Study On The Remediation Of Cadmium And Arsenic Contaminated Farmland By Intercropping Of Pumpkin And Amaranth

The problem of heavy metal pollution in farmland soil needs to be solved urgently.How to realize the production side repair is the focus of current research.Different crops have different absorption of heavy metals.Even the same crops,the difference in heavy metal absorption between different varieties is very large.Therefore,the selection of heavy metal and low accumulation crops can effectively utilize heavy metal contaminated farmland.In this experiment,the economical crops with large biomass,pumpkin and cadmium super-enriched plant amaranth,were used as experimental materials to conduct field experiments,and the heavy metal low-grade pumpkin varieties were screened,and the pumpkin and cadmium super-enriched plants were studied.The effects of different planting patterns,different fertilizers on cadmium and arsenic absorption in pumpkin,and the transformation and migration of As and Cd in soil-pumpkin,and the effects of different patterns on growth,physiological indexes and yield of pumpkin were observed.The main findings are as follows:1.The weight of single fruit of the 25 pumpkin varieties tested was significantly different.The weight of single fruit of different pumpkin varieties ranged from 0.550 to 2.960 kg/piece.This is related to the genotype of the pumpkin itself.The cadmium content of roots,stems,leaves and fruits of pumpkin was significantly different.The cadmium content of most pumpkin cultivars was root>leaf>stem>fruit.The cadmium content of pumpkin root is in the range of 0.051-0.0.462 mg/kg,and the average value is 0.148 mg/kg.The leaf cadmium content ranged from 0.017 to 0.430 mg/kg with an average of 0.100 mg/kg.Stem cadmium content ranged from 0.010 to 0.248 mg/kg with an average of 0.076 mg/kg.The cadmium content of the fruit ranged from 0.002 to 0.05 mg/kg with an average of 0.014 mg/kg.The arsenic content of roots,stems,leaves and fruits of pumpkin was significantly different.The arsenic content of most pumpkin cultivars was root>leaf>stem>fruit.The arsenic content of pumpkin root is in the range of 0.287-1.27 mg/kg,and the average value is 0.643 mg/kg.Leaf arsenic content ranged from 0.1 to 0.460 mg/kg with an average of 0.249 mg/kg.Stem arsenic content ranged from 0.027 to 0.353 mg/kg with an average of 0.135 mg/kg.The fruit arsenic content ranged from 0 to 0.006 mg/kg with an average of 0.0001 mg/kg.The cadmium and arsenic enrichment factors and transport coefficients of roots,stems and leaves of different pumpkin cultivars were significantly different.The cadmium and arsenic enrichment coefficients of all parts of pumpkin were all <1,indicating that the accumulation ability of pumpkin to cadmium and arsenic was not strong.Among them,the cadmium and arsenic enrichment ability of pumpkin leaves is slightly stronger than that of stems,but it is still lower than root accumulation ability,and the fruit enrichment ability is the lowest.It has been verified by field experiments that most of the pumpkin itself has very little absorption of cadmium and arsenic.Planting on moderately mild cadmium and arsenic contaminated soil can also ensure the quality and safety of agricultural products.2.The use of pumpkin and grain intercropping system to repair cadmium and arsenic complex contaminated farmland can repair heavy metal contaminated soil while producing qualified agricultural products.The test results showed that the yield difference between single crop and intercropped pumpkin was not significant.Compared with the single crop,the intercropping reduced the biomass of the pumpkin.Among them,the biomass of the amaranth in the initial period was inhibited,but in the later stage,the biomass of the intercropped grain was significantly increased.Compared with monocropping,the difference of cadmium content in the rhizome of pumpkin was not significant,but the cadmium content in the leaves of pumpkin increased significantly.The intercropping significantly reduced the arsenic content in the stem of pumpkin,and had no significant effect on the absorption of arsenic in the rest of pumpkin.The pumpkin fruit did not exceed the national standard limit.However,intercropping significantly increased the amount of cadmium and arsenic extracted from grain amaranth.In terms of enrichment,the enrichment of cadmium by intercropping of alfalfa increased by 100%,and the enrichment of arsenic increased by 233%.However,from the extraction of unit area,the extraction of alfalfa from monocropping maximum.3.The application of different types of fertilizers has a significant effect on the absorption of cadmium by the pumpkin seed meal intercropping system.The experimental results show that the application of sludge as fertilizer to the soil will significantly increase the effective state of cadmium in the soil and reduce the p H value of the soil,thus causing the plants to absorb more cadmium,so the sludge has certain risks for agricultural use;The ability to help plants grow is not as good as that of chicken manure.However,after applying pig manure,the effective content of cadmium in soil is the lowest,and the cadmium content in plants is also the lowest,indicating that pig manure can effectively inhibit the transfer of cadmium to plants.