王 鵬,齊述華,陳 波
(1:江西師范大學鄱陽湖濕地與流域研究教育部重點實驗室,南昌 330022;2:江西師范大學地理與環(huán)境學院,南昌 330022 ;3:中國科學院陸地水循環(huán)及地表過程重點實驗室,北京 100101)
土地利用方式影響下的贛江硝態(tài)氮濃度和氮穩(wěn)定同位素分布特征*
王 鵬1,2,3,齊述華1,2,陳 波1,2
(1:江西師范大學鄱陽湖濕地與流域研究教育部重點實驗室,南昌 330022;2:江西師范大學地理與環(huán)境學院,南昌 330022 ;3:中國科學院陸地水循環(huán)及地表過程重點實驗室,北京 100101)
贛江;鄱陽湖;硝態(tài)氮;氮穩(wěn)定同位素;土地利用
1.1 樣品采集與分析
圖1 贛江流域采樣點與子流域劃分(S1~S20表示采樣點,Z1~Z20表示相應子流域)Fig.1 Sample sites and sub basins in Ganjiang Basin (S1-S20 represent sample sites, and Z1-Z20 represent sub basins)
1.2 子流域與土地利用類型
對S1~S20采樣點,基于Aster 30m精度的DEM數(shù)據(jù),利用ArcGIS的Hydrology模塊劃分采樣點對應的子流域,相應劃分為20個子流域.土地利用數(shù)據(jù)利用2010年秋季獲取的無云Landsat衛(wèi)星遙感影像,經(jīng)過幾何糾正,參照《環(huán)境狀況評價技術規(guī)范》(HJ/T 192-2006)中土地利用分類方法,基于ArcInfo Workstation,并結合人工目視解譯獲得.該土地利用體系的一級分類劃分為林地、草地、居民建設用地、水域、旱地、水田和未利用地共7種類型,根據(jù)地形地貌、林地郁閉度和草地覆蓋度等條件建立二級分類體系(圖2).該數(shù)據(jù)庫經(jīng)過內業(yè)校核和外業(yè)核查,一級分類的總體精度達到90%以上,二級分類精度大于85%.
1.3 數(shù)據(jù)分析
圖2 贛江流域土地利用類型(圖例代碼見表1)Fig.2 Land use patterns in Ganjiang Basin(Legend code are shown in table 1)
一級分類(代碼)二級分類(代碼)水田山區(qū)水田(111);丘陵水田(112);平原水田(113);大于25°坡地水田(114)旱地山區(qū)旱地(121);丘陵旱地(122);平原旱地(123);大于25°坡地旱地(124)林地 有林地(21):郁閉度>50%的天然林和人工林;灌木林(22):郁閉度>40%、高度在2m以下的矮林地和灌叢林地;疏林地(23):郁閉度為10%~30%;其它林地(24):未成林造林地、跡地、苗圃及各類園地草地 高覆蓋度草地(31):覆蓋度>50%;中覆蓋度草地(32):覆蓋度20%~50%;低覆蓋度草地(33):覆蓋度5%~20%水域河渠(41);湖泊(42);水庫坑塘(43);灘地(46)居民建設用地城鎮(zhèn)用地(51);農(nóng)村居民用地(52);其它工礦建設用地(53)未利用土地沼澤地(64);裸土地(65);裸巖石礫地(66)
1) 將采樣點控制的子流域分為相鄰控制流域和總控制流域2種空間尺度.相鄰控制流域指從某采樣點至上游相鄰采樣點間的流域匯水范圍,總控制流域指某采樣點在贛江流域內總的流域匯水范圍.如S3的相鄰控制流域為Z3,總控制流域為Z1+Z2+Z3.
圖3 贛江濃度和值的分布(S19和S20點位只在6月采集,S10點位6月沒有檢測出值)
圖4 贛江濃度和值的關系(生活污水、土壤氮和合成化肥的15N取值范圍參考文獻[19-20])(Ranges of 15N for domestic sewage, soil N and fertilizer are taken from references[19-20])
流域劃分參數(shù)月份旱地林地草地水田居民建設用地水域相鄰控制流域NO-3-N1月-0.67**0.49* 6月-0.57*0.58* δ15N-NO-31月-0.51*0.59**6月-0.46*總控制流域NO-3-N1月-0.55*-0.63**0.54* 0.62**0.69**6月δ15N-NO-31月-0.81**-0.60**0.67**0.55* 0.73**6月-0.73**
**表示在0.01水平(雙側)上顯著相關,*表示在0.05水平(雙側)上顯著相關,下同.
流域劃分參數(shù)月份相關性結果相鄰控制流域NO-3-N1月水庫坑塘0.57*;農(nóng)村用地0.73**;山區(qū)旱地-0.63**;平原旱地0.64**6月 湖泊0.50*;水庫坑塘0.53*;山區(qū)水田-0.51*;丘陵水田0.57*;山區(qū)旱地-0.48*δ15N-NO-31月水庫坑塘0.52*;農(nóng)村用地0.59**;平原水田0.56*;平原旱地0.54*6月總控制流域 NO-3-N 1月 高覆蓋度草地-0.51*;湖泊0.58*;水庫坑塘0.73**;城鎮(zhèn)用地0.73**;農(nóng)村用地0.65**6月湖泊0.52*;城鎮(zhèn)用地0.55*δ15N-NO-3 1月 高覆蓋度草地-0.66**;河渠0.64**;湖泊0.53*;水庫坑塘0.63**;城鎮(zhèn)用地0.50*;農(nóng)村用地0.56*6月高覆蓋度草地-0.62**;湖泊0.46*
致謝:本研究的同位素分析實驗得到中國科學院遺傳與發(fā)育生物學研究所的研究生趙煥、孔曉樂和梁慧雅的幫助,在此表示感謝.
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Characteristics of nitrate and nitrogen stable isotope in Ganjiang River under the influence of land use
WANG Peng1,2,3, QI Shuhua1,2& CHEN Bo1,2
(1:KeyLaboratoryofPoyangLakeWetlandandWatershedResearch,MinistryofEducation,JiangxiNormalUniversity,Nanchang330022,P.R.China2:SchoolofGeographyandEnvironment,JiangxiNormalUniversity,Nanchang330022,P.R.China3:KeyLaboratoryofWaterCycleandRelatedLandSurfaceProcesses,ChineseAcademyofSciences,Beijing100101,P.R.China)
Identifying the source of nitrate in the Ganjiang River has great significance to eutrophication control in the Lake Poyang,since the nitrate in the Ganjiang River is the main source of nitrogen input into the lake. Based on the investigation of NO -3 -N andδ15N-NO -3 in the mainstream and major tributaries of the Ganjiang River in January and June of 2013,the characteristics of nitrateand nitrogen stable isotope and the influence from land use were analyzed through different spatial scales and classification levels.The ranges of NO -3 -N concentration in dry season and wet season were 0. 52 - 4. 58 mg /L and 0. 81-2. 60 mg /L,respectively,andtheir mean value had no significant difference between the two seasons. The ranges of δ15N-NO -3 in dry season and wet season were- 1. 31‰-8. 60‰ and 2. 49‰-8. 51‰,respectively,which were significantly lower in dry season. Land use with larger spatialscales had more significant correlation with NO -3 -N and δ15N-NO -3 . The NO -3 -N concentration and δ15N-NO -3 in Gangjiang Riverwere significantly positively correlated with the area of paddy field,residential land and water,and significantly negatively correlated with the area of forest land and grass land. However,this correlation decreased in wet season. Compared to the first level of land use classification,the second level of land use classification was more helpful to reflect the correlation of land use with NO -3 -N,while little help for δ15N-NO -3 . Agricultural land,especially hill paddy field and plain dry land,was the main source of NO -3 -N. Compared with other area in the Yangtze River Basin,there was a smaller proportion of NO -3 -N coming from domestic sewage in the Ganjiang River Basin.
Ganjiang River; Lake Poyang; nitrate; nitrogen stable isotope; land use
J.LakeSci.(湖泊科學), 2015, 27(6): 1011-1019
DOI 10.18307/2015.0604
?2015 byJournalofLakeSciences
國家自然科學基金項目(41201033)、鄱陽湖濕地與流域研究教育部重點實驗室主任開放基金項目(ZK2013009)、中國科學院陸地水循環(huán)及地表過程重點實驗室開放基金項目(WL2013004)和江西省重大生態(tài)安全問題監(jiān)控協(xié)同創(chuàng)新中心項目(JXS-EW-00)聯(lián)合資助.
2014-12-19收稿;2015-02-11收修改稿.
王鵬(1982~),男,博士,副教授;E-mail:wangpengjlu@gmail.com.