基于工程措施的喀斯特落水洞土壤及养分流失阻控效果

为揭示前期研发的阻控工程措施对喀斯特峰丛洼地土壤及养分流失的阻控效果,采用室内模拟和原位监测,采集暴雨后经阻控和未阻控的水流样品,分析样品中土壤、总养分及溶解性养分含量变化。结果表明,室内模拟暴雨条件下,生物质炭对土壤和养分流失的阻控效果表现为前期好于后期,且阻控效果与过滤材料粒径相关,以40目效果好于20目。其中,在暴雨初期(0 h),40目生物质炭对总氮、总磷、总钾流失的阻控率分别为31.9%、35.9%和37.2%,显著高于20目生物质炭对相应养分的阻控率(19.1%、16.6%和18.4%)。原位条件下,暴雨后24 h内工程措施(使用混合过滤材料)对总氮、总磷和总钾的阻控率分别达40.0%、92.3%和62.6%,对硝态氮、磷酸盐流失的阻控率分别为35.3%和12.5%,对其它有效态养分流失的阻控效果不明显(0.66%～3.70%)。总体上,采用工程措施对于暴雨后经喀斯特峰丛洼地落水洞流失土壤及总养分的阻控效果明显,但对水溶态养分的阻控效果有限。

Controlling effect of soil and nutrient loss via doline by engineering measure in karst area

In order to reveal the effect of a previously developed engineering measure on controlling the loss of soil and nutrients in karst peak-cluster depression area, the experiments based on laboratory simulation and in situ monitoring were conducted to determine the contents of soil, total nutrients and dissolved nutrients in water samples which via the interceptive measure. The simulation experiment result showed that the interceptive effect of the engineering measure on controlling soil and nutrient loss was better at early stage than at late stage. In addition, the interceptive effect was dependent on the particle size of biochar, showing a better interception effect of 40 mesh than 20 mesh. Specifically, at the beginning of rainstorm, the interceptive proportions total nitrogen, total phosphorus and total potassium by 40 mesh biochar were 31.9%, 35.9% and 37.2%, which were significantly higher than those by 20 mesh biochar (19.1%, 16.6% and 18.4%). In the in situ monitoring experiment which using mixed materials, the interceptive proportions of total nitrogen, total phosphorus and total potassium within 24 hours after the rainstorm reached to 40.0%, 92.3%, 62.6%, respectively. Meanwhile, the interceptive proportions of nitrate nitrogen and phosphate were 35.3% and 12.5% correspondingly, whereas the interceptive effect on other dissolved nutrients was not obvious (the proportions ranged from 0.66% to 3.70%). In short, the engineering measure had good interceptive effect on soil and total nutrient loss via doline after rainstorm in karst peak-cluster depression area, but the effect on dissolved nutrient loss was limited.