Previous soil pot and field experiments demonstrated that co-cropping the hyperaccumulator Sedum alfredii with maize increased Zn phytoextraction by S. alfredii and decreased Zn uptake by maize shoots. This hydroponic...Previous soil pot and field experiments demonstrated that co-cropping the hyperaccumulator Sedum alfredii with maize increased Zn phytoextraction by S. alfredii and decreased Zn uptake by maize shoots. This hydroponic experiment was conducted to investigate whether the facilitation of Zn phytoextraction by S. alfredii resulted from improved dissolution in this co-cropping system and its relation to root exudates. S. alfredii and maize were mono-and co-cropped （without a root barrier） in nutrient solution spiked with four Zn compounds, ZnS, ZnO, Zn3（PO4）2 and 5ZnO·2CO3·4H2O （represented as ZnCO3 ） at 1000 mg/L Zn for 15 days without renewal of nutrient solution after pre-culture. The root exudates were collected under incomplete sterilization and analyzed. The results indicated that the difference in Zn salts had a greater influence on the Zn concentration in maize than for S. alfredii, varying from 210-2603 mg/kg for maize shoots and 6445-12476 mg/kg for S. alfredii in the same order： ZnCO3 〉 ZnO 〉Zn3（PO4）2 〉 ZnS. For the four kinds of Zn sources in this experiment, co-cropping with maize did not improve Zn phytoextraction by S. alfredii. In most cases, compared to co-cropped and mono-cropped maize, mono-cropped S. alfredii resulted in the highest Zn2＋ concentration in the remaining nutrient solution, and also had a higher total concentration of low molecular weight organic acids （LMWOA） and lower pH of root exudation. Root exudates did partly influence Zn hyperaccumulation in S. alfredii.展开更多
‘Lvbao-701’ is a cultivar of Chinese flowering cabbage(Brassica parachinensis) that exhibits low cadmium(Cd) accumulation and high Cd tolerance.In this study, this cultivar was compared with a high-Cd accumulating c...‘Lvbao-701’ is a cultivar of Chinese flowering cabbage(Brassica parachinensis) that exhibits low cadmium(Cd) accumulation and high Cd tolerance.In this study, this cultivar was compared with a high-Cd accumulating cultivar, ‘Chixin-4’, to characterize the mechanisms influencing Cd accumulation in B. parachinensis. Root cell walls were isolated by dissolving the cytoplasm with an organic solvent, and root Cd and phytochelatin(PC) contents were analyzed. In addition, a PC synthase gene fragment was cloned and expressed under Cd stress conditions. The proportions of Cd bound to root cell walls were higher in the ‘Lvbao-701’ plants(68.32%–76.80%) than in the ‘Chixin-4’ plants(35.36%–54.18%) after exposure to Cd stress. The proportions of Cd bound to root cell walls measured using cell walls isolated with a non-destructive method were higher than those obtained using a conventional method that required grinding and centrifugation. Exposure to Cd stress induced the PC production and resulted in higher PC contents in the ‘Lvbao-701’ plants than in the ‘Chixin-4’ plants. Cloning and expression analysis of a B. parachinensis PC synthase cDNA fragment indicated that PC synthase gene expression was induced by Cd and occurred mainly in the roots of both ‘Lvbao-701’ and ‘Chixin-4’ plants. However, the PC synthase gene expression level was higher in the‘Lvbao-701’ roots than in the ‘Chixin-4’ roots. Therefore, a higher abundance of Cd in the root cell walls of ‘Lvbao-701’ and up-regulated PC production in the roots are probably the main reasons why ‘Lvbao-701’ exhibits lower Cd translocation to the shoots and higher tolerance to Cd than ‘Chixin-4’.展开更多
Soil heavy metal pollution is one of the biggest issues that we are facing today,which poses serious threats to ecosystems and communities.However,a lack of efficient means and incomplete monitoring data are the main ...Soil heavy metal pollution is one of the biggest issues that we are facing today,which poses serious threats to ecosystems and communities.However,a lack of efficient means and incomplete monitoring data are the main obstacles impeding soil pollution management and prevention in China.Moreover,it is rare to examine the possibility and reliability of using field-collected earthworms to assess the pollution degree of soil heavy metals in real-world situations at a large field scale.In this study,we investigate the potential use of field-collected earthworms as bio-indicators to assess the pollution characteristics and risks of heavy metals(Zn,Pb,Cu,As,Cd,and Cr)across three typical regions(Xiaokeng Reservoir,Dabaoshan Mine,and Smelter/Steel Plants)in Shaoguan,one of six trial zones identified for the Soil Pollution Prevention and Control Action Plan in China.Our results unveil the existence of significant differences in the spatial distribution and bioavailability of heavy metals in soils and earthworms across these regions.The average contents of Zn,Pb,Cu,As,Cr,and Cd in soils were 329.7±476.5,180.9±262.4,82.9±197.8,66.6±61.6,53.3±53.6,and 7.2±8.2 mg/kg,while those in earthworms were 113.6±112.1,99.4±106.8,90.0±126.9,24.7±30.8,8.8±9.4,and 5.1±3.4 mg/kg,respectively.The internal exposure dose of heavy metals in earthworms is found to more accurately reflect their bioavailability under true environmental conditions than the external exposure dose in soils.The bioaccumulation factor(BAF)exhibited the highest values for Cd(0.01−24.40),followed by those for Pb(0.06−9.94),Cu(0.12−5.23),Cr(0.02−1.90),As(0.02−1.18),and Zn(0.06−1.17).Further principal component analysis(PCA)and random forest(RF)classification ascertain that earthworms are more capable of differentiating heavy metal pollution in different regions than soil alone.Compared to the routine analysis of the total heavy metal content in soils,our novel strategy demonstrates the superiority of employing field-collected earthworms as bio-indicators for monitoring heavy metal pollution and discriminating potential sources of soil pollution in a real scenario.展开更多
The treatment and disposal of municipal sewage sludge(MSS)is an urgent problem to be resolved in many countries.Safely using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could...The treatment and disposal of municipal sewage sludge(MSS)is an urgent problem to be resolved in many countries.Safely using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could contribute to achieving sustainable development.An indirect use of MSS in ditches alongside Pennisetum hybridum plants was studied in field plots for 30 months and the contents of heavy metals and macronutrients were monitored in soil,sludge and plant samples.We found that the yield of P.hybridum was significantly increased by 2.39 to 2.80 times and the treated plants had higher N content compared with no sludge.In addition,the organic matter(OM)and N contents in the planted soil increased significantly compared with the initial soil.The OM content in the planted soil of the MSS treatment was 2.9 to 5.2 times higher than that with no sludge,and N increased by 2.0 to 3.8 times.However,MSS had no significant effect on the N,P and K contents in the soil at the bottom of the MSS ditch,and the content of heavy metals(Cd,Pb,Cu and Zn)were also within the safe range.Moreover,the moisture content and phytotoxicity of MSS after this indirect use were reduced and the heavy metal contents changed little,which is favorable to the further disposal of recovered MSS.Therefore,this indirect use of MSS is beneficial to agricultural production,soil quality and environmental sustainability.展开更多
基金supported by the National Natural Science Foundation of China (No. 40571141, 410713061)
文摘Previous soil pot and field experiments demonstrated that co-cropping the hyperaccumulator Sedum alfredii with maize increased Zn phytoextraction by S. alfredii and decreased Zn uptake by maize shoots. This hydroponic experiment was conducted to investigate whether the facilitation of Zn phytoextraction by S. alfredii resulted from improved dissolution in this co-cropping system and its relation to root exudates. S. alfredii and maize were mono-and co-cropped （without a root barrier） in nutrient solution spiked with four Zn compounds, ZnS, ZnO, Zn3（PO4）2 and 5ZnO·2CO3·4H2O （represented as ZnCO3 ） at 1000 mg/L Zn for 15 days without renewal of nutrient solution after pre-culture. The root exudates were collected under incomplete sterilization and analyzed. The results indicated that the difference in Zn salts had a greater influence on the Zn concentration in maize than for S. alfredii, varying from 210-2603 mg/kg for maize shoots and 6445-12476 mg/kg for S. alfredii in the same order： ZnCO3 〉 ZnO 〉Zn3（PO4）2 〉 ZnS. For the four kinds of Zn sources in this experiment, co-cropping with maize did not improve Zn phytoextraction by S. alfredii. In most cases, compared to co-cropped and mono-cropped maize, mono-cropped S. alfredii resulted in the highest Zn2＋ concentration in the remaining nutrient solution, and also had a higher total concentration of low molecular weight organic acids （LMWOA） and lower pH of root exudation. Root exudates did partly influence Zn hyperaccumulation in S. alfredii.
基金This study was supported by the National Natural Science Foundation of China(No.41371308),the Science and Technology Supporting Project of China(No.2015-BAD05B05)the Research Project of the Education Department of Guangdong Province,China(No.2013-CXZDA007).
文摘‘Lvbao-701’ is a cultivar of Chinese flowering cabbage(Brassica parachinensis) that exhibits low cadmium(Cd) accumulation and high Cd tolerance.In this study, this cultivar was compared with a high-Cd accumulating cultivar, ‘Chixin-4’, to characterize the mechanisms influencing Cd accumulation in B. parachinensis. Root cell walls were isolated by dissolving the cytoplasm with an organic solvent, and root Cd and phytochelatin(PC) contents were analyzed. In addition, a PC synthase gene fragment was cloned and expressed under Cd stress conditions. The proportions of Cd bound to root cell walls were higher in the ‘Lvbao-701’ plants(68.32%–76.80%) than in the ‘Chixin-4’ plants(35.36%–54.18%) after exposure to Cd stress. The proportions of Cd bound to root cell walls measured using cell walls isolated with a non-destructive method were higher than those obtained using a conventional method that required grinding and centrifugation. Exposure to Cd stress induced the PC production and resulted in higher PC contents in the ‘Lvbao-701’ plants than in the ‘Chixin-4’ plants. Cloning and expression analysis of a B. parachinensis PC synthase cDNA fragment indicated that PC synthase gene expression was induced by Cd and occurred mainly in the roots of both ‘Lvbao-701’ and ‘Chixin-4’ plants. However, the PC synthase gene expression level was higher in the‘Lvbao-701’ roots than in the ‘Chixin-4’ roots. Therefore, a higher abundance of Cd in the root cell walls of ‘Lvbao-701’ and up-regulated PC production in the roots are probably the main reasons why ‘Lvbao-701’ exhibits lower Cd translocation to the shoots and higher tolerance to Cd than ‘Chixin-4’.
基金supported by the National Key Research and Development Program of China(2022YFC3701302)Youth Innovation Promotion Association of Chinese Academy of Sciences(2019042).
文摘Soil heavy metal pollution is one of the biggest issues that we are facing today,which poses serious threats to ecosystems and communities.However,a lack of efficient means and incomplete monitoring data are the main obstacles impeding soil pollution management and prevention in China.Moreover,it is rare to examine the possibility and reliability of using field-collected earthworms to assess the pollution degree of soil heavy metals in real-world situations at a large field scale.In this study,we investigate the potential use of field-collected earthworms as bio-indicators to assess the pollution characteristics and risks of heavy metals(Zn,Pb,Cu,As,Cd,and Cr)across three typical regions(Xiaokeng Reservoir,Dabaoshan Mine,and Smelter/Steel Plants)in Shaoguan,one of six trial zones identified for the Soil Pollution Prevention and Control Action Plan in China.Our results unveil the existence of significant differences in the spatial distribution and bioavailability of heavy metals in soils and earthworms across these regions.The average contents of Zn,Pb,Cu,As,Cr,and Cd in soils were 329.7±476.5,180.9±262.4,82.9±197.8,66.6±61.6,53.3±53.6,and 7.2±8.2 mg/kg,while those in earthworms were 113.6±112.1,99.4±106.8,90.0±126.9,24.7±30.8,8.8±9.4,and 5.1±3.4 mg/kg,respectively.The internal exposure dose of heavy metals in earthworms is found to more accurately reflect their bioavailability under true environmental conditions than the external exposure dose in soils.The bioaccumulation factor(BAF)exhibited the highest values for Cd(0.01−24.40),followed by those for Pb(0.06−9.94),Cu(0.12−5.23),Cr(0.02−1.90),As(0.02−1.18),and Zn(0.06−1.17).Further principal component analysis(PCA)and random forest(RF)classification ascertain that earthworms are more capable of differentiating heavy metal pollution in different regions than soil alone.Compared to the routine analysis of the total heavy metal content in soils,our novel strategy demonstrates the superiority of employing field-collected earthworms as bio-indicators for monitoring heavy metal pollution and discriminating potential sources of soil pollution in a real scenario.
基金supported by R and D program of Guangdong Provincial Department of Science and Technology,China(Nos.2019BT02L218 and 2018B030324003)Water Resources Innovation Project of Guangdong Province,China(Nos.2017-07 and 2017-29)+1 种基金National Natural Science Foundation of China(Grant No.21606092)Pearl River S and T Nova Program of Guangzhou,China(No.201710010109).
文摘The treatment and disposal of municipal sewage sludge(MSS)is an urgent problem to be resolved in many countries.Safely using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could contribute to achieving sustainable development.An indirect use of MSS in ditches alongside Pennisetum hybridum plants was studied in field plots for 30 months and the contents of heavy metals and macronutrients were monitored in soil,sludge and plant samples.We found that the yield of P.hybridum was significantly increased by 2.39 to 2.80 times and the treated plants had higher N content compared with no sludge.In addition,the organic matter(OM)and N contents in the planted soil increased significantly compared with the initial soil.The OM content in the planted soil of the MSS treatment was 2.9 to 5.2 times higher than that with no sludge,and N increased by 2.0 to 3.8 times.However,MSS had no significant effect on the N,P and K contents in the soil at the bottom of the MSS ditch,and the content of heavy metals(Cd,Pb,Cu and Zn)were also within the safe range.Moreover,the moisture content and phytotoxicity of MSS after this indirect use were reduced and the heavy metal contents changed little,which is favorable to the further disposal of recovered MSS.Therefore,this indirect use of MSS is beneficial to agricultural production,soil quality and environmental sustainability.
