CAJ | 학술논문

针对重金属铬(Cr)污染严重的现象，基于简单的二层非完全混合模型，将降雨时农田土壤与积水整个系统分为混合区及混合区以下两个部分，根据水量平衡原理和溶质质量守恒定律，研究土壤在非线性Langmuir吸附条件下，吸附性溶质 Cr(VI)的径流流失规律。试验模拟的田间地表径流是由降雨引起的，根据降雨期间土壤与雨水相互作用情况，将降雨过程分为4个阶段分别求解进行研究。利用室内模拟降雨-径流试验所得数据进行模拟计算，并通过敏感性分析和模型参数对径流流失量的影响分析，阐明模型参数对土壤中吸附性溶质径流流失规律的影响。研究结果表明：此二层非完全混合模型能预测土壤在非线性Langmuir吸附条件下，吸附性溶质Cr(VI)的径流流失规律。该模型对入渗水溶质与土壤混合层溶质之间的非完全混合系数γ非常敏感，对土壤混合层溶质与地表积水-径流水溶质之间的非完全混合系数α不敏感，对Langmuir吸附方程中的参数B、C也不敏感。其中γ和α对模拟径流流失过程的影响主要作用于降雨前期，而Langmuir吸附方程中的参数B对模拟过程的影响作用于降雨前期，C也主要作用于降雨前期，但对后期的影响比其他参数更大。试验数据显示地表径流中溶质含量很低，说明该次试验中混合层溶质进入地表积水-径流层量很少，而模拟α值很小，与实际情况吻合，同时也说明，土壤中流失的污染物重金属Cr(VI)大多存在于地下排水中。
침대중금속락(Cr)오염엄중적현상，기우간단적이층비완전혼합모형，장강우시농전토양여적수정개계통분위혼합구급혼합구이하량개부분，근거수량평형원리화용질질량수항정률，연구토양재비선성Langmuir흡부조건하，흡부성용질 Cr(VI)적경류류실규률。시험모의적전간지표경류시유강우인기적，근거강우기간토양여우수상호작용정황，장강우과정분위4개계단분별구해진행연구。이용실내모의강우-경류시험소득수거진행모의계산，병통과민감성분석화모형삼수대경류류실량적영향분석，천명모형삼수대토양중흡부성용질경류류실규률적영향。연구결과표명：차이층비완전혼합모형능예측토양재비선성Langmuir흡부조건하，흡부성용질Cr(VI)적경류류실규률。해모형대입삼수용질여토양혼합층용질지간적비완전혼합계수γ비상민감，대토양혼합층용질여지표적수-경류수용질지간적비완전혼합계수α불민감，대Langmuir흡부방정중적삼수B、C야불민감。기중γ화α대모의경류류실과정적영향주요작용우강우전기，이Langmuir흡부방정중적삼수B대모의과정적영향작용우강우전기，C야주요작용우강우전기，단대후기적영향비기타삼수경대。시험수거현시지표경류중용질함량흔저，설명해차시험중혼합층용질진입지표적수-경류층량흔소，이모의α치흔소，여실제정황문합，동시야설명，토양중류실적오염물중금속Cr(VI)대다존재우지하배수중。
Farmland has become less and less in China, but the heavy metal pollution is very serious recently. So, the study on the loss of adsorptive solute of six-valence chromium, i.e. Cr(VI) from soil to surface runoff becomes very important, which is of great significance to understand the expansion of heavy metal pollution in the field. The problem of chromium pollution has been a very serious and worldwide concern recently. In this paper, based on the water balance and solute mass conservation, a simple two-layer incomplete mixing model is used to study adsorptive solute of Cr(VI) loss from soil into surface runoff with nonlinear Langmuir adsorption. Based on the water infiltration, the rainfall process is divided into four stages. Experimental data under the condition of laboratory simulated rainfall-runoff is used to verify the model with nonlinear Langmuir isotherm adsorption equation. Influences of model parameters on the soil solute loss to surface runoff and model sensitivity are analyzed. The results suggest that model simulations with Langmuir isotherm equation agree well with the observed data, which means that the simple two-layer incomplete mixing model is reliable to predict the adsorptive solute of Cr(VI) loss from soil into surface runoff with nonlinear Langmuir adsorption. Parameters γ, which is the incomplete mixing parameter of the solute between the infiltration water and the soil water in the mixing layer, is more sensitive thanαwhich is the incomplete mixing parameter of the solute between the soil water in the mixing layer and the ponding-runoff water. The parametersγandαhave a greater impact on the simulated results of the model in the early stages and smaller impact in the late stages of rainfall, and the parameter B, which is related to the saturated adsorption capacity in nonlinear isotherm equation, has a greater impact on the simulated result in the early stages than the impact in the late stages of rainfall. The parameter C, which is related to the adsorption-desorption equilibrium constant for a reversible reaction and the saturated adsorption capacity adsorbed by single molecular layer in nonlinear isotherm equation, has a greater impact in the early rainfall stage, but a relatively greater impact than other parameters in the model in the later stages. Experimental data indicates that the solute concentration and amount is very small, which means the solute in the mixing layer does not transfer much into ponding-surface runoff layer. This is also proved by the small value of the simulatedα, which also suggests that the most of lost solute of soil Cr(VI) is in the drainage water. The study results will provide references to prevent and reduce the agricultural non-point heavy metal pollution in the field.