Growing Responses And Hyperaccumulating Characteristics Of Plants To As-P Combined Pollution

This issue has caused wide public concern which is the pollution problem, especiallycombined pollution, of heavy metals in soils. And it is one of the environmental hot spotsor difficulties and problems researching of the important points both at home and abroadfor preventing pollution of heavy metals in soils, includes phytoremediation.It is the important foundation for achieving phytoremediation for pollution of heavymetals in soils to research and try to find out growing responses and hyperaccumulatingcharacteristics of plants to arsenic(As) and phosphorus(P) combined pollution or interaction.Therefore, the research works are carried out in this field on two target plants of Polygonumlapathifolium L. and Rumex dentatus L. growing at a nonferrous metals mining area inYunnan through outdoor observation and solution culture in a greenhouse.In the first place, an experimental and research method is given out related to designon research scheme, sampling and pretreating on samples of plants and soils, experiment onsolution culture, process on quality control and quality assurance(QC/QA), etc.(1) It is introduced in research scheme that the study of object and their properties. Onthis basis, this paper provides the experimental methods of through outdoorobservation and solution culture in a greenhouse and technology process,determines the terms and methods of analysis.(2) It is for relating to the credibility of research results and the accuracy of researchconclusions that the ways and means of sampling and pretreating on the samples ofplants are right or not. It must make a liberal allowance for them. The recognizedways and means of knowing in the field of botany are adopted in sampling andpretreating on the samples of plants.(3) The ways and means provided for by China National Standards GB 15618-1995Environmental quality standard for soils and by Environmental Trade StandardsHJ/T 166-2004 The Technical Specification for Soil Environmental Monitoring areadopted in sampling and pretreating on the samples of soils.(4) The experiment on solution culture carried out in a greenhouse. It includes todispense with solution culture according to Hoagland-Arnon(1938) General Recipeadded as an additional constituents of As and P with different percentages, and toestablish with experimental plan according to a method of factors analysis. (5) Many measures have been taken by means of establishing QC/QA System in thecourses of studies including sampling, experiment on solution culture, selectinganalytical methods, determination samples, processing data, etc. in order to ensurethe data and results having representative, accuracy, comparable and integrity.And Secondly, the science researches on growing responses and hyperaccumulatingcharacteristics of plants to As and P combined pollution or interaction are carried outaccording to the plan. It is investigated on the mechanism for two target plants ofPolygonum lapathifolium L. and Rumex dentatus L. absorption As. The results indicatedthat:(1) There are potential hyperaccumulating characteristics to As for the dominantspecies of plants of Pteris vittata L., Equesetum difusm D.Don, Polygonumlapathifolium L., Rumex dentatus L., Buddleja officinalis Maxim, Kicinuscommunis L., Bidens pilosa etc. at a nonferrous metals mining area in Yunnan. Thebioaccumulation coefficient(BC) and translocation coefficient(TC) of the plantsare far exceed 1.(2) The mechanism for two target plants of Polygonum lapathifolium L. and Rumexdentatus L. absorption As shows the plant effects of soil combined pollution orinteraction with As such as synergistic and antagonistic action etc. as well as theways and chemical action of the plants absorption As such as reaction between anacid and a base, oxidation-reduction reaction, complexing reaction, biochemicalreaction, activation and fixed, adsorption and desorption etc. As and P combinedpollution has a synergy under specified conditions. So the issue of soil combinedpollution or interaction should be pay great attention to it.(3) The main factors which affect the plants to absorb As in soil are the kind of plant,the characteristics of As, the state of oxidation-reduction of soil, acid-baseproperties of soil, cation exchange capacity of soil and graininess and granularityof soil, etc.At finally, the researches are did for growing responses and hyperaccumulatingcharacteristics of plants to As and P combined pollution or interaction, and compared withexperiments of outdoor observation and solution culture in a greenhouse. The resultsshowed that:(1) The growing responses of two target plants of Polygonum lapathifolium L. andRumex dentatus L. were different one another, depending on their species such asgrowing state, dry weight, chlorophyll contents and height of target plants, etc., and hyperaccumulating characteristics of plants to As such as contents of As indifferent parts of the plants, BC and TC etc. The sequence of tolerance to As-Pcombined pollution was Rumex dentatus L. and Polygonum lapathifolium L., andAs had Rumex dentatus L. more effects on the growth of plants, and Polygonumlapathifolium L. had less.(2) There are many factors that effect on growing responses and hyperaccumulatingcharacteristics to As of two target plants of Polygonum lapathifolium L. and Rumexdentatus L. under As-P combined pollution. For the two plants, the interactiveeffect of As and P were complicated, not simply additive, antagonistic andsynergistic, but also related with many factors including various concentrationcombinations of As-P, plant species and different tissues.