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.

Rhizospheric Precipitation of Manganese by Phosphate: A Novel Strategy to Enhance Mn Tolerance in the Hyperaccumulator Phytolacca americana.

Manganese (Mn) exclusion in the Mn hyperaccumulator pokeweed (Phytolacca americana L.) was investigated. Hydroponic experiments were carried out to observe the responses of pokeweeds continually exposed to high levels of Mn. In this study, crystals were observed to appear firstly on the root hair, and soon after, more crystals appeared on the root surface, and crystals of Mn phosphate were observed to appear on the root surface in a time sequence negatively correlated with the number of leaves treated with 5 mM Mn. Crystals were identified via phase analysis of X-ray diffraction and element analysis, and these white insoluble crystals were identified using XRD to be Mn phosphate, with the molecular formula (Mn,Fe)3(PO4)2·4H2O. The nutrient solution pH increased from 4.5 to about 5.6 before the crystals appeared. Mn phosphate crystals appeared in all solutions except those without phosphate and emerged earlier in the solutions containing no Fe. Compared with control group, pokeweed accumulated much more Mn in the leaves when treated without phosphate or Fe. The present study suggests that pokeweed can exclude Mn by means of rhizosphere precipitation by phosphate to form Mn phosphate crystals that accumulate on the root surface. Although the detailed mechanism requires further investigation, this study provides the first direct evidence of a novel strategy to inhibit Mn uptake in the roots of a hyperaccumulator in a P-enriched environment.

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.

Cooking oil fume-derived PM2.5 induces apoptosis in A549 cells and MAPK/NF-кB/STAT1 pathway activation.

Cooking oil fumes (COFs) are the major sources of indoor air pollution in Asia. It is well known that alveolar cells are key participants in the development of respiratory system; however, it still remains unknown whether alveolar cells are affected by COFs. Therefore, the present study investigated the effects of COFs on alveolar cells (A549 cells) and illuminated its apoptotic mechanism in response to COF-PM2.5 exposure. When A549 cells were exposed to COF-PM2.5, cell viability was substantially decreased, while the generation of ROS increased, and LDH levels and CCK-8 levels gradually changed within a dose-dependent manner. The nitrite concentration in the supernatants was augmented, while the SOD activity and GSH recycling were decreased upon COF-PM2.5. Moreover, COF-PM2.5 treatment increased mRNA levels of COX-2, inducible NO synthase, and TNF-α, and Elisa assay suggested that secretory proteins IL-6 and TNF-α were also increased. Furthermore, the Bax/Bcl-2 mRNA ratio was increased, and cleaved caspase-3 protein was activated in the A549 cells. Strikingly, COF-PM2.5 induced the phosphorylation of STAT1 at Tyr701/Ser727 and activation of NF-кB and ERK1/2, p38, and JNK of the MAPK pathway. In short, our study suggested that COF-PM2.5 resulted in inflammation, apoptosis, and cell damage in A549 cells, which might be modulated via the activation of MAPK/NF-кB/STAT1 pathway.

Assessment of trace metal bioavailability in garden soils and health risks via consumption of vegetables in the vicinity of Tongling mining area, China.

Environmental pollution due to mining activities has been reported in many countries. In this study, 283 vegetable and 44 corresponding garden soil samples were collected in the vicinity of the Tongling mining area, China. The aim was to evaluate the bioavailability of trace metals (Cu, Zn, Pb and Cd) to vegetables by comparing different methods (trace metals in DTPA, EDTA, HCl, NH(4)NO(3), NH(4)OAC aqueous solutions and total metals in garden soils), and assess the potential health risks of trace metals to the local population via vegetable consumption. The results showed that the mean values of total Cu and Cd in the soil samples exceeded the Grade II national standard in China. Average concentrations of Cd and Pb in some vegetable samples were higher than the maximum permissible concentration in China. The transfer factors for trace metals in different vegetables showed a trend of Cd>Zn>Cu> Pb. Asteraceae vegetables had stronger metal uptake than Liliaceae. The total target hazard quotient (THQ) value was greater than 1, suggesting that trace metals in vegetables could present some potential health risks. The effectiveness of the studied methods for estimating soil metal bioavailability was generally dependent on the particular metal and vegetable species. Overall, 1.0M NH(4)OAC provided the best estimate of Cd and Zn bioavailability in multi-elemental contaminated soils. None of the studied soil metal extraction methods appeared suitable for measuring Cu or Pb bioavailability, especially for Pb, which showed almost no correlation between metal concentration in soil and vegetables.

Lysine-specific demethylase 1 expression in zebrafish during the early stages of neuronal development.

Lysine-specific demethylase 1 (Lsd1) is associated with transcriptional coregulation via the modulation of histone methylation. The expression pattern and function of zebrafish Lsd1 has not, however, been studied. Here, we describe the pattern of zebrafish Lsd1 expression during different development stages. In the zebrafish embryo, lsd1 mRNA was present during the early cleavage stage, indicating that maternally derived Lsd1 protein is involved in embryonic patterning. During embryogenesis from 0 to 48 hours post-fertilization (hpf), the expression of lsd1 mRNA in the embryo was ubiquitous before 12 hpf and then became restricted to the anterior of the embryo (particularly in the brain) from 24 hpf to 72 hpf. Inhibition of Lsd1 activity (by exposure to tranylcypromine) or knockdown of lsd1 expression (by morpholino antisense oligonucleotide injection) led to the loss of cells in the brain and to a dramatic downregulation of neural genes, including gad65, gad75, and reelin, but not hey1. These findings indicate an important role of Lsd1 during nervous system development in zebrafish.

Effects of lead on neurogenesis during zebrafish embryonic brain development.

Lead neurotoxicity has caused wide public concern in recent decades, yet little is known about its effects on cellular and molecular mechanisms during the sensitive early life stages of animals. This study examines neurological deficits caused by lead acetate (Pb) during early embryonic stages in the zebrafish (Danio rerio) and further explores its potential molecular mechanism. Zebrafish embryos showed varying levels of toxicity, which was proportional to the concentration of Pb to which the embryos were exposed. Following Pb exposure (0.2mM), embryos showed obvious neurotoxic symptoms with "sluggish" action, slow swimming movements and slow escape action. Whole mount in situ hybridization showed that gfap and huC gene expression patterns decreased significantly throughout the brains of the Pb-treated embryos, particularly in the diencephalon region. RT-PCR further proved the downregulation of the two genes. However, ngn1 and crestin gene expression patterns were similar in both the Pb-treated embryos and the control embryos. The TUNEL assay demonstrated that the reduction of nerve cells was due to increased apoptosis of neuron and glia cells. In conclusion, these findings identify that Pb-induced neurotoxicity can be caused by impaired neurogenesis, resulting in markedly increased apoptosis of special types of neural cells, neuron and glia cells.

Subcellular distribution and chemical forms of cadmium in Phytolacca americana L.

Phytolacca americana L. (pokeweed) is a promising species for Cd phytoextraction with large biomass and fast growth rate. To further understand the mechanisms involved in Cd tolerance and detoxification, the present study investigated subcellular distribution and chemical forms of Cd in pokeweed. Subcellular fractionation of Cd-containing tissues indicated that both in root and leaves, the majority of the element was located in soluble fraction and cell walls. Meanwhile, Cd taken up by pokeweed existed in different chemical forms. Results showed that the greatest amount of Cd was found in the extraction of 80% ethanol in roots, followed by 1 M NaCl, d-H(2)O and 2% HAc, while in leaves and stems, most of the Cd was extracted by 1 M NaCl, and the subdominant amount of Cd was extracted by 80% ethanol. It could be suggested that Cd compartmentation with organo-ligands in vacuole or integrated with pectates and proteins in cell wall might be responsible for the adaptation of pokeweed to Cd stress.

Interaction of Pseudomonas putida CZ1 with clays and ability of the composite to immobilize copper and zinc from solution.

The present study was conducted to determine the abilities of the living and nonliving Pseudomonas putida CZ1 cells, clays (goethite, kaolinite, smectite and manganite) and their composites to accumulate copper and zinc from a liquid medium, and elucidate the role of microbes on the mobility of heavy metals. Various mixtures of bacteria and clays were exposed to solutions of 0.025 mM or 0.5mM Cu(II) and Zn(II) in 0.01M KNO(3) to differentiate between so-called "high-affinity" sites and "low-affinity" sites. Clays associated in an edge-on orientation to the cells was observed by electron microscope (EM) examination of these metal-treated bacteria-clay aggregates. Adsorption experiments and desorption with 1.0M CH(3)COOK solution indicated that clays contain more high-affinity copper binding sites and less high-affinity zinc binding sites than that of bacteria, however, bacteria are involved in more low-affinity heavy-metal-binding sites. Carboxyl group activity is more important at weak-binding sites than at strong-binding sites. TEM-EDS analysis confirmed that most of Zn removed from solution was associated with P. putida CZ1 in the composites. These results suggest that bacteria play an important role in regulating the mobility of heavy metals in the soil environment.

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.