國家水體污染控制與治理科技重大專項(2012ZX07102)資助.2014-12-17收稿;2015-07-02
收修改稿. 鄧偉明(1984~),男,碩士,助理工程師;E-mail:ming_605@163.com。
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滇池表層沉積物銨態(tài)氮吸附特征*
*國家水體污染控制與治理科技重大專項(2012ZX07102)資助.2014-12-17收稿;2015-07-02
收修改稿. 鄧偉明(1984~),男,碩士,助理工程師;E-mail:ming_605@163.com。
(昆明市環(huán)境科學(xué)研究院湖泊水庫中心,昆明650032)
摘要:為研究滇池內(nèi)源污染特征,2013年利用GIS軟件針對滇池全湖布設(shè)36個采樣點,采集表層沉積物,研究滇池表層沉積物銨態(tài)氮-N)吸附特征,同時分析沉積物的理化性質(zhì)對-N吸附特性的影響.結(jié)果表明:滇池表層沉積物對-N的吸附量在前2 h之內(nèi)呈增長趨勢,吸附速率較大,之后沉積物對-N的吸附量不隨時間變化而變化,基本達到平衡,最大吸附速率均發(fā)生在0~5 min內(nèi);不同區(qū)域表層沉積物-N最大吸附速率平均值表現(xiàn)為:外海南部>湖心區(qū)>外海北部>草海,最大吸附量平均值表現(xiàn)為:湖心區(qū)>外海南部>外海北部>草海,吸附效率平均值表現(xiàn)為:外海北部>草海>湖心區(qū)>外海南部;沉積物對-N的吸附量與-N的初始濃度大致呈線性關(guān)系,并且低濃度下表現(xiàn)出很好的吸附/解吸特征;滇池表層沉積物-N的吸附解吸平衡濃度(ENC0)高于上覆水中-N濃度,表明沉積物中-N有向上覆水中釋放的風(fēng)險,沉積物在很長一段時間內(nèi)起到水體污染“源”的作用;ENC0與沉積物中總氮-N含量呈顯著正相關(guān),本底吸附量和有機質(zhì)總量呈顯著負相關(guān),沉積物吸附-N主要受有機質(zhì)的影響。
關(guān)鍵詞:滇池;沉積物;銨態(tài)氮;吸附
圖1 滇池沉積物與水樣監(jiān)測點位Fig.1 Sediment and water monitoring sites of Lake Dianchi
1 材料與方法
1.1 研究區(qū)概況
滇池(24°28′~25°28′N,102°30′~103°0′E)位于昆明市南的西山腳下,是我國第6大淡水湖泊[7],呈南北向分布,東北部有一長4 km的天然沙堤,將滇池分為南北兩部分,分別稱為外海和草海;草海面積7.52 km2,湖容0.188×108m3,外海面積為287.10 km2,湖容約13.60×108m3,最大水深10.24 m,平均水深4.40 m[8]。
1.2 研究點位及采樣方法
2013年在滇池全湖布設(shè)36個點位,包含常規(guī)監(jiān)測點位、入滇河流入湖口監(jiān)測點位和疏浚區(qū)監(jiān)測點位,然后利用GPS定位進行采樣,研究位點分布如圖1所示。
利用彼得森采泥器采集滇池表層10 cm沉積物樣品,樣品裝入塑料密封袋排出空氣密封,及時送回實驗室冷凍干燥,然后研磨過200目篩備用。
1.3 測定方法
實驗數(shù)據(jù)分別采用Excel 2007、SPSS 16.0以及ArcGIS軟件進行統(tǒng)計檢驗、多元回歸和作圖.
2 結(jié)果與分析
2.1 滇池表層沉積物中不同形態(tài)氮含量的分布特征
滇池表層沉積物總氮(TN)含量介于1596.25~5558.50 mg/kg之間,平均值為3307.26 mg/kg.長江中下游湖泊沉積物中TN含量在770.00~2630.00 mg/kg之間[10],洱海沉積物中TN含量在2084.40~6515.30 mg/kg之間[11],滇池沉積物TN含量與高原湖泊洱海相當(dāng),是長江中下游湖泊的2.5倍左右,表明其TN含量處于較高水平。
表1 2013年滇池沉積物中不同形態(tài)氮含量(mg/kg)
圖2 滇池表層沉積物不同形態(tài)氮含量的空間分布Fig.2 The spatial distribution of different forms of nitrogen content in the surface sediments of Lake Dianchi
圖3 滇池表層沉積物-N吸附動力學(xué)曲線Fig.-N in the surface sediments of Lake Dianchi
表2 不同時間段滇池表層沉積物對的吸附速率(mg/(kg·min))
圖4 滇池表層沉積物對-N的最大吸附速率Fig.-N in the surface sediments of Lake Dianchi
表3 滇池表層沉積物吸附-N
q=a+b·lnt
(1)
圖5 滇池表層沉積物對-N的吸附-解吸特征曲線Fig.-N in the surface sediments of Lake Dianchi
Q=NAN+Kd·ENC0
(2)
表4 滇池表層沉積物對-N的吸附-釋放特征參數(shù)
表5 不同湖泊沉積物對-N的吸附/
湖泊(年份)NAN/(mg/kg)ENC0/(mg/L)滇池(2013年)500.134.39太湖(2003年)39.091.78鄱陽湖(2003年)21.541.20洪澤湖(2003年)31.861.22
圖6 滇池表層沉積物對-N的吸附等溫線Fig.-N in the surface sediments of Lake Dianchi
Q=Qmax·K·C/(1+K·C)
(3)
圖7 滇池表層沉積物對-N的最大吸附量的分布Fig.7 The distribution of the maximum adsorption quantity -N in the surface sediments of Lake Dianchi
表6 滇池表層沉積物對-N的吸附等溫線特征參數(shù)
表7 滇池表層沉積物-N的吸附特征參數(shù)與其理化指標(biāo)的相關(guān)系數(shù)
*表示P<0.05。
3 結(jié)論
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J.LakeSci.(湖泊科學(xué)), 2016, 28(1): 75-85
?2016 byJournalofLakeSciences
Sorption and desorption characteristics of ammonium in the surface sediments of Lake Dianchi
DENG Weiming, XU Xiaomei, CHEN Chunyu, HE Jia**, XU Di & WANG Li
(ResearchCenterofLakesandReservoirs,KunmingInstituteofEnvironmentalSciences,Kunming650032,P.R.China)
Abstract:In order to study the endogenous pollution characteristics of Lake Dianchi, 36 samples were set in whole Lake Dianchi using the GIS exploring in 2013. Through collecting the surface sediment samples, adsorption characteristics of ammonia on surface sediments were studied and the influence of physical and chemical properties of sediments on the adsorption characteristics of ammonia was also analyzed. The results showed that the adsorption quantity of ammonia nitrogen on surface sediments of the Lake Dianchi showed a growing trend in 2 h and the adsorption rate was relatively high. After 2 h, the adsorption quantity of ammonia on surface sediments did not change with time and attain the basic balance. The maximum adsorption rate appeared during 0-5 min. An order of the average maximum adsorption rate of ammonia on sediments of different sub-lake waters was: the south of Lake Waihai>the center of the lake>the south of Lake Waihai>Lake Caohai. An order of the average of maximum adsorbent quantity was: the center of the lake>the south of Lake Waihai>the north of Lake Waihai>Lake Caohai. A order of the average adsorption efficiency was: the north of Lake Waihai>Lake Caohai>the center of the lake>the south of Lake Waihai. The adsorption quantity of ammonia on sediments showed a rough linear relationship with the initial concentration of ammonia. Under a low concentration condition, a good adsorption/desorption characteristic occurred. Through comparing the concentration of adsorption/desorption of ammonia on sediments and the concentration between overlying water and sediments, the results showed that the ENC0of ammonia in sediments was higher than that in overlying water, indicating that the ammonia had the releasing risk from sediments to overlying water. These inferred that the sediments would play a role of the water pollution “source” in a long time. As ENC0had the positive correlation with total nitrogen and ammonium nitrogen in sediments and NAN had negative correlation with total organic matter, we recognized that the ammonia adsorbed by sediments was mainly influenced by organic matter。
Keywords:Lake Dianchi;sediments;ammonia nitrogen;adsorption
通信作者鄧偉明,徐曉梅,陳春瑜,何佳*;E-mail:dcszxb@163.com.,許迪,王麗
DOI10.18307/2016.0109