摘要
Artificial floating islands ( AFIs),which was well know for its purification in lakes,ponds and reservoirs,was receiving a particular attention by the scientific and economic fields in recent years.In this study,AFIs were firstly selected as one of in - situ eco - technique to reduce the pollution in the LC Channel in Nanhai district,Foshan City.The total installation of AFIs was around 600 meters long,covering 3000m2 at 3 separated sections,i.e.,LC section,LA section and WZ section.In the meantime,regularly weekly sampling and monitoring were carried out from April to July to confirm the removal effect.On the AFIs,7 kinds of emergent macrophytes including umbrella plant ( Cyperus alterniflius L.),pickerel weed ( Pontederia cordata L.),canna lily (Canna generalis Bailey),powdery alligator - flag ( Thalia dealbata Fraser),yellow flag (Iris pseudoacorus L.),blue flag (Iris tectorum Maxim) and giant cane (Arundo donax var.versicolor (Mill.) Stokes) and 1 kindof submerged plant,water - milfoil (Myriophyllum verticllatum L.),were planted.In order to enhance the removal efficiency on pollutants,those plants were arranged alternatively in various combinations.The physiochemical factors indicated that AFIs had remarkable effect on the nutrient removal between the vegetated floating area ( the treated area) and the non - installed area ( the control area).The removal rate of 4 major parameters (TN,TP,COD,NH4 -N) ranged from 16% to 25% in average.In general,the water quality was tend to be more healthy with the Secchi depth increased 15cm in average in the end of the July.The biological data showed that there was a stable and slow effect on the recovery of ecosystem.Totally,137 species belonging to 53 genera,15 orders of phytoplankton were found in this channel,there are a little difference in species composition between treated area and control area.However,obvious community succession can be found based on the dominant species.The biomass of phytoplankton was increased much after restoration.The constructed AFIs also provided a good habitat for the wild life.During the survey period,2 kinds of amphibians (Rana sp.,Bufo melanostictus Schneider ),3 kinds of insects (Pieris canidia (Sparrman),Leptotes sp.,Ischnura senegalensis ( Ramhur ) ) and 2 kinds of birds ( Parus major Linnaeus,Passer montanus (L.) ) were frequently found on the vegetated AFIs.Our results showed that the AFIs was a kind of useful in - situ eco - technique for the control of water pollutions in the urban channels.
