Simulation of sludge－dredging effects in controlling nutrient release of LakeKasumigaura with large－size core samples

Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes are less in aerobic than those in anaerobic. In different simulated dredged depth, the phosphate release showed large divergence in the anaerobic than in the aerobic. There was a larger accumulated release of phosphate and ammonia at actual dredged (St. B) than the undredged (St. A) in anaerobic condition. This showed that the sludge-dredging was effective of controlling phosphorus and nitrogen release. A preliminary assessment is drawn from the experiments that the sludge-dredging work in Tsuchiura Bay of Lake Kasumigaura can reduce about 15. 9% of phospbate and 56. 2% of anunonia release from the sediments respectively.

Kinetics of antimony biogeochemical processes under pre-definite anaerobic and aerobic conditions in a paddy soil

While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of quantitative understanding of Sb transformation in soil. Therefore, in this study, the kinetics of exogenous Sb in paddy soils were investigated under anaerobic and aerobic incubation conditions. The dissolved Sb(V) and the Sb(V) extracted by diffusive gradient technique decreased under anaerobic conditions and then increased under aerobic conditions. The redox reaction of Sb occurred, and Sb bioavailability significantly decreased after 55 days of incubation. The kinetics of Fe and the scanning transmission electron microscopy analysis revealed that the Fe oxides were reduced and became dispersed under anaerobic conditions, whereas they were oxidized and re-aggregated during the aerobic stage. In addition, the redox processes of sulfur and nitrogen were detected under both anaerobic and aerobic conditions. Based on these observations, a simplified kinetic model was established to distinguish the relative contributions of the transformation processes. The bioavailability of Sb was controlled by immobilization as a result of S reduction and by mobilization as a result of Fe reductive dissolution and S oxidation, rather than the p H. These processes coupled with the redox reaction of Sb jointly resulted in the complex behavior of Sb transformation under anaerobic and aerobic conditions. The model-based method and findings of this study provide a comprehensive understanding of the Sb transformation in a complex soil biogeochemical system under changing redox conditions.

Impact of microbial self-induced anaerobiosis fermentation(SIAF)on coffee quality

The fermentation of natural(NC)and pulped coffee(PC)was performed with a conventional method(platform)and under self-induced anaerobic fermentation(SIAF).Of the 12 samples analyzed during the fermentation process,the highest temperature was obtained by the SIAF method(30.5℃ for NC and 29.67℃ for PC)with 87 h of fermentation.Nonvolatile compounds(36 samples)were evaluated by high-performance liquid chromatography.Fermentation in the SIAF method contributed to the maximum amount of citric acid(2.534 mg/g)in pulped coffee and acetic acid(6.04 mg/g)and lactic acid(2.533 mg/g)in NC.Furan was the primary chemical class detected,followed by ketones and pyrazines.All coffees(12 samples)were evaluated five times and classified as specialty coffees(>80 points)following Specialty Coffee Association(SCA)protocols.The pulped coffee processed by the SIAF method showed a 2.83-point increase in the sensory score compared to the conventional method.Therefore,the SIAF method is accessible to producers,contributes to coffees with differentiated sensory profiles,and increases beverage quality.