Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon （SOC）. SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-100 were simulated using stochastic modelling. Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration. Therefore, there was a counteract effect on SOC dynamics between climate warming and elevated CO2. For different soil erosion extents, warming 1℃ and elevated atmospheric CO2 resulted in SOC increase at least 15%, while warming 5 ℃ and elevated CO2 resulted in SOC decrease more than 29%. SOC predictions with uncertainty assessment were conducted for different scenarios of soil erosion, climate change, and elevated CO2. Statistically, SOC decreased linearly with the probability. SOC also decreased with time and the degree of soil erosion. For example, in 2100 with a probability of 50%, SOC was 1 617, 1 167, and 892 g m^-2, respectively, for no, minimum, and maximum soil erosion. Under climate warming 5 ℃ and elevated CO2, the soil carbon pools became a carbon source to the atmosphere （P 〉 95%）. The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2.
To find new strain in the microbial fuel cell (MFC) for quinoline removal from wastewater and soil, a facultative anaerobic bacterium strain was isolated from the anode of MFC, utilizing quinoline as the carbon source and electron donor. Based on the 16S rRNA sequence analysis, the bacterium strain was Gram-negative and identified as Pseudomonas sp. Q1 according to its morphology and physiochemical properties. The strain was inoculated into a double-chambered MFC using various quinoline concentrations (0, 50, 75, 86, 100, 150, 200 and 300 mg L-1 ) combining with 300 mg L-1 glucose as the fuel. Results showed that electricity was generated from the MFC, in which quinoline was degraded simultaneously. The values of Coulombic efficiency (CE) increased with the increase of quinoline concentrations from 0 to 100 mg L-1 then decreased with the increase of quinoline concentration from 100 to 300 mg L-1 , and the maximum CE 36.7% was obtained at the quinoline concentration of 100 mg L-1 . The cyclic voltammetry analysis suggested that the mechanism of electron transfer was through excreting mediators produced by the strain Q1. The MFC should be a potential method for the treatment of quinoline-contaminated water and soil.
As the bioelectrochemical system, the microbial fuel cell （MFC） and the microbial electrolysis cell （MEC） were developed to selectively recover Cu^2＋ and Ni^2＋ ions from wastewater. The wastewater was treated in the cathode chambers of the system, in which Cu^2＋ and Ni^2＋ ions were removed by using the MFC and the MEC, respectively. At an initial Cu^2＋ concentration of 500 mg· L^-1, removal efficiencies of Cu^2＋ increased from 97.0%±1.8% to 99.0%±0.3% with the initial Ni^2＋ concentrations from 250 to 1000 mg· L^-1, and maximum power densities increased from 3.1±0.5 to 5.4±0.6W.m-3. The Ni^2＋ removal mass in the MEC increased from 6.84-0.2 to 20.54-1.5 mg with the increase of Ni^2＋ concentrations. At an initial Ni^2＋ concentration of 500 mg· L^-1, Cu^2＋ removal etticiencies decreased from 99.1%±0.3% to 74.2%±3.8% with the initial Cu^2＋ concentrations from 250 to 1000 mg -L1, and maximum power densities increased from 3.0±0.1 to 6.3±1.2W.m^-3. Subsequently, the Ni^2＋ removal efficiencies decreased from 96.9%-4-3.1% to 73.3%4-5.4%. The results clearly demonstrated the feasibility of selective recovery of Cu2~ and Ni2~ from the wastewater using the bioelectrochemical system.
Haiping LUO Bangyu QIN Guangli LIU Renduo ZHANG Yabo TANG Yanping HOU
