巢湖流域丰乐河洪水事件营养盐输出动态研究
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摘要
洪水期是非点源污染输出的关键时期。通过对巢湖典型农业型流域丰乐河桃溪断面两次暴雨洪水过程(发生于2010年6月初的Event06和8月底的Event08)进行集中取样监测,结合该断面流量数据,分析了洪水过程中氮和磷营养盐不同指标(包括总氮、铵氮、硝态氮、总磷和可溶磷)浓度和瞬时负荷的动态变化规律。结果表明:Event06氮磷各指标浓度最小值、最大值及平均值均比Event08大,这与6月初农作物大量施肥,氮磷来源丰富有很大关系。丰乐河洪水事件氮输出的形式以可溶性无机氮(铵氮和硝态氮)为主,而磷则以颗粒态为主,但在涨水段的初、中期颗粒态氮和颗粒态磷所占比例比其它时段高。洪水过程中主要氮、磷指标浓度和瞬时负荷随流量增大而总体呈上升趋势(除了硝态氮),在流量峰值前达到最大值,然后呈总体下降趋势。总磷、总氮浓度与流量呈比较典型的顺时针圈形结构,表明暴雨洪水较强烈的冲刷输送作用。虽然进一步的负荷累积分析并没有显示显著的初期冲刷效应,但洪水期,特别是涨水段营养盐输出的重要性已较明显。丰乐河流域面积较大、地势较平坦,以农业活动为主,水体污染的非点源来源与农业活动有关,具体的洪水过程对营养盐的输出动态也有一定影响。
Non-point source pollutants are mainly transported during flood events.The Fengle River,one of the main tributaries of the Chao Lake in the middle-east part of China,was chosen to study non-point source nutrient export characteristics in a large-sized agricultural catchment.Two summer events(Event06,in the beginning of June and Event08,at the end of August,2010) were intensively sampled at Taoxi section of the river and analyzed for Total Nitrogen(TN),Ammonia,Nitrate,Total Phosphorus(TP) and Dissolved Phosphorus.Hourly discharge and rainfall data were also available at the same section.The drainage area of this section is 1500 km2 with elevatio between 6-463m and main stream length is about 50km.Land use includes agriculture(about 45%),forest(39%),town and roads(10%) and water area(ponds and river,6%).No large cities or industry factories are located in this drainage catchment.Both events demonstrated single peak hydrograph.But Event06,which was caused by one storm,was relatively more intensive than Event08 which was caused by 3 separated storms.The base,peak and average discharge were 22.6,216.3 and 131.3m3/s for Event06 and 65.4,156.4 and 109.4m3/s for Event08,respectively.The minimum,maximum and average concentration values of each indicator of Event06 were much higher than those of Event08,which was mainly due to the fertilization at the end of May or in beginning of June just before the transplanting of rice seedling.Another reason might be that Event06 was more intensive and thus demonstrated stronger erosion and transportation capacity than Event08.The average concentrations of TN and TP were 4.05 and 0.11 mg/L for Event06 and 1.62 and 0.08 mg/L for Event08,respectively.Nitrogen was mainly exported in dissolved inorganic forms,i.e.ammonium and nitrate,which were at similar level.Particulate phosphorus export was relatively more important than dissolved form.The transportation of particulate forms of both nitrogen and phosphorus was more important in the beginning and middle phase of rising limb than the rest flood phases.During the flood events,both concentrations and instantaneous loads of most of the determinants(with an exception of nitrate in one of the events) fluctuated but generally increased in the rising limb,attained the peak values before peak discharge and then declined.The relationships between concentrations of TN and TP and discharge over both events resulted in typical clockwise hysteresis,demonstrating the important washing off and transport capacity of flood water flow in the rising phase.Although obvious 'first flush' effect was not obtained through the cumulative mass and cumulative discharge analysis based on the two monitored events mainly due to the relatively large catchment area and gentle topography in most part of the catchment,the importance of nutrient export during flood event had been emphasized.The detailed pollutant accumulation processes in the river reaches and/or the area near the river reach and their transportation should be influenced by successive flood events,which need further study through detailed field and modeling work.
Non-point source pollutants are mainly transported during flood events.The Fengle River,one of the main tributaries of the Chao Lake in the middle-east part of China,was chosen to study non-point source nutrient export characteristics in a large-sized agricultural catchment.Two summer events(Event06,in the beginning of June and Event08,at the end of August,2010) were intensively sampled at Taoxi section of the river and analyzed for Total Nitrogen(TN),Ammonia,Nitrate,Total Phosphorus(TP) and Dissolved Phosphorus.Hourly discharge and rainfall data were also available at the same section.The drainage area of this section is 1500 km2 with elevatio between 6-463m and main stream length is about 50km.Land use includes agriculture(about 45%),forest(39%),town and roads(10%) and water area(ponds and river,6%).No large cities or industry factories are located in this drainage catchment.Both events demonstrated single peak hydrograph.But Event06,which was caused by one storm,was relatively more intensive than Event08 which was caused by 3 separated storms.The base,peak and average discharge were 22.6,216.3 and 131.3m3/s for Event06 and 65.4,156.4 and 109.4m3/s for Event08,respectively.The minimum,maximum and average concentration values of each indicator of Event06 were much higher than those of Event08,which was mainly due to the fertilization at the end of May or in beginning of June just before the transplanting of rice seedling.Another reason might be that Event06 was more intensive and thus demonstrated stronger erosion and transportation capacity than Event08.The average concentrations of TN and TP were 4.05 and 0.11 mg/L for Event06 and 1.62 and 0.08 mg/L for Event08,respectively.Nitrogen was mainly exported in dissolved inorganic forms,i.e.ammonium and nitrate,which were at similar level.Particulate phosphorus export was relatively more important than dissolved form.The transportation of particulate forms of both nitrogen and phosphorus was more important in the beginning and middle phase of rising limb than the rest flood phases.During the flood events,both concentrations and instantaneous loads of most of the determinants(with an exception of nitrate in one of the events) fluctuated but generally increased in the rising limb,attained the peak values before peak discharge and then declined.The relationships between concentrations of TN and TP and discharge over both events resulted in typical clockwise hysteresis,demonstrating the important washing off and transport capacity of flood water flow in the rising phase.Although obvious 'first flush' effect was not obtained through the cumulative mass and cumulative discharge analysis based on the two monitored events mainly due to the relatively large catchment area and gentle topography in most part of the catchment,the importance of nutrient export during flood event had been emphasized.The detailed pollutant accumulation processes in the river reaches and/or the area near the river reach and their transportation should be influenced by successive flood events,which need further study through detailed field and modeling work.
引文
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[20]LEE J H,BANG K W,KETCHUM L H,et al.First flushanalysis of urban storm runoff[J].The Science of the TotalEnvironment,2002,293:163-175.
[21]ROSSI L,KREJCI V,RAUCH W,et al.Stochastic modelingof total suspended solids(TSS)in urban areas during rainevents[J].Water Research,2005,9:4188-4196
[22]张汪寿,李晓秀,王晓燕,等.北运河下游灌区不同土地利用方式非点源氮素输出规律[J].环境科学学报,2004,31(12):2698-2706.
[23]YANG J L,ZHANG G L,SHI X Z,et al.Dynamic changes ofnitrogen and phosphorus losses in ephemeral runoff processesby typical storm events in Sichuan Basin,Southwest China[J].Soil and Tillage Research,2009,105(2):292-299.
[24]李家科,李怀恩,沈冰,等.渭河干流典型断面非点源污染监测与负荷估算[J].水科学进展,2011,22(6):818-828.
[25]张恒,曾凡棠,房怀阳,等.连续降雨对淡水河流域非点源污染的影响[J].环境科学学报,2011,31(5):927-934.
[26]HOUSE W A.Geochemical cycling of phosphorus in rivers[J].Applied Geochemistry,2003,18:739-748.
[27]DAVID A,PERRIN J L,ROSAIN D,et al.Implication of twoin-stream processes in the fate of nutrients discharged by sew-age system into a temporary river[J].Environmental Monito-ring and Assessment,2011,181(1-4):491-507.
[2]储茵,夏守先.丰乐河污染输出特征研究[J].安徽农业大学学报,2009,36(3):476-482.
[3]王雪,余辉,燕姝雯,等.太湖流域上游河流污染空间分布特征研究[J].长江流域资源与环境,2012,21(3):341-348.
[4]BOWES M J,HOUSE W A,HODGKINSON R A,et al.Phosphorus-discharge hysteresis during storm events along ariver catchment:The River Swale,UK[J].Water Research,2005,39:751-762.
[5]孟伟,于涛,郑丙辉,等.黄河流域氮磷营养盐动态特征及主要影响因素[J].环境科学学报,2007,27(12):2046-2051.
[6]杨乐,张烨,侯培强,等.三峡水库中下游水体氮磷时空变化与机制分析[J].长江流域资源与环境,2012,21(06):732-738.
[7]MCDIFFETT W F,BEIDLER A W,DOMINICK T F,et al.Nutrient concentration-stream discharge relationships duringstorm events in a first-order stream[J].Hydrobiologia,1989,179:97-102.
[8]STUTTER M I,LANGAN S J,COOPER R J.Spatial contri-butions of diffuse inputs and within-channel processes to theform of stream water phosphorus over storm events[J].Jour-nal of Hydrology,2008,350:203-214.
[9]BLANCO A C,NADAOKA K,YAMAMOTO T,et al.Dynamic evolution of nutrient discharge under stormflow andbaseflow conditions in a coastal agricultural watershed in Ishi-gaki Island,Okinawa,Japan[J].Hydrological Processes,2010,24:2601-2616.
[10]OEURNG C,SAUVAGE S,COYNEL A,et al.Fluvial trans-port of suspended sediment and organic carbon during floodevents in a large agricultural catchment in southwest France[J].Hydrological Processes,2011,23:2365-2378.
[11]高超,朱继业,朱建国.极端降水事件对农业非点源污染物迁移的影响[J].地理学报,2005,60(6):991-997.
[12]许其功,刘鸿亮,沈珍瑶,等.三峡库区典型小流域氮磷流失特征[J].环境科学学报,2007,27(2):326-331.
[13]LITTLEWOOD I G.Estimating contaminant loads in rivers:A review[R].Institute of Hydrology,Crowmarsh Gifford,Wallingford,Oxfordshire,OX10 8BB,UK,1992.
[14]MERRITT W S,LETCHER R A,JAKEMAN A J.A reviewof erosion and sediment transport models[J].EnvironmentModel&Software,2003,18(8-9):761-799.
[15]SCANLON T M,KIELYA G,XIE Q S.A nested catchmentapproach for defining the hydrological controls on non-pointphosphorus transport[J].Journal of Hydrology,2004,291:218-231.
[16]HOUSE W A,WARWICK M S.Hysteresis of the soluteconcentration/discharge relationship in rivers during storms[J].Water Research,1998,32(8):2279-2290.
[17]李如忠,汪家权,钱家忠.巢湖流域非点源营养物控制对策研究[J].水土保持学报,2004,18(1):119-121,129.
[18]SALLES C,TOURNOUD M G,CHU Y.Estimating nutrientand sediment flood loads in a small Mediterranean river[J].Hydrological Processes,2008,22:242-253.
[19]LAWLER D M,PETTS G E,FOSTER I D L,et al.Turbiditydynamics during spring storm events in an urban headwaterriver system:The Upper Tame,West Midlands,UK[J].Scienceof the Total Environment,2006,360:109-126.
[20]LEE J H,BANG K W,KETCHUM L H,et al.First flushanalysis of urban storm runoff[J].The Science of the TotalEnvironment,2002,293:163-175.
[21]ROSSI L,KREJCI V,RAUCH W,et al.Stochastic modelingof total suspended solids(TSS)in urban areas during rainevents[J].Water Research,2005,9:4188-4196
[22]张汪寿,李晓秀,王晓燕,等.北运河下游灌区不同土地利用方式非点源氮素输出规律[J].环境科学学报,2004,31(12):2698-2706.
[23]YANG J L,ZHANG G L,SHI X Z,et al.Dynamic changes ofnitrogen and phosphorus losses in ephemeral runoff processesby typical storm events in Sichuan Basin,Southwest China[J].Soil and Tillage Research,2009,105(2):292-299.
[24]李家科,李怀恩,沈冰,等.渭河干流典型断面非点源污染监测与负荷估算[J].水科学进展,2011,22(6):818-828.
[25]张恒,曾凡棠,房怀阳,等.连续降雨对淡水河流域非点源污染的影响[J].环境科学学报,2011,31(5):927-934.
[26]HOUSE W A.Geochemical cycling of phosphorus in rivers[J].Applied Geochemistry,2003,18:739-748.
[27]DAVID A,PERRIN J L,ROSAIN D,et al.Implication of twoin-stream processes in the fate of nutrients discharged by sew-age system into a temporary river[J].Environmental Monito-ring and Assessment,2011,181(1-4):491-507.
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