Research progress and mechanism of nanomaterials-mediated in-situ remediation of cadmium-contaminated soil: A critical review.

Cadmium contamination of soil is a global issue and in-situ remediation technology as a promising mitigation strategy has attracted more and more attention. Many nanomaterials have been applied for the in-situ remediation of cadmium-contaminated soil due to their excellent properties of the nano-scale size effect. In this work, recent research progress of various nanomaterials, including carbon nanomaterials, metal-based nanomaterials and nano mineral materials, in the removal of cadmium and in-situ remediation of cadmium-contaminated soil were systematically discussed. Additional emphases were particularly laid on both laboratory and field restoration effects. Moreover, the factors which can affect the stability of cadmium, main interaction mechanisms between nanomaterials and cadmium in the soil, and potential future research direction were also provided. Therefore, it is believed that this work will ultimately contribute to the myriad of environmental cleanup advances, and further improve human health and sustainable development.

Colorimetric detection of Ba2+, Cd2+ and Pb2+ based on a multifunctionalized Au NP sensor.

In this work, we developed a colorimetric method for the detection of three kinds of ions with one kind of detection reagent. In detail, gold nanoparticles (Au NPs) multifunctionalized with 3-mercaptonicotinic acid and 4-aminobenzo-18-crown-6 (3-MPA-abc) were prepared and used as a colorimetric sensor for the simple and rapid detection of Ba2+, Cd2+ and Pb2+ ions. After adding Ba2+/Cd2+/Pb2+, the oxygen atom in the crown ether cavity and the carboxyl group of 3-mercaptopropionic acid can react with Ba2+/Cd2+/Pb2+ to form coordination bonds, resulting in the aggregation of the functionalized Au NPs and the color change of Au NP solution. The LOD of the colorimetric sensor for Ba2+/Cd2+/Pb2+ is 20 nM, 20 nM and 50 nM by the naked eye, respectively. A good linear relationship (R2 = 0.9984, R2 = 0.9917, R2 = 0.9934) between the absorbance ratio and Ba2+/Cd2+/Pb2+ concentrations indicates that our Au NP based colorimetric sensor can be used for the quantitative assay of Ba2+/Cd2+/Pb2+, and this detection method was successfully applied in the detection of Ba2+/Cd2+/Pb2+ in real environmental samples.

Multifunctional polyaniline modified calcium alginate aerogel membrane with antibacterial, oil-water separation, dye and heavy metal ions removal properties for complex water purification.

With the rapid development of urbanization, the discharge of industrial wastewater has led to increasingly critical water pollution issues. Additionally, heavy metals, organic dyes, microorganisms and oil pollution often coexist and have persistence and harmfulness. Developing materials that can treat these complex pollutants simultaneously has important practical significance. In this study, a calcium alginate-based aerogel membrane (PANI@CA membrane) was prepared by spraying, polymerization, Ca2+ cross-linking and freeze-drying using aniline and sodium alginate as raw materials. Oil-water emulsion can be separated by PANI@CA membrane only under gravity, and the separation efficiency was as high as 99 %. At the same time, the membrane can effectively intercept or adsorb organic dyes and heavy metal ions. The removal rates of methylene blue and Congo red were above 92 % and 63 % respectively even after ten times of cyclic filtration. The removal rate of Pb2+ was up to 95 %. In addition, PANI@CA membrane shows excellent photothermal conversion ability, and it can effectively kill Staphylococcus aureus under 808 nm laser irradiation. PANI@CA membrane has the advantages of low cost, simple preparation, good stability and high recycling ability, and has potential application prospects in wastewater treatment.

Remediation effects and mechanisms of typical minerals combined with inorganic amendment on cadmium-contaminated soil: a field study in wheat.

The remediation of cadmium (Cd)-contaminated soil has gained much attention recently because Cd in soil threatens human health through the food chain. Although tremendous progress has been made in the remediation of Cd-contaminated soil in rice acid soil system, the mechanism and effects of Cd-contaminated soil remediation under these amendments in wheat weak alkaline soil are still limited. In this study, the remediation effect and related mechanism of Cd in weakly alkaline soil were carried out using zeolite, diatomite, and sodium bentonite as the main remediation components, supplemented by calcium dihydrogen phosphate and fulvic acid. The results of field experiments showed that the concentration of Cd reduced by 27.3 ~ 31.2% in rhizosphere soil and 34.3 ~ 54.2% in non-rhizosphere soil, and the maximum reduction rate of Cd concentration in wheat grain was 25.5%. The main factors affecting the concentration of Cd in wheat grains include the change in exchangeable Cd, the absorption capacity of wheat root, and the inhibitory effect on Cd transport from stem to grain in this paper. In general, this work provides a new potential management feasible pathway to alleviate the Cd toxicity of weakly alkaline soil and wheat grain.

[Spatio-temporal characteristics of forest fires in China between 2001 and 2017]. / 2001­2017年我国森林火灾时空分布特征.

The remotely sensed burned area (BA) products can provide continuous and spatiotemporally explicit characteristics of fire patches, which are critical data sources for understanding regional fire regimes. However, their accuracy remains to be improved. In this study, a global BA product (i.e., CCI_Fire) at 250 m resolution was integrated with global forest change (GFC) product at 30 m to generate a refined BA product, named CCI_GFC product, whose accuracy was evaluated through comparing the BA with pre-existing fire patches data. To reveal the characteristics of forest fire in China between 2001 and 2017, we conducted a grid analysis at 0.05°×0.05° spatial resolution based on the refined BA product and the spatial pattern of eco-regions at the macro scale. The results showed that the accuracy metrics including the recognition rate (RR), variance explained (R2), root mean squared error (RMSE), mean absolute percentage error (MAPE) of the CCI_GFC product (i.e., 83%, 0.91, 0.28, and 8.5% respectively) were all superior to the CCI_Fire product (i.e., 74%, 0.86, 0.36, and 11.8% respectively) and the MCD64A1 product (i.e., 35%, 0.78, 0.48, and 17.3% respectively). The total burned area of forest was approximately 12.11 million hm2 for the whole country from 2001 to 2017, while the annual burned area temporally decreased. Forest fires in China were dominated by the low-frequency [0

Preparation of modified sodium alginate aerogel and its application in removing lead and cadmium ions in wastewater.

A low-cost, environment-friendly sodium alginate-meso-2,3-dimercaptosuccinic acid hybrid aerogel (SA-DMSA) was synthesized by simple chemical grafting and vacuum freeze-drying method and used to remove heavy metal ions in wastewater. The as-prepared SA-DMSA showed high affinity for heavy metal ions, such as Pb2+, Cd2+, Cu2+, Cr3+, and Co2+, and can remove >90% of the metal ions from the corresponding solution. SA-DMSA also exhibited high selectivity to Pb2+ and Cd2+, and the maximum adsorption capacities for Pb2+ and Cd2+ reached 116.4 and 91.2 mg/g, respectively. The SA-DMSA adsorbent can be regenerated by a simple one-step acid washing, and the adsorption performance remained stable after repeated use. Given its low-cost and easy-to-obtain raw materials, simple preparation process, and simple regeneration process of the adsorbent, SA-DMSA has broad application prospects in the treatment of low-concentration heavy metal ions, especially for wastewater containing Pb2+ and Cd2+.

A novel hybrid nanoadsorbent for effective Hg2+ adsorption based on zeolitic imidazolate framework (ZIF-90) assembled onto poly acrylic acid capped Fe3O4 nanoparticles and cysteine.

This research reports a new mercury adsorbent in which Fe3O4 as a core was embedded into the shell of ZIF-90 in a one-pot synthesis and the subsequent post synthesis modification (PSM) of its surface with cysteine covalently, via a Schiff's base reaction. Poly acrylic acid (PAA) was capped on the surface of nanoparticles to prevent agglomeration of the nanoparticles. In addition, -COOH groups of PAA coordinated with Zn2+ of ZIF-90 and this provided the platform for ZIF-90 to grow on the nanoparticles forming the core-shell structure. Based on the strong interactions between the thiol groups on the adsorbent and mercury ions as elucidated by the XPS analysis, the as-synthesized adsorbent showed selectivity for Hg2+. The sorbent exhibited high adsorption capacity of 900 mg g-1 towards Hg2+ as calculated at pH 4 and the adsorption kinetics followed pseudo-second-order kinetics model better. The Hg2+ loaded adsorbent was easily regenerated and it maintained about 70 % efficiency after the third use. Low-cost, readily available and green materials, facile preparation, efficient removal and the breakthrough in three times recyclability give the novel ZIF-90 based hybrid nanoadsorbent wide prospects in the field of environmental remediation as a good adsorbent for Hg2+ removal in wastewater.

[Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass.

[Studies on relationship between the expression of hTNF-alpha gene and photosynthesis in Anabaena sp. IB02].

The effects of illumination on growth of Anabaena sp. IB02 and hTNF-alpha expression were studied. Photosynthetic activity, PS I and PS II activity of Anabaena sp. IB02 were assayed. Illumination enhanced the growth of Anabaena sp. IB02 and hTNF-a expression. Some relations were observed between hTNF-alpha expression and ture photosynthesis activity, PS I, PS II activity of Anabaena sp. IB02. Significant differences of the photosynthetic activity of host were detected simultaneously when hTNF-a expressed: the respiration rate increased (-68%), the light saturation point descended (+66%), all these suggested that the metabolic charge of host were increased and grow faster than wild type under low illumination.