Study on the solidification performance and mechanism of heavy metals by sludge/biomass ash ceramsites, biochar and biomass ash.

Industrial by-products are stored in large quantities in the open, leading to wasted resources and environmental pollution, and the natural environment is similarly faced with phosphate depletion and serious water and soil pollution. This study uses these by-products to produce a new sludge/biomass ash ceramsite that will be used to adsorb nitrogen and phosphorus from wastewater, and solidify heavy metals in the soil while releasing Olsen P. The sludge/biomass ash ceramsites are made using sewage sludge and biomass ash in a certain ratio calcined at high temperatures and modified for the adsorption of nitrogen and phosphorus from wastewater. Sludge/biomass ash ceramsites before and after phosphorus adsorption, biochar and biomass ash were compared to analyze their heavy metal adsorption capacity and potential as phosphate fertilizer. After phosphorus adsorption, the sludge/biomass ash ceramsites released effective phosphorus steadily and rapidly in the soil, with a greater initial release than biochar and biomass ash, and the ceramsites were in a granular form that could be easily recycled. Biochar and biomass residue, due to their surface functional groups, are better at solidifying heavy metals than sludge/biomass ash ceramsites. Biochar, biomass ash and sludge/biomass ash ceramsites significantly reduced the concentrations of Cd, Cu, Pb and Zn in the soil. Correlation analysis demonstrated that there was a synergistic relationship between the increase in soil Olsen P content and the change in pH, with the increase in soil Olsen P content and the increase in pH contributing to heavy metal solidification.

Effects of soil properties on heavy metal bioavailability and accumulation in crop grains under different farmland use patterns.

Mining activities have increased the accumulation of heavy metals in farmland soil and in food crops. To identify the key soil properties influencing heavy metal bioavailability and accumulation in food crops, 81 crop samples and 81 corresponding agricultural soil samples were collected from rape, wheat, and paddy fields. Heavy metal (copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), iron (Fe), and manganese (Mn)) concentrations in soils and rape, wheat, rice grains were determined using inductively coupled plasma atomic emission spectroscopy, and soil physicochemical properties (pH, organic matter, total nitrogen, total phosphorus, available phosphorus, and available potassium (AK)) were analyzed. Soil extractable metals were extracted using various single extractants (DTPA, EDTA, NH4OAc, NH4NO3, and HCl). The average concentrations of Cu, Zn, Pb, Cd, and Mn in the soil samples all exceeded the local geochemical background value (background values of Cu, Zn, Pb, Cd, and Mn are 43.0, 81.0, 28.5, 0.196, and 616 mg/kg, respectively), and Cd over-standard rate was the highest, at 98%. Furthermore, soil total Cd concentrations (0.1-24.8 mg/kg) of more than 86% of the samples exceeded the soil pollution risk screening value (GB 15618-2018). The sources of Cu, Zn, Pb, Cd, and Mn in soils were mainly associated with mining activities. The key factors influencing heavy metal bioavailability were associated with the types of extractants (complexing agents or neutral salt extractants) and the metals. Cd and Pb concentrations in most wheat and rice grain samples exceeded the maximum allowable Cd and Pb levels in food, respectively, and Cd concentrations in approximately 10% of the rice grain samples exceeded 1.0 mg/kg. Furthermore, rice and wheat grains exhibited higher Cd accumulation capacity than rape grains, and despite the high soil Cd concentrations in the rape fields, the rape grains were safe for consumption. High soil pH and AK restricted Cd and Cu accumulation in wheat grains, respectively. Soil properties seemed to influence heavy metal accumulation in rice grains the most.

Effect of extracts of trichosanthes root tubers on HepA-H cells and HeLa cells.

AIM: To investigate the cytotoxic activity of extracts of trichosanthes root tubers (EOT) on HepA-H cells and HeLa cells compared with trichosanthin (TCS), and to explore the possible mechanism of growth inhibitory effect of EOT on HeLa cells. METHODS: Tumor cells were cultured in vitro, and then microculture tetrzoalium assay (MTT) was used to investigate drugs' cytotoxic activity. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe ultrastructural changes of cells, and electrophoresis was performed to detect changes of biochemical characteristics of intercellular DNA. RESULTS: TCS and EOT had no obvious effects on HepA-H cells (P>0.05), but had remarkable effects on HeLa cells in a time and dose dependent manner (r>0.864, P<0.05 or P<0.01). The inhibitory rate of EOT was much higher than that of TCS (P<0.01). Median inhibitory rates (IC50) of TCS and EOT on HeLa cells were 610.9 mg/L and 115.6 mg/L for 36 h, and 130.7 mg/L and 33.4 mg/L for 48 h respectively. Marked morphologic changes were observed including microvillus disappearance or reduction, cell membrane bledding, cell shrinkage, condensation of chromosomes and apoptotic bodies with complete membranes. Meanwhile, apoptosis of HeLa cells was confirmed by DNA ladder formation on gel electrophoresis. CONCLUSION: TCS and EOT have no obvious effects on HepA-H cells, but have significant inhibitory effects on HeLa cells, indicating that EOT is superior to TCS in anti-tumor activity.

[Preliminary study on effects of Trichosanthes kirilowi root on hela cells].

OBJECTIVE: To investigate the cytotoxic effect of extracts of Trichosanthes kirilowi (TK) root on Hela cells in vitro and its probable anti-tumor mechanism. METHODS: The cytotoxic effect in vitro on the growth of Hela cells was evaluated by microculture tetrazolium assay (MTT). Cell ultrastructural changes were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and DNA agarose electrophoresis was performed to determine apoptosis and biochemical changes of Hela cells. RESULTS: Exposure of Hela cells to TK extracts for 24-48 hrs resulted in a cell growth arrest, which showed in a time- and dose-dependent manner (r > 0.880, P < 0.01). With SEM and TEM, marked changes were observed, including microvilli disappearance or reduction, cell membrane vesiculation, cell shrinkage, condensation of chromosomes and apoptotic bodies with complete membrane. Besides, the apoptosis of Hela cells was confirmed by typical DNA ladder formation on gel electrophoresis. CONCLUSION: Extracts of TK has a marked anti-tumor activity and could induce apoptosis of Hela cells.