重庆紫色土区不同森林恢复类型对土壤质量的影响

为了探讨不同森林恢复类型对土壤质量的影响,对南方紫色土区4种主要森林恢复类型及对照地土壤物理和化学特性进行了比较研究。结果表明：4种森林类型的土壤质量均高于长期干扰下对照的土地,天然次生林土壤质量又高于人工林,5种不同状况下土壤质量综合指数由大到小为：天然次生林（0.97）、石栎（Lithocarpus glaber）×木荷（Schima superba）阔叶混交林（0.77）、枫香（Liquidambar formsana）×木荷×石栎×香樟（Cinnamomum camphora）阔叶混交林（0.67）、杉木纯林（0.41）、对照（0.04）。导致人工林和对照地土壤质量相对较低的主要原因是：周期性的森林抚育使土壤结构较差、凋落物量较低和土壤养分流失严重。研究表明,在植被恢复初期阶段,自然恢复是最大限度发挥森林功能的有效途径。     

福建洛阳江口红树林湿地恢复对蟹类密度的影响

底栖动物尤其是蟹类对红树林湿地生态系统的生态功能恢复有重要意义,研究检验不同红树林种类及林龄和郁闭度是否对蟹类分布情况存在显著影响。从福建洛阳江口红树林湿地动态变化对蟹类密度的影响可以看出：不同植被类型对蟹类密度的影响达到极显著水平。光滩与成熟的秋茄（Kandelia candel）,桐花树（Aegiceras corniculatum）和白骨壤（Avicennia marina）之间有显著性差异（P〈0.05）,而桐花树、秋茄、白骨壤之间无显著性差异（P〉0.05）。在不同红树林树种和林龄2因素对蟹类密度的影响的双因素分析中：树种、林龄、树种和林龄间互作均对蟹类密度的影响达到极显著水平;在不同红树林树种和郁闭度2因素对蟹类密度的影响的双因素方差分析中：树种对蟹类密度的影响达到极显著水平,郁闭度对蟹类密度的影响达到显著水平;树种和郁闭度之间互作对蟹类密度的影响不显著。     

成都地震重灾区生态影响分区及恢复对策

地震是造成生态破坏较为严重的自然灾害之一,震后生态恢复的总体对策是决策者亟待获取的重要信息,因此有必要及时开展地震生态影响分区研究.以成都地震重灾区为例,利用汶川地震前后2期TM影像灰度差提取了地质灾害区;从敏感性和诱导性两方面,采用层次分析法对地震重灾区进行了生态危险度分类;基于不同区域的生态破坏强度及危险度特征,开展了地震生态影响分区,并以此作为生态恢复过程中优先级及措施的总体布局. 结果表明:成都地震重灾区地质灾害面积为118.3 km2,占区域总面积的2.36%;其中,应首先采用生物与工程相结合的手段进行修复的面积为40.7 km2,通过生物措施修复的面积为66.2 km2,其余的则依靠自然演替逐渐恢复.      

水葫芦修复富营养化湖泊水体区域内外底栖动物群落特征

于2010年8~10月对滇池白山湾人工控制性种养的约70hm2的水葫芦区、近水葫芦区和远水葫芦区采样分析,探讨了水葫芦种养工程区域内外底栖动物群落结构特征.结果表明,在水葫芦区、近水葫芦区及远水葫芦区,底栖动物总密度分别为294.5,159,261ind/m2,其中寡毛类的霍甫水丝蚓(Limnodrilus hoffmeisteri)为绝对优势种,分别占各自区域总密度的68.3%,59.6%和86.0%.逐步回归分析显示,水体总磷(TP)和底泥非稳定态磷(Labile-P)与霍甫水丝蚓密度呈显著性正相关(P < 0.01),表明霍甫水丝蚓对水体的富营养状况有很好的指示作用.水葫芦区物种组成及生物多样性指数均高于近水葫芦区和远水葫芦区(P < 0.05),在水葫芦区、近水葫芦区和远水葫芦区分别共采集到底栖动物14种、10种和6种;Shannon-Wiener多样性指数分别为1.10,0.57和0.54.种植水葫芦后,在水葫芦区及近水葫芦区,10月份的Margalef、Shannon-Wiener、Simpson和Peilou指数较8月份和9月份有显著性增加(P < 0.05),而远水葫芦区,却未出现类似的结果.一定面积控制性种养水葫芦对大型富营养化湖湾水体无脊椎底栖动物群落结构未表现出不利影响.     

基于农户生计演化的山地生态恢复研究综述

农户生计演化对山地生态系统恢复的影响是恢复生态学和乡村地理学关注的焦点。针对该学术背景,论文对国内外相关研究进行了总结,系统梳理了农户生计变化的内涵、驱动因素及其对山地生态系统恢复的影响;得出农户生计变化与山地生态系统演化是紧密相关的,农户生计状况最终决定着山地生态系统的特征,农户生计的改善往往驱动着山地生态系统的正向演替。最后,针对当前的研究和实践现状,建议进一步加强对农户生计和生态恢复相互关系的研究;针对当前的新农村建设和环境保护项目,要深入探究其对农户生计乃至山地生态系统恢复的影响;并建议优化中国地方官员考核标准,增强各级部门对农户生计以及环境保护的重视。     

BANKFULL DISCHARGE RECURRENCE INTERVALS AND REGIONAL HYDRAULIC GEOMETRY RELATIONSHIPS: PATTERNS IN THE PACIFIC NORTHWEST,USA1

ABSTRACT: The model bankfull discharge recurrence interval (annual series) (T_a) in streams has been approximated at a 1.5‐year flow event. This study tests the linkage between regional factors (climate, physiography, and ecoregion) and the frequency of bank‐full discharge events in the Pacific Northwest (PNW). Patterns of Ta were found to be significant when stratified by EPA Ecoregion. The mean value for T_a in the PNW is 1.4 years; however, when the data is stratified by ecoregion, the humid areas of western Oregon and Washington have a mean value of 1.2 years, while the dryer areas of Idaho and eastern Oregon and Washington have a mean value of 1.4 to 1.5 years. Among the four factors evaluated, vegetation association and average annual precipitation are the primary factors related to channel form and T_a. Based on the results of the T_a analyses, regional hydraulic geometry relationships of streams were developed for the PNW, which relate variables, such as bank‐full cross‐sectional area, width, depth, and velocity, to bankfull discharge and drainage area. The verification of T_a values, combined with the development of regional hydraulic geometry relationships, provides geographically relevant information that will result in more accurate estimates of hydraulic geometry variables in the PNW.     

黑河下游河道渗漏规律研究

黑河下游河道都是天然河道,断面不规则,属宽浅型沙质河床,河道渗漏量大。下游的天然生态正是由于河道的渗漏水量补给地下水来支撑天然植被的生长,所以河道的渗漏对于下游生态意义重大。而对于黑河下游河道渗漏情况,长期以来没有系统地进行监测,利用常规的渗透系数法无法计算,目前大多是估计或者简化处理。论文根据水量实时调度和长系列水资源配置的需要,根据断面流量相关关系对其渗漏规律进行分析,分别得到了短期实时调度考虑河道前期水情状况影响下的河道渗漏规律以及长系列水资源配置情况下平均的渗漏规律。     

An approach for restoration of the water quality with emphasis on the removal of organochlorine pesticides and eutrophic conditions in tropical rivers

This work deals with an approach for the water quality restoration with emphasis on the removal of organochlorine pesticides and eutrophic conditions in tropical rivers, causing influence on the management of the central-regional aqueduct, as a source of water supply for human consumption (4 million people) and industrial production in the states of Carabobo, Cojedes and Aragua, Venezuela, testing the phytoremediation techniques through Vetiveria zizanioides (VZ) species and coupled bioreactors, Sequencing Batch Reactor (SBR) followed by an Upflow Anaerobic Filter in Three Separate Stages (UAF-3SS). Five rivers are involved known as Chirgua, Paito Guacara, Ereigüe, and Tucutunemo, whose waters have been classified as hypereutrophic, and containing organochlorine pesticides (OCPs). As a sample, for Tucutunemo River, OCPs included to DDT (dichlorodiphenyltrichloroethane) and its isomers and DRINs (Aldrin, Endrin and Dieldrin) dissolved in water and sorbed on sediments, which were measured during the dry and rainy seasons in the period 2013 to 2016, in three monitoring stations distributed in a reach of 15 km. The results indicated that p.p′-DDT concentration dissolved in water was increased up to 10 times from rainy to dry seasons, indicating that a permanent use of it is being carried out by farmers in the agricultural activity development. Steady concentrations of the DTT isomers (e.g., p.p′-DDD and p.p′-DDE) and Aldrin isomers (e.g., Dieldrin) demonstrated that the anaerobic and aerobic biodegradation processes occurred along the river and between climatic seasons. At experimental scale, VZ hydroponic system developed over a period of 6 months for the removal of nutrients demonstrated moderately low to high removal efficiencies. With respect coupled bioreactors, each bioreactor has been experimentally tested, demonstrating satisfactory performance in Chemical Oxygen Demand (COD) removal from industrial wastewater containing recalcitrant and inhibitory substances (46%–98%), which was estimated in the influent ranging from 3500 to 5500 mg/L, evidencing that coupling of bioreactors might lead to a effluent COD complying with environmental regulations.     

Diffusive wave models for operational forecasting of channel routing at continental scale

Operational forecast models require robust, computationally efficient, and reliable algorithms. We desire accurate forecasts within the limits of the uncertainties in channel geometry and roughness because the output from these algorithms leads to flood warnings and a variety of water management decisions. The current operational Water Model uses the Muskingum-Cunge method, which does not account for key hydraulic conditions such as flow hysteresis and backwater effects, limiting its ability in situations with pronounced backwater effects. This situation most commonly occurs in low-gradient rivers, near confluences and channel constrictions, coastal regions where the combined actions of tides, storm surges, and wind can cause adverse flow. These situations necessitate a more rigorous flow routing approach such as dynamic or diffusive wave approximation to simulate flow hydraulics accurately. Avoiding the dynamic wave routing due to its extreme computational cost, this work presents two diffusive wave approaches to simulate flow routing in a complex river network. This study reports a comparison of two different diffusive wave models that both use a finite difference solution solved using an implicit Crank–Nicolson (CN) scheme with second-order accuracy in both time and space. The first model applies the CN scheme over three spatial nodes and is referred to as Crank–Nicolson over Space (CNS). The second model uses the CN scheme over three temporal nodes and is referred to as Crank–Nicolson over Time (CNT). Both models can properly account for complex cross-section geometry and variable computational points spacing along the channel length. The models were tested in different watersheds representing a mixture of steep and flat topographies. Comparing model outputs against observations of discharges and water levels indicated that the models accurately predict the peak discharge, peak water level, and flooding duration. Both models are accurate and computationally stable over a broad range of hydraulic regimes. The CNS model is dependent on the Courant criteria, making it less computational efficient where short channel segments are present. The CNT model does not suffer from that constraint and is, thus, highly computationally efficient and could be more useful for operational forecast models.     

垃圾填埋场植被恢复及其环境影响因子的研究

对中山市一个关闭了5a左右的垃圾卫生填埋场进行植被恢复、土壤、填埋气和植物自然定居与植被恢复等方面的调查研究。结果表明：垃圾填埋场的土壤偏碱性，场内土壤的盐分、含水量、有机质和重金属等含量远远高于场外的对照土壤。填埋场的植被自然恢复得很好，总盖度达到98％，以草本植物为主，灌木为辅，另外还有少量的藤本植物和乔本存在。本次调查共记录高等植物74种，隶属63属30科。优势种为狗牙根，亚优势种包括苦楝、胜红蓟、蟛蜞菊、加拿大飞蓬、小牵牛、鸭跖草、少花龙葵、鸡矢藤、红斑一品红、牛筋草、类芦和田菁等12种植物。其中类芦、加拿大飞蓬和胜红蓟是本垃圾填埋场植被恢复先锋植物。场内的填埋气含量显著地高于对照样方，但与其它垃圾填埋场相比，其填埋气的含量较低，因此填埋气对植被恢复的限制作用也相对较小。影响本填埋场植被恢复的环境因子主要是土壤的营养成分、重金属和填埋气。最后，提出了对垃圾填埋场进行植被恢复时应采取的关键措施。图1表5参19。