4种不同生活型湿地植物对富营养化水体的净化效果

选择4种湿地植物菖蒲、香蒲、浮萍和金鱼藻,研究单一及组合湿地植物对高浓度污水(污水处理厂进水)、低浓度污水(污水处理厂出水)中营养物质的去除效果.结果表明: 水体中总氮(TN)、总磷(TP)、化学需氧量(COD)浓度呈现试验前期快速下降,后期缓慢下降的趋势,表明湿地植物能有效净化污水中的TN、TP、COD,但不同湿地植物及湿地植物组合的净化效果存在差异.多种湿地植物组合比单种湿地植物对TN的净化作用强,其中香蒲＋浮萍＋金鱼藻对TN的净化效果最佳;高浓度污水中,单种挺水植物对TP的净化效果较好,低浓度污水中,则是多种湿地植物组合对TP的去除率较高;高浓度污水中,湿地植物对COD的去除率为85.1%～96.0%,其中菖蒲、香蒲去除效果最佳,低浓度污水中,湿地植物对COD去除率为76.9%～94.8%,以菖蒲＋浮萍＋金鱼藻去除效果最好.总体看来,湿地植物对高浓度污水中TN、TP、COD的净化效果好于低浓度污水,两种水体的pH都得到改善.     

四种冬季水生植物组合对富营养化水体的净化效果

选择10种耐低温的水生植物构建4种植物组合,研究了冬季低温环境下不同水生植物组合对富营养化水体的净化效果.结果表明:组合1[常绿水生鸢尾(Iris hexagonus Hybrid)*羊蹄(Rumex japonicus)+金叶“金钱蒲”(Acorus gramineus“Ogan”)+反曲灯心草“蓝箭”(Juncus inflexus“Blue Arrows”)]4种植物均能在试验富营养化水体中茂盛生长,且对TN、NOx-N、NH4-N和TP的去除率分别为47.8％、52.2％、32.4％和70.1％;组合2[常绿水生鸢尾+羊蹄+金叶“金钱蒲”+大苞萱草(Hemerocallis middendorfii)]4种植物也都能在试验富营养化水体中存活,并且有一定量的生长,对TN、NOx-N、NH4-N和TP的去除率分别为44.2％、58.5％、34.6％和67.8％;而未种植物的对照对TN、NOx-N、NH4-N和TP的去除率分别为40.0％、25.9％、27.3％和64.5％;组合1和2对富营养化水体有较好的净化效果.组合3和组合4中由于吊兰(Chlorophytum comosum)和三穗薹草(Carex tristachya)等植物长势较差,仅对NOx-N具有较明显去除能力,对其他指标去除效果不明显.通过这些水生植物在富营养化水体中生长特性和对营养元素的去除能力,发现冬季组合1和2的净化效果较好,是低温条件下适宜的浮床植物组合形式.     

4种水生植物对富营养化水体氮磷去除效果的研究

以灯心草、水田芥、菹草和轮藻为试验对象,研究了其在两种不同程度富营养化水体中的生长状况及对水体中总氮(TN)、总磷(TP)、氨氮(NH4+-N)和化学耗氧量(COD)的净化效果。结果表明,在轻度富营养化水体中水田芥效果最好,培养20 d后的水田芥对总氮、总磷、氨氮和化学耗氧量的吸收率分别为75.28%、93.00%、76.35%和83.74%,其它3种水生植物对水体也都有较好的净化效果;在重度富营养化水体中灯心草效果最好,培养20天后的灯心草对总氮、总磷、氨氮和化学耗氧量的吸收率分别为89.30%、83.11%、83.41%和78.56%,但水田芥和轮藻的净化效果相对较差。     

铁-碳内电解质下4种水生植物的净水效果

为比较湿地生态系统中常见水生植物的净水效果,在铁-碳内电解质下以凤眼莲、睡莲、菖蒲、芦苇4种水生植物为研究对象,比较分析植物及其组合在不同试验时间(1～5 d)对污水中铵氮、化学需氧量(COD)、总磷(TP)的净化效果.结果表明:与无植物的对照相比,铁-碳内电解质下单种水生植物对污水中的铵氮、COD、TP去除效果更好,但物种间存在明显差异.在污水处理2 d时,凤眼莲对铵氮的去除率达到100%;3 d时,铵氮在菖蒲水体中的浓度接近0;各类型植物组合对铵氮的去除效果均较好.在污水处理2 d时,凤眼莲的水体COD浓度接近0,菖蒲次之,凤眼莲-菖蒲组合水体的COD浓度降为最低(4.33 mg·L^-1),去除率为85.1%.在处理4 d时,凤眼莲的TP浓度最低,芦苇次之;处理2 d时,凤眼莲-菖蒲水体的TP浓度最低.内电解质与植物的组合效果比单纯内电解质对污水的净化效果好,植物的配置应依据污染物水平进行优化.     

人工沉床对富营养化河道净化效果及水体微生物群落的影响

对于透明度低、富营养化严重的河道,难以直接在河底种植沉水植物净化水质。通过构建穗花狐尾藻人工沉床系统,对上海临港一典型富营养化河道进行生态修复。结果表明：人工沉床可通过沉水植物吸收和改变微生物群落结构及多样性,达到脱氮除磷、提高水体透明度效果。沉床修复30 d后,水体透明度升高了152.2%,水体叶绿素a浓度降低了87.4%,总氮(TN)、总磷(TP)、氨氮(NH₃-N)和活性磷(PO₄^3--P)浓度平均去除率分别为61.0%、76.4%、91.8%和76.6%,与对照区差异显著(P<0.05)。修复后水体微生物多样性提高,改变了门、属水平群落结构以及水体氮处理细菌结构,提高了磷处理细菌丰度;冗余分析进一步表明,TP、NH₃-N、NO₃^--N和PO₄^3--P是导致沉床修复不同时期水体门水平群落结构差异的主要驱动因子,变形菌门、厚壁菌门和拟杆菌门与TP、NH₃-N、PO₄     

伊乐藻对富营养化水体的净化作用分析

利用室内静态模拟生长体系,研究了沉水植物伊乐藻在夏季高温季节5种不同氮磷营养条件水体中的生长状况及其对水体中氮、磷的净化效果。结果表明:低氮(1.0～5.5mg.L-1)、低磷(0.3～1.3mg.L-1)营养盐水体中的伊乐藻生长状态良好,但在高浓度氮(8.0mg.L-1)、磷(2.0mg.L-1)营养盐条件下,伊乐藻生长在后期受到部分抑制。伊乐藻对水体氮磷的去除效果随水体氮磷浓度的增加而增强,与起始水体氮磷含量相比,不同营养盐条件处理50d时,各处理伊乐藻对水体总氮的去除率分别达到55.88%、85.51%、88.18%、93.57%、95.97%,总磷的去除率分别达到47.55%、74.31%、57.75%、79.23%、74.92%。可见,伊乐藻在夏季高温季节对水体氮磷有一定去除效果,且对氮的去除效率高于磷,其对高氮、高磷环境有一定的耐受能力。     

云南高原湿地湖滨带植物不同空间配置对生活污水N、P去除的影响

采用野外调查和室内模拟实验相结合的方法,对云南高原湿地常见的7种湖滨带植物群落开展污水净化试验研究,为云南高原退化湿地恢复与污染湖泊治理中植物的选择与空间配置提供依据。结果表明,湖滨带植物群落对污水浓度的耐受和净化降解是有限度的,在适合植物生长的污水浓度范围(TN:8.39～22.95mg·L-1;TP:0.61～1.96mg·L-1;NH4+-N:6.42～19.80mg·L-1)内,植物群落才能对污水起到高效的净化效果,对TP和NH4+-N的去除率均能达到30%以上,对TN的去除率也能达到20%。在较高浓度范围内,由茭草(Zizana caduciflora)、蓖齿眼子菜(Potamogeton pectinatus)和金鱼藻(Ceratophyllumdemersum)几种喜氮、磷植物组成的群落对污水的净化效果更好。但不同植物群落对污水的净化效果存在着差异(P<0.05),含同一种植物但其他组成植物不同的群落净化效果不同,表明植物种间存在相互作用,不同种类、不同生活型间相互协作,发挥着最大功能作用。     

菖蒲和石菖蒲的生长特性及其对生活污水净化功能的比较研究

以菖蒲和石菖蒲为对象,通过漂浮栽植研究了其在不同浓度生活污水中的生长特性及其对污水TN、NH3-N、TP、CODCr的去除情况。结果表明,菖蒲在中浓度污水中生长最好,其生物量显著高于低、高浓度,而石菖蒲在低浓度污水中生长最好,其生物量显著高于中、高浓度。菖蒲对中浓度污水中TN、TP、CODCr的去除率分别为96.85%、82.62%、88.89%,对低浓度污水中TN、TP、CODCr的去除率分别为99.87%、91.38%、83.34%,净化效果均高于高浓度(96.58%、80.96%、77.55%),但对NH3-N的去除率在高浓度污水中最好,为99.46%。石菖蒲净化中浓度污水的效果最好,对TN、NH3-N、TP、CODCr的去除率分别为94.20%、78.06%、89.43%、74.98%,对高浓度污水中的NH3-N、TP、CODCr的去除效果也较好,去除率分别为94.62%、91.95%、87.08%,但对TN去除率为59.14%,显著低于低浓度(98.73%)和中浓度(94.20%)。     

潜水式生态介质箱对黑臭水体的修复效果

生态浮床作为一种常规治理技术得到了广泛使用,但其只能修复表层富氧水体,对下层缺氧水体的修复能力有限.本研究针对实际黑臭水体的修复需要,设计了潜水式生态介质箱(潜水组),并以传统的生态浮床(浮床组)为对照进行对比试验,研究修复前后黑臭水体的水质变化,考察了水生植物的生长状况及N、P积累能力.结果表明:随着修复时间的延长,两组处理对各污染物的去除率均逐渐升高,其中潜水组去除全氮(TN)、铵氮(NH4^+-N)、全磷(TP)的能力优于浮床组,但其去除化学需氧量(CODMn)的能力稍逊;潜水组植物(苦草)的生长状况优于浮床组植物(菖蒲),且苦草对水体中TN、TP的吸收积累能力和去除贡献率均优于菖蒲;此外,苦草的质膜透性、丙二醛和叶绿素含量均低于菖蒲,说明苦草更适于在黑臭水体中生长,该潜水式生态介质箱是新型的一体化原位修复装置,更适用于黑臭水体的修复实践.     

几种植物去除高度富营养化湖水中氮磷及抑藻效果初步研究

利用漂浮水生植物和陆生植物对去除超富营养化湖水的总氮总磷能力及抑藻效果进行研究(10月～11月),在45d的培养周期中,水龙、水禾、凤眼莲、竹叶菜对总氮的平均去除速率用平均生物量法计算分别是31.91、32.91、21.65、38.27mg.kg-1.d-1,去除率分别是80%,77%,87%,86%;对磷平均去除速率用平均生物量法计算,分别是6.45、2.58、4.01、3.97mg.kg-1.d-1,去除率分别是85%,51%,94%,77%;研究了这些植物的生长速率、抑藻效果、干物质含量,初步探讨了乡土物种在水质净化中的应用。     

Phytoremediation Potential of Selected Plants for Nitrate and Phosphorus from Ground Water

The phytoremediation potential of three aquatic plants namely, water lettuce(Pistia stratioes), water hyacinth (Eichhornia crassipes), and water spinach (Ipomoea aquatica) for nitrate N and phosphorus from nutrient treated ground water was assessed. A total of twelve treatment combinations including four levels of nitrate (expressed as nitrate N 0, 20, 40, and 60 mg/l) and three levels of phosphorus (0, 20, and 40 mg/l) were treated for the total volume of 1 and 20 liters of water respectively, for Pistia stratiotes and Eichhornia crassipes. For Ipomoea aquatica ten treatment combinations with five levels of nitrate N (0, 10, 20, 40, and 50 mg/l) and two levels of phosphorus (0 and 5 mg/l) were treated to 3 liters of water. The design used was a two factor factorial with three replicates. Water was analyzed at weekly interval for nitrate N and phosphorus. Pistia stratiotes, Eichhornia crassipes and Ipomoea aquatica had the potential to remove nitrate N between 61.5–91.8%, 40–63.5%, and 29.3–75% during the period of six, three and three and weeks, respectively. In addition, 90–99%, 75–97.2%, and 75–83.3% of phosphorus was removed from water by Pistia stratiotes, Eichhornia crassipes and Ipomoea aquatica respectively, during the same period.     

Effects of macrophytes on feeding and life-history traits of the invasive apple snail Pomacea canaliculata

1. Biological invasions have become a serious threat to ecosystems worldwide. Various factors can contribute to the success of biological invasion. We examined how different macrophyte food affected feeding and life‐history traits of the invasive herbivorous snail Pomacea canaliculata, and whether differences in snail life‐history traits could explain its successful infestation of agricultural and non‐agricultural wetlands in Asia. 2. We tested five cultivated and five wild semi‐aquatic macrophytes. Snail daily feeding rate varied substantially with plant species, ranging from 1.3% to 22% of its body mass. Snails fed with four (Amaranthus gangeticus, Apium graveolens dulce, Ipomoea aquatica and Nasturtium officinale) of the five cultivated macrophyte species exhibited high survivorship, fast growth and high fecundity. Snails fed with Colocasia esculenta, however, grew poorly, did not reproduce and eventually died. 3. Of the five wild species (Eichhornia crassipes, Ludwigia adscendens, Murdannia nudiflora, Myriophyllum aquaticum and Polygonum hydropiper), M. nudiflora supported a high snail survival, but snails had slower growth and lower fecundity than those reared on the four palatable cultivated species. Snails fed with L. adscendens grew substantially slower than those fed with M. nudiflora, and produced only a small clutch of eggs. Snails fed with E. crassipes, M. aquaticum and P. hydropiper had very low survivorship, grew very little and did not reproduce. 4. We determined six plant properties and their correlation with the feeding, growth and reproduction of the apple snails. Cultivated macrophytes in general had a higher nutritional value and lower physical and chemical defences. Phenolic content was negatively correlated with snail feeding rate, while plant nitrogen and phosphorus contents were positively correlated with snail egg production and growth, respectively. 5. These results indicate that, due to their higher nutritional value and lower chemical and physical defences, cultivated macrophytes are in general desirable for the apple snail which may partly explain its successful invasion into wet agricultural areas in Asia. This snail may also selectively graze poorly defended wild macrophytes in non‐agricultural wetlands, leading to changes in floral diversity and wetland functioning. Management of this and other apple snails with similar life‐history traits should thus focus on the prevention of their further spread.     

Effects of Eichhornia crassipes and Ceratophyllum demersum on Soil and Water Environments and Nutrient Removal in Wetland Microcosms

Wetland plants are important components that influence the biogeochemistry of wetland ecosystems. Therefore, remediation performance in wetlands can differ depending on the growth forms of plants. In this study, the effects of Eichhornia crassipes (floating plant) and Ceratophyllum demersum (submerged plant) on the wetland soil and water environments were investigated using a microcosm study with simulated hydrology of retention-type wetlands between rainfall events. The C. demersum microcosm (SP) showed the fastest recovery with a diel fluctuation pattern of dissolved oxygen, pH, and oxidation-reduction potential (ORP) from the impacts of nutrient inflow. Moreover, SP exhibited the lowest decrease in sediment ORP, the highest dehydrogenase activity, and more organic forms of nitrogen and phosphorus. E. crassipes microcosms exhibited the lowest water temperature, and efficiently controlled algae. In the presence of plants, the total nitrogen and phosphorus concentrations in water rapidly decreased, and the composition of organic and inorganic nutrient forms was altered along with a decrease in concentration. The results indicate that wetland plants help retain nutrients in the system, but the effects varied based on the wetland plant growth forms.     

Assessing the true status of the fish species Labeo cylindricus (Peters 1868) (Teleostei: Cyprinidae) in Lake Baringo,Kenya

Eutrophication contributes to the proliferation of alien invasive weed species such as water hyacinth Eichhornia crassipes. Although the South American moth Niphograpta albiguttalis was released in South Africa in 1990 as a biological control agent against water hyacinth, no post-release evaluations have yet been conducted here. The impact of N. albiguttalis on water hyacinth growth was quantified under low-, medium- and high-nutrient concentrations in a greenhouse experiment. Niphograpta albiguttalis was damaging to water hyacinth in all three nutrient treatments, but significant damage in most plant parameters was found only under high-nutrient treatments. However, E. crassipes plants grown in high-nutrient water were healthier, and presumably had higher fitness, than plants not exposed to herbivory at lower-nutrient levels. Niphograpta albiguttalis is likely to be most damaging to water hyacinth in eutrophic water systems, but the damage will not result in acceptable levels of control because of the plant's high productivity under these conditions. Niphograpta albiguttalis is a suitable agent for controlling water hyacinth infestations in eutrophic water systems, but should be used in combination with other biological control agents and included in an integrated management plan also involving herbicidal control and water quality management.     

Host specificity assessment and potential impact of Megamelus scutellaris (Hemiptera: Delphacidae) on waterhyacinth Eichhornia crassipes (Pontederiales: Pontederiaceae)

The delphacid Megamelus scutellaris Berg was evaluated for host specificity and potential impact as part of a biological control program targeting Eichhornia. crassipes. Survival and development of adults and nymphs were used as metrics with no-choice, two-choice, nymph transfer, and sustainability tests conducted under quarantine conditions. A total of 69 plant species were tested including 12 from the Pontederiaceae (including E. crassipes). Additionally, 27 native and 5 exotic associated wetland species and 11 economic species were tested. Megamelus scutellaris exhibited a high level of oviposition and developmental fidelity to E. crassipes by failing to sustain populations on any non-target test plant past the F₁ generation. Nymph transfer tests which simulated potential spill-over events found that survival was virtually non-existent on associated wetland plants, regardless of taxonomic relatedness, including on Pontederia cordata, an important and widespread native species. Eichhornia crassipes plants exposed to two consecutive generations of feeding produced 66.9% less biomass and 73.4% fewer leaves than those in the controls. We conclude that Megamelus scutellaris is safe to release on E. crassipes in the United States.     

Azotobacter chroococcum in the phyllosphere of water hyacinth (Eichhornia crassipes Mort. Solms)

Summary Water hyacinth (Eichhornia crassipes) harbours Azotobacter chroococcum in large numbers on and in its leaves. This may account for its prolific growth of the plants in water containing only traces of combined nitrogen. re]19721201     

凤眼莲入侵程度对金鱼藻和黑藻生长及种间关系的影响

湿地生态系统中凤眼莲（Eichhornia crassipes）入侵造成湿地植物群落结构退化及功能崩溃,直接影响沉水植物的生长繁殖及初级生产力。目前关于凤眼莲的入侵机制有一定的研究,而关于凤眼莲入侵程度对沉水植物金鱼藻（Ceratophyllum demersum）和黑藻（Hydrilla verticillate）生长及种间关系的影响相对缺乏。以外来入侵植物凤眼莲,沉水植物金鱼藻和黑藻为研究对象,设计凤眼莲入侵程度（无入侵,轻度入侵对应盖度25%,重度入侵对应盖度75%）交叉定植方式（黑藻单种模式、金鱼藻单种模式,金鱼藻和黑藻混种模式）的控制实验,探究凤眼莲入侵强度对沉水植物金鱼藻和黑藻生长及种间关系的影响。结果表明,凤眼莲入侵程度显著降低了金鱼藻的生物量、分枝数;黑藻的株高、分枝数和分节数。无凤眼莲入侵时,两种沉水植物生物量均最大,两者种间竞争关系较强;随凤眼莲入侵盖度增加,两种沉水植物的生物量先急剧降低后略微增加,种间关系经过微弱促进后又变为竞争作用,其中黑藻表现出明显的竞争优势。此外,凤眼莲入侵略微降低了水体中的总氮、总磷含量。结构方程模型分析结果表明凤眼莲入侵以及水体总氮、总磷等水体理化性质对沉水植物生长均有显著负向影响（P<0.05）,且水体理化性质对沉水植物生长的影响强于凤眼莲入侵。总之,凤眼莲入侵显著降低了金鱼藻和黑藻生长繁殖,随着凤眼莲入侵程度增加,两种沉水植物种间关系由竞争转变为促进再转变为竞争。研究结果为凤眼莲入侵有效控制及湿地沉水植被的恢复与重建提供了一定的理论依据和技术支撑。     

The role of eutrophication in the biological control of water hyacinth, <Emphasis Type="Italic">Eichhornia crassipes</Emphasis>, in South Africa

South Africa has some of the most eutrophic aquatic systems in the world, as a result of the adoption of an unnecessarily high 1 mg l⁻¹ phosphorus (P) standard for all water treatment works in the 1970 s. The floating aquatic macrophyte, water hyacinth (Eichhornia crassipes (Mart.) Solms (Pontederiaceae)), has taken advantage of these nutrient rich systems, becoming highly invasive and damaging. Despite the implementation of a biological control programme in South Africa, water hyacinth remains the worst aquatic weed. A meta-analysis of published and unpublished laboratory studies that investigated the combined effect of P and nitrogen (N) water nutrient concentration and control agent herbivory showed that water nutrient status was more important than herbivory in water hyacinth growth. Analysis of long-term field data collected monthly from 14 sites around South Africa between 2004 and 2005 supported these findings. Therefore the first step in any water hyacinth control programme should be to reduce the nutrient status of the water body.     

Sulfate-Reducing Bacteria in Floating Macrophyte Rhizospheres from an Amazonian Floodplain Lake in Bolivia and Their Association with Hg Methylation

Five subgroups of sulfate-reducing bacteria (SRB) were detected by PCR in three macrophyte rhizospheres (Polygonum densiflorum, Hymenachne donacifolia, and Ludwigia helminthorriza) and three subgroups in Eichhornia crassipes from La Granja, a floodplain lake from the upper Madeira basin. The SRB community varied according to the macrophyte species but with different degrees of association with their roots. The rhizosphere of the C₄ plant Polygonum densiflorum had higher frequencies of SRB subgroups as well as higher mercury methylation potentials (27.5 to 36.1%) and carbon (16.06 ± 5.40%), nitrogen (2.03 ± 0.64%), Hg (94.50 ± 6.86 ng Hg g⁻¹), and methylmercury (8.25 ± 1.45 ng Hg g⁻¹) contents than the rhizosphere of the C₃ plant Eichhornia crassipes. Mercury methylation in Polygonum densiflorum and Eichhornia crassipes was reduced when SRB metabolism was inhibited by sodium molybdate.     

Optimization of arsenic phytoremediation using Eichhornia crassipes

This study aimed to evaluate the pH, phosphate, and nitrate in the process of arsenic absorption by Eichhornia crassipes (water hyacinth), using the surface response methodology, in order to optimize the process. The plants were exposed to a concentration of arsenic of 0.5 mg L^?1 (NaAsO₂) over a period of 10 days. The results indicated optimal levels for the absorption of arsenic by E. crassipes at pH equal to 7.5, absence of phosphate, and minimum nitrate level of 0.0887 mmol L^?1. For the tested concentration, E. crassipes was able to accumulate 498.4 mg kg^?1 of As (dry base) in its plant tissue and to reduce 83% of the initial concentration present in the aqueous medium where it was cultivated. The concentration of phosphorus in solution linearly increased the phosphorus content in the plants and negatively influenced the absorption of arsenic. The concentration of 0.5 mg L^?1 of As did not significantly affect the relative growth rate (RGR) and the tolerance index (TI). 94% of As (III) initially solubilized in water was converted by the end of the experiment period into As (V). The water hyacinth was important in the phytoremediation of arsenic when cultivated under optimal conditions for its removal.