Modeling Parent and Metabolite Fate and Transport in Subsurface Drained Fields With Directly Connected Macropores1

Abstract: Few studies exist that evaluate or apply pesticide transport models based on measured parent and metabolite concentrations in fields with subsurface drainage. Furthermore, recent research suggests pesticide transport through exceedingly efficient direct connections, which occur when macropores are hydrologically connected to subsurface drains, but this connectivity has been simulated at only one field site in Allen County, Indiana. This research evaluates the Root Zone Water Quality Model (RZWQM) in simulating the transport of a parent compound and its metabolite at two subsurface drained field sites. Previous research used one of the field sites to test the original modification of the RZWQM to simulate directly connected macropores for bromide and the parent compound, but not for the metabolite. This research will evaluate RZWQM for parent/metabolite transformation and transport at this first field site, along with evaluating the model at an additional field site to evaluate whether the parameters for direct connectivity are transferable and whether model performance is consistent for the two field sites with unique soil, hydrologic, and environmental conditions. Isoxaflutole, the active ingredient in BALANCE^® herbicide, was applied to both fields. Isoxaflutole rapidly degrades into a metabolite (RPA 202248). This research used calibrated RZWQM models for each field based on observed subsurface drain flow and/or edge of field conservative tracer concentrations in subsurface flow. The calibrated models for both field sites required a portion (approximately 2% but this fraction may require calibration) of the available water and chemical in macropore flow to be routed directly into the subsurface drains to simulate peak concentrations in edge of field subsurface drain flow shortly after chemical applications. Confirming the results from the first field site, the existing modification for directly connected macropores continually failed to predict pesticide concentrations on the recession limbs of drainage hydrographs, suggesting that the current strategy only partially accounts for direct connectivity. Thirty‐year distributions of annual mass (drainage) loss of parent and metabolite in terms of percent of isoxaflutole applied suggested annual simulated percent losses of parent and metabolite (3.04 and 1.31%) no greater in drainage than losses in runoff on nondrained fields as reported in the literature.     

石臼漾人工湿地冬夏季全程氨氧化微生物的分布、群落结构及其影响因素研究

湿地作为水体与陆地之间的过渡地带,具有独特的生态环境特性,是氮循环反应的关键区域.研究湿地生态系统中的全程氨氧化过程（complete ammonia oxidation,comammox）,解析该区域中comammox细菌的分布与群落结构特征,补充了此前该新型氨氧化微生物在湿地生态系统中分布特征的研究空白,对于完善comammox细菌在各种不同生态系统中分布情况的研究具有重要意义.本研究在石臼漾人工湿地中于冬夏两季分别采集了大沟中心、大沟边缘、小沟中心和小沟边缘的表层沉积物样品,利用PCR、荧光定量PCR和amoA功能基因高通量测序等方法,解析人工湿地中comammox细菌的时空分布与群落结构特征.主要研究结果如下：①所有样品中均检测到了comammox细菌,其丰度为1.77×10⁵~4.07×10⁷ copies·g^-1.冬季,comammox细菌丰度在大沟中高于氨氧化细菌（ammonia oxidizing bacteria,AOB）和氨氧化古菌（ammonia oxidizing archaea,AOA）,在小沟中高于AOB,但低于AOA;夏季,comammox细菌丰度在所有样点中均高于AOB和AOA.②冬夏两季样品中,comammox细菌丰度与底物NH₄⁺-N浓度均呈负相关关系,且夏季样品中呈显著性负相关.③主坐标分析（Principle Coordinate Analysis,PCoA）与多样性分析结果表明,comammox细菌群落结构具有空间异质性,且冬季物种多样性高于夏季.     

Performance of different macrophytes in the decontamination of and electricity generation from swine wastewater via an integrated constructed wetland-microbial fuel cell process

Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH_4~+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH_4~+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m~3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.     

腾冲县北海湿地自然保护区生态旅游开发初探

充分利用自然保护区的旅游资源优势发展旅游业，但不合理的开发会使生态环境遭到破坏、生物多样性逐渐丧失、湿地水质面临污染等等。在分析腾冲北海湿地自然保护区发展生态旅游的基础上对旅游开发中存在的问题提出对策和建议。     

河南省黄河湿地生态旅游资源的开发与保护研究

河南黄河湿地旅游资源丰富,有各具特色的湿地景观、复杂多样的生物景观、丰富的地文景观、悠久的历史人文景观和工程园林景观等多种景观类型;但目前存在着开发利用程度较低,市场营销不够、景点开发质量不高,旅游设备简陋、基础设施落后,景点少、点热面冷,人才缺乏、经营管理水平低等众多问题;最后从旅游功能分区、旅游开发、旅游管理、旅游线路设计、旅游环境监测、区域旅游联合、加大宣传力度等方面提出了河南黄河湿地生态旅游资源开发的对策.     

人工湿地的发展概况和面临的问题

人工湿地是近年来发展的一种新型污水处理技术。主要介绍了人工湿地的几种主要构建类型:表面流型人工湿地、潜流型人工湿地、垂直流型人工湿地和复合垂直流人工湿地,并分别指出它们的优缺点。同时简要阐述了人工湿地去除污染物质的机理。     

水量衡算条件下人工湿地对有机物的去除研究

构建了芦苇和无植物2种人工湿地，在系统水量衡算的基础上比较了2种湿地对生活污水中有机物的去除效果。结果证明，在植物收割后的冬季，芦苇湿地对有机物的去除率低于无植物湿地系统约2％；在其他季节，芦苇湿地对污水CODcr的去除率比无植物湿地高出3.3％-5％。但对BOD5的去除率却比无植物湿地低了1.9％-2.7％。因此，芦苇湿地对有机物的去除效果比无植物湿地高，但提高不多。比较了2种系统的氧化还原电位，芦苇湿地比无植物湿地的高（P〈0.05），这种提高主要集中在湿地水面以下约10cm的深度；从整个湿地床体来看。2块连续运行的潜流水平湿地内部氧化还原状态大部分相同。主要是厌氧状态。比较了2种人工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。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〉0.99）。     

洞庭湖区湿地资源可持续利用途径研究

湿地具有特殊的生态功能和社会经济价值。洞庭湖区湿地垦殖强度大,造成了生态环境严重退化的恶果。研究表明:控制人口总量,退田还湖,建立湿地自然保护区,大力发展避洪耐涝型湿地特色产业是保护和合理利用湿地资源的有效途径,且已取得了良好的社会、经济、生态效益。由此认为,如何协调好人口、资源与环境的关系是实现湿地资源可持续利用的战略目标。     

Distribution characteristics of ammonia-oxidizing bacteria in the Typha latifolia constructed wetlands using fluorescent in situ hybridization(FISH)

A molecular biology method, fluorescent in situ hybridization（FISH）, in which the pre-treatment was improved in allusion to the media of the constructed wetlands（CW）, e.g. the soil and the grit, was used to investigate the vertical distribution characteristics of ammonia-oxidizing bacteria（AOB） quantity and the relation with oxidation-reduction potential（ORP） in the Typha latifolia constructed wetlands under three different Ioadings in summer from May to September. Results showed that the quantity of the AOB decreased in the Typha latifolia CW with the increase of vertical depth. However, the AOB quantity was 2-4 times the quantity of the control in the root area. Additionally, ORP in the rhizosphere was found to be higher than other areas, which showed that Typha latifolia CW was in an aerobic state in summer when using simulated non-point sewage at the rural area of Taihu Lake in China and small town combined sewage.     

中国红树林湿地资源及其保护

红树林是我国海岸湿地类型之一，自然分布于海南、广西、广东、福建、台湾等省区。现有面积约1．5万hm^2，包括26种真红树，11种半红树。中国红树林湿地直接经济价值不高，而防浪护岩、维持海岸生物多样性和渔业资源、净化水质、美化环境等生态环境功能显，属于特别容易被价值低估的海岩生态关键区。1960年代以来的毁林转海造田或盐田，毁林围塘养殖，毁林围海搞城市建设等人类不合理开发活动，使红树林面积剧减，环境恶化，红树林湿地资源濒危，急需加强管理和保护。现已建成各级红树林自然保护区18个，还需要吸收科学家积极参与，加强科学研究和宣传教育，以尽快扭转退化趋势，实现红树林湿地生态系统的恢复和可持续发展。