应用生物制剂修复黑臭河涌试验研究

应用固定化生物催化剂(IBC)对江门市某河涌进行生物修复。结果表明:向底泥投加IBC能增加底泥中有益微生物量,优化底泥微生物群落,使河涌底泥中有机质逐渐降解;同时能抑制硫酸盐还原菌(SRB)繁殖,降低底泥中硫化物含量。试验进行4个月后,底泥有机质去除率达到54.7%⁶3.7%,底泥中SRB数量减少了92.8%63.7%,底泥中SRB数量减少了92.8%⁹4.5%,底泥硫化物含量降低了81.9%94.5%,底泥硫化物含量降低了81.9%⁸7.5%,河涌黑臭现象基本消除;向上覆水体投加IBC,在IBC中微生物和多种酶的协同作用下,水中有机污染物被快速降解,上覆水体的COD和氨氮浓度逐渐下降,试验进行4个月时,去除率分别达到20.0%87.5%,河涌黑臭现象基本消除;向上覆水体投加IBC,在IBC中微生物和多种酶的协同作用下,水中有机污染物被快速降解,上覆水体的COD和氨氮浓度逐渐下降,试验进行4个月时,去除率分别达到20.0%³5.2%和32.9%35.2%和32.9%⁴4.1%,提高了河涌的生物自净能力。     

广州市河涌底泥中主要污染物的垂直分布特征

分析了广州市3条河涌底泥中有机质、石油烃、Cd、Cr、Cu、Ni、Pb、Zn等主要污染物的垂直分布特征。结果表明:曾边涌、南村涌、会江涌底泥中有机质平均值分别为43.15mg/kg、10.80 mg/kg、34.81 mg/kg,石油烃含量平均值分别为:1644 mg/kg,2427 mg/kg,6763 mg/kg。有机质和石油烃垂直变化特征相似,曾边涌呈现表层底泥含量低而底层高的特征,南村涌呈现随深度增加而降低的趋势,会江涌呈现先降低后上升的趋势,3条河涌底泥中不同重金属垂直变化规律不一样;河涌底泥中污染物所呈现的垂直分布规律并不总是上层污染物浓度高而下层低的正常沉积特征。因此,在考虑通过清淤改善河流水质时,应考虑河流污染的历史,并调查沉积物中污染物垂直分布的实际情况。     

悬浮液直接进样石墨炉原子吸收法测定湖泊底泥中的铅

试验了悬浮液直接进样平台石墨炉原子吸收分光光度法测定湖泊底泥中的铅。方法特征灵敏度为2 1× 10 -11g/ 0 0 0 44 (A·s) ,检测限 (3σ)为 2 5× 10 -11g ,相对标准差 (n =6 )小于 4% ,加标回收率在 90 %～ 110 %之间     

Investigation on the eco-toxicity of lake sediments with the addition of drinking water treatment residuals

Drinking water treatment residuals(WTRs) have a potential to realize eutrophication control objectives by reducing the internal phosphorus(P) load of lake sediments. Information regarding the ecological risk of dewatered WTR reuse in aquatic environments is generally lacking, however. In this study, we analyzed the eco-toxicity of leachates from sediments with or without dewatered WTRs toward algae Chlorella vulgaris via algal growth inhibition testing with algal cell density, chlorophyll content, malondialdehyde content, antioxidant enzyme superoxide dismutase activity, and subcellular structure indices. The results suggested that leachates from sediments unanimously inhibited algal growth, with or without the addition of different WTR doses(10% or 50% of the sediment in dry weight) at different p H values(8–9), as well as from sediments treated for different durations(10 or 180 days). The inhibition was primarily the result of P deficiency in the leachates owing to WTR P adsorption, however, our results suggest that the dewatered WTRs were considered as a favorable potential material for internal P loading control in lake restoration projects, as it shows acceptably low risk toward aquatic plants.     

坡度和雨强对喀斯特地区坡面产流产沙的影响

利用径流小区观测法,分析了坡度和雨强对贵州喀斯特地区4种地类坡面产流产沙的影响。结果表明,随坡度的增大,各地类坡面产流产沙量并没有表现出一致增大或减小的趋势,它们在很大程度上受土地利用方式和土壤类型的制约;随最大30 min雨强(I)的增大,坡面的产流产沙量增大。坡度为13°时,坡耕地在各地类中的产流产沙量最小,随坡度增大逐渐超过其他地类;除13°径流小区外,经济林地(梨树)在各种坡度、雨强范围内的产流产沙量均为各地类中最少;水保林地(香樟)在各种情况下的产流量虽较大,但产沙量相对较小;裸地在观测条件下的产流产沙量均较大。     

Creation of a Gilded Trap by the High Economic Value of the Maine Lobster Fishery

Abstract: Unsustainable fishing simplifies food chains and, as with aquaculture, can result in reliance on a few economically valuable species. This lack of diversity may increase risks of ecological and economic disruptions. Centuries of intense fishing have extirpated most apex predators in the Gulf of Maine (United States and Canada), effectively creating an American lobster (Homarus americanus) monoculture. Over the past 20 years, the economic diversity of marine resources harvested in Maine has declined by almost 70%. Today, over 80% of the value of Maine's fish and seafood landings is from highly abundant lobsters. Inflation‐corrected income from lobsters in Maine has steadily increased by nearly 400% since 1985. Fisheries managers, policy makers, and fishers view this as a success. However, such lucrative monocultures increase the social and ecological consequences of future declines in lobsters. In southern New England, disease and stresses related to increases in ocean temperature resulted in more than a 70% decline in lobster abundance, prompting managers to propose closing that fishery. A similar collapse in Maine could fundamentally disrupt the social and economic foundation of its coast. We suggest the current success of Maine's lobster fishery is a gilded trap. Gilded traps are a type of social trap in which collective actions resulting from economically attractive opportunities outweigh concerns over associated social and ecological risks or consequences. Large financial gain creates a strong reinforcing feedback that deepens the trap. Avoiding or escaping gilded traps requires managing for increased biological and economic diversity. This is difficult to do prior to a crisis while financial incentives for maintaining the status quo are large. The long‐term challenge is to shift fisheries management away from single species toward integrated social‐ecological approaches that diversify local ecosystems, societies, and economies.     

Reducing the Maladaptive Attractiveness of Solar Panels to Polarotactic Insects

Abstract: Human‐made objects (e.g., buildings with glass surfaces) can reflect horizontally polarized light so strongly that they appear to aquatic insects to be bodies of water. Insects that lay eggs in water are especially attracted to such structures because these insects use horizontal polarization of light off bodies of water to find egg‐laying sites. Thus, these sources of polarized light can become ecological traps associated with reproductive failure and mortality in organisms that are attracted to them and by extension with rapid population declines or collapse. Solar panels are a new source of polarized light pollution. Using imaging polarimetry, we measured the reflection–polarization characteristics of different solar panels and in multiple‐choice experiments in the field we tested their attractiveness to mayflies, caddis flies, dolichopodids, and tabanids. At the Brewster angle, solar panels polarized reflected light almost completely (degree of polarization d ≈100%) and substantially exceeded typical polarization values for water (d ≈30–70%). Mayflies (Ephemeroptera), stoneflies (Trichoptera), dolichopodid dipterans, and tabanid flies (Tabanidae) were the most attracted to solar panels and exhibited oviposition behavior above solar panels more often than above surfaces with lower degrees of polarization (including water), but in general they avoided solar cells with nonpolarizing white borders and white grates. The highly and horizontally polarizing surfaces that had nonpolarizing, white cell borders were 10‐ to 26‐fold less attractive to insects than the same panels without white partitions. Although solar panels can act as ecological traps, fragmenting their solar‐active area does lessen their attractiveness to polarotactic insects. The design of solar panels and collectors and their placement relative to aquatic habitats will likely affect populations of aquatic insects that use polarized light as a behavioral cue.     

Deltas at risk

The long-term sustainability of populated deltas is often more affected by large-scale engineering projects than sea-level rise associated with global warming and the global ocean volume increase. On deltas, the rate of relative eustatic sea-level rise is often smaller than the rate for isostatic-controlled subsidence and of the same order of magnitude as natural sediment compaction. Accelerated compaction associated with petroleum and groundwater mining can exceed natural subsidence rates by an order of magnitude. The reduction in sediment delivery to deltas due to trapping behind dams, along with the human control of routing river discharge across delta plains, contributes to the sinking of world deltas. Consequences include shoreline erosion, threatened mangroves swamps and wetlands, increased salinization of cultivated land, and hundreds of millions of humans put at risk.     

Dynamics of copper and zinc sedimentation in a lagooning system receiving landfill leachate

This study characterises the sediment dredged from a lagooning system composed of a settling pond and three lagoons that receive leachates from a municipal solid waste (MSW) landfill in France. Organic carbon, carbonate, iron oxyhydroxides, copper (Cu) and zinc (Zn) concentrations were measured in the sediment collected from upstream to downstream in the lagooning system. In order to complete our investigation of sedimentation mechanisms, leachates were sampled in both dry (spring) and wet (winter) seasonal conditions. Precipitation of calcite and amorphous Fe-oxyhydroxides and sedimentation of organic matter occurred in the settling pond. Since different distributions of Zn and Cu concentrations are measured in sediment samples collected downstream in the lagooning system, it is suggested that these elements were not distributed in a similar way in the leachate fractions during the first stage of treatment in the settling pond, so that their sedimentation dynamics in the lagooning system differ. In the lagoons, it was found that organic carbon plays a major role in Cu and Zn mobility and trapping. The presence of macrophytes along the edges provided an input of organic matter that enhanced Cu and Zn scavenging. This edge effect resulted in a two-fold increase in Cu and Zn concentrations in the sediment deposited near the banks of the lagoons, thus confirming the importance of vegetation for the retention of Cu and Zn in lagooning systems.     

Assessing Potential Removal of Low-Head Dams in Urban Settings: An Example from the Ottawa River,NW Ohio

This is a study of the scientific component of an effort to restore an urban river by removing a low-head dam. The Secor Dam is owned by a local government entity near Toledo, Ohio. The proposed removal of the last structure impeding flow on the Ottawa River has broad appeal, but the owner is concerned about liability issues, particularly potential changes to the flood regime, the presence of contaminated sediments behind the dam, and possible downstream transport of reservoir sediments. Assessing sediment contamination involved sediment sampling and analysis of trace metals and organic contaminants. Forecasting sediment transport involved field methods to determine the volume and textural properties of reservoir and upstream sediment and calculations to determine the fate of reservoir sediments. Forecasting changes in the flood regime involved HEC-RAS hydrological models to determine before and after dam removal flood scenarios using LiDAR data imported into an ArcGIS database. The resulting assessment found potential sediment contamination to be minor, and modeling showed that the removal of the dam would have minimal impacts on sediment transport and flood hazards. Based on the assessment, the removal of the dam has been approved by its owners.