Effects of Bacillus-based inoculum on odor emissions co-regulation, nutrient element transformations and microbial community tropological structures during chicken manure and sawdust composting.

This study aims to evaluate whether different doses of Bacillus-based inoculum inoculated in chicken manure and sawdust composting will provide distinct effects on the co-regulation of ammonia (NH3) and hydrogen sulfide (H2S), nutrient conversions and microbial topological structures. Results indicate that the Bacillus-based inoculum inhibits NH3 emissions mainly by regulating bacterial communities, while promotes H2S emissions by regulating both bacterial and fungal communities. The inoculum only has a little effect on total organic carbon (TOC) and inhibits total sulfur (TS) and total phosphorus (TP) accumulations. Low dose inoculation inhibits total potassium (TK) accumulation, while high dose inoculation promotes TK accumulation and the opposite is true for total nitrogen (TN). The inoculation slightly affects the bacterial compositions, significantly alters the fungal compositions and increases the microbial cooperation, thus influencing the compost substances transformations. The microbial communities promote ammonium nitrogen (NH4+-N), TN, available phosphorus (AP), total potassium (TK) and TS, but inhibit nitrate nitrogen (NO3--N), TP and TK. Additionally, the bacterial communities promote, while the fungal communities inhibit the nitrite nitrogen (NO2--N) production. The core bacterial and fungal genera regulate NH3 and H2S emissions through the secretions of metabolic enzymes and the promoting or inhibiting effects on NH3 and H2S emissions are always opposite. Hence, Bacillus-based inoculum cannot regulate the NH3 and H2S emissions simultaneously.

The Levels and Potential Carcinogenic Risks of PAHs in Liaohe Estuarine Reed Wetland Soils.

Sixteen polycyclic aromatic hydrocarbons (PAHs) were quantified by GC/MS in 30 soil samples of Liaohe estuarine reed wetland. The total concentrations of 16 PAHs ranged from 235 to 374 ng g-1, and seven carcinogenic PAHs concentrations were in the range of 83-109 ng g-1. A probabilistic carcinogenic potential for three age groups (including children, teenagers, and adults) exposed to soil PAHs via three pathways was quantitatively calculated based on Monte Carlo simulations. The 95th percentiles carcinogenic risks of PAHs for children, teenagers, and adults were 7.80 × 10-8, 4.03 × 10-8, and 1.14 × 10-7, respectively. The carcinogenic risk levels were all below 10-6, indicating no potential for cancer development. Dermal contact and accident ingestion of soil were the dominant exposure pathways to soil PAHs. BaP and DBahA were the major contributors to carcinogenic risk in this study. Sensitivity analysis demonstrated that exposure duration and PAH concentrations in soil were the key exposure parameters in calculating carcinogenic risk. Results from this study will provide valuable information for potential scientific evaluation and prevention for carcinogenic risk exposed to soil PAHs.

Independent and combined effects of antibiotic stress and EM microbial agent on the nitrogen and humus transformation and bacterial community successions during the chicken manure composting.

This study aimed to investigate the independent and combined effects of antibiotic and EM microbial agent on the nitrogen and humus (HS) transformations as well as the bacterial community successions during the chicken manure and rice husk composting. EM microbial agent accelerated the oxytetracycline (OTC) degradation, but slowed down the norfloxacin (NOR) degradation. OTC inhibited the TN retention and promoted the HS accumulation, both NOR and EM microbial agent inhibited the TN retention and HS accumulation, while EM microbial agent showed an antagonistic effect on TN immobilization with antibiotics and reduced the impacts of antibiotics on HS. Obvious bacterial community successions occurred. Firmicutes were related to HS transformation, while Firmicutes, Actinobacteriota and Proteobacteria were associated with nitrogen conversion. NOR promoted the transformations of NH4+-N to NO3--N and FA to HA. The findings provided theoretical data for the recycle of antibiotic-contaminated manure and the efficient production of high-quality compost.

[Behaviors and Mechanisms of CIP and OFL Adsorption by Magnetic Biochar].

A magnetic reed biochar (MBC) was fabricated through chemical coprecipitation first and subsequent pyrolysis of reed stalk powder precipitated with Fe2+/Fe3+ at 873.15 K. The structure and properties of the MBC were characterized using SEM, BET, FTIR, and VSM. Adsorption experiments were carried out to investigate the adsorption behaviors and mechanisms of ciprofloxacin (CIP) and ofloxacin (OFL) onto the MBC. The MBC possessed roughness and pores within its structure and contained a large amount of oxygen-containing functional groups on the surface. The BET surface area of the MBC was 254.6 m2·g-1, and the total pore volume was 0.257 cm3·g-1, thus the MBC exhibited a relatively high porosity. The adsorption process was found to be pH and temperature dependent. The relative contributions of adsorbate species (cations, zwitterions, and anions) to overall adsorption varied for different pH values. Thermodynamic parameters indicated that the CIP and OFL adsorption onto MBC was a spontaneous, endothermic, and entropy-increasing process. Kinetics and isotherm data of CIP and OFL adsorption onto MBC were well depicted by the pseudo-second-order model and the Langmuir model. The equilibrium adsorption capacities of CIP and OFL onto MBC were 27.84 mg·g-1 and 22.00 mg·g-1, respectively. Pore-filling effects, π-π interaction between electron donors and acceptors, hydrogen bonding formation, hydrophobic interaction, and electrostatic interaction may be important mechanisms for CIP and OFL adsorption onto the MBC.