| 不同气候类型高原湖区浅层地下水中氮素来源及其贡献的差异 |
| 摘要点击 1421 全文点击 281 投稿时间：2023-11-17 修订日期：2024-01-13 |
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| 中文关键词 气候类型 高原湖泊 浅层地下水 硝酸盐来源 同位素 |
| 英文关键词 climate type plateau lake shallow groundwater NO3- source isotope |
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| 中文摘要 |
| 明确不同气候类型高原湖区浅层地下水中氮的浓度、主要来源及其贡献差异可为区域地下水硝酸盐（NO3-）污染治理提供新的方向.以亚热带季风气候区的洱海和金沙江干热河谷区的程海湖区浅层地下水为研究对象,利用水化学指标和多同位素技术（δ15N-NO3-、δ18O-NO3-、δ18O-H2O和δ2H-H2O）,并结合稳定同位素（SIAR）模型,分析洱海和程海湖区浅层地下水氮浓度差异,识别NO3-来源并计算各污染源的贡献率.结果表明,洱海和程海湖区超过33%和5%的浅层地下水采样点硝态氮（NO3--N）浓度劣于地下水质量标准（GB/T 14848）Ⅲ类水质要求（20 mg·L-1）.洱海和程海湖区浅层地下水的氢氧同位素（δ18O-H2O和δ2H-H2O）均平行于全球和中国的大气降水线,且存在较大截距,表明大气降水并不是两个区域地下水的主要补给源.洱海湖区浅层地下水中NO3-来源的贡献率为土壤有机氮（53.77%）最高,其次是氮肥（21.75%）和粪便及污水（21.55%）,大气沉降氮（2.93%）最低,地下水氮的转化过程中存在反硝化作用.程海湖区浅层地下水中NO3-来源的贡献率为：粪便和污水（44.88%）>土壤有机氮（37.03%）>氮肥（16.17%）>大气沉降氮（1.92%）,地下水氮的转化过程中存在硝化作用.气候类型显著影响着浅层地下水位,改变着氮素的迁移和转化过程,进而影响着地下水氮的浓度和NO3-主要来源贡献,但NO3-主要来源并不受气候类型的影响,更多受土地利用、农业活动和粪污处理方式等影响. |
| 英文摘要 |
| Clarifying the concentration, major sources, and contribution differences of nitrogen in shallow groundwater in plateau lake areas with different climate types can provide a novel direction for the control of nitrate （NO3-） pollution in regional groundwater. Taking the shallow groundwater around Erhai Lake in the subtropical monsoon climate zone and Chenghai Lake in the dry-hot valley area of the Jinsha River as the research objects, using hydrochemical indexes and multi-isotope techniques （δ15N-NO3-, δ18O-NO3-, δ18O-H2O, and δ2H-H2O） combined with the stable isotope （SIAR） model； the differences in nitrogen concentration in shallow groundwater around Erhai Lake and Chenghai Lake were analyzed, the sources of NO3- were identified, and the contribution rates of each pollution source were calculated. The results showed that water quality of more than 33% and 5% of shallow groundwater sampling points around Erhai Lake and Chenghai Lake was worse than the groundwater Class Ⅲ quality requirements （GB/T 14848） of 20 mg·L-1 for nitrate nitrogen （NO3--N）, respectively. The δ18O-H2O and δ2H-H2O in shallow groundwater around Erhai Lake and Chenghai Lake were parallel to the global and Chinese atmospheric precipitation lines, and a large intercept was present, indicating that atmospheric precipitation was not the major recharge source of groundwater in the two regions. The contribution rate of different NO3- sources in shallow groundwater around Erhai Lake was the highest for soil organic nitrogen （53.77%）, followed by nitrogen fertilizer （21.75%） and manure and sewage （21.55%）, and atmospheric deposition nitrogen （2.93%） was the lowest. Denitrification occurred in the transformation process of nitrogen in groundwater. The contribution rate of different NO3- sources in shallow groundwater around Chenghai Lake was manure and sewage （44.88%） > soil organic nitrogen （37.03%） > nitrogen fertilizer （16.17%） > atmospheric deposition nitrogen （1.92%）, and nitrification occurred in the transformation process of nitrogen in groundwater. The climate type significantly affected the shallow groundwater level, altering the migration and transformation process of nitrogen, thereby affecting the nitrogen concentration in groundwater and the contribution of NO3- as the chief source. However, the major source of NO3- was not affected by the climate type； however was more affected by land use, agricultural activities, and manure treatment methods. |
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