况，实践研究了优化方法．     

湿法脱硫后高湿烟气中SO3酸雾监测方法研究

利用三氧化硫(SO3)发生装置以及模拟烟气湿法脱硫系统,研究了烟气再热温度、恒温水浴温度、采样速率、冷凝管类型规格及吸收瓶个数等不同采样参数对SO3酸雾采集率的影响。结果表明,当烟气再热温度低于烟气酸露点时会导致SO3酸雾收集率下降,采用控制冷凝法采样时应使用大流量(10L/min)采样,冷凝管应选择外套长度为400 mm的蛇形螺旋冷凝管,并将冷凝管置于温度为65℃左右的恒温水浴中;用碱液吸收法采样时应串联3个吸收瓶后,使用小流量(1L/min)采样。烟气温湿度、二氧化硫(SO2)浓度以及烟气中共存组分等对碱性吸收法的采集影响较大,而对控制冷凝法几乎没有影响。因此确立了针对湿法脱硫后高湿烟气环境下SO3酸雾的监测方法为控制冷凝法更为适宜。