Treatment of flow-through trout aquaculture effluents in a constructed wetland

A study on effluent treatment with sub-surface flow (SF) constructed wetlands was conducted in a small commercial scale Bavarian (Germany) flow-through trout farm. Under limited spatial and financial conditions a most suitable wetland was constructed. The wetland treatment efficiency at high hydraulic loading rates during raceway runoff and cleaning situation in comparison to sedimentation as initial treatment method was examined.

The constructional solution involved the alteration of six existing sedimentation basins (SB) to SF horizontal flow constructed wetlands with a pre-sedimentation area. As constructional materials only local, cheaply available materials were used in order to reduce the costs. The SF wetland had high treatment efficiencies in the two operational modes examined. During cleaning situation at a hydraulic loading rate (HLR) of 13.6 m/day treatment efficiency for total suspended solids (TSS) was highest and reached 68%. While during raceway runoff situation total ammonia nitrogen (TAN) treatment efficiency of 88% overtopped the efficiency of the other nutrients examined at a HLR of 10.6 m/day. In both treatment situations the SF wetland efficiency was significantly higher than the effect of the SB. SF constructed wetlands treating high hydraulic loading rates accompanied with short retention times were effective on dissolved nutrient treatment only for TAN and nitrite nitrogen (NO₂–N), while other dissolved nutrients like nitrate nitrogen (NO₃–N) and phosphate phosphorous (PO₄–P) showed no or even negative treatment effects through the wetland passage. To reduce these nutrients, other treatment conditions or wetland configurations are needed.     

Pushed to the edge: Environmental factors drive ecological responses of Aphanius fasciatus when in sympatry with invasive Gambusia holbrooki

1. Interspecific competition may be particularly exacerbated when occurring between native and invasive alien species, with environmental conditions affecting drivers of natural selection and shaping spatio-temporal dynamics of animal communities. The effects of invaders are particularly evident in aquatic ecosystems with delicate and complex balances, such as Mediterranean coastal wetlands, characterized by unpredictable water flows and variable reserves. Understanding how native species respond to human-induced biological invasions is of paramount importance for planning management measures aiming at conservation purposes.
2. This study investigated whether the occurrence of a competing invader species resulted in changes in the ecological adaptations of a native species by comparing two coastal wetland fish species: the invasive eastern mosquitofish Gambusia holbrooki and the native Mediterranean killifish Aphanius fasciatus of conservation concern. The hypothesis was tested by sampling fishes at a coastal Ramsar site in central Italy, over 2 years.
3. Generalized linear mixed models were used to examine the occurrence of killifish in relation to water parameters and the presence of its putative competitor. The aim was to determine whether salinity, temperature, and water depth influenced the presence and abundance of killifish when in sympatry with mosquitofish.
4. Both the probability of presence and abundance of killifish increased with water salinity, but this increase was stronger when mosquitofish was present. Increasing water temperature and water depth were associated with a higher probability of presence and abundance of killifish respectively, although the effect of water depth was small. Both salinity and the presence of the invader acted synergistically in characterizing and shaping the population structure of the native species.
5. Living in the most extreme and stressed environments, the killifish is potentially at higher risk of extinction. These results highlight the importance of considering the interplay between multiple abiotic stressors combined with comparative data between invasive and native species as increasingly critical to aid in conservation efforts.

     

Integrating freshwater wetland science into planning for Great Barrier Reef sustainability

1. The paper ‘Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion, northern Australia’, published in Aquatic Conservation: Marine and Freshwater Ecosystems in 2015, has contributed in several ways to the integration of freshwater wetland science within new catchment management policies and practices for Great Barrier Reef (GBR) sustainability.
2. The Tully–Murray biodiversity study developed novel protocols to sample larval, juvenile, and adult fish life‐history stages in floodplain lagoons using a combination of boat‐based backpack electrofishing and fyke netting. In addition, hydrological and hydrodynamic models were applied in a completely new way to quantify the timing, extent, and duration of water connectivity across floodplain streams, cane drains, and wetlands. Combining the two novel approaches enabled an analysis of lagoon fish assemblage patterns in relation to environmental gradients, especially floodplain hydrology, connectivity patterns, and measures related to agricultural land use.
3. In demonstrating the importance of different levels of connectivity for different biodiversity outcomes in freshwater floodplain lagoons of the Tully–Murray catchment, the subject paper established that floodplain connectivity needs to be taken into consideration in wetland management practices.
4. The timing of the subject publication was fortuitous. It coincided with the preparation of the evidence‐based 2017 Scientific Consensus Statement on land‐based water quality impacts on the GBR. As one of the few freshwater wetland ecology publications for the catchments of the GBR at that time, this paper played an important role in demonstrating freshwater wetland values, fish conservation options, and management imperatives to sustain wetland ecological health and services in GBR catchments.
5. By advancing the understanding of factors driving biodiversity patterns, and the importance of connectivity and ecohydrological processes in freshwater floodplain wetlands of the GBR catchment, the Tully–Murray study helped to drive new policy directives for the protection and restoration of catchment, floodplain, and estuary functions, and connectivity, now embedded in the Reef 2050 Long‐Term Sustainability Plan 2018, an overarching strategy for managing the GBR over the next 35 years, and complementary Queensland environmental legislation.

     

一类简化的竹编水泥沼气池力学模型分析

针对目前在滇南一带开发推广的竹编水泥沼气池，在实地测试和实验室测试研究的基础上，建立一类简化的三次超静定力学模型，并采用力法对赘余力进行严格的数学，力学分析与计算，构造与实际结构接近的理论模型，针对壁厚3,5cm的情形进行数值计算，计算与实测结果基本一致，说明所讨论的模型及力学算法分析是正确的，计算程度是可靠的。     

中国湿地文化分区研究

依据文化地理学及自然地理学理论,对中国湿地文化进行了系统的分区,将其分为七个区十九个亚区,并简单概述了不同区域的湿地文化特征。     

水力负荷对垂直流人工湿地堵塞的影响

[目的]为了缓解人工湿地的堵塞问题,探讨水力负荷对垂直流人工湿地堵塞的的影响。[方法]该试验通过人工土柱模拟垂直流人工湿地,设置4个水力负荷水平即50、100、150、200 cm/d,找出水力负荷对人工湿地堵塞的影响,并探索该因素运行过程的阈值。[结果]不同水力负荷水平在人工湿地堵塞过程中影响较大,在高水力负荷条件200 cm/d下,系统有效使用寿命只有半年时间,而且可以推测单因素水力负荷的阈值应该处于100~150 cm/d之间;低水力负荷系统的运行时间还可以持续6个月,中水力负荷系统的运行时间还可以持续3个月。[结论]对以后湿地堵塞试验提供分析依据。     

人工湿地处理生活污水的研究进展

近年来,随着工业化城镇化的快速发展,大量生活污水未经处理即排放到自然水体中,导致我国地表水水质显著下降,富营养化现象严重,生活污水的处理日益受到广泛重视。人工湿地被证明是处理生活污水的一种经济有效手段,已成为生活污水处理的重要工艺之一。通过较为系统地综述表面流、水平潜流和垂直流3种流程人工湿地在处理生活污水时常用的植物种类、基质类型、水力负荷及净化效果,总结了目前人工湿地在生活污水处理中存在的一些问题,并展望了其未来发展方向。     

罗氏沼虾池塘间歇运转人工湿地调控水质效果及其生长特征

兼用塘内微泡增氧机与净水网,以间歇运转人工湿地生态系统循环处理罗氏沼虾生产性养殖废水,研究间歇运转湿地调控虾塘水质效果与虾生长特征。由表面流与水平潜流组成的复合人工湿地生态系统(582.2 m2)水力负荷1.03 m/d,含斜坡区、挺水植物区与蓄水池。养殖周期内(117 d)无换水与用药,31 d后间歇运转湿地循环处理虾塘水,NO3--N与CODMn去除率分别为66.4%、39.6%(P≤0.01),TAN显著去除(45.0%,P≤0.05),NO2--N去除率为33.3%,维持极低浓度[(0.006±0.005)mg/L]。试验塘主要水化指标处于罗氏沼虾生长适宜与安全范围,蓝绿藻得以有效抑制。对照塘遭受蓝绿藻毒性作用,收获虾规格与产量(8.70 g,0.32 kg/m2)均低于试验塘(9.51~10.72 g,0.38~0.41 kg/m2)。试验建立了表征罗氏沼虾体重与体长、体重和体长分别与养殖时间的3组生长方程,可为制定罗氏沼虾养殖生产计划、调整生产措施以及预估产量提供科学依据。试验结果表明,在未用药与换水条件下,兼用塘内简易设施,间歇运转人工湿地可节省能源,有效调控虾塘水质,确保养殖成功。     

三种人工湿地填料的除磷效果研究

由沸石、碎石、火山石等3种填料和风车草构建了4个垂直流人工湿地处理单元,在设计水力停留时间2d ,间歇进出水的情况下,研究了不同处理单元对污水中磷的去除效果。结果表明：火山石单元对污水中总磷的去除效果最好,碎石单元次之,沸石单元效果最差,栽种有风车草的碎石单元对磷去除效果得到了提高。当进水中总磷的质量浓度分别小于2.5mg／L、3.5mg／L、4.0mg／L时,沸石、碎石、火山石单元的总磷去除率大于47.2％、73.2％、89.8％。当总磷的质量浓度升高至一定程度时,去除率开始显著下降。     

人工湿地对水体悬浮泥沙的影响

根据自然水体湿生植物(挺水植物)、浮叶植物以及沉水植物的空间分布规律,利用水生高等植物菖蒲(Acorus calamus)、菱(Trapa incisa)、黑藻(Hydrilla verticillata)、苦草(Vallisneria spiralis)和狐尾藻(Myriophyllum spicatum)构建的阶梯式人工湿地,定量化研究了植物群落对不同浓度悬浮泥沙水体在不同水力停留时间下的影响,并对输入悬浮泥沙浓度、输出悬浮泥沙浓度、水力停留时间等参数进行了比较分析。结果表明:(1)输入悬浮泥沙浓度依次为98.69,191.76,273.13 mg/L,平均为187.76 mg/L,流经人工湿地植物群落后,输出植物组的水体悬浮泥沙平均浓度为26.52 mg/L,为对照组平均浓度51.96 mg/L的51.04%;(2)输出人工湿地的悬浮泥沙浓度随输入悬浮物浓度的增加而增加,随水力停留时间的延长而降低,回归方程为Cplant out=1.231 0.170Cin-0.356H;(3)试验水体中滞留的悬浮泥沙浓度随输入悬浮物浓度的增加而增加,随水力停留时间的延长而减小,回归方程为Cplant water=1.158 0.261Cin-0.623H;(4)悬浮泥沙在人工湿地中的沉降量随输入悬浮物浓度的增加和水力停留时间的延长而增加,回归方程为Wplant=0.810Cin 0.886H-2.340;(5)要维持人工湿地沉水植物生长需要的透明度条件,输入悬浮泥沙浓度(Cin)与最小水力停留时间(Hmin)要满足如下关系:Hmin=0.419Cin-38.478(98.7相似文献