寒冷地区多级垂直流人工湿地系统设计及氮磷去除效率

为了解决北方寒冷地区人工湿地冬季效率低、运行不稳定的问题,设计建设了两个多级垂直流人工湿地系统(multistage vertical-flow constructed wetlands,MVCWs),处理北京房山区居民生活污水,通过工程设计以及添加碳源强化系统脱氮效果,增加磷吸附基质等措施,提高系统稳定性和污染物的去除效率。研究结果表明,湿地系统Ⅰ化学需氧量(chemical oxygen demand,COD)的平均去除率为87.3%;总磷(total phosphorus,TP)的平均去除率为91.9%;总氮(total nitrogen,TN)的平均去除率为68.9%,能够全年稳定运行。湿地系统Ⅱ采取半间歇式运行方式,在0.5 m3/(m2·d)的水力负荷条件下,对COD、TN、TP的平均去除率分别为92.5%、53.8%、77.2%。湿地系统Ⅱ厌氧单元添加62 kg木块后,COD/TN从0.93上升到1.85,比添加31 kg木块单元对TN的去除率提高15.6%。木块作为厌氧阶段的外加碳源,有效促进了垂直流人工湿地系统对氮的去除。通过垂直流人工湿地多级合理的单元设计,在厌氧阶段添加碳源有利于反硝化脱氮以及添加吸附磷的基质,提高冬季没有植物参与时高效除氮、磷,有效地保证对各种污染物的去除效率。使该研究中的人工湿地系统能够全年稳定运行,该研究结果可为人工湿地在中国北方的推广应用提供参考。     

综述中国水环境中抗生素的行为和归趋与采用人工湿地处理

Overuse of antibiotics has become a serious ecological problem worldwide.There is growing concern that antibiotics are losing their effectiveness due to an increased antibiotic resistance in bacteria.During the last twenty years,consumption of antibiotics has increased rapidly in China,which has been cited as one of the world's worst abusers of antibiotics.This review summarizes the current state of antibiotic contamination in China's three major rivers (the Yangtze River,Yellow River,and Pearl River) and illustrates the occurrence and fate of antibiotics in conventional municipal wastewater treatment plants (WWTPs).The analytical data indicate that traditional WWTPs cannot completely remove these concerned pharmaceuticals,as seen in the large difference between the distribution coefficient (Kd) and the uneven removal efficiency of various types of antibiotics.Although constructed wetlands (CWs) offer a potential way to remove these antibiotics from water supplies,knowledge of their mechanisms is limited.There are four main factors affecting the performance of CWs used for the treatment of antibiotics in water supplies,the types and configurations of CWs,hydraulic load rates,substrates,and plants and microorganisms.Further researches focusing on these factors are needed to improve the removal efficiency of antibiotics in CWs.     

农业生态与土壤中化学元素关系的研究

研究农业生态与土壤环境中化学元素的关系结果表明，农业生态与土壤的N、P、K、Na、Ca、Mg、S、Fe、Mn、Cu、Zn、B、Mo、V、Co、Ni、Cr、Pb、Cd、Hg、Se、F、Tl、Ba、Te、Ta、Sr、Ti、Si及稀土元素密切有关。     

Comparison of litter decomposition in a natural versus coal‐slurry pond reclaimed as a wetland

Decomposition is a key function in reclaimed wetlands, and changes in its rate have ramifications for organic‐matter accumulation, nutrient cycling, and production. The purpose of this study was to compare leaf litter decomposition rates in coal‐slurry ponds vs. natural wetlands on natural floodplain wetlands in Illinois, USA. The rate of decomposition was slower in the natural wetland vs. the coal pond (k = 0·0043 ± 0·0008 vs. 0·0066 ± 0·0011, respectively); the soil of the natural wetland was more acidic than the coal pond in this study (pH = 5·3 vs. 7·9, respectively). Similarly, higher organic matter levels were related to lower pH levels, and organic matter levels were seven‐times higher in the natural wetland than in the coal pond. The coal slurry pond was five years old at the time of the study, while the natural oxbow wetland was older (more than 550 years). The coal‐slurry pond was originally a floodplain wetland (slough); the downstream end was blocked with a stoplog structure and the oxbow filled with slurry. The pattern of decomposition for all species in the coal pond was the same as in the natural pond; Potomogeton nodosus decomposed more quickly than Phragmites australis, and both of these species decomposed more quickly than either Typha latifolia or Cyperus erythrorhizos (k = 0·0121±0·0008, 0·0051 ± 0·0006, 0·0024 ± 0·0001, 0·0024 ± 0·0004, respectively). Depending on how open or closed the system is to outside inputs, decomposition rate regulates other functions such as production, nutrient cycling, organic‐layer accumulation in the soil, and the timing and nature of delivery of detritus to the food chain. Copyright © 2004 John Wiley & Sons, Ltd.     

三江平原环型湿地土壤溶解性有机碳的时空变化特征

土壤溶解性有机碳(DOC)是指溶解于土壤水、且能通过0.45 μm微孔滤膜的有机态碳,是土壤有机碳中最活跃的组成部分[1-2].一般认为,土壤DOC的产生源自有机物的不完全降解,因此冷湿或贫营养环境、土壤有机质和C/N摩尔比高的区域有利于DOC的产生[3].自然湿地,尤其是位于中纬度地区的湿地,储存了大量的碳,是重要的DOC库和河流DOC的主要来源[4-5].     

Performance of Phragmites Australis and Cyperus Papyrus in the treatment of municipal wastewater by vertical flow subsurface constructed wetlands

The use of constructed wetlands to treat municipal wastewater reduces energy consumption and therefore economic costs, as well as reduces environmental pollution. The purpose of this study was to compare the purification capacity of domestic wastewater using two species of plants sown in subsurface constructed wetlands with vertical flow built on a small scale that received municipal wastewater with primary treatment. The species used were Phragmites Australis and Cyperus Papyrus. For this purpose, a constant flow of 0.6 m³ day⁻¹ was fed from the primary lagoon to each of the two wetlands built on a pilot scale with continuous flow. Each unit was filled with granite gravel in the lower part and with silicic sand in the upper part of different granulometry, the porosity of the medium was 0.34, with a retention time of 1.12 days and a hydraulic load rate of 0.2 m day⁻¹. To analyze the purification capacity of wastewater, physical, chemical and biological parameters were monitored during three months. Samples were taken at the entrance and exit in each experimental unit. The results obtained in the experimental tests for the two species of plants, indicated that the Cyperus Papyrus presented a greater capacity of pollutants removal as biochemical oxygen demand (80.69%), chemical oxygen demand (69.87%), ammoniacal nitrogen (69.69%), total phosphorus (50%), total coliforms (98.08%) and fecal coliforms (95.61%). In the case of Phragmites Australis retains more solids. The species with greater efficiency in the treatment of municipal wastewater for this study was Cyperus Papyrus.     

莱州湾南岸滨海湿地的氮、磷循环过程及调控对策

在莱州湾南岸滨海湿地的生物地球化学循环过程中,N、P元素主要来源于通过河流输入的工业废水、城市生活污水、农田地表径流、灌溉余水和海水养殖池养殖废水,通过潮上带、潮间带湿地最终被输送到潮下带近海湿地,引起潮下带近海湿地水体N、P含量的不断升高,2000年通过河流输入到莱州湾南岸的N总量为46271.1t,P总量为2092.1t.潮上带、潮间带自然湿地的底质、土壤和植物对N、P元素有显著的吸收、净化作用.以2000年为例,若不考虑自然湿地的吸收、净化作用,仅靠水体交换、扩散稀释,输送到潮下带近海湿地的N、P在海水中的含量为6.74mg·L-1、0.299mg·L-1,而当年潮下带近海湿地水体N、P含量实测值分别为0.086mg·L-1、0.029mg·L-1,计算值分别是实测值的78.4倍、10.3倍;说明自然湿地对输入的N、P有明显的吸收净化效应.为降低莱州湾南岸潮下带近海湿地海水中的N、P含量,提出了发展循环经济,减小莱州湾南岸滨海湿地的N、P输入通量,对自然湿地进行有效的保护和生态恢复,建设人工湿地、提高湿地的环境净化功能等调控措施.     

Burning,biomass removal and tillage effects on soil organic carbon and nutrients in seasonal wetlands (Dambos) of Chiota smallholder farming area,Zimbabwe

Seasonal wetland (dambo) cultivation in smallholder farming areas is important because it improves household food security. However, most farming practices, such as burning of vegetation and conventional tillage in dambo gardens, may reduce soil organic carbon (SOC) and nutrient dynamics. We evaluated the effects of simulated burning, vegetation clearing and clipping, and conventional tillage in dambo gardens on SOC, nutrient contents and biomass production over a 3-year period. The results showed that clearing and clipping of vegetation and conventional tillage reduced SOC, soil nutrient contents and biomass yields, while burning increased SOC and soil nutrient contents. For the 0–10 cm depth, conventional tillage, clearing and clipping resulted in a 37%, 34% and 18% decrease in SOC, respectively, after three seasons, burning resulted in a 25% increase in SOC, while there were no changes in the control after 3 years. For the 0–40 cm depth, the average change in SOC was 32%, 25% and 16% for conventional tillage, clearing and clipping, respectively. Locally and regionally, conventional tillage, clearing and clipping reduce SOC, nutrient contents and biomass production in dambos. Though annual burning increased SOC and nutrient contents in the short term, the long-term effects are uncertain, hence there is a need for long-term studies.     

Fungal biomass changes during the decomposition of leaves of Michelia nilagirica and Semecarpus coriaceae in an upper montane rainforest in Sri Lanka

The agar-film method was used to assess fungal biomass and standing crop in several analogous decomposition stages of two leaf species (the fast decomposing Michelia nilagirica and the slow decomposing Semecarpus coriaceae), both from an upper montane rainforest in Sri Lanka. At all decomposition stages the fungal biomass on Michelia litter was significantly higher (P<0.001) than for Semecarpus and had developed much more rapidly (17.04 mg g⁻¹ at the first decomposition stage compared with 4.39 mg g⁻¹ for Semecarpus). These figures are considerably higher than those for a cool temperate deciduous forest, but when the data are given as fungal biomass per area the reverse is true. Data are given on the contribution of different hyphal types showing a trend for change (hyaline to dark hyphae) during the course of decomposition. The mass of dead hyphae is considerably lower than data from temperate forests. Data on immobilization of C and of plant nutrients (N, P, K, Ca, Mg and Na) are provided plus hyphal nutrient contents expressed as % of total contents in the leaf litter. These data are comparable to those from temperate forests.     

Occurrence of dark septate endophytes in Phragmites australis in the Baiyang Lake and their resistance to Cd stress

Heavy metal pollution poses a serious hazard to human health, and microbial remediation of heavy metals in soil has been widely studied. A group of ascomycetes classified as dark septate endophytes (DSEs) colonize plant roots and benefit host plants under abiotic stress conditions. In this study, Phragmites australis, a common remediation plant in the Baiyang Lake in North China, was investigated. Soils and roots of P. australis were collected in typical heavy metal-contaminated sites, and the species diversity and community structure of DSEs in P. australis roots were studied. In addition, DSE strains were isolated, cultured, and tested for their tolerance to Cd stress. The results showed that DSEs occurred extensively in P. australis roots, forming typical dark septate hyphae, with a total colonization rate of 19.7%-83.1%. Morphological and internal transcribed spacer sequencing analyses were used to identify 10 species within 9 genera of DSE fungi. Among these fungi, 6 strains with considerable resistance to Cd stress were identified. The biomasses of Poaceascoma helicoides, Alternaria doliconidium, and Acrocalymma vagum strains increased as the Cd levels increased. These results can not only help to understand plant-DSE interactions in wetland environments, but also provide a theoretical basis for making full use of DSE fungi to alleviate heavy metal contamination in soil.