Peri-urban agriculture of food crops is practiced in many slum areas in developing countries. This often uses waste water whose levels of essential and non-essential elements are largely unknown but would be feared to...Peri-urban agriculture of food crops is practiced in many slum areas in developing countries. This often uses waste water whose levels of essential and non-essential elements are largely unknown but would be feared to contaminate soils, consequently exposing man to associated health risks. Inhabitants in Kibera slum, Nairobi City practice these growing kales, amaranthus, arrowroots, and spinach. Health risk assessment was done using daily intake of metals (DIM), target hazard quotient (THQ) and incremental lifetime cancer risk (ILCR). Atomic absorption spectroscopy was employed for elemental analysis. The levels of essential elements ranged as follows;Mn 91.04 - 374.44, Mg 261.28 - 532.96, Fe 350.74 - 1273.68, and Zn 1.18 - 6.3 μg/g per dry weight were found to be below the recommended limits by FAO/WHO. Non-essential elements ranged as follows;Cr 1.15 - 4.32 and Pb 0.14 - 0.91 μg/g above the EU recommendation. DIM of Fe 5.81 - 27.61 and Mn 1.97 - 8.12 μg/g is above the recommended daily intake amounts. THQ values for Mn and Fe were more than unit. THQ values for non-essential elements were generally below unit. ILCR showed that from lead alone 73 people (0.043% of 0.17M residents) are likely to develop cancer. There are foreseen health risks associated with consumption of food crops grown in Kibera slum that requires immediate address.展开更多
For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by c...For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire growth period of winter wheat. Compared with no biochar control(CK), application of the three types of biochar significantly(P < 0.01) reduced grain PAH concentration, total equivalent concentration(TEC), and incremental lifetime cancer risk(ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly(P < 0.05)reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly(P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by15.9%–33.7%. It was found that the degradation rate of high-molecular-weight(HMW) PAHs(5-and 6-ring PAHs) was significantly(P < 0.05) higher than that of low-molecular-weight(LMW) PAHs(2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.展开更多
Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the Nort...Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.展开更多
文摘Peri-urban agriculture of food crops is practiced in many slum areas in developing countries. This often uses waste water whose levels of essential and non-essential elements are largely unknown but would be feared to contaminate soils, consequently exposing man to associated health risks. Inhabitants in Kibera slum, Nairobi City practice these growing kales, amaranthus, arrowroots, and spinach. Health risk assessment was done using daily intake of metals (DIM), target hazard quotient (THQ) and incremental lifetime cancer risk (ILCR). Atomic absorption spectroscopy was employed for elemental analysis. The levels of essential elements ranged as follows;Mn 91.04 - 374.44, Mg 261.28 - 532.96, Fe 350.74 - 1273.68, and Zn 1.18 - 6.3 μg/g per dry weight were found to be below the recommended limits by FAO/WHO. Non-essential elements ranged as follows;Cr 1.15 - 4.32 and Pb 0.14 - 0.91 μg/g above the EU recommendation. DIM of Fe 5.81 - 27.61 and Mn 1.97 - 8.12 μg/g is above the recommended daily intake amounts. THQ values for Mn and Fe were more than unit. THQ values for non-essential elements were generally below unit. ILCR showed that from lead alone 73 people (0.043% of 0.17M residents) are likely to develop cancer. There are foreseen health risks associated with consumption of food crops grown in Kibera slum that requires immediate address.
基金financially supported by the National Natural Science Foundation of China (Nos. 42077325 and 41571456)the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2019JZ-25)。
文摘For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire growth period of winter wheat. Compared with no biochar control(CK), application of the three types of biochar significantly(P < 0.01) reduced grain PAH concentration, total equivalent concentration(TEC), and incremental lifetime cancer risk(ILCR), indicating that biochar application, especially MSB, reduced the risk of exposure to PAHs in wheat grain. Furthermore, all three types of biochar significantly(P < 0.05)reduced PAH uptake and accumulation in wheat roots and stems, probably because biochar application enhanced the degradation of PAHs in the rhizosphere soil. Compared with CK, application of the three types of biochar significantly(P < 0.05) reduced the concentration of PAHs in the rhizosphere soil by15.9%–33.7%. It was found that the degradation rate of high-molecular-weight(HMW) PAHs(5-and 6-ring PAHs) was significantly(P < 0.05) higher than that of low-molecular-weight(LMW) PAHs(2–4-ring PAHs) regardless of the type of biochar used. Additionally, all three types of biochar significantly increased the relative abundance of the dominant bacterial phyla and genera in soil. Redundancy and correlation analyses also showed that there was a strong correlation between the removal rate of PAHs and dominant bacteria in the rhizosphere soil. This study indicated that biochar effectively reduced the health risk from dietary exposure to PAHs in wheat grains by increasing the abundance of bacteria related to PAH degradation, promoting the biodegradation of PAHs in the rhizosphere soil, and consequently reducing PAH uptake by wheat.
基金supported by the National Key Research and Development Program of China(No.2017YFC0212603)the National Natural Science Foundation of China(No.41773124)+2 种基金the Open Research Program of Laboratory of Basin Hydrology and Wetland Eco-restoration,China University of Geosciences(Wuhan)(No.BHWER201503(A))the Open Research Fund of Hubei Key Laboratory of Mine Environmental Pollution Con-trol&Remediation,Hubei Polytechnic University(No.201702)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGL170208)。
文摘Variations of levels,possible source and air mass transmission were investigated for 16 USEPA priority-controlled PAHs in PM2.5 during 2018 Chinese Spring Festival(CSF)in Xiangyang City,central China which is the North-South pollutant airmass transport channel of China.Totally 37 samples were collected.Mass concentrations of 16 PAHs for the Pre–CSF day(Pre–CSFD),during the CSF day(CSFD)and after the CSF day(Af–CSFD)are 33.78±17.68 ng/m3,22.98±6.49 ng/m3,and 8.99±4.44 ng/m3,respectively.High resolution samples showed that 16 PAHs are higher in the morning(06:00–11:00)or afternoon(11:30–16:30),than those in the evening(17:00–22:00)and at night(22:30–05:30),whereas the result is reversed during the CSFD.Fireworks burning can obviously increase the mass concentration of PAHs.Air mass trajectory indicated that Xiangyang is a sink area of pollutants for northwest and southeast,and the sources of the northeast and southwest.The air mass only can be transmitted out through northeast and southwest.It is effective for improvement of air quality in Wuhan and Hunan to control fireworks emission in Henan and local areas.Fireworks burning was an important source for PAHs during CSFD,biomass,coal combustion,and traffic emission were the main sources of PAHs for Pre–CSFD and Af–CSFD periods.The health risk on the CSFD was higher than the acceptable levels,especially during the intensive fireworks burning,the risk value far exceed 1.0×10^-4,controlling burning fireworks is required.
