Research On Ecosystem Vulnerabilization And Its Cascading Spread Mechanisms Caused By Dust Discharge

The waste discharged from mine dust during the mining of mineral resources enters the environment through surface runoff and airborne particles,which has a serious impact on the atmospheric environment and the surface eco-environment.From the perspective of pollution discharge process,integrating the problems of vulnerability assessment and cascade spread,the aims of this paper are to reveal the spatial distribution characteristics of mine dust emission sources and migration,to analyze the cascade spread law of vulnerability in the contaminated area,and to propose a suitable method for eco-environment vulnerability assessment caused by mine dust and a cascade spread model of mine dust migration-induced vulnerability.The study of eco-environment vulnerability provides scientific basis for the restoration and reconstruction of fragile eco-environment and is an important prerequisite for regional sustainable development planning.At the same time,it is of great significance to study the cascade spread of the vulnerability of the eco-environment in the related areas for the joint control and control of pollution emissions in the eco-environment.The main research works in this paper are as follows:First,based on Petri nets(PN)of chemical reactions,this paper endows the elements of traditional PNs with chemical meanings,constructs air compound pollution PNs caused by exhaust gas through chemical reactions and conservation relations of various places,and excavates the chain reaction process that initial pollutant generates secondary pollution from the outlet in a coal mine.And in this paper,the formulas of different forms of secondary pollution damage degree are defined.Applying the above formulas to the evaluation model,an evaluation model for the damage degree ofatmospheric compound pollution based on chemical reaction PNs is proposed,and the corresponding algorithm is given.Second,a new dynamic evaluation model of ecosystem vulnerability named object function PN model,which introduces the concept of function into traditional object PN,was put forward.The facilitating and suppressing factors to ecosystem degradation were analyzed in this evaluation model.Trigger conditions of vulnerability were depicted as transitions and the state of ecosystem in the process of change were depicted as object places;indexes of evaluation were depicted as attributes and actions which updated attributes were depicted as functions.Logical causality of environmental degradation could be represented directly.Through object-function Petri net,thereby combining the rules of model,a reasoning algorithm was posed.Third,in order to solve uncertain problem induced by the fuzzy boundary of the complicated ecosystem and the redundant problems caused by the large number of similar processes,a new evaluation model of ecosystem vulnerability is put forward based on object PN and rough set theories.Using three equivalent relations in the rough object PN,the space of equivalent class partition of transitions,place and object,are established.Thereby two precise upper and lower approximation nets as boundary lines are used to characterize the uncertainty of ecosystem in object space.Fourth,to describe the cascading spread problems of ecosystem vulnerability with continuous disturbance,a novel model based on object function GeoPetri net,which introduces the GIS into traditional object function net,is constructed.The model makes elements of the PN fully reflect in ecosystem;the trajectory of pollutant migration can be depicted as cascading spread path;ecological subsystems can be depicted as object places;geographical relations and logical relations can be depicted as transitions;triggering conditions can be depicted as arcs from place to transition;comprehensively considered not only the paths of pollutant migration but also the geographical relationships between ecological subsystems,eco-environment PN based on cascading spread could be constructed in a graphical manner.On this basis,the concepts of vulnerability and ecological threshold based on the model of OFGPN are defined.The relationship between them is used to analyze the probability with cascade spread,in order to identify three states of cascading spread.In addition,an effective new global indicator of the scale of cascade spread is put forward to measure the vulnerability withcascading spread in the whole ecosystem.The optimal parameters of the model on the scale with cascade spread can be obtained by the random searching algorithm.Finally,in order to describe the cascade spread of pollution related networks in the eco-environment under multi-source dust migration,a new object function colored GeoPetri net model was proposed by using colored PNs to distinguish pollution sources in different mining areas.And based on the HYSPLIT model of spatial distribution of dust pollution,this paper defines three relationships,and constructs a multi-source pollution linked eco-environment vulnerability cascade spraed Petri net.In the model,the vulnerability of multi-source pollution,the ecological threshold based on land use type and the cascade spread scale caused by pollution association are redefined.The cascade spread process of pollution Association network,the influence of correlation on vulnerability and the influence of threshold change on the cascade spread scale under the influence of pollution association are analyzed.At present,the existing research has made certain contributions to the evaluation of the vulnerability of the ecosystem.However,from the source of pollution,the modeling method and research of the evaluation of the dust emission leads to the continuous vulnerability of the ecosystem and the vulnerability cascade spread in pollution-related areas under migration and sedimentation are still in the exploration stage.In view of the shortcomings of the above studies,this paper reveals the cascade spread characteristics of eco-environment vulnerability in the associated areas under the migration of mineral dust,proposes a vulnerability cascade analysis method based on the object function GeoPetri pollution correlation area,and constructs the theoretical analysis framework of eco-environment vulnerability assessment and cascade spread caused by mine dust emission.To sum up,this paper not only expands the theory and method of eco-environment vulnerability assessment,but also has important application value.