Chen Qingfei, Chen Anqiang, Min Jinheng, Li Lin, Hu Wanli, Wang Chi, Fu Bin, Guo Shufang, Zhang Dan
College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China; Agricultural Environment and Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming 650201, China.
Agricultural Environment and Resources Institute, Yunnan Academy of Agricultural Sciences, Kunming 650201, China.
Sci Total Environ. 2024 Nov 10;950:175300. doi: 10.1016/j.scitotenv.2024.175300. Epub 2024 Aug 5.
Excessive accumulation of nitrogen (N) in the soil profile in the intensive agricultural region will seriously threaten groundwater quality and safety. However, the impact of shallow groundwater table (SGWT) fluctuations driven by seasonal variations on the N accumulation characterizations in the soil profiles has not been well quantified, particularly in the regions with thin layer vadose zone. Through in-situ monitoring and simulation experiments, the changes in the SGWT and N accumulation of soil profile in intensive cropland around 7 plateau lakes in Yunnan were studied during the rainy season (RS) and dry season (DS), and the N loss in soil profile of cropland driven by SGWT fluctuations was estimated. The results showed that the SGWT and N accumulation in soil profile of cropland around the plateau lakes had obvious seasonal variation characteristics. The proportion of N storage in different forms in 60-100 cm soil layer in the RS was greater than that in the DS, particularly the proportion of NH-N storage was as high as 55 %, while N accumulation in surface soil was obvious in the DS. Compared with the DS, due to the rising SGWT in the RS, the maximum storages of TN and NO-N in the 0-100 cm soil layer decreased by17% and 36 %, respectively. The TN loss intensities from the 0-100 cm soil profiles of cropland around Fuxian Lake, Yilong Lake, Qilu Lake, Dianchi Lake, Yangzong Lake, Erhai Lake, and Xingyun Lake were 74, 54, 127, 105, 93, 72 and 207 kg/ha, respectively. Moreover, if the SGWT was <30 cm, the average TN loss intensity and amount could reach 177 kg/ha and 1250 t, respectively. Therefore, the SGWT regulation was one of the key measures to reducing soil N loss from the thin layer vadose zone of cropland around plateau lakes and improving groundwater quality.
集约化农业地区土壤剖面中氮（N）的过量积累将严重威胁地下水质量和安全。然而，由季节变化驱动的浅层地下水位（SGWT）波动对土壤剖面中氮积累特征的影响尚未得到很好的量化，特别是在包气带较薄的地区。通过原位监测和模拟实验，研究了云南7个高原湖泊周边集约化农田在雨季（RS）和旱季（DS）期间SGWT和土壤剖面氮积累的变化，并估算了由SGWT波动驱动的农田土壤剖面氮损失。结果表明，高原湖泊周边农田土壤剖面中的SGWT和氮积累具有明显的季节变化特征。雨季60-100cm土层中不同形态氮储量的比例大于旱季，特别是NH-N储量比例高达55%，而旱季表层土壤中的氮积累明显。与旱季相比，由于雨季SGWT上升，0-100cm土层中TN和NO-N的最大储量分别减少了17%和36%。抚仙湖、异龙湖、杞麓湖、滇池、阳宗海、洱海和星云湖周边农田0-100cm土壤剖面的TN损失强度分别为74、54、127、105、93、72和207kg/ha。此外，如果SGWT<30cm，平均TN损失强度和损失量分别可达177kg/ha和1250t。因此，调控SGWT是减少高原湖泊周边农田包气带土壤氮流失、改善地下水质量的关键措施之一。
