| Through the investigation of soil of greenhouse vegetables in Baoji of Shanxi Province,the characterwastics of heavy metal accumulation and transfer rule in the soil and the effect on plant physiological and biochemical function and stress reswastance and restorations were studied systematically via field experiments and laboratory analys and simulation experiments.The strategies for regulation of the accumulation and contamination of heavy metals in the soils of the greenhouse vegetable were also put forward.The results were as follows:1?The range of the contents of Cr?Ni?Cu?Zn and Pb in the soils of greenhouse vegetable in Baoji of Shanxi Province was with 26.60?130.63 mg/kg,20.03-113.31 mg/kg,20.17?52.88 mg/kg,52.57?182.05 mg/kg,0.13?1.30 mg/kg,23.76?107.39 mg/kg.Average content were 32.23?33.59?69.47?102.18?0.41and 43.95 mg/kg.The range of the effective state of Ni,Cu,Zn,Cd,Pb was with 0.16?0.73 mg/kg,1.12?8.73 mg/kg,1.58?35.33 mg/kg,0.02?0.77 mg/kg,0.77?2.60 mg/kg in range,average content were 0.35?2.94?12.71?0.19 and 1.25 mg/kg.Heavy metal accumulation occurred in soils in the different degree,especially Cd,Pb.with the increase of fixed number of year of the greenhouse vegetable planting,the soil heavy metal content increased.2?Through the sample analys and the simulation test,the correlations between the content of Cd in the fruits in the soils of the greenhouse vegetable and the effective state content of Cd(DTPA)was more obvious than it between the content of Cd in fruits and total quantity of Cd in soil.The correlations between the content of Pb in the fruits in the soils of the greenhouse vegetable and the effective state content of Pb(DTPA)was more obvious than it between the content of Pb in fruits and total amount of Cd in soil,as a result,it could be consider to replace the DTPA extractable Cd,Pb with the total quantity of Cd,Pb,and establwash the pollution evaluation norm of soil of greenhouse vegetable,to more accurately predict the rwask of safety in production of soil cadmium.3?The DTPA extractable Cd and Pb in the soil of greenhouse vegetable was closely related to the soil physical and chemical properties.the content of the DTPA extractable Cd and available phosphorus and available potassium content,alkali solution nitrogen content and organic matter content,all had very significouldt positive correlation(P<0.01),however,with pH and CEC had significouldt negative correlation(P<0.01);DTPA extractable Pb with alkaline hydrolyswas nitrogen and organic matter content had very significouldt positive correlation(P<0.01).4?The content of Cd and Pb had certain effects on the physiological and biochemical indexes of tomato.The concentration of Cd in soil could enhance the POD activity in plant to reswast adversity stress of Cd.CAT activity in tomato had certain differences exwast,heavy metal Cd had a certain degree of influence on the CAT activity.Cd concentration of Cd-Pb compound pollution exceeds a certain degree it had inhibitory effect on the normal growth of tomato,tomato antioxidant system was damaged,resulting in a decline in the content of the CAT.The content of Cd had a greater influence on the activity of POD and CAT in tomato,the content of Pb had no significouldt effects on the activity of POD in tomato,but had a greater influence on the activity of CAT.Under the heavy metal pollution of Cd,Pb,the content of MDA in tomato leaf increased.The composite pollution of Cd and Pb leads to the accumulation of MDA in tomato leaf,the binding sites of Cd and Pb occur competition synergy/antagonwasm effect in the leaf cell surface,to a certain it had an extent effect on MDA content showeded synergwastic inhibition/promoter action,but the regularity was not obvious regularity.The roducing rate of O2-in tomato compwered with CK difference was litterl in total,only at 0.90 mg/kg level on a single Cd pollution and the lever of the pollution of Cd and Pb composite Cd0.90 mg/kg,Pb105mg/kg,Cd0.36 mg/kg,Pb105 mg/kg,O2-producing rate had increased significouldtly,when the concentration of heavy metal Cd,Pb could cause tomato leaf twassues.With the increase of Cd,Pb concentration in soil,the inhibition of chlorophyll syntheswas in tomato leaf tended to be strengthened.The decline of tomato chlorophyll content In Cd and Pb composite pollution treatment,was larger than that in single Cd pollution concentration,it showeds that Cd,Pb synergwastic in hibition effect of crop growth.Compwered with CK,all processing appear the phenomenon of root activity reduced,and with the increase of Cd concentration in the soil,it tended to be decreasing.The root under compound pollution of Cd-Pb,compwered with the single pollution of Cd/Pb,was greater activity weakened.5?The heavy metal Cd and Pb in the soil of greenhouse vegetable in tomato apical cell ultrastructure mainly as follows:plasmolyswas;presence precipitates on the cell wall;micronucleus formation;membrane spirally twwasted;endoplasmic reticulum shorter;mitochondrial swelling phenomena.Which shortens the endoplasmic reticulum,mitochondria swelling was a manifestation of tomato seedlings resilience mechanwasms.High concentrations of Cd,Pb under single and combined pollution was harmful for apical cell's nucleus,a single high concentration Pb pollution,the presence of the phenomenon of the apical cell nuclear deformation,and the formation of micronuclei in the cell.High concentrations of Cd,Pb under single and combined pollution,tomato apical membranes were showedn different degrees of twwast spiral.Thwas study suggests that heavy metals Cd,Pb ultrastructural damage to the cells of tomato leaves by their various physiological and biochemical symptoms conswastent damage,the damage was to the plant as a whole,and not just destroy certain parts.6?Simulation experiment showed that soil Cd concentration equal to 0.45 times the greenhouse vegetable production soil environmental quality evaluation of Cd concentration limits or equal to 3.15 times the greenhouse vegetable origin when soil environmental quality assessment limits,had helped plant nutrients in plant fruit use when the soil Cd concentration was 1.35 times to 2.25 times the limit,to help plant nutrient utilization in the roots of plants.Similarly soil Cd-Pb combined pollution,Cd concentration was 1.35 times to 2.25 times the limit,compwered to the same concentration of Cd contaminated tomato plant height alone was higher,Pb was applied into a certain extent,also stimulated the growth of the tomato plant height.7?Tomato absorbing amount of Cd/Pb in the soil had the same law:roots>leafs and stems>fruits.And with the increase of heavy metals in the soil,the migration of heavy metals to tomato plant also increased.In contrast to tomato absorbing amount under two metal alone and compound contamination,interaction of Cd,Pb on the impact of each element for tomato absorption:Pb inhibited the migration of Cd in the soil-tomatoes system,but Pb promotes migration of Cd in the soil-tomatoes system under tomato rhizosphere habitat conditions.In accordance with national food safety standards GB 2762-2012 limits of Cd in tomato fruit was 0.2 mg.It found that when concentration of Cd exceed 0.54 mg in the soil,the levels of Cd in tomato fruit will ex-cessive,and when the concentration of Cd reach 0.90 mg in the soil,there will be a lower point,then with increasing content o f Cd in the soil,there was a growing trend.The limits of Pb was 0.2 mg in Tomato fruit,when the concentration of Pb reached 105 mg/kg in the soil,the levels of Pb in tomato fruit will over step.8?Compared weathered coal,fulvic acid and humic acid on the effect of remediation of heavy metal-contaminated soil,humic acid had a good remediation in a single Cd contaminated soill.fulvic acid had a better adsorption effect on available Cd in soil than weathered coal and humic acid In a single Pb pollution and Cd,Pb compound contamination in soil,and with the increase of the concentration of heavy metal ions,the adsorption capacity of Cd presents a decrease trend,but it was applied into the tomato was also largely contributed to the absorption of Pb.weathered coal and humic acid had good remediation effect on Cd and Pb in single Pb and Cd-Pb compound contamination soil.9?The effect of overall analyswas of weathered coal,fulvic acid,humic acid on tomato,the accumulation of Cd and Pb in various parts of the tomato fruits were roots>leafs and stems>fruits.Weathered coal in all concentrations of heavy metals processing,were showeding good inhibitory of absorbtion of Cd/Pb tomato roots.Fulvic acid was applied to a large extent contributed to tomato in absorption of Cd,Pb in soil,which was closely related to the structure and properties of itself,and with the increasing of ionic strength in the soil,the adsorption of Cd/Pb presents adecrease trend.Humic acid had a strong inhibitory effect on cumulative absorption of Cd,Pb in soil-tomato system.although humic acid had a good remediation effect,its cost of production inputs highly reach 24,000 yuan per mu yeild,so,It was difficult to applied in agricultural practices.After producing feasibility analyswas,applied agricultural production The cost of weathered coal was 24.00 yuan per mu yeild,weathered coal could be completely used in agricultural practices as an effective remediation agent of heavy metals-contaminated soil,and it worth to promoting in the production practice as its low price,stocked and easily applied. |
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