Water pollution is one of the most important issues of the 21<sup>st</sup> century. It takes place when the pollutants are being entered into a water reservoir without any treatment. Heavy metals are one o...Water pollution is one of the most important issues of the 21<sup>st</sup> century. It takes place when the pollutants are being entered into a water reservoir without any treatment. Heavy metals are one of the major harmful pollutants that exist in the water;therefore, it is necessary to remove these toxic metals to keep our environment safe. Biosorption is an ecofriendly and economical technique for the elimination of these toxic metals from polluted water. In this research work roots, stems, and leaves of Momordica charantia (Bitter gourd) were used as biosorbent for the elimination of Pb (II) ions from aqueous solution. Many different parameters such as metal ion solution pH, biomass dosage, initial metal ions concentration and contact time were optimized in the batch experiments. The calculated results revealed that biosorption of Pb (II) was maximum at solution pH 5, biosorbent dosage of 0.1 g and 100 ppm of initial metal ions concentration within 240 minutes of contact time. M. charantia’s leaves showed the highest level of lead biosorption capacity (47.62%), followed by stems (42.36%) and roots (38.47%). The Freundlich isotherm and pseudo-second order kinetics model fitted well for the analytical data. The results indicated that Momordica charantia is an effective biosorbent for Pb (II) ions elimination from wastewater.展开更多
This study was conducted to assess availability, phytotoxicity and bioaccumulation of lead （Pb） to ryegrass （Lolium perenne L.） and millet （Echinochloa crusgalli） based on the 0.1 mol/L Ca（NO3）2 extraction. Ef...This study was conducted to assess availability, phytotoxicity and bioaccumulation of lead （Pb） to ryegrass （Lolium perenne L.） and millet （Echinochloa crusgalli） based on the 0.1 mol/L Ca（NO3）2 extraction. Effect of soil properties on availability, phytotoxicity and bioaccumulation of Pb to the two plants was also evaluated. Five soils with pH values varying from 3.8 to 7.3, organic carbon （OC） contents from 0.7% to 2.4%, and clay contents from 11.6% to 35.6% were selected. Soils were spiked with Pb to achieve a range of concentrations： 250, 500, 1000, 3000 and 5000 mg/kg. Pb availability in the spiked soils was estimated by extracting soil with 0.1 mol/L Ca（NO3）2. The results indicate that plants yield decreased with decreasing soil pH and increased with increasing soil clay and OC content. Negative relationship between available Pb and the relative dry matter growth （RDMG） of the two plants were significantly related. Available Pb used to assess EC20 （20% effective concentration） and EC50 （50% effective concentration） of millet was 119 and 300 mg/kg, respectively. Available Pb used to assess EC20 and EC50 of ryegrass was 63 and 157 mg/kg, respectively. Bioaccumulation, expressed as bioconcentration factors of Pb, was inversely related to soil pH, soil OC and clay content. Strong relationships were found between available lead and uptake by the two plants （P was 0.92 and 0.95 respectively）. In general, 0.1 mol/L Ca（NO3）2 available Pb may be used to assess the availability, phytotoxicity and bioaccumulation of lead to the two plants tested.展开更多
Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its envi- ronmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of pro- c...Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its envi- ronmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of pro- creation function and descending of genital immunity. Experiments on pot-growth of paddies and corns in this study indicated that these crops did not show any macro-toxic symptoms in the observed contents of Pb added (0–4000 mg/kg) in soils. However, lead in soils can be easily absorbed by crops and accumulated in the different parts of plants. Statistical analysis showed that Pb contents in the crops are strongly positively correlated to the Pb contents in soils. In the crops, the Pb contents of roots are highest, tens to thousands of times those of straws and seeds. It is suggested that the root is a barrier of Pb absorbed by straws and seeds. Based on this fact, Pb pollution in soils can be gradually reduced by planting crops and subsequently removing the roots from the soil. This biotechnology may be used in environmental remediation, which embraces the quality of sustainable agricultural economy and a healthy environment.展开更多
This study was carried out to detect content of heavy metals( Pb,Cd,and As) in vegetables,understand the current situation of heavy metal contamination in vegetables,and to provide scientific reference for further res...This study was carried out to detect content of heavy metals( Pb,Cd,and As) in vegetables,understand the current situation of heavy metal contamination in vegetables,and to provide scientific reference for further researches. It randomly selected 6 large vegetable markets and 6 supermarkets in Changsha City,selected 8 types of typical vegetables,and detected 96 samples. In accordance with maximum level of contaminants in foods in existing GB2762- 2012 standard,Nemerow composite pollution index( Pt) and grading standards,it made evaluation: uncontaminated( Pt≤ 1),mildly contaminated( 1 < Pt≤2),moderately contaminated( 2 < Pt≤3),and highly contaminated( Pt>3). Among 96 samples,range of content of Pb,Cd and As is( 0. 06- 1. 41),( 0. 06- 1. 26) and( 0. 00- 0. 91) mg / kg respectively; the over- limit rate of these metals exceeding the safety level is 78. 13%,45. 83%,and 34. 38% separately; the composite pollution index is in( 0. 90-6. 05),the eggplant is 6. 05 and hot pepper is 3. 24; the content of Pb( F =23. 908,P =0. 001) and Cd( F =64. 908,P =0. 000)are significantly different between 8 types of vegetables and there is no significant difference between the content of As( F = 4. 634,P = 0. 705> 0. 05) in 8 types of vegetables. Study shows that common vegetables in Changsha City has problem of excess Pb,Cd and As,and the Pb over- limit rate is the highest. The composite pollution index indicates that most heavy metal contamination of vegetables is mild and moderate contamination,melon,fruit and vegetable contamination is high contamination,and Cd is the major factor leading to contamination of melons,fruits and vegetables.展开更多
文摘Water pollution is one of the most important issues of the 21<sup>st</sup> century. It takes place when the pollutants are being entered into a water reservoir without any treatment. Heavy metals are one of the major harmful pollutants that exist in the water;therefore, it is necessary to remove these toxic metals to keep our environment safe. Biosorption is an ecofriendly and economical technique for the elimination of these toxic metals from polluted water. In this research work roots, stems, and leaves of Momordica charantia (Bitter gourd) were used as biosorbent for the elimination of Pb (II) ions from aqueous solution. Many different parameters such as metal ion solution pH, biomass dosage, initial metal ions concentration and contact time were optimized in the batch experiments. The calculated results revealed that biosorption of Pb (II) was maximum at solution pH 5, biosorbent dosage of 0.1 g and 100 ppm of initial metal ions concentration within 240 minutes of contact time. M. charantia’s leaves showed the highest level of lead biosorption capacity (47.62%), followed by stems (42.36%) and roots (38.47%). The Freundlich isotherm and pseudo-second order kinetics model fitted well for the analytical data. The results indicated that Momordica charantia is an effective biosorbent for Pb (II) ions elimination from wastewater.
基金The Strategic Environment Research and Development Program(SERDP), USA Project and the Alcoa Foundations Conservation andSustainability Fellowship Program (SDRAC)
文摘This study was conducted to assess availability, phytotoxicity and bioaccumulation of lead （Pb） to ryegrass （Lolium perenne L.） and millet （Echinochloa crusgalli） based on the 0.1 mol/L Ca（NO3）2 extraction. Effect of soil properties on availability, phytotoxicity and bioaccumulation of Pb to the two plants was also evaluated. Five soils with pH values varying from 3.8 to 7.3, organic carbon （OC） contents from 0.7% to 2.4%, and clay contents from 11.6% to 35.6% were selected. Soils were spiked with Pb to achieve a range of concentrations： 250, 500, 1000, 3000 and 5000 mg/kg. Pb availability in the spiked soils was estimated by extracting soil with 0.1 mol/L Ca（NO3）2. The results indicate that plants yield decreased with decreasing soil pH and increased with increasing soil clay and OC content. Negative relationship between available Pb and the relative dry matter growth （RDMG） of the two plants were significantly related. Available Pb used to assess EC20 （20% effective concentration） and EC50 （50% effective concentration） of millet was 119 and 300 mg/kg, respectively. Available Pb used to assess EC20 and EC50 of ryegrass was 63 and 157 mg/kg, respectively. Bioaccumulation, expressed as bioconcentration factors of Pb, was inversely related to soil pH, soil OC and clay content. Strong relationships were found between available lead and uptake by the two plants （P was 0.92 and 0.95 respectively）. In general, 0.1 mol/L Ca（NO3）2 available Pb may be used to assess the availability, phytotoxicity and bioaccumulation of lead to the two plants tested.
文摘Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its envi- ronmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of pro- creation function and descending of genital immunity. Experiments on pot-growth of paddies and corns in this study indicated that these crops did not show any macro-toxic symptoms in the observed contents of Pb added (0–4000 mg/kg) in soils. However, lead in soils can be easily absorbed by crops and accumulated in the different parts of plants. Statistical analysis showed that Pb contents in the crops are strongly positively correlated to the Pb contents in soils. In the crops, the Pb contents of roots are highest, tens to thousands of times those of straws and seeds. It is suggested that the root is a barrier of Pb absorbed by straws and seeds. Based on this fact, Pb pollution in soils can be gradually reduced by planting crops and subsequently removing the roots from the soil. This biotechnology may be used in environmental remediation, which embraces the quality of sustainable agricultural economy and a healthy environment.
基金Supported by Student Innovation Project of Central South University(YC12355)
文摘This study was carried out to detect content of heavy metals( Pb,Cd,and As) in vegetables,understand the current situation of heavy metal contamination in vegetables,and to provide scientific reference for further researches. It randomly selected 6 large vegetable markets and 6 supermarkets in Changsha City,selected 8 types of typical vegetables,and detected 96 samples. In accordance with maximum level of contaminants in foods in existing GB2762- 2012 standard,Nemerow composite pollution index( Pt) and grading standards,it made evaluation: uncontaminated( Pt≤ 1),mildly contaminated( 1 < Pt≤2),moderately contaminated( 2 < Pt≤3),and highly contaminated( Pt>3). Among 96 samples,range of content of Pb,Cd and As is( 0. 06- 1. 41),( 0. 06- 1. 26) and( 0. 00- 0. 91) mg / kg respectively; the over- limit rate of these metals exceeding the safety level is 78. 13%,45. 83%,and 34. 38% separately; the composite pollution index is in( 0. 90-6. 05),the eggplant is 6. 05 and hot pepper is 3. 24; the content of Pb( F =23. 908,P =0. 001) and Cd( F =64. 908,P =0. 000)are significantly different between 8 types of vegetables and there is no significant difference between the content of As( F = 4. 634,P = 0. 705> 0. 05) in 8 types of vegetables. Study shows that common vegetables in Changsha City has problem of excess Pb,Cd and As,and the Pb over- limit rate is the highest. The composite pollution index indicates that most heavy metal contamination of vegetables is mild and moderate contamination,melon,fruit and vegetable contamination is high contamination,and Cd is the major factor leading to contamination of melons,fruits and vegetables.
