劉 倩,龐 燕*,項(xiàng) 頌,萬 玲

駱馬湖表層沉積物有機(jī)質(zhì)分布特征及來源解析

劉 倩1,2,龐 燕1,2*,項(xiàng) 頌1,2,萬 玲3

(1.中國(guó)環(huán)境科學(xué)研究院湖泊生態(tài)環(huán)境研究所,北京 100012；2.湖泊水污染治理與生態(tài)修復(fù)技術(shù)國(guó)家工程實(shí)驗(yàn)室,北京 100012；3.蘇州科技大學(xué),江蘇 蘇州 215009)

為解析駱馬湖富營(yíng)養(yǎng)化沉積物的影響因素,2018年9月采集了駱馬湖表層沉積物32個(gè)點(diǎn)位樣品,分析了沉積物的總有機(jī)碳(TOC)、總氮(TN)、有機(jī)碳同位素(δ13C)和氮同位素(δ15N)指標(biāo),研究了沉積物中有機(jī)質(zhì)分布特征及來源.研究表明:表層沉積物TOC含量在0.55%～3.76%,平均值為1.62%;TN含量在0.04%～0.46%,平均值為0.19%;δ13C含量在-27.32‰～-8.36‰,平均值為-14.98‰;δ15N含量在-1.92‰～10.17‰,平均值為7.72‰,TN與TOC在空間分布呈正相關(guān),有機(jī)碳、氮同位素受不同來源有機(jī)質(zhì)影響空間分布有較大差異.對(duì)δ15N、δ13C與C/N進(jìn)行定性分析和端元混合模型定量計(jì)算,得出駱馬湖表層沉積物有機(jī)質(zhì)來源主要有三個(gè):一是人類活動(dòng)帶來的土壤有機(jī)質(zhì)貢獻(xiàn)率最大,特別是東岸休閑旅游區(qū)貢獻(xiàn)較高;二是圍網(wǎng)養(yǎng)殖造成的源污染,加大了湖泊富營(yíng)養(yǎng)化程度;第三是湖泊來水?dāng)y帶較高濃度的污水有機(jī)質(zhì),對(duì)“典型過水性”駱馬湖水質(zhì)影響較大.為了降低駱馬湖水體富營(yíng)養(yǎng)化程度,改善水生態(tài)環(huán)境質(zhì)量,急需對(duì)湖體有機(jī)質(zhì)的來源加大控制.

表層沉積物；有機(jī)質(zhì)；碳氮同位素；C/N；來源解析

駱馬湖位于江蘇省北部,是淮河流域第3大淡水湖泊、江蘇省第4大淡水湖泊,蘇北地區(qū)重要的水系之一,同時(shí)也是國(guó)家南水北調(diào)東線輸水工程的主要調(diào)節(jié)水庫(kù)之一.其北面通過運(yùn)河與山東南四湖相連、南面與洪澤湖相連,繼而與長(zhǎng)江水系相通,是典型的過水性湖泊[1-2].近幾十年來,隨著駱馬湖流域城市化和圍網(wǎng)養(yǎng)殖的發(fā)展,大量營(yíng)養(yǎng)物質(zhì)不斷流入湖泊,水質(zhì)日益下降,對(duì)駱馬湖的生態(tài)環(huán)境造成極大影響.

湖泊沉積物中的營(yíng)養(yǎng)鹽和有機(jī)質(zhì)是引起湖泊水體富營(yíng)養(yǎng)化的主要因素之一,是湖泊水體中物質(zhì)的重要的“源”與“匯”,沉積物包含了豐富的生物、理化信息,保存了原始生產(chǎn)力狀況、水體營(yíng)養(yǎng)狀況轉(zhuǎn)變過程及自然水質(zhì)改變進(jìn)程等重要?dú)v史信息,可以用來推演湖泊生產(chǎn)力變化過程,從而為恢復(fù)湖泊生態(tài)環(huán)境提供重要依據(jù)[3-8].沉積物中的穩(wěn)定同位素碳、氮值以及C/N比值經(jīng)常被用來指示水生系統(tǒng)中有機(jī)質(zhì)來源或循環(huán)隨時(shí)間的變化情況,這些示蹤是建立在不同來源的有機(jī)質(zhì)、不同的C/N比值和穩(wěn)定同位素組成的基礎(chǔ)上[9-10]. 對(duì)于此方面研究,國(guó)外學(xué)者早在20世紀(jì)70年代起首次提出利用δ15N-NO3-識(shí)別地表水中的氮污染源,且此方法已變成了識(shí)別水中NO3-來源的主要方式.近些年來,國(guó)內(nèi)越來越多地學(xué)者將穩(wěn)定同位素應(yīng)用于環(huán)境示蹤,其中一種應(yīng)用是利用同位素比值定量地確定幾種污染源對(duì)混合物的比例貢獻(xiàn),通過此手段能有效識(shí)別湖泊環(huán)境的變化過程和影響因素[11-12].目前駱馬湖湖區(qū)大部分處于中度富營(yíng)養(yǎng)狀態(tài),少部分處于重度富營(yíng)養(yǎng)化狀態(tài),而現(xiàn)有研究圍繞水體、沉積物的營(yíng)養(yǎng)鹽、重金屬、抗生素含量和分布、湖區(qū)魚類資源和浮游植物群落結(jié)構(gòu)的結(jié)構(gòu)和分布等方面來分析,對(duì)于駱馬湖目前富營(yíng)養(yǎng)化狀態(tài)的原因解析未曾發(fā)表過,本研究通過對(duì)駱馬湖表層沉積物有機(jī)碳、氮穩(wěn)定同位素等指標(biāo)進(jìn)行分析,得出其分布特征,通過端元混合模型定性和定量分析有機(jī)質(zhì)來源和貢獻(xiàn)率,進(jìn)而分析駱馬湖受人類活動(dòng)影響的湖泊生產(chǎn)力變化和富營(yíng)養(yǎng)化過程.

1 材料與方法

1.1 采樣點(diǎn)布設(shè)與樣品采集

駱馬湖為淺水湖泊,湖底高程一般在21.17～ 23.17m,北起堰頭村圩堤,南至揚(yáng)河灘(宿遷市)閘口,西連中運(yùn)河,東部靠著嶂山嶺,東西寬15～20km,南北長(zhǎng)35km,湖區(qū)總面積達(dá)到375km2.主要入湖河流有沂河水系,南四湖水系和邳蒼地區(qū)共40多條支流.出湖河流有三處,一處經(jīng)嶂山閘入新沂河,一處經(jīng)皂河閘入中運(yùn)河(南),一處經(jīng)洋河灘閘入六塘[13-15].本研究于2018年9月進(jìn)行駱馬湖表層沉積物樣品采集,采樣點(diǎn)位置及數(shù)量根據(jù)《湖泊生態(tài)安全調(diào)查與評(píng)估技術(shù)指南》確定,按網(wǎng)格法共設(shè)置32個(gè)(圖1),但由于湖內(nèi)分布大量的圍網(wǎng)和網(wǎng)箱,個(gè)別預(yù)定樣點(diǎn)(L11和L12)無法到達(dá)指定位置,故實(shí)際采樣中共獲得30個(gè)樣品.表層沉積物使用彼得遜采泥器采集,去除石塊、塑料雜草等,將剩余沉積物裝入密封袋,迅速帶回實(shí)驗(yàn)室冷凍干燥保存.

圖1 駱馬湖采樣點(diǎn)分布示意

樣品冷凍干燥后過100目,密封保存.加入10mL 0.5mol/L鹽酸進(jìn)行預(yù)處理2h,再用超純水淋洗后通過離心機(jī)3000r/min離心,反復(fù)3次以保證呈中性,然后將去除無機(jī)碳的樣品在60℃烘箱中烘干[16],樣品TOC和TN采用元素分析儀(德國(guó)Elementar vario Macro CNS元素分析儀)進(jìn)行測(cè)定.有機(jī)碳氮同位素的測(cè)定使用elementar公司vario PYRO cube元素分析儀和Isoprime100質(zhì)譜聯(lián)用測(cè)定.實(shí)驗(yàn)中的δ13C數(shù)據(jù)以美國(guó)南卡羅萊納州白堊系PDB為標(biāo)準(zhǔn)品,δ15N數(shù)據(jù)以大氣中的N2為標(biāo)準(zhǔn)品,計(jì)算公式為:

δ13C (‰) =[(1sample1standard)/1standard]′1000,1=13C/12C δ15N(‰) =[(2sample-2standard)/2standard]′1000,2=15N/14N

式中:sample為湖泊樣品同位素比值,standard標(biāo)準(zhǔn)物同位素比值.

實(shí)驗(yàn)在中國(guó)農(nóng)業(yè)科學(xué)院農(nóng)業(yè)資源與農(nóng)業(yè)區(qū)劃研究所土壤肥料測(cè)試中心進(jìn)行.

1.2 數(shù)據(jù)統(tǒng)計(jì)

針對(duì)本次駱馬湖的研究,使用Excel 2019對(duì)駱馬湖現(xiàn)場(chǎng)數(shù)據(jù)進(jìn)行分析和處理,使用畫圖軟件ArcGIS 10.5結(jié)合現(xiàn)場(chǎng)采樣具體情況繪制駱馬湖采樣點(diǎn)分布圖,使用Origin 2018繪制表層沉積物有機(jī)質(zhì)碳、氮穩(wěn)定同位素分布圖及定性、定量分析圖.

2 結(jié)果與分析

2.1 表層沉積物TOC、TN、δ13C、δ15N分布特征

駱馬湖表層沉積物總有機(jī)碳TOC含量分布范圍為0.55%～3.76%,平均值為(1.62±0.77)%;總氮TN含量分布范圍為0.04%～0.46%,平均值為(0.19± 0.10)%;有機(jī)碳同位素δ13C分布范圍為-27.32‰～ -8.36‰,平均值為(-14.98±4.71)‰;有機(jī)氮同位素δ15N分布范圍為-1.92‰～10.17‰,平均值為(7.72± 2.55)‰.δ13C和δ15N各點(diǎn)位變化幅度較大,且δ13C變化范圍比δ15N范圍廣,主要基于不同來源的碳、氮同位素對(duì)應(yīng)不一樣的特征區(qū)間,在不同環(huán)境條件下,沉積物中的δ13C、δ15N會(huì)產(chǎn)生差異,由此可以識(shí)別研究沉積物受到何種污染[17].

圖3 表層沉積物TOC和TN相關(guān)性

各指標(biāo)的空間分布圖中可見,TOC污染嚴(yán)重的地區(qū)大部分出現(xiàn)在湖區(qū)沿岸(圖2),分析原因一方面由于湖區(qū)地表徑流和入湖河流攜帶的面源污染等造成的污染物沉積,另一方面由于工業(yè)廢棄物等通過湖區(qū)沿岸排污口進(jìn)入湖體.最高點(diǎn)出現(xiàn)在L9,為中運(yùn)河入湖口處,此點(diǎn)位于中運(yùn)河入湖前一段營(yíng)養(yǎng)鹽污染較為嚴(yán)重,且此段高程逐漸變大,加之水域內(nèi)部、北部沿岸出現(xiàn)灘涂和用土攔出的魚塘,這些因素在一定程度上會(huì)改變?cè)热牒髁飨蚝退形镔|(zhì)的沉降,導(dǎo)致該處TOC含量較高.TN的空間分布情況大致與TOC相同,通過對(duì)TN、TOC進(jìn)行相關(guān)性分析(圖3),TN與TOC呈現(xiàn)出顯著的正相關(guān)(<0.01),這表明沉積物中的TN、TOC有很好的同源性.

有機(jī)碳同位素δ13C含量較高分布從南部湖心處向西南岸延伸,最高值為L(zhǎng)18,此點(diǎn)正為魚塘分布集中區(qū)域,密集河網(wǎng)間缺乏足夠緩沖帶,加之?dāng)z食性魚類的高密度放養(yǎng),外源性飼料的大量投入,水體環(huán)境富營(yíng)養(yǎng)化程度加大,營(yíng)養(yǎng)鹽蓄積到沉積物中,導(dǎo)致該點(diǎn)位δ13C含量異常高;有機(jī)碳同位素δ15N在中運(yùn)河與駱馬湖連接處前端、北部沿岸以及湖泊東北岸出現(xiàn)高值,最高值為L(zhǎng)9,與TOC和TN出現(xiàn)位置相同.

2.2 表層沉積物有機(jī)質(zhì)來源解析

2.2.1 端元物質(zhì)的確定 穩(wěn)定同位素對(duì)于湖泊沉積物有機(jī)質(zhì)來自內(nèi)源和陸源的研究應(yīng)用中占有重要地位,其中碳氮比值(C/N)可有效判別湖泊沉積物有機(jī)質(zhì)來源的指標(biāo),這些因子對(duì)了解湖泊地球化學(xué)環(huán)境變化過程有十分重要意義[18-21].一般來說,把C/N的內(nèi)、外源貢獻(xiàn)的值界定為8,當(dāng)C/N高于8,表明有機(jī)質(zhì)既受陸源影響,也受湖泊本身水環(huán)境的影響,屬于混合來源;當(dāng)C/N小于8時(shí),湖泊沉積物有機(jī)質(zhì)主要為自生來源,湖泊自生具有較高的初級(jí)生產(chǎn)力.

但由于生物地球化學(xué)作用可能會(huì)對(duì)穩(wěn)定同位素的遷移過程產(chǎn)生影響,僅運(yùn)用單一指標(biāo)C/N進(jìn)行分析可能會(huì)產(chǎn)生偏差,因此運(yùn)用多重指標(biāo)辨析有機(jī)質(zhì)來源更具有說服力,國(guó)內(nèi)外已經(jīng)有不少此方面相關(guān)研究.劉俊等[22]在通過將洞庭湖表層沉積物中的δ15N和C/N解析,得出洞庭湖的有機(jī)質(zhì)主要來自于土壤有機(jī)質(zhì).吳丹丹等[23]利用C/N和δ13C分析長(zhǎng)江口沉積物有機(jī)質(zhì)來源及不同來源的貢獻(xiàn)率.王毛蘭等[3]研究發(fā)現(xiàn)δ13C和C/N 值可以看出土壤有機(jī)質(zhì)是鄱陽湖有機(jī)質(zhì)的主要來源之一.倪兆奎等[24]研究測(cè)定了δ13C和δ15N與C/N含量,并結(jié)合210Pb 和137Cs 沉積物年代測(cè)定技術(shù),探究了近百年太湖沉積物有機(jī)質(zhì)和氮的來源.Thornton等[25]使用碳、氮穩(wěn)定同位素比值和C/N比值,對(duì)蘇格蘭泰河流域和河口沉積物中的顆粒有機(jī)物(POM)的來源進(jìn)行了評(píng)估,研究每種示蹤劑估算陸源物質(zhì)對(duì)土壤的貢獻(xiàn)能力,通過使用多種示蹤劑能為系統(tǒng)中沉積POM的來源提供更多的信息.

本研究采用δ13C、δ15N與C/N值相結(jié)合對(duì)湖泊沉積物有機(jī)質(zhì)來源進(jìn)行雙重分析,確定端元物質(zhì).湖泊有機(jī)質(zhì)來源主要來自兩個(gè)方面,即陸源有機(jī)質(zhì)和內(nèi)源有機(jī)質(zhì),其中陸源有機(jī)質(zhì)包括陸生C3和C4植物、污水有機(jī)質(zhì)、土壤有機(jī)質(zhì),內(nèi)源有機(jī)質(zhì)包括淡水藻類和浮游生物.駱馬湖區(qū)內(nèi)有大面積的圍網(wǎng)養(yǎng)殖,因此通過采取魚塘土樣測(cè)定碳氮同位素作為其中一個(gè)端元物質(zhì).所選定的端元值見表1.

表1 典型沉積物端元物質(zhì)的δ13C、δ15N和C/N值的分布[26-28]

注:①來自本研究.

2.2.2 定性分析 駱馬湖表層沉積物碳氮比值C/N為7.82～12.63 ,平均值為9.21,表明駱馬湖表層沉積物高于8,可以確定其沉積物來源屬于混合來源,同時(shí)受到內(nèi)源和外源的影響.通過上述表中所選定端元值將δ15N和C/N及δ13C和C/N的值相結(jié)合,區(qū)分出外源有機(jī)質(zhì)包括陸生C3和C4植物、污水有機(jī)質(zhì)、土壤有機(jī)質(zhì),內(nèi)源有機(jī)質(zhì)包括淡水藻類和浮游生物,魚塘有機(jī)質(zhì)6種類型來源的有機(jī)質(zhì),將所采集的駱馬湖表層沉積物相對(duì)應(yīng)的數(shù)據(jù)投影在Meyers[29]研究類型圖上(圖4).

可以看出駱馬湖表層沉積物主要來自于四個(gè)因素,分別為污水有機(jī)質(zhì)、土壤有機(jī)質(zhì)、魚塘有機(jī)質(zhì)、淡水藻類和浮游植物.駱馬湖湖區(qū)北部上游分布有城鎮(zhèn)和大面積的農(nóng)田,工農(nóng)業(yè)污水和城鎮(zhèn)居民生活污水的排放污染湖區(qū);東部沿岸進(jìn)行開發(fā),打造旅游、休閑、餐飲、住宅等人類活動(dòng)密集區(qū),大量的生活、餐飲污水進(jìn)入湖泊,對(duì)駱馬湖產(chǎn)生污染.駱馬湖是一個(gè)過水型湖泊,導(dǎo)致藻類不容易泛濫,2015年前駱馬湖大肆采砂,導(dǎo)致菹草成為駱馬湖的優(yōu)勢(shì)種群.當(dāng)菹草大面積泛濫死亡,其腐爛并沉入淤泥中,增加沉積物中有機(jī)質(zhì)含量[30].此外,湖區(qū)內(nèi)擁有大面積的圍網(wǎng)養(yǎng)殖,部分未被魚類攝食的餌料,魚類尸體及其排泄物進(jìn)入湖水和沉積物中[31],也造成了內(nèi)源有機(jī)質(zhì)增加.上述結(jié)果表明,駱馬湖的δ15N和C/N聯(lián)用對(duì)探究駱馬湖的有機(jī)質(zhì)來源識(shí)別具有可行性.δ13C和C/N關(guān)系圖中,少部分點(diǎn)位于端元物質(zhì)范圍之外,但整體上,端元物質(zhì)仍為污水有機(jī)質(zhì)、土壤有機(jī)質(zhì)、魚塘有機(jī)質(zhì)、淡水藻類和浮游植物,這與上述δ15N和C/N得出的結(jié)果相一致.

2.2.3 定量分析 為了深入分析駱馬湖表層沉積物有機(jī)質(zhì)來源,本研究引入端元混合模型,探究每種物質(zhì)來源的貢獻(xiàn)率,其原理為穩(wěn)定同位素在不同端元物質(zhì)形成過程中的保守性和質(zhì)量守恒定律[32].根據(jù)圖4的研究,將污水有機(jī)質(zhì)、土壤有機(jī)質(zhì)、魚塘有機(jī)質(zhì)、淡水藻類和浮游植物設(shè)定為固定的有機(jī)質(zhì)來源,采用三元混合模型,具體計(jì)算各端元貢獻(xiàn)率,修改公式如下:

δ15N樣=δ15N1·?1+δ15N2·?2+δ15N3·?3+δ15N4·?4

δ13C樣=δ13N1·?1+δ13N2·?2+δ13N3·?3+δ13N4·?4

C/N樣=C/N1·?1+ C/N2·?2+ C/N3·?3+ C/N4·?4

1= ?1+ ?2+ ?3+?4

式中:δ15N表示有機(jī)質(zhì)的氮同位素組成,C/N為有機(jī)質(zhì)中TOC與TN的比值,?代表不同端元占據(jù)的比例,角標(biāo)1是淡水藻類和浮游植物,角標(biāo)2是污水有機(jī)質(zhì),角標(biāo)3是土壤有機(jī)質(zhì),角標(biāo)4是魚塘有機(jī)質(zhì).在開始計(jì)算前,根據(jù)表1將各端元分布范圍的中間值作為各端元值,得出:(1)淡水藻類和浮游植物的δ13C =-30, δ15N=6.5,C/N=10;(2)污水有機(jī)質(zhì)δ13C =-23,δ15N=16, C/N=11;(3)土壤有機(jī)質(zhì)δ13C =-22,δ15N=7,C/N=12;(4)魚塘有機(jī)質(zhì)δ13C =-19,δ15N=7,C/N=11.將上述確定的端元值代入模型中,對(duì)各端元貢獻(xiàn)率進(jìn)行求解,結(jié)果見圖5.

圖5 不同端元對(duì)駱馬湖有機(jī)質(zhì)的貢獻(xiàn)率

四個(gè)端元中,土壤有機(jī)質(zhì)的貢獻(xiàn)率普遍是最大的,其次是魚塘有機(jī)質(zhì),最后是污水有機(jī)質(zhì).由于該計(jì)算完全使用數(shù)學(xué)方法,有大部分點(diǎn)位的淡水藻類和浮游植物的貢獻(xiàn)率為負(fù)值,且偏離幅度較大,因此在湖泊整體上來說,駱馬湖表層沉積物受到該端元的影響極小,這也印證了駱馬湖作為一個(gè)過水型湖泊,藻類難以在湖泊泛濫.位于東岸沿岸的L24、L23、L28、L32、L31處的土壤有機(jī)質(zhì)的貢獻(xiàn)率較高,人為因素影響較大,可能與東岸沿岸休閑旅游區(qū),人口活動(dòng)密集有關(guān).除L6和L15點(diǎn)外,剩余點(diǎn)位魚塘有機(jī)質(zhì)的貢獻(xiàn)率均僅次于土壤有機(jī)質(zhì),主要原因是駱馬湖很多區(qū)域有圍網(wǎng)養(yǎng)殖,養(yǎng)殖場(chǎng)投放餌料和魚種途徑攜帶了大量氮磷,加重了湖泊富營(yíng)養(yǎng)化狀態(tài).黃文鈺等[33]計(jì)算了1998年度駱馬湖氮磷入湖量扣除出湖量后,網(wǎng)圍養(yǎng)殖使湖體總氮增加了339t、總磷增加了57t,分別占湖體滯留氮磷總量的27%和33%.因此,圍網(wǎng)養(yǎng)殖帶入的營(yíng)養(yǎng)鹽量占湖體滯留量相當(dāng)高的比例.污水有機(jī)質(zhì)主要出現(xiàn)在L22點(diǎn)位之前,其中位于中運(yùn)河入湖L9及位于駱馬湖北部沿岸L14、L4、L5點(diǎn)均出現(xiàn)高值,分析原因一方面可能來自于岸邊人為活動(dòng),另一方面可能源自中運(yùn)河、老沂河、沂河的來水.

3 結(jié)論

3.1 駱馬湖表層沉積物的δ13C、δ15N的分布范圍分別是為-27.32‰～-8.36‰、-1.92‰～10.17‰,δ13C呈現(xiàn)出由北向南漸增的趨勢(shì),δ15N則在東北部湖岸向湖心處慢慢減少.C/N平均值為9.21,表明駱馬湖表層沉積物有機(jī)質(zhì)來源為混合型.

3.2 通過δ15N、δ13C值和C/N比值雙重分析定性識(shí)別駱馬湖有機(jī)質(zhì)來源,結(jié)果表明駱馬湖表層沉積物主要來自于四個(gè)因素,分別為污水有機(jī)質(zhì)、土壤有機(jī)質(zhì)、魚塘有機(jī)質(zhì)、淡水藻類和浮游植物,其中δ15N和C/N圖的代表性更好.

3.3 不同端元有機(jī)質(zhì)貢獻(xiàn)率結(jié)果顯示,駱馬湖表層沉積物有機(jī)質(zhì)來源主要有三個(gè),土壤有機(jī)質(zhì)的貢獻(xiàn)率最大,人類活動(dòng)帶來的外源污染不容忽視,特別是東岸沿岸的休閑旅游區(qū)貢獻(xiàn)較高;其次是魚塘,圍網(wǎng)養(yǎng)殖造成的內(nèi)源污染加大了湖泊富營(yíng)養(yǎng)化程度;最后是污水有機(jī)質(zhì),較高濃度污染物的來水對(duì)駱馬湖“典型過水性”湖泊沖擊力很大,特別是由于特殊的湖底地形又加大了這種污染物的沉積.通過對(duì)以上三種有機(jī)質(zhì)的來源采取有效的措施進(jìn)行控制,對(duì)降低駱馬湖富營(yíng)養(yǎng)化程度有重大意義.

[1] 張慶吉,王業(yè)宇,王金東,等.駱馬湖浮游植物演替規(guī)律及驅(qū)動(dòng)因子[J]. 環(huán)境科學(xué), 2020,41(4):1648-1656.

Zhang Q J, Wang Y Y, Wang J D, et al. Succession pattern of phytoplankton and its drivers in Lake Luoma, Jiangsu Province [J]. Environmental Science, 2020,41(4):1648-1656.

[2] 鄒 偉,李太民,劉 利,等.蘇北駱馬湖大型底棲動(dòng)物落結(jié)構(gòu)及水質(zhì)評(píng)價(jià)[J]. 湖泊科學(xué), 2017,29(5):1177-1187.

Zou W, Li T M, Liu L, et al. Macrozoobenthic community structure and water quality assessment of Lake Luoma, Jiangsu Province, China [J]. Journal of Lake Sciences, 2017,29(5):1177-1187.

[3] 王毛蘭,賴建平,胡珂圖,等.鄱陽湖表層沉積物有機(jī)碳、氮同位素特征及其來源分析[J]. 中國(guó)環(huán)境科學(xué), 2014,34(4):1019-1025.

Wang M L, Lai J P, Hu K T, et al. Compositions and sources of stable organic carbon and nitrogen isotopes in surface sediments of poyang lake [J]. China Environmental Science, 2014,34(4):1019-1025.

[4] Wu J L, Michael K, Gagan, et al. Sedimentary geochemical evidence for recent eutrophication of Lake Chenghai, Yunnan, China [J]. Journal of Paleolimnology, 2004,32:85-94.

[5] Yamamuro M, Kanai Y. A 200-year record of natural and anthropogenic changes in water quality from coastal lagoon sediments of Lake Shinji, Japan [J]. Chemical Geology, 2005,218:51-61.

[6] Hollander D J, Smith M A. Microbially mediated carbon cycling as a control on the δ13C of sedimentary carbon in eutrophic Lake Mendota (USA): New models for interpreting isotopic excursions in the sedimentary record [J]. Geochimica et Cosmochimica Acta, 2001, 65(23):4321-4337.

[7] Herczeg A L, Smith A K, Dighton J C. A 120 year record of changes in nitrogen and carbon cycling in Lake Alexandrina,South Australia:CN, δ15N, and δ13C in sediments [J]. Applied Geochemistry, 2001,16: 73-84.

[8] Andreas L, Gerhard H S, Bernd Z, et al. A lateglacial and holocene organic carbon isotope record of lacustrine palaeoproductivity and climatic change derived from varved lake sediments of Lake Holzmaar, Germany [J]. Quaternary Science Reviews, 2003,22:569-580.

[9] Cloern J E, Canuel E A, Harris D. Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system [J]. Limnology and Oceanography, 2002,47(3):713- 729.

[10] Weihmann J, Mansfeldt T, Schulte U. Stable carbon (12/13C) and nitrogen (14/15N) isotopes as a tool for identifying the sources of cyanide in wastes and contaminated soils-A method development [J]. Analytica Chimica Acta, 2007,582(2):375-381.

[11] 梁 越,劉小真,賴勁虎.湖泊氮的生物地球化學(xué)過程及其氮同位素技術(shù)的應(yīng)用 [J]. 湖北農(nóng)業(yè)科學(xué), 2014,53(10):2238-2243.

Liang Y, Liu X Z, Liu J H. Nitrogen biogeochemical process of lake and its application of nitrogen isotope techniques [J]. Hubei Agricultural Sciences, 2014,53(10):2238-2243.

[12] 林 琳,吳敬祿,曾海鰲,等.人類活動(dòng)對(duì)太湖水環(huán)境影響的穩(wěn)定氮同位素示蹤 [J]. 湖泊科學(xué), 2012,24(4):546-552.

Lin L, Wu J L, Zeng H A, et al.Stable nitrogen isotope tracing anthropogenic influence on Lake Taihu [J]. Journal of Lake Sciences, 2012,24(4):546-552.

[13] 周亞琳.駱馬湖濕地資源調(diào)查及生態(tài)保護(hù)研究[D]. 南京:南京林業(yè)大學(xué), 2007.

Zhou Y L, Investigation and ecological protection of luoma Lake wetland resources [D]. Nanjing: Nanjing Forestry University, 2007.

[14] 張 芹,張圣虎,汪 貞,等.駱馬湖表層水體中32種PPCPs類物質(zhì)的污染水平、分布特征及風(fēng)險(xiǎn)評(píng)估[J]. 環(huán)境科學(xué), 2017,1:162-169.

Zhang Q, Zhang S H, Wang Z, et al. Pollution level, distribution characteristics and risk assessment of 32PPCPs in surface water of Luomahu Lake [J]. Environmental Science, 2017,1:162-169.

[15] 葉 玲.駱馬湖面臨的環(huán)境問題和保護(hù)對(duì)策[J]. 污染防治技術(shù), 2015,28(6):87-88,96.

Ye L. The environmental problems and protection counter measures of Luoma Lake [J]. Pollution Control Technology, 2015,28(6):87-88,96.

[16] 凌郡鴻,張依章,王民浩,等.深圳茅洲河下游柱狀沉積物中碳氮同位素特征[J]. 環(huán)境科學(xué), 2017,38(12):5081-5089.

Ling J, Zhang Y Z, Wang H M, et al. Characteristics of carbon and nitrogenin the down stream columnar sediment of Maozhou River, Shenzhen [J]. Environmental Science, 2017,38(12):5081-5089.

[17] H Kohl D, B Shearer G., B Commoner. Fertilizer nitrogen: contribution to nitrate in surface water in a corn belt watershed. [J]. Science (New York, N.Y.), 1971,174(4016).

[18] 王潤(rùn)梅,唐建輝,黃國(guó)培,等.環(huán)渤海地區(qū)河流河口及海洋表層沉積物有機(jī)質(zhì)特征和來源[J]. 海洋與湖沼, 2015,46(3):497-507.

Wang R M, Tang J H, Huang G P, et al. Provenance of organic matter in estuarine and marine surface sediments around the Bohai sea [J]. Oceanologia et Limnologia Sinica, 2015,46(3):497-507.

[19] Krishnamurthy R V, Bhattacharya S K, Kusumgar S. Palaeoclimatic changes deduced from13C/12C and C/N ratios of Karewa lake sediments, India [J]. Nature, 1986,323(6084):150-152.

[20] Paul W J, Hamilton D P, Ostrovsky I, et al. Catchment land use and trophic state impacts on phytoplankton composition: a case study from the Rotorua lakes' district, New Zealand [J]. Hydrobiologia, 2012,698 (1):133-146.

[21] Lazerte B D. Stable carbon isotope ratios: Implications for the source of sediment carbon and for phytoplankton carbon assimilation in lake memphremagog Quebec [J]. Canadian Journal of Fisheries & Aquatic Sciences, 1983,40(10):1658-1666.

[22] 劉 俊,田學(xué)達(dá),王琳杰,等.洞庭湖表層沉積物營(yíng)養(yǎng)鹽空間分布及來源解析[J]. 環(huán)境工程技術(shù)學(xué)報(bào), 2019,9(6):701-706.

Liu J, Ting X D, Wang L J, et al. Spatial distribution and source analysis of surface sediment nutrients in Lake Dongting [J]. Journal of Environmental Engineering Technology, 2019,9(6):701-706.

[23] 吳丹丹,葛晨東,高 抒,等.長(zhǎng)江口沉積物碳氮元素地球化學(xué)特征及有機(jī)質(zhì)來源分析[J]. 地球化學(xué), 2012,41(3):207-215.

Wu D D, Ge C D, Gao S. Carbon, nitrogen geochemical character and source analyses in Changjiang estuarine sediments [J]. Geochimica, 2012,41(3):207-215.

[24] 倪兆奎,李躍進(jìn),王圣瑞,等.太湖沉積物有機(jī)碳與氮的來源[J]. 生態(tài)學(xué)報(bào), 2011,v.31(16):4661-4670.

Ni Z K, Li Y J, Wang S R, et al. The sources of organic carbon and nitrogen in sediment of taihu lake [J]. Acta Ecologica Sinica, 2011, 31(16): 4661-4670.

[25] Thornton S. F, McManus J. Application of organic carbon and nitrogen stable isotope and C/N ratios as source indicators of organic matter provenance in estuarine systems: Evidence from the Tay Estuary, Scotland [J]. 1994,38(3):219-233.

[26] Kendall C, Silva S R, Kelly V J. Carbon and nitrogen isotopic compositions of Particulate organic matter in four large river systems across the United States. Hydrology Process, 2001,15:1301-1346.

[27] Hedes J I, Clark A W, Richey J E, et al. Compositions and fluxes of particulate organic material in the Amazon River [J]. Limnology and Oceanography. 1986,31(4):717-738.

[28] Parton W J, Schimel D. S, Cole C V, et al. 1987. Analysis of factors controlling soil organic matter levels in Great Plains grasslands [J]. Soil Science Society America Journals, 51(5):1173-1179.

[29] Meyers P A. 1994. Preservation of elemental and isotope source identification of sedimentary organic matter [J]. Chemical Geology, 114: 289-302.

[30] 曹 毅,王 輝.基于Landsat 7影像的駱馬湖菹草時(shí)空分布研究[J]. 環(huán)境監(jiān)控與預(yù)警, 2014,6(4):46-47.

Cao Y, Wang H. The temporal and spatial distribution of potamogeton grispus in Luoma Lake based on Landsat 7 image [J]. Environmental Monitoring and Forewarning, 2014,6(4):46-47.

[31] 張 敏,李建秋,周易勇.網(wǎng)箱養(yǎng)殖對(duì)東湖沉積物有機(jī)質(zhì)含量以及磷的酶促水解與吸附行為的影響[J]. 水產(chǎn)學(xué)報(bào), 2002,(6):510-518.

Zang M, Li J Q, Zhou Y Y .Influence of cage-culture on the contents of organic matter and enzymatic hydrolysis as well as adsorption behavior of phosphorus in sediments of Lake Donghu [J]. Journal of fisheries of china, 2002,(6):510-518.

[32] 楊文煥,周明利,申 涵,等.寒旱區(qū)湖泊冰封期有機(jī)碳氮同位素研究[J]. 中國(guó)環(huán)境科學(xué), 2020,40(2):789-797.

Yang W H, Zhou M L, Shen H, et al. Organic carbon and nitrogen isotopes of lakes in cold and arid region during the frozen period. [J]. China Environmental Science, 2020,40(2):789-797.

[33] 黃文鈺,許朋柱,范成新,等.網(wǎng)圍養(yǎng)殖對(duì)駱馬湖水體富營(yíng)養(yǎng)化的影響[J]. 農(nóng)村生態(tài)環(huán)境, 2002,18(1):22-25.

Huang W Y, Xu P Z, Fang C X, et al. Effect of cage aquiculture on eutrophication in Luoma Lake [J]. Rural Eco-Environment, 2002, 18(1):22-25.

Distribution characteristics and source analysis of organic matter in surface sediments of Luoma Lake.

LIU Qian1,2, PANG Yan1,2*, XIANG Song1,2, WAN Lin3

(1.Institute of Lake Environment,Chinese Research Academy of Ecological and Environmental Science, Beijing 100012, China；2.National Engineering Laboratory For Lake Pollution Control and Ecological Restoration,Beijing 100012, China；3.Master Dissertation of Suzhou University, Suzhou 215009, China)., 2021,41(10)：4850～4856

In order to analyze the influencing factors of eutrophication sediment in Luoma Lake, In September 2018, samples of surface sediments at 32point positions of Luoma Lake were collected, and their biogeochemical indexes including total organic carbon (TOC), total nitrogen (TN), organic carbon isotope (δ13C) and nitrogen isotope (δ15N) were analyzed, with the aim to explore the distribution characteristics and sources of organic matter in the surface sediments of such area. The results showed that TOC content in surface sediments ranged from 0.55% to 3.76%, with an average value of 1.62%; TN content of the total nitrogen ranged from 0.04% to 0.46%, with an average value of 0.19%; δ13C content of organic carbon isotope ranged from -27.32‰ to -8.36‰, with an average value of -14.98‰; δ15N content of organic nitrogen isotope ranged from -1.92‰ to 10.17‰, with an average of (7.72±2.55)‰. The spatial distribution of TN and TOC was positively correlated, and the spatial distributions of organic carbon and nitrogen isotopes affected by different sources of organic matter were quite different. Through the qualitative analysis of δ15N and δ13C with C/N and the quantitative calculation of the end-member hybrid model, it is concluded that there were three main sources of organic matter in the surface sediments of Luoma Lake. The first is that the contribution rate of exogenous contamination of soil organic matter caused by human activities was generally the largest,especially in the leisure tourism areas along the east coast. The second is that the endogenous pollution caused by barrier net aquiculture had increased the degree of lake eutrophication. The third is that the organic matter of sewage with higher concentration of pollutants brought by the inflow water of the lake had a great impact on the "typical water-carrying" lake of Luoma Lake. Therefore, there is need to intensify controls over the sources of the abovementioned three kinds of organic matters, thus reducing the degree of lake eutrophication.

surface sediments；organic matter；carbon and nitrogen isotope；carbon-nitrogen ratio；source analysis

X522

A

1000-6923(2021)10-4850-07

劉 倩(1984-),女,河北衡水人,碩士,工程師,主要研究方向?yàn)楹雍鷳B(tài)保護(hù)修復(fù)技術(shù).發(fā)表論文13篇.

2021-03-11

國(guó)家重大科技專項(xiàng)(2018ZX07208-005)

* 責(zé)任作者, 研究員, pangy@craes.org.cn