Improved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands. The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland. Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro-algae were collected in July and November 1999 in two basins of the wetland system. One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees. Potential nitrification was measured using the isotope-dilution technique, and potential denitrification was determined using the acetylene-inhibition technique in laboratory microcosm incubations. Nitrification rates were highest on the twigs. These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively. Potential denitrification rates were highest in the sediment. These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil. The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column. Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs.

Potential nitrification and denitrification on different surfaces in a constructed treatment wetland (vol 32, pg 2414, 2003)

Successful control of internal phosphorus loading after sediment dredging for 6 years: A field assessment using high-resolution sampling techniques

The effects of dredging on nitrogen balance in sediment-water microcosms and implications to dredging projects

Exchanges of nitrogen and phosphorus across the sediment-water interface influenced by the external suspended particulate matter and the residual matter after dredging.

Fifteen-year study of environmental dredging effect on variation of nitrogen and phosphorus exchange across the sediment-water interface of an urban lake ☆

A laboratory experiment was carried out to study the effects of sediment dredging on phosphorus(P)release from lake sediments using incubation of undredged(control)and dredged cores through a year.We found that dredging the upper 30cm layer of the sediment can efficiently reduce the interstitial pO_4(3-)-P concentration and different P forms in the sediment.The P fluxes of the undredged and dredged cores ranged from-237.3 to 3047.6μg/(m~2·d)and-143.8 to 14.4μg/(m~2·d),respectively.The fluxes of the dredged cores were generally lower than those of the undredged(control)cores,with significant(P0.05)differences between the fluxes of the dredged and undredged cores occurring between March and October of 2006.The sediment P in the dredged cores had a lower release potential than those in the control cores.Our results suggested that dredging may be a useful approach for decreasing internal P loading in Lake Taihu once the external P loading is effectively controlled in advance.

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湖泊底泥疏浚环境效应：i．内源磷释放控制作用

通过为期一年的疏浚模拟试验，在试验室培养疏浚与对照柱样研究了底泥疏浚对内源氮释放的控制效果．研究结果发现，疏浚表层30cm能够有效的消减沉积物中有机质含量与孔隙水中NH4^＋含量．在一年的试验周期内，疏浚和对照柱沉积物-水界面的NH4’通量分别为5．3至18．6mg／（m2·d）与-9．4至67．5mg／（m2·d），疏浚柱沉积物-水界面的Nm＋通量总体上低于未疏浚对照的通量，尤其是在温度较高的月份，从2006年5-12月疏浚柱沉积物-水界面NH4^＋释放通量显著低于未疏浚对照柱，疏浚沉积物的NH4^＋的释放潜力低于未疏浚对照沉积物．研究结果表明，在外源得到有效控制的前提下，底泥疏浚是消减研究区内源氮负荷有效的技术手段．

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湖泊底泥疏浚环境效应:ii.内源氮释放控制作用

A laboratory experiment for studying the effects of sediment dredging on microbial activity and functional diversity of microbial community of sediments was carried out through one year.Using incubation of undredged(control) and dredged cores,we found that dredging the upper 30cm layer of sediment remarkably affected physico-chemical and microbial characteristics of sediments in the study area of Meiliang Bay,Lake Taihu.The microbial activity in dredged sediments was significantly lower(P0.05)than that in undredged sediments.Sediment dredging affected considerably microbial activity in sediments,and the microbial activity in dredged sediments could not recovery in one year experiment.Sediment dredging also affected the functional diversity of microbial community in sediment,the diversity index of microbial community in early dredged sediments was significantly lower (P0.05) than that in undredged sediments.Sediment dredging modified the community composition of sediment microbial ecosystem and resulted in decreasing of diversity of microbial community.Sediment dredging affected microbial activity and functional diversity of microbial community,which consequently affected the cycling of biogenic elements in sediments.

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湖泊底泥疏浚环境效应:iv.对沉积物微生物活性与群落功能多样性的影响及其意义

A laboratory experiment for studying the effects of sediment dredging on denitrification process was carried out through a one-year incubation of undredged sediments (control) and dredged sediment cores. Denitrification rates in the sediments were estimated by means of the acetylene blockage technique. During the experiments, the denitrification rates in the undredged and dredged sediments ranged from 21.6 to 102.7nmol/(g·h) and from 6.9 to 26.9nmol/(g·h), respectively. The denitrification rates in the undredged sediments were significantly higher (P 0.05) than those in the dredged sediments throughout the incubation period, with an exception of February 2006. The relative importance of various environmental factors on denitrification was assessed, and the results indicated that denitrification rates in both undredged and dredged sediments were regulated by temperature controls. Nitrate was likely to be the key factor limiting denitrification rates in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Potential denitrification in the early dredged sediments couldn’t reach a high rate as that in undredged sediments, which should be considered as a potential negative effect for nitrogen removal.

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刘国锋

Papers

湖泊底泥疏浚环境效应：i．内源磷释放控制作用

湖泊底泥疏浚环境效应:ii.内源氮释放控制作用

湖泊底泥疏浚环境效应:iv.对沉积物微生物活性与群落功能多样性的影响及其意义

湖泊底泥疏浚环境效应:iii.对沉积物反硝化作用的影响