Diversity and seasonal variations of mycorrhiza and rhizosphere bacteria in three common plant species at the Slovenian Ljubljana Marsh

Interactions between plants and microorganisms can significantly affect plant health and productivity as well as ecosystem functioning. Detailed knowledge of the tripartite relationships between plants, fungi, and bacteria, and their environment is still limited. In the present study, the soils adjacent to three plant species (Cruciata laevipes, Mentha piperita, Equisetum arvense) in the Ljubljana Marsh and the bulk, plant-free soil were analyzed for their bacterial community structure in June and October 2006. The terminal restriction fragment length polymorphism analysis indicated a different bacterial community structure in the rhizosphere and in bulk soil, however, with almost no seasonal changes between late spring and autumn samples and no apparent impact of the three plant species. In addition, root colonization of the three plant species by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) was microscopically assessed monthly from May until October 2006. A presumably accidental correlation between monthly precipitation and the degree of arbuscule formation, with the latter lagging 1 month, was noted for M. piperita, the most heavily colonized of the three plant species. With all three plants, the phosphorus content in roots correlated positively with most AMF structures. Microsclerotia of DSE were mainly abundant in autumn samples. Fungal diversity in roots was estimated using temporal temperature gradient gel electrophoresis separation of the fungal polymerase chain reaction products obtained for both 18S-rDNA and the 5.8S-ITS2-28S rDNA segments. No specific effects of either plant species or seasonal changes on mycorrhizal community structure were discernible.     

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.     

复合池塘循环水养殖系统生态足迹分析

生态足迹模型已广泛应用于可持续发展的评估中。将生物塘、人工湿地、生态沟渠等生态工程系统与传统养殖塘有机结合而构建形成的复合池塘循环水养殖系统,作为一种新养殖模式,它具有循环微流水养殖、种养结合、水陆交互作用的特点。本文运用生态足迹方法对这一新养殖模式进行了定量分析。结果表明:就单位利润生态足迹量而言,复合池塘循环水养殖模式为2.92 ghm2/万元,而传统池塘养殖模式为4.91ghm2/万元,复合模式具有更高的生态经济综合效益,更符合可持续发展要求。     

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。     

美人蕉（Canna indica Linn.）和芦苇（Phragmites australis L.）人工湿地对含铬生活污水的净化效果及植物的生理生态变化

选取美人蕉（CannaindicaLinn.）、芦苇（PhragmitesaustralisL.）为植物材料,以不同浓度K2Cr2O（7分别含0、1、20、50mg.L-1Cr6＋）的生活污水作为Cr6＋污染源,研究了不同浓度Cr6＋及处理时间下两种湿地对污水净化效果、植物体Cr6＋积累量及根系活力（TTC）、叶片超氧化歧化酶（SOD）活性、过氧化物酶（POD）活性、净光合速率（Pn）和丙二醛（MDA）等生理指标的影响。结果表明：（1）在试验的初期30d内,随处理时间的延长,两种人工湿地COD、氨氮去除率均呈逐渐上升的趋势,30d后,随着Cr6＋处理时间的延长及Cr6＋浓度的逐渐升高,两种湿地系统对COD、氨氮去除率均逐渐下降。在20、50mg.L-1Cr6＋处理条件下,两种湿地对COD、氨氮的净化效果显著低于对照及1mg.L-1Cr6＋处理,对照与1mg.L-1Cr6＋处理条件下差异不显著。（2）在不同Cr6＋浓度处理下,两种人工湿地对TP净化效果的能力较为稳定,同时随处理时间的延长,美人蕉、芦苇体内Cr6＋积累量逐渐加大。（3）1mg.L-1Cr6＋处理可提高美人蕉和芦苇的TTC、叶片的SOD、POD、Pn,而20、50mg.L-1Cr6＋处理对以上指标均有不同程度的抑制作用,且抑制效果与处理浓度、时间呈正相关。（4）MDA含量随处理时间的延长和浓度升高呈逐渐增加趋势。可见,低浓度Cr6＋能有效促进美人蕉、芦苇生长,使之能够维持正常的净化功能,因此,利用它们作为人工湿地植物来修复Cr6＋污染具有一定的实用价值。     

微孔曝气对潜流人工湿地处理稀土氨氮废水效果的影响

以包头某稀土厂稀土生产废水为处理对象,研究了微孔曝气对所构建的潜流人工湿地处理稀土氨氮废水的效果。研究发现,在所构建的潜流人工湿地系统中,微孔曝气有利于稀土废水中氨氮的去除,对潜流人工湿地运行的稳定性和可靠性均有增强。在曝气量为50和100 L/h时,所构建的潜流人工湿地能在40 d内实现稳定运行,稀土氨氮废水中的氨氮去除率由95.4%提高到98.2%以上,出水氨氮浓度稳定在5~24 mg/L,低于《稀土工业污染物排放标准(GB26451-2011)》所规定的氨氮直接排放浓度25 mg/L的要求。考虑到潜流人工湿地的运行成本,理想的曝气量应选为50 L/h。     

沙田人工湿地植物生长特性及除污能力的研究

采用人工模拟小试系统,研究了沙田人工湿地9种植物的长势、生物量变化及对污染物的去除能力,分析了各种植物的生长特性、环境适应性和在系统中的作用。结果表明,在深圳的气候条件下,植物生长期可贯穿全年,但长势受季节等环境因素的影响仍非常明显。植物茎叶的生物量受收割季节和周期的影响较大,根系的生物量及根区范围随植物收割呈周期性变化。在热带砾石床中,红花美人蕉(Cannaindica)、水葱(S.tabernaemotaniGmel)难以适应环境,芦苇(Ph.australisTrin)、再力花(Thaliadealbata)、荻(M.sacchariflorus)一直生长旺盛,但荻的除污能力较差;纸莎草(Cyperuspapyrus)和美人蕉长速较快,较适合于需快速启动的湿地系统。     

间歇曝气对生物填料人工湿地氮磷去除性能的影响

采用部分生物填料替换页岩构建生物填料人工湿地处理津河富营养化水体,并在填料内部设置曝气装置研究间歇曝气对湿地氮磷去除效果的影响.设计水力负荷800 mm·d-1,气水比15∶1.结果表明,当氨氮(NH4-N)、总氮(TN)、溶解性反应磷(SRP)和总磷(TP)平均进水浓度为4.61、5.68、0.338和0.464 mg·-1时,无曝气条件下NH4-N、TN、SRP、TP平均去除率分别为65.9%、65.3%、62.2%和56.9%.中部曝气使NH4-N、TN、SRP和TP平均去除率分别提高15.9%、8%、13.7%和8.9%,底部曝气则为24.4%、12.9%、16.1%和12%,间歇曝气能够有效提高生物填料人工湿地NH4-N、TN、SRP和TP去除效率.但是曝气产生的有氧环境不利于硝酸盐氮(NO3-N)去除,试验期间底部曝气和中部曝气NO3-N出水浓度均高于无曝气系统.     

4种湿地植物的生理性状对人工湿地床设计的影响

野外调查分析了4种常见湿地植物的最长根长,根系体积,植物密度,植株的氮、磷和锌含量等对人工湿地去除污染物、人工湿地设计和人工湿地使用寿命的影响.结果表明,最长根长以美人蕉为最长(43.73 cm),芦苇其次(32.50 cm),黄花鸢尾最短(12.57 cm);根系体积以美人蕉最大(66.72 cm3),芦苇其次(17.42 cm3),黄花鸢尾最低(4.70 cm3);密度以芦苇最高(257株·m-2),美人蕉其次(61株·m-2),茭白最低(54株·m-2);单位面积上芦苇、美人蕉、茭白和黄花鸢尾地上部分生物量分别是4.27、2.12、0.94和O.78 kg·m-2.相应地,单位面积上植物地上部分对氮、磷和锌的吸收量以芦苇最高,美人蕉其次.黄花鸢尾最低.不同植物对人工湿地的使用寿命没有显著影响,但植物的最长根长和密度可作为人工湿地基质深度设计和植物数量配置的依据.     

人工湿地基质微生物和酶活性的空间分布

测定了人工湿地基质微生物和酶活性,结果表明,人工湿地基质好氧微生物数量下行池大于上行池;基质上层好氧微生物数量显著大于中下层基质;人工湿地基质中酶活性下行池大于上行池;基质上层磷酸酶、脲酶和蛋白酶的活性显著大于中下层基质;不同时间的基质酶活性不同.基质上层区域是人工湿地污水处理系统最有效的净化空间.由于人工湿地下行池基质中好氧微生物数量和酶活性大于上行池,在人工湿地净化污水的过程中,下行池的作用占主导地位.