Microbial-Toxicological Combined Response Mechanism And Simulation Of Groundwater Polluted By Farming In Desertification Areas

The key point to investigate the combination responses mechanism of the index of microbial-toxicological indicators(Total bacterial community,Total E.coli community)is the soil water matrix environment.The key scientific problems in the response of different matrix environmental conditions to groundwater microbial-toxicological indicators can be illustrated as follows: the combination responses mechanism of the index of groundwater microorganism-toxicology and the prediction of the index of the microorganism-toxicology in the karst groundwater.In this paper,the orthogonal test was introduced to the rough set method and the initial decision tables were established.The influencing factors of the index of groundwater microorganism-toxicology were screened.Subsequently,the research object was chosen as the karst groundwater,which located at the typical XiaoJiang river basin in the desertification area.The response relationships of the index of the microorganism-toxicology in the karst groundwater were investigated based on the different environment conditions,such as temperature,PH values,and porosity.Finally,the prediction model of the index of the microorganism-toxicology in the karst groundwater at the desertification area was proposed and established.The main conclusions were as follows:The main environmental factors which influenced the index of the microorganism-toxicology in the karst groundwater were determined as the temperature,PH values,and porosity.The seepage process of the soil water was implemented in the laboratory tests to simulate the undisturbed soil in the desertification area.The initial decision tables based on the rough set method were established according to the orthogonal tests,and then the influencing factors of temperature,illumination,PH,particle sizes,porosity,NaCl concentration,and velocity of water flow were reduced according to the attribute.The results show that: the main influencing factors of the index of the microorganism-toxicology are temperature,PH,and porosity(the cumulative contribution reached at 85.93%).The response mechanisms of the index of the microorganism-toxicology in the karst groundwater were revealed by the main influencing factors,i.e.,temperature,PH,and porosity.Temperature is the direct influencing factors that affect the index of the microorganism-toxicology.PH and porosity changed the oxygen content of the soil water environment and the charge coverage of the medium surface,then,these variations directly or indirectly changed the positive and negative charge of the groundwater environment and the redox environment.Consequently,the index of the microorganism-toxicology of the groundwater was evolved by these variations.The prediction model of the index of the microorganism-toxicology in the karst groundwater at the desertification area was established.Although the main influencing factors(temperature,PH,and porosity)showed different responses mechanisms to the index of the microorganism-toxicology,the algorithm of support vector machine based on the particle swarm optimization(PSO-SVM)could map the laboratory data to the multi-space with nonlinear transformation,and established the training samples of the index of the microorganism-toxicology.Then,the optimal linear classification surface was calculated based on the convex quadratic programming,which meant that the extremal solution was the global optimal solution.Finally,the prediction model of the index of the microorganism-toxicology in the karst groundwater at the desertification area was established.In summary,the response mechanisms of the index of the microorganism-toxicology in the groundwater were revealed under different matrix environment conditions,and the prediction model of the index of the microorganism-toxicology in the karst groundwater at the desertification area was established.The degree of ecological environment pollution in karst water resources and soil zone could be accurately judged,which could provide scientific basis for sustainable utilization of groundwater resources and effective prevention and control of groundwater pollution.