Abstract The high-temperature pyrolysis oxidation method was adopted to prepare reed biochar, and reed biochar was used as the immobilized material to load the dominant petroleum hydrocarbon degrading bacteria, and the effects of biochar immobilized microorganisms on the remediation effect and enzyme activity of petroleum hydrocarbon contaminated soil were studied. The results showed that after 40 days of remediation of petroleum hydrocarbon contaminated soil by immobilized microorganisms with reed biochar, the removal rate of petroleum hydrocarbon in soil reached 55.01%, which was significantly higher than that of single biochar (45.82%) and blank treatment group (24.83%). It was also found that biochar immobilized microorganisms could significantly improve the activities of dehydrogenase, catalase, urease and polyphenol oxidase in soil. The use of biochar immobilized microorganism technology can not only improve the remediation efficiency of petroleum hydrocarbon contaminated soil, but can also significantly increase the soil biological enzyme activity.

Abstract Farmland soil is the material basis of grain production, and its quality is related to the national economy and the people's livelihood. With the development of economy and society, the content of Pb and Zn in farmland soil is increasing day by day. At present, the research on the total amount and form distribution of Pb and Zn in farmland soil and their influencing factors is relatively scattered, and there is a lack of systematic arrangement and cognition on the mutual transformation mechanism and pollution status of different forms. In order to further clarify the pollution status of heavy metals in soil and the distribution and mutual transformation mechanism of different forms, this study analyzes the pollution level, form distribution and influencing factors of Pb and Zn in farmland soil in China through data integration, and evaluates the ecological risk of heavy metals based on principal component analysis and geological accumulation index. The results showed that the average contents of Pb and Zn were 4045 mg · kg-1 and 10699 mg · kg-1, respectively; the proportion of Pb residual state is the highest in Northwest China, and the proportion of exchangeable state is the highest in Southwest China, and the proportion of residual Zn exceeds 50%; through analysis, it is found that ph is the main factor affecting the speciation distribution of heavy metals; the comprehensive analysis results of geological accumulation index and potential ecological risk index RI show that Pb in the study site is higher than Zn, but both are of slight hazard level; the comprehensive analysis of soil environmental factors showed that the speciation distribution of heavy metals reached the equilibrium state of speciation transformation by the combined action of multiple factors.

Abstract The objective of this paper is to discuss the approach of the journalism on the use of pesticides as a situation that generates environmental injustice. To make such reflection, we rely on the series of Zero Hora reports published in December 2016 on the contamination of Ceasa products, in Porto Alegre, by pesticides banned in Rio Grande do Sul (Brazil) or used above the limit set by law. We start from Acselrad's (2010) conception of environmental justice. This is a notion that refers to socio-political dynamics, since it includes conflicts arising from the violation of the rights of human communities due to unsustainable use of the environment. To assess the impact of injustices in the media, we resorted to the assumptions of Environmental Journalism, a perspective that defends the mobilizing function of journalism based on a complex view of the phenomena (Girardi et al. , 2012) from a descriptive and qualitative analysis (Mar- tins, 2001). Among the results, it is noted that the series does not incorporate a systemic view of the problem, ignoring the impacts of pesticides on the entire production chain and ecosystems.

Abstract In Mexico, an agricultural soil poor in nitrogen (N) contaminated by a hydrocarbon derivative such as automotive residual oil (ARA), with a relatively high concentration of 100,000 ppm, is an environmental problem, but also because it drastically affects soil properties associated with the mineralization of organic matter and loss of fertility, since it exceeds the maximum accepted limit of 4,400 ppm of the ­Mexican standard ­called, NOM-138-SEMARNAT-2012 (NOM-138). An alternative solution is to treat it with ecological actions to eliminate the ARA and recover fertility. Therefore, the objectives of this research were: i) bioremediation of soil contaminated by 100000 ppm of ARA ii) phytoremediation using Sorghum vulgare with Aspergillus inger and Penicillium chrysogenum to decrease ARA to a value below 4400 ppm of NOM-138. For this purpose, soil recovery was performed using the variable-response: disappearance of ARA by Soxhlet at the beginning and after bioremediation and at the end of phytoremediation with S. vulgare with phenology and biomass to seedling. All experimental data were validated by ANOVA/Tukey HSD P<0.05%. The results indicated that bioremediation and phytoremediation of soil contaminated by 100,000 ppm of ARA, decreased it to 3400 ppm, a value lower than the maximum established by NOM-138, sufficient for soil recovery in agricultural production, in 120 days, a relatively short period of time.

Abstract In order to solve the problem of cadmium (CD) pollution in Enshi mountain vegetable soil, pot experiment was used to study the effects of different passivators (biochar, hydroxyapatite, lime powder, fly ash and mixed organic passivators) on the passivation effect of Cd in the test soil and the yield, quality and Cd content of Chinese cabbage. The results showed that except the lime powder treatment inhibited the growth of Chinese cabbage, other treatments promoted the fresh weight and plant height of Chinese cabbage, and the fly ash treatment increased the fresh weight of Chinese Cabbage by 109.72% Hydroxyapatite, lime powder and mixed passivator increased soil ph by 25.18%, 36.61% and 28.21% respectively. Each treatment had no significant effect on the activities of soil urease, cellulase and sugarcane enzyme; Biochar and mixed passivator treatment significantly increased phosphatase activity by 52.85% and 69.82%, while lime powder treatment significantly inhibited phosphatase activity. The five passivator treatments all reduced the content of heavy metal Cd in Chinese cabbage. Among them, biochar, hydroxyapatite, lime powder and mixed passivator all achieved significant absorption inhibition effect, and lime powder was the best, reducing 73.80%. Each treatment had no significant effect on the quality of Chinese cabbage. Biochar and mixed passivator treatment reduced the total Cd content in soil by 27.21% and 46.98% respectively; The treatment of lime powder and mixed passivator reduced the ion-exchange CD43 in soil 67%, 47.35%. The application of five passivators can reduce the CD content of Chinese cabbage. The mixed passivator treatment not only does not affect the yield and quality of Chinese cabbage, but also enhances the soil enzyme activity and reduces the proportion of total Cd and effective CD (ionic and water-soluble) in the soil.