Application of biochar to soils may result in plant contamination and human cancer risk due to exposure of polycyclic aromatic hydrocarbons

Wang, Jian; Xia, Kang; Waigi, Michael Gatheru; Gao, Yanzheng; Odinga, Emmanuel Stephen; Ling, Wanting; Liu, Juan

doi:10.1016/j.envint.2018.09.010

Cited by 84 publications

(34 citation statements)

References 39 publications

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“…The results obtained from our pot experiment suggest that co-application of biochar with N fertilizer could markedly decrease rice yield under B400, but not B700, compared with the nonbiochar control (Table 5). Our finding lends support to Jian et al (2018) that laboratoryproduced biochar at higher pyrolysis temperature contained lower bioavailable concentrations of polycyclic aromatic hydrocarbons and did not release volatile organic compounds at room temperatures. Wheat-straw biochar (12 t ha −1 ) was previously found to have no significant effect on rice production in the first season (Xie et al, 2013).…”

Section: Biochar Application Decreases Rice Productivity In Short-tersupporting

confidence: 82%

Peer Review #2 of "Biochar prepared at different pyrolysis temperatures affects urea-nitrogen immobilization and N2O emissions in paddy fields (v0.1)"

2019

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Background. Food safety has become a major issue, with serious environmental pollution resulting from losses of nitrogen (N) fertilizers. N is a key element for plant growth and is often one of the most important yield-limiting nutrients in paddy soil. Urea-N immobilization is an important process for restoring the levels of soil nutrient depleted by rice production and sustaining productivity. The benefits of biochar application include improved soil fertility, altered N dynamics, and reduced nutrient leaching. However, due to high variability in the quality of biochar, the responses of N loss and rice productivity to biochar amendments, especially those prepared at different pyrolysis temperatures, are still unclear. The main objectives of the present study were to examine the effects of biochar prepared at different pyrolysis temperatures on fertilizer N immobilization in paddy soil and explore the underlying mechanisms. Methods. Two biochar samples were prepared by pyrolysis of maize straw at 400°C (B400) and 700°C (B700), respectively. The biochar was applied to paddy soil at three rates (0, 0.7, and 2.1%, w/w), with or without N fertilization (0, 168, and 210 kg N ha-1). Pot experiments were performed to determine nitrous oxide (N 2 O) emissions and 15 N recovery from paddy soil using a 15 N tracer across the rice growing season. Results. Compared with the non-biochar control, biochar significantly decreased soil bulk density while increasing soil porosity, irrespective of pyrolysis temperature and N fertilizer level. Under B400 and B700, a high biochar rate decreased N loss rate to 66.42 and 68.90%, whereas a high N level increased it to 77.21 and 76.99%, respectively. Biochar also markedly decreased N 2 O emissions to 1.06 (B400) and 0.75 kg ha −1 (B700); low-N treatment caused a decrease in N 2 O emissions under B400, but this decrease was not observed under B700. An application rate of biochar of 2.1% plus 210 kg ha −1 N fertilizer substantially decreased the N fertilizer-induced N 2 O emission factor under B400, whereas under B700 no significant difference was observed. Biochar combined with N fertilizer treatment decreased rice biomass and grain yield by an average of 51.55 and 23.90 g pot-1 , respectively, but the yield reduction under B700 was lower than under B400. Conclusion. Irrespective of pyrolysis temperature, biochar had a positive effect on residual soil 15 N content, while it negatively affected the 15 N recovery of rice, N 2 O emissions from soil, rice biomass, and grain yield in the first year. Generally, a high application rate of biochar prepared at high or low pyrolysis temperature reduced the N fertilizer-induced N 2 O emission factor considerably. These biochar effects were dependent on N fertilizer level, biochar application rate, and their interactions.

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Section: Biochar Application Decreases Rice Productivity In Short-tersupporting

confidence: 82%

Peer Review #2 of "Biochar prepared at different pyrolysis temperatures affects urea-nitrogen immobilization and N2O emissions in paddy fields (v0.1)"

2019

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“…It is noteworthy that some researches already showed a clear evidence that biochar application led to an accumulation of PAHs in plants and pose a risk to human health (Wang et al 2018b). Because of this health risk, many efforts were devoted to understand or reduce the total and bioavailable PAHs inside the biochars (Sharma and Hajaligol 2003;Zielinska and Oleszczuk, 2016).…”

Section: Dissolvable Contaminantsmentioning

confidence: 99%

Environmental behavior of engineered biochars and their aging processes in soil

Duan

Oleszczuk

Pan

et al. 2019

Biochar

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In recent years, due to the broad application of biochars, the preparation, environmental behavior and aging processes of biochars have attracted wide attention globally, especially the modification of biochars. However, most of the studies only consider the improvement of biochar properties right after the modification, but neglect a complete evaluation of the longterm stability and eco-toxicity of these newly developed materials after entering the environment. With the development and utilization of biochars, engineered biochars (EngBCs) will soon enter the market, but its environmental risk still remains unclear. The literature does not provide adequate information on how aging of EngBCs will affect their properties, and indirectly impact the properties of soils (cycle of elements and organic matter). Therefore, this review paper summarizes the aging process and environmental risk of biochars, aiming at better understanding the interactions between EngBCs and soil components or pollutants. More importantly, this review is to point out the contradictory speculations of environmental behavior of EngBCs studied at the present stage. Due to the modification, the EngBCs stability may be significantly reduced. However, the formation of functional group on EngBCs will enhance their interaction with soil minerals to form biocharsmineral complex, and thus EngBCs could be protected. The impacts of EngBCs after entering the environment are also ambiguous. Therefore, understanding EngBCs environmental behavior is critical, which is helpful to reduce the potential risk and to produce EngBCs following the rule of sustainable development and safety to the environment.

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“…Polycyclic aromatic hydrocarbon (PAHs), a class of toxic organic pollutants, are composed of multiple fused aromatic rings in linear, angular or cluster arrangements. In addition, 16 PAHs have been listed by the US Environmental Protection Agency (US-EPA) as priority contaminants [1][2][3]. PAHs have generated extreme concern due to their toxicity, teratogenicity, carcinogenicity, and mutagenesis to humans and the wider environment.…”

Section: Introductionmentioning

confidence: 99%

Removal of Bound PAH Residues in Contaminated Soils by Fenton Oxidation

et al. 2019

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The availability of bound residues of polycyclic aromatic hydrocarbons (PAHs), in reference to their parent compounds, can be enhanced by microbial activity and chemical reactions, which pose severe risks for the ecosystems encompassing contaminated soils. Considerable attention has been raised on how to remove these bound residues from PAH-contaminated soils. This paper provides a novel application of Fenton oxidation in the removal of bound residues of model PAHs, such as naphthalene (NAP), acenaphthene (ACP), fluorene (FLU) and anthracene (ANT), from naturally contaminated soils. The citric acid-enhanced Fenton treatment resulted in the degradation of bound PAH residues that followed pseudo-first-order kinetics, with rate constants within 4.22 × 10−2, 1.25 × 10−1 and 2.72 × 10−1 h−1 for NAP, FLU, and ANT, respectively. The reactivity of bound PAH residues showed a correlation with their ionization potential (IP) values. Moreover, the degradation rate of bound PAH residues was significantly correlated with H2O2-Fe2+ ratio (m/m) and H2O2 concentrations. The highest removal efficiencies of bound PAH residues was up to 89.5% with the treatment of chelating agent oxalic acid, which was demonstrated to be superior to other acids, such as citric acid and hydrochloric acid. This study provides valuable insight into the feasibility of citric acid-Fenton and oxalic acid-Fenton treatments in rehabilitating bound PAH residues in contaminated soils.

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Application of biochar to soils may result in plant contamination and human cancer risk due to exposure of polycyclic aromatic hydrocarbons

Cited by 84 publications

References 39 publications

Peer Review #2 of "Biochar prepared at different pyrolysis temperatures affects urea-nitrogen immobilization and N2O emissions in paddy fields (v0.1)"

Peer Review #2 of "Biochar prepared at different pyrolysis temperatures affects urea-nitrogen immobilization and N2O emissions in paddy fields (v0.1)"

Environmental behavior of engineered biochars and their aging processes in soil

Removal of Bound PAH Residues in Contaminated Soils by Fenton Oxidation

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