同位素溯源解析地下水庫對地下水氮分布影響

康萍萍,許士國,禹守泉

(1.大連理工大學水利學院水環境研究所,遼寧 大連　116024; 2.萊州市水務局,山東 萊州　261400)

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同位素溯源解析地下水庫對地下水氮分布影響

康萍萍1,許士國1,禹守泉2

(1.大連理工大學水利學院水環境研究所,遼寧 大連116024; 2.萊州市水務局,山東 萊州261400)

地下水庫;氮氧同位素;環境影響;氮來源;IsoSource;氮貢獻比例

1　材料與方法

1.1研究區概況

王河流域位于山東省萊州市東北部。氣候屬于暖溫帶東亞季風區大陸性氣候。多年平均氣溫為12.4℃,多年平均降水量為1 172.4 mm,多年平均蒸發量為2 039.6 mm。5月和6月蒸發量最大,是同期降雨量的9～16倍。地下水補給以大氣降水、王河地表水下滲和海水倒灌為主。流域內土地利用以耕地為主,分布著村莊,東部近海區分布著大面積的海水養殖池。

自1977年以來,王河流域多年持續干旱,水源緊缺,為了滿足工農業及生活用水需要,流域內開始開采地下水。到1980年,年平均超采地下水0.61億m3,使地下水位大幅度下降。1977—1992年間全市地下水位總計下降8.02 m,負值區達282.2 km2。超采改變了地下淡水與海水之間的極限平衡,造成海水大面積入侵。截至1992年底,海水入侵面積達到234.15 km2，近1.33萬hm2農田荒廢,平均減產40%。為了充分利用王河流域水資源,抑制萊州灣海水進一步入侵，在王河下游修建了王河地下水庫。

王河地下水庫位于萊州市西北15 km處、西由村附近王河下游,距離萊州灣約2 km。王河地下水庫東倚山前崗地,西與渤海平原相接,東西寬5～9 km,南北為呈帶狀展布的沖洪積平原。地下水庫含水層巖性為礫質粗砂、微含土礫質粗礫、中細砂及沙壤土。王河地下水庫總庫容為5 693萬m3,最大調節庫容為3 273萬m3,最高運行水位為1.0 m, 死水位為-9.0 m, 工業用水日供水量為3萬t。地下壩主要包括北壩、西壩、副壩地下防滲墻工程。北壩西起倉上村北,東至街西村西北,壩長2.7 km,西壩南起朱由鎮武家村龍王河北岸,北與倉上殘丘相接,壩長8.25 km,副壩位于西由鎮新合村南,壩長0.84 km。地下壩防滲墻采用高壓擺噴灌漿、高壓定噴灌漿和高壓旋噴灌漿。庫區內土地利用類型主要是耕地和村莊,庫區外土地利用類型較為復雜,西部近海區主要是海水養殖,內陸區主要是耕地和荒地,零星分布著村莊。

1.2地下水樣品采集

圖1　研究區位置及采樣點分布

1.3氮濃度分析

1.4氮氧同位素分析

(1)

式中:Rsa和Rst分別為樣品和標準樣品的15N/14N和18O/16O比值。

(2)

(3)

表1　王河地下水庫內外地下水水樣檢測結果

2　結果分析與討論

2.1庫區內外地下水中氮濃度特征

圖2　不同來源[12]的和及王河地下水庫的和

圖3　王河地下水庫庫區內外地下水中與的關系

圖4　王河地下水庫庫內地下水污染源貢獻比例

圖5　王河地下水庫庫外地下水污染源貢獻比例

3　結　語

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Analysis of influence of underground reservoir on nitrogen distribution through tracing of isotope source

KANG Pingping1, XU Shiguo1, YU Shouquan2

(1.InstituteofWaterandEnvironmentalResearch,FacultyofInfrastructureEngineering,DalianUniversityofTechnology,Dalian116024,China;2.LaizhouWaterAuthority,Laizhou261400,China)

Taking the Wanghe River Underground Reservoir in Shandong Province as an example, we used nitrogen and oxygen isotopes to analyze the distribution, sources, and transformation of nitrogen in groundwater. We used the IsoSource software to calculate the contribution ratios of different pollution sources, in order to analyze the influence of the underground reservoir on nitrogen distribution in groundwater. The results show that NO3-and TN in groundwater within the underground reservoir had higher concentrations and smaller spatial differences than they did outside of the underground reservoir, and the main nitrogen source was fertilizer in groundwater within the underground reservoir. Denitrification occurred in groundwater within the underground reservoir. The nitrogen in groundwater outside of the underground reservoir was mainly from mariculture and fertilizers. All the results mentioned above indicate that the underground reservoir prevents nitrogen from flowing horizontally, resulting in the accumulation of nitrogen and the enhancement of denitrification of nitrogen in groundwater within the underground reservoir.

underground reservoir; nitrogen and oxygen isotopes; environmental effects; nitrogen sources; IsoSource; nitrogen contribution ratio

10.3880/j.issn.1004-6933.2016.05.016

國家重點基礎研究發展計劃(973計劃)資助項目(2013CB430403)

康萍萍(1985—),女,博士研究生,研究方向為水環境保護與修復。E-mail: kpp@mail.dlut.edu.cn

許士國,教授。E-mail:sgxu@dlut.edu.cn

P597.2; X523

A

1004-6933(2016)05-0079-06

2015-11-24編輯：徐娟)