Leaf Structure Characteristics And Spectral Responses Of Dominant Plant Rumex Acetosa In Mining Area Under Pb Contamination

In this paper,Experimental object was Rumex acetosa,which is the dominant plant of mine.A pot experiment was carried out indoor to analyse the enrichment and tolerance characteristics of Rumex acetosa under heavy metal contamination stress.In seeding,peak and mature period of Rumex acetosa 's growth,the changes on 23 parameters of leaf anatomical structural,such as total blade area,area of upper epidermis and perimeter of epidermis,and their the relationships with leaves concentration of Pb and leaf structure parameter N in PROSPECT model were studied,and establishing the fitting model of N by finding the well associated leaf anatomical structural parameters.Also the correlativity between chlorophyll concentration,leaf structure parameter N,leaves concentration of Pb and leaf reflectance spectrum of Rumex acetosa in different growing stages were studied,the best growth period with high correlation was found out and the estimation model of Pb concentration in leaves was established.Being possible to provide reference for the treatment and phytoremediation of heavy metal pollution in the mine and lay the foundation for monitoring Pb pollution by remote sensing.The main results were as follows:(1)By analysing the transfer factor,enrichment coefficient and Pb concentration of Rumex acetosa,finding out that enrichment coefficient was less than 1 and transfer factor was more than 1.Rumex acetosa was not the hyperaccumulator of Pb,but its biomass was large and it had strong endurance to Pb.(2)Under Pb contamination stress,there were great changes in the internal anatomical structure of the leaves.The number of cells in the leaves decreased,the distribution of cells was irregular,and the development of tissue was abnormal.In the peak period of Rumex acetosa 's growth,the perimeter of the upper epidermis was significantly influenced by the concentration of Pb in leaves and has the best fitting effect with the concentration of Pb in leaves.The leaf anatomical structural parameters which were strikingly related to the leaf structure parameters N were selected and respectively established the stepwise regression equations,single-variable linear and nolinear regression equations with N.Among them,the logarithmic equation with the area of upper epidermis as the independent variable in the peak period of Rumex acetosa 's growth was the best estimation model and the precision of this model was 98.91%.(3)In the mature period of Rumex acetosa 's growth,the spectral response band and spectral characteristic parameter to chlorophyll a content were 736nm~787nm and the peak of near-infrared.In the seeding period of Rumex acetosa 's growth,the spectral response bands and spectral characteristic parameter to chlorophyll b content were 389nm~421nm,538nm~573nm,585nm~660nm,728nm~773nm and yellow edge area.In the peak period of Rumex acetosa 's growth,the spectral response bands and spectral characteristic parameter to N were 541 nm ~ 566 nm,592nm ~ 608 nm,720nm ~ 732 nm,764nm ~ 767 nm and yellow edge amplitude.(4)In different periods of Rumex acetosa 's growth,the sensitive bands of leaf Pb content were concentrated in the visible and infrared band.By means of correlation analysis,sensitive bands were picked out from reflectance spectra in different periods of Rumex acetosa 's growth,and the relationship between leaf Pb content and sensitive bands were established using stepwise regression analysis model.As a result of correlation analysis,the spectral characteristic parameters which were significantly correlated with leaf Pb content were picked out,furthermore,the relationship between leaf Pb content and the spectral characteristic parameters were established by using linear regression model.At last,sensitive bands were much better than spectral characteristic parameters in terms of capability of estimating leaf Pb content,moreover,the stepwise regression estimation model had better precision.And the mature period of Rumex acetosa 's growth was the best time for inversion calculation of leaf Pb content.During this period,the accuracy of multiband stepwise regression model was as high as 99%.