Mosquito larvae density and pollutant removal in tropical wetland treatment systems in Honduras

Constructed wetlands offer a low-cost wastewater treatment option for tropical developing countries. The vast majority of published treatment wetland research has been conducted in temperate regions. Because the function of treatment wetlands is related to the environmental conditions, more research specific to the tropics should be completed. A six-cell free water surface (FWS) wetland mesocosm was constructed in Santa Rosa de Copán, Honduras that received input from an open-sewer/wastewater-impacted stream. Three cells were planted with Typha domingensis Pers., and three cells were left unplanted. Both planted and unplanted wetlands were constructed with three different surface areas to concurrently study different hydraulic retention times (HRTs) and hydraulic loading rates (HLRs). Results from 6 months of operation showed improved water quality and mosquito larvae populations affected by their specific environment. Five-day biochemical oxygen demand (BOD) removal appeared to be proportional to HRT and HLR, and BOD concentration in the effluent was higher in unplanted cells than in planted cells (P<0.05). BOD removal approached 60% for greater than 3.5 days HRT. Total phosphorus (P) removal and coliform bacteria removal were found to be correlated with pollutant load, and P removal was found to be correlated with HRT but not HLR. A second municipal wastewater FWS treatment wetland in Copán Ruinas, Honduras that had been established for 15 years, was also evaluated. BOD removal in the Copán Ruinas system was determined to be 93% with 2.6 day HRT. These pollutant removal rates are higher than would be expected in temperate regions. Mosquito larvae density was correlated with depth of the wetland. Mosquito larvae densities were higher in cells that were operating below design depth of 0.2 m (P<0.005). Results indicate that it is possible to design FWS wetlands in the tropics for effective BOD removal and reduced mosquito larvae development.     

Post-depositional redistribution and gradual accumulation of 137Cs in a riparian wetland ecosystem in Sweden

After the Chernobyl accident, high activity concentrations of (137)Cs (>1 MBq m(-2)) were detected in a riparian swamp in the central-eastern part of Sweden. The objective of this study was to clarify the redistribution processes behind the accumulation of (137)Cs in the wetland. A mass balance budget of (137)Cs was calculated based on soil and sediment samples and reports in the literature. Results showed that accumulation occurred over several years. Of all the (137)Cs activity discharged between 1986 and 2002 from the upstream lake, 29% was estimated to be retained in the wetland. In 2003, measurements showed that 17 kBq m(-2) sedimented on the stream banks of the wetland. Continuing overbank sedimentation by spring flooding prolongs the time that the wetland will contain high activity concentrations of (137)Cs. Consequently, organisms living in wetlands serving as sinks for (137)Cs may become exposed over long time periods to high activity concentrations.     

Distribution of pesticides, PAHs and heavy metals in prawn ponds near Kolleru lake wetland, India

This paper discussed the distribution of pesticides, polycyclic aromatic hydrocarbons (PAHs) and heavy metals in water, sediment and prawn from intensive prawn ponds (n=8) near the Kolleru lake wetland, India and assessed the quality of prawn for human consumption and also discussed the possible effects of these pollutants on pond environment and aquatic environment. The chemicals and other products used in prawn ponds near the Kolleru lake wetland were documented. The sediment, prawn and water samples were collected six times from selected prawn ponds during the production period of 3 months. Water samples were analyzed for selected physico-chemical parameters. The levels of pesticides, PAHs and heavy metals were found to decrease in the order sediment followed by prawn and water. The maximum concentrations of pesticides in sediment, prawn and water were alpha-BHC (174.2 microg g(-)(1)), gamma-BHC (234 microg g(-)(1)), malathion (256 microg g(-)(1)), chloripyrifos (198.5 microg g(-)(1)), endosulfan (238 microg g(-)(1)), dieldrin (19.6 microg g(-)(1)) and p,p'-DDT (128.6 microg g(-)(1)). Isodrin was found below detectable limit. The maximum concentrations of PAHs in sediment, prawn and water are anthracene (0.901 microg kg(-)(1)), fluranthene (0.601 microg kg(-)(1)), pyrene (0.786 microg kg(-)(1)), chrysene (0.192 microg kg(-)(1)), benzo(a)pyrene (0.181 microg kg(-)(1)) and benzo(ghi)perylene (227 microg kg(-)(1)). Benzo(e)pyrene, perylene, isomers of dibenzoanthracene and coronene were found below detectable limits. The maximum concentrations of heavy metals in sediment, prawn and water and also in prawn feed are Cu (791 microg g(-)(1)), Pb (270 microg g(-)(1)), Cd (1.07 microg g(-)(1)), Mn (4417 microg g(-)(1)), Ni (8.1 microg g(-)(1)), Co (5.8 microg g(-)(1)), Zn (1076 microg g(-)(1)), Cr (36.4 microg g(-)(1)), As (2.9 microg g(-)(1)), Se (6.3 microg g(-)(1)), Th (2.1 microg g(-)(1)) and Mo (0.762 microg g(-)(1)).     

人类活动对安庆沿江湖泊湿地影响的初步研究

湖泊湿地不仅具有丰富的资源,还有着强大的环境功能和生态效益。人类大规模的开发利用湖泊湿地资源,在获取大量生产、生活资料的同时,也给湖泊湿地生态系统带来了负面影响,如湖面减少,水质下降,生态环境退化等。安庆沿江湖泊湿地为省级自然保护区,相对长江中下游大湖普遍退化而言,该湿地有着良好的自然性,正吸引着有关专家和研究组织的重视和关注。对安庆沿江湖泊湿地资源和功能展开分析,并从水利建设、围湖垦殖、森林砍伐和水土流失、农业污染、公路建设及渔业开发等方面探讨了人类活动对湿地的影响。提出了保护安庆沿江湖泊湿地资源和环境的建议和对策,以促进湿地资源与环境的可持续发展。     

Artificial wetlands and water quality improvement

This paper illustrates the role of plants to assist the treatment of water pollution in man-made wetlands in tropical and temperate climates. It also considers the potential for environmental education of these wetland systems. The management and natural treatment of pollution is described in the Mai Po Marshes, Hong Kong and a wetland in London which is also an important site for birds. The design of the Putrajaya Lake and Wetland system in Malaysia is compared with a constructed wetland and lake for the treatment of urban surface runoff in a new residential development in the United Kingdom. The benefits of these natural systems are discussed in the context of the global trend for introducing sustainable methods of environmental management and low cost pollution treatment systems.     

厦门海岸带湿地变化的研究

通过“压力-状态-响应”分析模型，对厦门海岸带湿地变化的主要原因（压力）、成分退化和结构改变（状态）以及对厦门海岸带生态系统的主要影响（响应力）之间的作用机制进行了探讨。提出厦门海岸带湿地面临的主要压力来自海岸带围垦造地、近海滩涂养殖和九龙江河口输入；状态变化突出表现在浅海海域面积的减少。红树林的面积减少。近岸泥沙淤积。沉积物类型改变和沉积物污染；主要影响是造成厦门海域水质下降、近海底橙生物类型改变、航道泥沙淤积、水产养殖产量下降和珍稀海洋物种分布和数量改变。     

Correlations between speciation of Cd,Cu, Pb And Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia

Total concentrations and speciation of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in surface sediment samples were correlated with the respective metal measured in the total soft tissue of the green-lipped mussel Perna viridis, collected from water off the west coast of Peninsular Malaysia. The aim of this study is to relate the possible differences in the accumulation patterns of the heavy metals in P. viridis to those in the surface sediment. The sequential extraction technique was employed to fractionate the sediment into 'freely leachable and exchangeable' (EFLE), 'acid-reducible,' 'oxidisable-organic' and 'resistant' fractions. The results showed that significant (P<.05) correlations were observed between Cd in P. viridis and Cd in the sediment (EFLE fraction and total Cd), Cu in P viridis and Cu in the sediment (EFLE and 'acid-reducible' fractions and total Cu) and Pb in P viridis and Pb in the sediment ('oxidisable-organic' fraction and total Pb). No significant correlation (P > .05) was found between Zn in P viridis and all the sediment geochemical fractions of Zn and total Zn in the sediment. This indicated that Zn was possibly regulated from the soft tissue of P. viridis. The present results supported the use of P viridis as a suitable biomonitoring agent for Cd, Cu and Pb.     

青藏公路路堤边坡水土保持措施及效益分析

公路建设加速了区域的原有侵蚀,为了摸清公路边坡的侵蚀特征,寻找有效的防治措施,在青藏公路边坡布设不同水土保持措施的径流观测小区,进行了两年的观测（2003年和2004年）,结果表明：（1）工程措施具有较好的水土保持效益,其减流（减沙）效益在第一年和第二年分别达到3883％（8189％）和48.72％（9581％）,其中截排水措施的水土保持效益一方面说明公路路面来水也是边坡侵蚀的重要动力,有效拦截路面来水将会极大地减少径流和泥沙,另一方面也说明要提高公路边坡土壤侵蚀的预测能力,应该将路面来水作为重要的驱动力之一;（2）植被措施可以起到一定的减流减沙效果,其中人工植被措施有很大的潜力,其减蚀效益都在50％以上;（3）综合措施表现出了极好的水土保持效益（减流在40％以上,减沙在97％以上）,尤其土工格室+植被措施,兼具水土保持与景观双重效益。该研究可以为青藏高原地区的水土保持设计和生态环境保护规划提供数据支持。〖     

Oxygen demand, nitrogen and copper removal by free-water-surface and subsurface-flow constructed wetlands under tropical conditions

This study was conducted to: (1) assess the role of wetland vegetation in the removal of oxygen demand and nitrogen under tropical conditions, (2) estimate the uptake of nitrogen and copper by wetland plants and (3) investigate the speciation of Cu in wetland media among four operationally defined host fractions, namely exchangeable, carbonate, reducible and organically bound. Four laboratory-scale wetland units, two free-water-surface (FWS) and two subsurface-flow (SF) with one of each planted with cattails (Typha augustifolia), were fed with primary-treated sewage and operated at nominal retention times of 0.6-7 days. The influent and effluent BOD/COD and nitrogen concentrations were monitored to assess the performance of the wetland units for various mass loading rates. At the end of the study, all cattail plants were harvested and analyzed for total Kjeldahl nitrogen (TKN). Four other wetland units, which were identical to the first four, were fed with domestic wastewater spiked with copper in increasing concentrations. Copper speciation patterns in the sand layer were determined at the end of the study. The results showed that wetland vegetation did not play an important role in oxygen demand removal but were capable of removing about 22% and 26% of the nitrogen input in the FWS and SF wetland units, respectively. Mass balance analysis indicated that less than 1% of copper introduced was taken up by the cattails. Copper speciation patterns in the sand media showed that the exchangeable fraction contributed 30-57% and 63-80% of the nonresidual copper in the planted and unplanted FWS wetlands, respectively. For SF units, the percentages were 52-62% and 59-67%, respectively. This indicates that large amount of copper in the media were potentially remobilizable.     

The use of constructed wetlands for removal of pesticides from agricultural runoff and drainage: A review

Pesticides are used in modern agriculture to increase crop yields, but they may pose a serious threat to aquatic ecosystems. Pesticides may enter water bodies through diffuse and point sources, but diffuse sources are probably the most important. Among diffuse pollution, surface runoff and erosion, leaching and drainage represent the major pathways. The most commonly used mitigation techniques to prevent pesticide input into water bodies include edge-of-field and riparian buffer strips, vegetated ditches and constructed wetlands. The first attempts to use wetland macrophytes for pesticide removal were carried out as early as the 1970s, but only in the last decade have constructed wetlands for pesticide mitigation become widespread. The paper summarizes 47 studies in which removal of 87 pesticides was monitored. The survey revealed that constructed wetlands with free water surface are the most commonly used type. Also, it has been identified that removal of pesticides is highly variable. The results of the survey revealed that the highest pesticide removal was achieved for pesticides of the organochlorine, strobilurin/strobin, organosphosphate and pyrethroid groups while the lowest removals were observed for pesticides of the triazinone, aryloxyalkanoic acid and urea groups. The removal of pesticides generally increases with increasing value of K_OC but the relationship is not strong.     

水量衡算条件下人工湿地对有机物的去除

构建了芦苇和无植物人工湿地,在系统水量衡算的基础上比较了两种湿地对生活污水中有机物的去除效果。结果表明,在植物收割后的冬季,有植物湿地对有机物的去除率低于无植物湿地2.2%;在其他季节,芦苇湿地对污水CODCr的去除率比无植物的高出3.2%～4.2%,但对BOD5的去除率却比无植物的低了1.8%～3.4%。有植物湿地对有机物的去除效果比无植物湿地有所改善,但是提高不多。比较了两种系统的氧化还原电位,有植物湿地比无植物湿地高（P<0.05）,这种提高主要集中在湿地水面以下约15 cm的范围,从整体来看,两块湿地内部氧化还原状态大体相同,主要是强还原环境。比较了两块湿地基质中降解有机物的细菌、放线菌和真菌的数量,二者没有明显的差别,但是,有植物湿地的根际效应明显。考察了湿地进水有机负荷与去除量的关系,二者呈现显著的线性相关性(R2>0.96)。      

丹江流域水沙变化特征分析

丹江流域是南水北调中线工程重要水源地,近年来受多种因素影响,径流泥沙情况发生了很大变化,准确把握其变化趋势对水资源管理及水土保持工作意义重大。该文基于荆紫关水文站1958～2015年径流和悬移质输沙量资料,运用Mann-Kendall 检验法、距平累积法、滑动t检验法以及双累积曲线法,阐明了丹江流域近60年径流量和悬移质输沙量变化特征,定量分析了各影响因素在径流泥沙变化中的作用。结果表明：丹江流域径流量与悬移质输沙量年际变化大,呈显著下降趋势,1958～1972、1982～1989年为丰水丰沙期,1972～1981年与1990～2015年处于枯水枯沙期,径流量和悬移质输沙量分别在1983年与1989年发生突变。人为因素和降水的贡献率分别为58.8%和41.2%,说明人为因素特别是水利水土保持工程是引起丹江流域输沙变化的主要因素。     

复合垂直流构建湿地净化污水机制研究 Ⅰ微生物类群和基质酶

构建湿地是 2 0世纪 70年代才蓬勃兴起的一种处理污水的方式 ,由于其造价和运行费用低 ,净化效果稳定 ,越来越引起各国的兴趣和高度重视。现已广泛应用于城市生活污水、工业污水和农业污水的控制 ,有着十分广阔的应用前景。虽然关于构建湿地净化污水的研究已有不少报道 ,但关于湿地基质中的微生物类群和基质酶在污水净化中的作用仍不清楚。通过对生长在复合垂直流构建湿地和天然环境条件下菰和石菖蒲根区微生物类群数量及其根区基质酶活性的测定发现 :同种植物在复合垂直流构建湿地根区微生物的数量比天然条件下的要高 ,特别是硝化细菌和反硝化细菌的数量 ,最高可达 3个数量级以上 ;同时复合垂直流构建湿地中不同植物根区的酶活性有较大差别 ,这为研究复合垂直流构建湿地净化污水的机理和以酶活性强弱作为净化效果的评价指标提供了科学资料 ,为进一步研究提供了一条新思路     

近60年赣江水沙变化特征及影响因素分析

赣江是鄱阳湖流域最大水系,赣江水沙变化对鄱阳湖入湖径流、泥沙等水文特征有重要影响。目前对赣江水沙研究主要集中在下游外洲站河段,不足以反映全流域水沙变化规律。选取赣江上游4站、吉安和外洲水文站分别代表上、中、下游河段,基于近60 a的实测流量、悬移质泥沙资料,采用水文学和数理统计相结合的方法,分析赣江水沙年际变化特征以及可能影响因素,以期为流域水沙资源管理提供参考。结果表明:(1)赣江径流年际变化大,1970s、1990s水量较丰,其它年代径流偏少,年径流序列无显著变化趋势和突变点;(2)输沙量年际变化剧烈,呈显著降低趋势,上游4站、吉安站、外洲站输沙序列突变点分别为2002年、1995年、1995年,突变后年输沙量较突变前减少52%、71%、67%;(3)赣江上游水土保持建设是上游4站输沙量减小的主要原因;1993年后万安水库拦沙是吉安、外洲站输沙量显著减少的主要原因,水土保持、河道采砂也是引起吉安、外洲站输沙量减少的直接因素。(4)水土保持减沙的作用是缓慢和滞后的,而万安水库对下游河道的减沙作用是迅速而显著的。可见,赣江入鄱阳湖的年径流无明显减少趋势,入湖输沙量显著减少,有利于减少鄱阳湖的泥沙淤积、促进湖泊生态的良性发展。     

长江流域水环境演化规律研究平台及切入点初探

对长江流域水环境演化规律的研究 ,应该针对国家迫切需要解决的、尤其是水质酸化和污染、洪涝灾害威胁加剧等水环境问题 ,提出科学的解释 ,为流域水环境修复提供基础理论。回顾和总结了 5 0多年来前人在长江流域水环境研究方面所取得的成果 ,这些成果为今后进一步开展研究构筑了良好的基础平台。对长江流域水环境的研究应出系统性、整体性和综合性 ,围绕长江干流水质保护和中游地区防洪两个重中之重 ,强化对水环境演变动力学机制的研究 ,摸清流域水、泥沙与污染物相互作用规律及其对水环境恶化的机制 ,建立流域水文、泥沙与水质之间非线性、复杂巨系统的耦合关系及其系统模拟。还提出了长江流域水环境研究的 7个切入点     

长江中下游流域人类活动强度及其对湿地景观格局影响研究

目前关于大尺度下人类活动强度对湿地景观格局影响的研究较少,为揭示长江中下游流域湿地景观格局与人类活动强度的关系,以1995～2015年的土地利用数据为基础,综合运用人类活动强度模型和景观指数等方法,分析研究区人类活动强度演变特征、湿地景观格局特征及人类活动强度对湿地景观格局的影响。结果表明:(1)人类活动高强度带面积增加,低强度带面积减少;1995～2015年,各强度带的人类活动强度平均值均呈增长趋势,强度带等级越高,平均值增幅越大。(2)20年间,湿地面积不断增加,占比分别为5.14%、5.27%和5.30%;湖泊和沼泽地分别减少了70.73 km~2和216.53 km~2,而水库坑塘面积增加了1 155.32 km~2,对湿地增加的贡献率达94.75%,研究期主要是人工湿地在扩张,而自然湿地在萎缩;湿地景观的破碎度减弱,景观多样性减少。(3)伴随人类活动强度的增强湿地相对变化呈"收缩"效应,且在人类活动强度越高的区域,"收缩"效应越明显;随着人类活动强度降低,湿地景观破碎度减弱,聚集度下降,景观多样性增强,景观形状趋于复杂。研究结果可为长江中下游湿地保护和人类活动管控提供决策支持。     

Sediment quality in Rio Guadiamar (SW, Spain) after a tailing dam collapse: contamination, toxicity and bioavailability

An integrated assessment of sediment quality in the Guadiamar River after a mining spill was conducted. The concentration of different metals and other conventional parameters were measured in sediments located along the river. Four sediment toxicity tests (Hyalella azteca 28-day survival and growth test; Chironomus riparius 10-day survival and growth test; Hexagenia spp. 21-day survival and growth test; and Tubifex tubifex 28-day reproduction and survival test) were carried out to determine the effects associated with the accidental spill. The geochemical fractions of 6 metals (Fe, Mn, Zn, Cu, Pb, and Cd) were determined to establish the bioavailability of the metals. The relationship found in the concentrations of metals associated with the mobile fractions of the sediments in the sites studied is similar to the toxic mud from tailing pond and confirms that the toxic effects are associated with the metals Zn and Cd originating from the spill.     

城市湿地损失和内涝灾害响应的遥感分析——以武汉市南湖为例

随着快速的城市化,城市湿地不断转化成建设用地,这打破了城市水量循环的均衡,城市内涝灾害的敏感性和危害性随之提高。选取城市快速扩张的武汉市南湖地区,基于1988～2015年近30 a南湖湿地多时相遥感影像,以武汉市南湖2016年7月内涝灾害为对象,运用遥感和GIS手段,分析南湖湿地损失过程、驱动因素以及城市涝灾害的响应情况。结果表明：（1）1988~2015年间南湖湿地持续损失,累计消减1 563 hm2;南湖湿地损失经历了快速损失（1988~1996）急剧损失（1996~2004）缓慢损失（1996~2010）相对静止（2010~2015）的4个阶段,每个阶段南湖湿地转化为建设用地量分别为35.3、135、30、5.4 hm2;损失过程从南湖湿地北部开始,逐渐向南部蔓延;（2）环湖地区房地产发展是湖泊湿地损失的主要原因,52%的损失湿地转换为住宅用地;（3）85.7%的内涝灾害区域位于原湖泊湿地内;南湖地区海拔较低,随着住宅用地以及其他建设用地对湖泊湿地的侵占,南湖地区不透水面面积增加,湿地蓄水排水能力下降,在降雨量较多的时段,原湖泊湿地区域更容易受到内涝侵袭。 关键词： 城市湿地; 湿地损失; 内涝灾害; 武汉市南湖     

人工湿地系统去除藻毒素研究

以含水华的鱼塘水作为进水灌溉两套上行流－下行流人工湿地系统,系统内种植芦苇等水生植物。灌溉一周后收集人工湿地进出水水样,用ＨＰＬＣ法检测其藻毒素定量,结合温度、电位、溶氧等理化指标和细菌、藻类数量的变化,分析人工湿地系统对藻毒素的去除效果及影响其效果的可能因素。结果表明,人工湿地系统对藻毒素有一定的去除效果优于茭白－石菖蒲组合的湿地系统。在三种主要藻毒素ＲＲ、ＹＲ、ＬＲ中,湿地对ＹＲ的去除效果最好     

Time history of trace elements in sediments from Standley Lake,Colorado

Eighteen trace elements were analyzed in sections from a 50 cm long sediment core from Standley Lake, Colorado. The core was dated by the use of bomb-produced ¹³⁷Cs. Ten of the elements measured (Ag, Cd, Cu, Ga, Hg, Pb, Se, Sn, Tl, and Zn) appear to be enriched in this sediment; seven (Al, As, Be, Co, Cr, Ni, and V) are probably of local geological origin; and Te was not detected. Several of the constituents increase with depth in the sediment, and the concentrations of some compare to levels in lake sediments near highly industrialized centers. Based upon comparisons with other work, fluxes, enrichment factors, benzo(a)pyrene concentrations, and other evidence we conclude that the primary source of the “excess” elemental concentrations is local stream pollution.