Ecological Feasibility Studies in Restoration Decision Making

The restoration of degraded systems is essential for maintaining the provision of valuable ecosystem services, including the maintenance of aesthetic values. However, restoration projects often fail to reach desired goals for a variety of ecologic, financial, and social reasons. Feasibility studies that evaluate whether a restoration effort should even be attempted can enhance restoration success by highlighting potential pitfalls and gaps in knowledge before the design phase of a restoration. Feasibility studies also can bring stakeholders together before a restoration project is designed to discuss potential disagreements. For these reasons, a feasibility study was conducted to evaluate the efficacy of restoring a tidal freshwater marsh in the Potomac River near Alexandria, Virginia. The study focused on science rather than engineering questions, and thus differed in approach from other feasibility studies that are mostly engineering driven. The authors report the framework they used to conduct a feasibility study to inform other potential restoration projects with similar goals. The seven steps of the framework encompass (1) initiation of a feasibility study, (2) compilation of existing data, (3) collection of current site information, (4) examination of case studies, (5) synthesis of information in a handbook, (6) meeting with selected stakeholders, and (7) evaluation of meeting outcomes. By conducting a feasibility study using the seven-step framework, the authors set the stage for conducting future compliance studies and enhancing the chance of a successful restoration.     

开化县外向型创汇林业的战略模式

我国森林资源少,消耗量大,林业建设资金短缺。如何发展当前的林业生产、筹集林业建设资金,开化县的外向型创汇林业为我们走出了一条具有中国特色的外向型林业建设道路。本文就开化县发展外向型创汇林业的优点、出口创汇的主要对策、主要商品、发展潜力及其前景进行了论述,对目前正在探索适合我国国情的、解决我国林业“两危”的战略对策提供了现实的典型范例。     

ENVIRONMENTAL IMPACT OF STREAM CHANNELIZATION1

ABSTRACT Geologic, engineering, and biological investigations of six Pennsylvania coldwater streams were undertaken to determine the impact of channel modifications instituted both prior to and following Hurricane Agnes. The primary focus of the study was on the ecological changes brought about by stream channelization. No long-term deleterious effects on water quality, attached algae, benthic fauna, or forage fish populations were found. Trout, however, were found to be greater in numbers and weight in natural than in channelized stream reaches. Lack of suitable physical habitat appears to be the primary cause of reduced trout populations in stream reaches which have been channelized.     

AGRICULTURE LAND‐USE EFFECTS ON NUTRIENT LOSSES IN WEST TIAOXI WATERSHED,CHINA1

ABSTRACT: Five types of land use/land covers in the West Tiaoxi watershed of China were studied for nutrient losses in artificial rainstorm runoff. A self‐designed rainfall simulator was used. In situ rainfall simulations were used to: (1) compare the concentrations of nitrogen and phosphorous in different land use/land covers and (2) evaluate the flux of nitrogen and phosphorous export from runoff and sediment in various types of land use/land covers. Three duplicated experiments were carried out under rain intensity of 2 mm/min, each lasting 32 minutes on a 3 m² plot. Characteristics of various species of nitrogen and phosphorous in runoff and sediment were investigated. The results showed that the concentrations of total nitrogen (TN) and total phosphorous (TP) were greatest in runoff from mulberry trees and smallest from pine forest. The TN and TP export was mainly from suspended particulate in runoff. TN and TP exports from the top 10 cm layer of five types of land use/land covers were estimated as high as 4.66 to 9.40 g/m² and 2.57 to 4.89 g/m², respectively, of which exports through sediment of runoff accounted for more than 90 percent and 97 percent. The rate of TN and TP exports ranged from 2.68 to approximately 14.48 and 0.45 to approximately 4.11 mg/m²/min in runoff; these rates were much lower than those of 100.01 to approximately 172.67 and 72.82 to approximately 135.96 mg/m²/min in the runoff sediment.     

ENVIRONMENTAL FACTORS INFLUENCING SUSPENDED SOLIDS IN THE LOXAIIATCHEE ESTUARY,FLORIDA1

ABSTRACT: A study was initiated to examine the effects of wind speed, wind direction, freshwater inflow, and tide height on suspended solid concentration and distribution in the Loxahatchee estuary, Florida. Recent efforts to increase freshwater flows in this system raised concerns that suspended solid concentrations would increase as well, which might result in negative impacts for the estuary. The data indicated that total suspended solids (TSS) in the estuary are derived primarily from the inlet and not from freshwater tributaries. In addition, total suspended solids and volatile suspended solids were correlated strongly with salinity, suggesting that suspended sediments act conservatively throughout this system. No one environmental factor had an overwhelming influence on suspended solid concentration throughout the estuary; different regions of the estuary were influenced by different factors. Freshwater inflow was negatively related to TSS in the upper reaches of the estuary but was positively related to TSS in the central embayment region of the estuary. We attribute this latter finding to the fact that extremely high inflows both prevented the normal transport upstream of tidal borne suspended sediments and promoted mixing when the freshwater front moving downstream confronted the tidal front moving upstream. Wind speed, wind direction, and tide height had relatively small effects on TSS concentration but were most influential in reaches upstream of the central embayment, where tidal velocity begins to diminish.     

CONTROL OF SUSPENDED SOLIDS AND PHYTOPLANKTON WITH FISHES AND A MUSSEL1

ABSTRACT: Filtering efficiency of the fathead minnow (Pimephales promelas), gizzard shad (Dorosoma cepedianum), carp (Cyprinus carpio), and a freshwater mussel (Elliptio coinpianata) was measured in field and laboratory trials to assess the ability of each species to control phytoplankton and suspended solid densities. All fish species tested were ineffective filterers and generally increased, rather than suppressed, algal and suspended solid concentrations. Filtering efficiencies of fish varied between -354 and 84 percent, depending on the size, shape, abundance, palatability, composition, and resistance to digestion of the particles. Because of poor filtering abilities, unpredictable feeding habits, and sensitivity to stress, the fish species examined are not effective biological controls in waste lagoons. In contrast, the freshwater mussel Elliptio was a highly effective control organism, averaging 66 percent filtering efficiency over a wide size range of algal and suspended particles. Filtration efficiency was positively correlated with mussel density. Elliptio was efficient at filtering small particles, which are particularly difficult to remove. Mean filtration rates ranged from 53 to 134 ml/mussel/h depending on the algal species consumed and algal densities (range 50–180,000 cells/ml) and 3 mg/L/mussel/h on suspended solids (range 14 to 112 mg/L). Water clarification was facilitated by both direct consumption and pseudofeces deposition. Elliptio and probably other mussel species can effectively control algae and suspended solids in wastewater lagoons and eutrophic lakes, if environmental conditions, especially dissolved oxygen levels, are suitable (>5 mg/L) for their survival.     

东营市地下淡水资源及其可持续开发利用

根据新兴城市东营市严重缺乏淡水资源的现实状况和本区内地下淡水资源是由浅层地下淡水、深层地下淡水和淡水透镜体组成的现状,在深入研究本区地下淡水的补给和动态变化的基础上,提出了从补给、开采和利用等各个层次上采取开源节流、循环利用、科学规划等方式,实现本区地下淡水资源的可持续利用.     

Linking Soil Erosion to Instream Dissolved Phosphorus Cycling and Periphyton Growth

Phosphorus (P) is a limiting nutrient in freshwater systems and when present in runoff from agricultural lands or urban centers may contribute to excessive periphyton growth. In this study, we examined the link between soil erosion and delivery of eroded soil to streams during flow events, and the impact of that freshly deposited soil on dissolved reactive P (DRP) concentrations and periphyton growth under baseflow conditions when the risk of stream eutrophication is greatest. A microcosm experiment was designed to simulate the release of P from soil which had been amended with different amounts of P fertilizer to overlying water during baseflow conditions. Unglazed tiles, inoculated for five days in a second order stream, were incubated for seven days in microcosms containing soil with eight levels of soil Mehlich‐3 plant available phosphorus (M3P) ranging from 20 to 679 mg/kg M3P. Microcosm DRP was monitored. Following incubation tiles were scraped and the periphyton analyzed for chlorophyll a. Microcosm DRP concentrations increased with increasing soil M3P and equilibrium phosphorus concentration (EPC₀). Relationships between M3P, EPC₀, and DRP were nonlinear and increases in soil M3P and/or DRP had a greater impact on biomass accumulation when these parameters were above threshold values of 30 mg/kg M3P and 0.125 mg/L DRP. Significantly, this ecological threshold corresponds to the agronomic thresholds above which increased soil M3P does not increase plant response.     

多溴联苯醚在典型电子垃圾污染区域水生食物链上的生物富集特征

为调查电子垃圾回收活动对当地水生生物造成的多溴联苯醚(PBDEs)污染,测定了广东某电子垃圾回收地附近水库中水生生物样品(水蛇、鱼类、草虾和田螺)和对照区样品(鲮鱼)中18种PBDEs含量,通过对样品氮同位素的测定,探讨了PBDEs在该地淡水食物链上的生物富集特征.研究结果显示,∑PBDEs(总PBDEs含量)在水蛇、鱼类、草虾和田螺中分别为39.6～186、1.82～75.7、4.60～17.1和7.26～17.0μg·g-1(脂重),比华南地区鱼体中∑PBDEs的平均含量高3个数量级,表明电子垃圾回收活动已对当地水生生物造成了PBDEs的严重污染.除BDE66、BDE99、BDE153、BDE183和BDE209外,其他13种PBDE单体在食物链上均存在着生物放大效应,但生物放大能力(B值)与正辛醇-水分配系数logKOW相关性不明显,可能是由于某些PBDE单体在生物体内存在代谢作用.以上结果表明,由电子垃圾回收活动导致的PBDEs污染存在较大的生态风险,应该引起高度关注.