Silica-magnesium coupling in lignin-based biochar: A promising remediation for composite heavy metal pollution in environment.

Lignin hydrothermal silica-carbon material served as a backbone for MgCl2 activation to prepare lignin-based silicon/magnesia biochar (ALB/Si-Mg) for Cd2+, Pb2+, Cu2+, and Zn2+ removal from water and soil environment. Characterization studies revealed a 1017.71-fold increase in the specific surface area of ALB/Si-Mg compared to the original lignin biochar (ALB), producing abundant oxygen functional groups (OC-O, Si-O, Mg-O), and mineral matter (Mg2SiO4 and MgO). Crucially, batch adsorption experiments demonstrated that the adsorption capacity of ALB/Si-Mg for Cd2+, Pb2+, Cu2+, and Zn2+ was 848.17, 665.07, 151.84, and 245.78 mg/g, which were 29.09-140.45 times of the ALB. Soil remediation experiments showed that applying ALB/Si-Mg increased soil effective silicon (109.04%-450.2%) and soil exchangeable magnesium (276.41%-878.66%), enhanced plant photosynthesis, and notably reduced the bioavailability of heavy metals in soil as well as the content of heavy metals in Pakchoi, thereby promoting Pakchoi growth and development. The presence of oxygen-containing functional groups on ALB/Si-Mg, along with Mg2SiO4 and MgO nanoparticles, enhanced the adsorption capacity for heavy metals through the promotion of heavy metal precipitation, ion exchange, and complexation mechanisms. This study establishes the groundwork for the coupling of silica and magnesium elements in biochar and the remediation of composite heavy metal environmental pollution.

Distribution characteristics, risk assessment, and relevance with surrounding soil of heavy metals in coking solid wastes from coking plants in Shanxi, China.

Heavy metal concentrations represent important pollution evaluation indices, and it is necessary to assess the potential environmental and health risks from heavy metals associated with coking wastes from coking plants. In this study, coking sludge (CS), tar residue (TR), coke powder (CP), and sulfur paste (SP) from three coking plants (Plant A, Plant B, and Plant C) in central, western, and southern Shanxi Province and from soils surrounding Plant A were selected as the research objects, and the distributions of Cu, Ni, Pb, Zn, Mn, Cd, and Cr were determined. The results showed that Cd in the four solid wastes far exceeded the soil background value by a factor of 16~195, and the contents of Pb in TR (three plants) and CS (Plant C) exceeded the soil background values 19.70-, 23.57-, 14.46-, and 12.56-fold, respectively. Similarly, the concentrations of Cu, Ni, Pb, Zn, and Cd in soils were higher than the background values by factors of 31.18, 8.35, 34.79, 29.48, and 3.43, respectively. In addition, the Cu, Ni, Pb, and Cr in the four solid wastes and soils mainly existed in the residual state. As depth increased, the overall Ni, Pb, Mn, and Cd concentrations in soils increased. The high ecological risks associated with the four solid wastes were mainly due to the enrichment of Cd. Workers in coking plants face certain Cr health risks. This study provides theoretical support for the coking industry with respect to the treatment, disposal, and management of solid wastes.

Toxic effects due to exposure heavy metals and increased health risk assessment (leukemia).

Heavy metals (HM) are among the elements that are rare in nature and threaten human health, animals, and the environment. Fix sources including (power plants, industries, homes) and mobile sources include (cars and motorcycles) are the main sources production and emission of HM. It is important to understand the main information about sources of emission, chemical processes (reactions, oxidation, and leaching), and how they precipitate. The aim of this study was to evaluation an increased risk of leukemia due to exposure to HM. In this article narrative, the first literature search was performed with 580 articles according to different databases: Elsevier, PubMed, Web of science, Spring, and Google Scholar databases. 70 articles were included in the analysis process. Finally, 8 full-text articles were selected in this research. The search was restricted to English-language papers published between 2000 and 2021. In final stage literature, there is a notable health effect (carcinogenic) because of exposure to heavy metals. According to the results of this research natural procedures and human activities (industrial processes, car exhaust, and cigarette smoke) are the most important of ways that heavy metals can enter the natural cycle. Air, food, soil, water, and groundwater are the main sources of heavy metals that can cause severe disorders in the human body. After entering the body through ingestion heavy metals produce stable bio-toxic compounds. These compounds by disrupting biological processes, interrupt the body's functions and cause various cancers in the human body. The results of this study can help to politicians for make comprehensive decisions to solve the problem and increase public awareness of the use of protective equipment.

Effects of Amendments and Indigenous Microorganisms on the Growth and Cd and Pb Uptake of Coriander (Coriandrum sativum L.) in Heavy Metal-Contaminated Soils.

Heavy metal (HM) contamination of soils is a worldwide problem with adverse consequences to the environment and human health. For the safe production of vegetables in contaminated soil, efficient soil amendments need to be applied such as nano-hydroxyapatite (n-HAP) and poly γ-glutamic acid (γ-PGA), which can mitigate heavy metal uptake and enhance crop yield. However, the combined effects of soil amendments and indigenous microorganisms (IMOs) on HMs immobilisation and accumulation by crops have received little attention. We established a pot experiment to investigate the effects of IMOs combined with n-HAP and γ-PGA on coriander (Coriandrum sativum L.) growth and its Cd and Pb uptake in two acidic soils contaminated with HMs. The study demonstrated that applying n-HAP, with and without IMOs, significantly increased shoot dry biomass and reduced plant Cd and Pb uptake and diethylenetriaminepentaacetic acid (DTPA) extractable Cd and Pb concentrations in most cases. However, γ-PGA, with and without IMOs, only reduced soil DTPA-extractable Pb concentrations in slightly contaminated soil with 0.29 mg/kg Cd and 50.9 mg/kg Pb. Regardless of amendments, IMOs independently increased shoot dry biomass and soil DTPA-extractable Cd concentrations in moderately contaminated soil with 1.08 mg/kg Cd and 100.0 mg/kg Pb. A synergistic effect was observed with a combined IMOs and n-HAP treatment, where DTPA-extractable Cd and Pb concentrations decreased in slightly contaminated soil compared with the independent IMOs and n-HAP treatments. The combined treatment of γ-PGA and IMOs substantially increased shoot dry biomass in moderately contaminated soil. These results indicate that solo n-HAP enhanced plant growth and soil Cd and Pb immobilisation, and mitigated Cd and Pb accumulation in shoots. However, the combination of n-HAP and IMOs was optimal for stabilising and reducing HMs' uptake and promoting plant growth in contaminated soil, suggesting its potential for safe crop production.

[Distribution Characteristics of Heavy Metals in Farmland Soils Around Mining Areas and Pollution Assessment].

In order to explore the spatial distribution and ecological risk of heavy metals in farmland soil around Tongguan Mining area, surface soil samples from Tongguan Mining area were collected in September 2020, and the contents and distribution characteristics of eight heavy metals (Pb, Cu, Cd, Hg, Cr, Ni, Zn, and As) in the samples were analyzed. The Nemerow comprehensive pollution index and potential ecological risk index were used to evaluate soil pollution. The results showed that the contents of the eight types of heavy metal elements in this area exceeded the standard, and the exceeding rates were 97.91%, 84.79%, 100%, 95.41%, 96.87%, 98.54%, 91.45%, and 28.95%, respectively. The variation coefficients of the eight heavy metals were ranked as Hg>Pb>Cu>Cd>Zn>As>Ni>Cr. The variation coefficients of Hg, Pb, Cu, Cd, and Zn were all greater than 1. Correlation analysis showed that these five heavy metals were obviously correlated. In terms of spatial distribution, Pb, Cd, Cu, Hg, Zn, and As were distributed in patches, whereas Cr and Ni were distributed in flakes. The high values of Hg, Cd, Pb, Cu, and Zn were mainly distributed in the southern and central part of the study area. The comprehensive pollution of Nemerow showed that the severe pollution rate reached 87.91%, and the moderate pollution rate and the mild pollution rate were 9.58% and 2.5%, respectively; thus, the overall pollution was severe. The potential ecological risk index showed that Hg, Cd, Pb, and Cu were the main risk elements. The total potential ecological risk index showed that the proportion of samples with strong pollution was 97.08%, and the proportion of extremely strongly, very strongly, and strongly polluted samples were 55.63%, 27.08%, and 14.37%, respectively, indicating that the overall potential ecological risk in the study area was very strong. Combining the two pollution assessment methods, it can be seen that the heavy metal pollution around Tongguan mining area, primarily by Hg, Cd, and Pb, was serious. These results can provide data support for regional pollution control, soil remediation, and ecological protection. It is suggested that the state of soil heavy metal pollution and its transformation in various media should be monitored continuously in the future.

Radionuclides in the environment around the uranium mines in Guangxi, China.

Uranium and plutonium are both poisonous radioactive elements, which are very harmful to human health and environment. Therefore, it is of great significance to study the distribution of 238U concentration and 239+240Pu activity in the uranium mine surrounding soils. We have collected some surface soil sediments within 2 km of two uranium mines and a solid waste management center in Guangxi Province. The 238U concentration in these study areas is in the range of 1.44-83.91 mg/g, and the 238U concentration in the A uranium mine surrounding surface soils is higher than that in the B uranium mine and the solid waste management center. While the B uranium mine and the solid waster management center don't pollute the surrounding soils because the 238U concentrations in their surrounding soils are similar to the average 238U concentration in the soil. The 239+240Pu activities in soil samples collected around the two uranium mines and the solid waste management center are close ranged from 0.06 mBq/g to 0.51 mBq/g. Moreover, the 240Pu/239Pu atom ratios in our study samples are ranged from 0.15 to 0.23, which indicate the Pu may come from the global fallout. In addition, we study heavy metals in our collected samples, only heavy metal Tl has weak positive correlations with 238U concentrations and 239+240Pu activities. And there is a weak positive correlation between 238U concentrations and 239+240Pu activities.

Quantitative evaluation of in-situ bioremediation of compound pollution of oil and heavy metal in sediments from the Bohai Sea, China.

Owing to the semi-enclosed environment of the Bohai Sea, the ecological effects caused by an oil spill would be significant. A typical in- situ bioremediation engineering project for of oil-spilled marine sediments was performed in the Bohai Sea and a quantitative assessment of the ecological restoration was performed. The bioremediation efficiencies of n-alkane and PAHs in the sediment are 32.84 ± 21.66% and 50.42 ± 17.49% after 70 days of bioremediation, and 60.99 ± 10.14% and 68.01 ± 18.60% after 210 days, respectively. After 210 days of bioremediation, the degradation rates of two- to three ring PAHs and four-ring PAHs are 84.44 ± 23.03% and 26.62 ± 43.76%, respectively. In addition, the concentrations of the heavy metals first increased by 6.00% due to oil spill degradation and release, and then decreased by 72.60% with the degradation of oil caused by bioremediation or vertical migration. According to the continuous tracking monitoring, the composition of the microbial community in the restored area was similar to that in the control area and the clean area in Bohai Sea after 210 days of bioremediation. These results may provide some theoretical and scientific data to understand the degradation mechanism and assessing the ecological remediation efficiency for oil spills in open sea areas.

The cadmium and lead content of the grain produced by leading Chinese rice cultivars.

The cadmium (Cd) and lead (Pb) content in both white and wholemeal flour milled from 110 leading rice cultivars was assessed. The white flour Cd content ranged from <0.0025 to 0.2530mg/kg (geometric mean (GM)=0.0150mg/kg), while its Pb content ranged from <0.0250 to 0.3830mg/kg (GM=0.0210mg/kg). The indica types took up higher amounts of Cd and Pb than did the japonica types. Although the heavy metal content of wholemeal flour tended to higher than that of white flour, nevertheless 84.5% (Cd) and 95.4% (Pb) of the entries were compliant with the national maximum allowable concentration of 0.2000mg/kg of each contaminant. An analysis of the Cd content in the white flour of three indica type cultivars grown in two consecutive years at two locations indicated that Cd content may be significantly affected by the conditions prevailing in the growing season.

Toxicity of Cu (II) to the green alga Chlorella vulgaris: a perspective of photosynthesis and oxidant stress.

The toxic effects of Cu (II) on the freshwater green algae Chlorella vulgaris and its chloroplast were investigated by detecting the responses of photosynthesis and oxidant stress. The results showed that Cu (II) arrested the growth of C. vulgaris and presented in a concentration- and time-dependent trend and the SRichards 2 model fitted the inhibition curve best. The chlorophyll fluorescence parameters, including qP, Y (II), ETR, F v /F m , and F v /F 0, were stimulated at low concentration of Cu (II) but declined at high concentration, indicating the photosystem II (PSII) of C. vulgaris was destroyed by Cu (II). The chloroplasts were extracted, and the Hill reaction activity (HRA) of chloroplast was significantly decreased with the increasing Cu (II) concentration under both illuminating and dark condition, and faster decline speed was observed under dark condition. Activities of superoxide dismutase (SOD) and catalase (CAT) and malondialdehyde (MDA) content were also significantly decreased at high concentration Cu (II), companied with a large number of reactive oxygen species (ROS) production. All these results indicated a severe oxidative stress on algal cells occurred as well as the effect on photosynthesis, thus inhibiting the growth of algae, which providing sights to evaluate the phytotoxicity of Cu (II).