垃圾渗沥液中氨氮的电化学氧化

针对目前国内外垃圾渗沥液处理中存在的问题,采用电化学氧化与上流式厌氧污泥床（UASB）相结合,研究建立了对香港垃圾渗沥液的二步法处理工艺．本文着重探讨了电化学间接氧化去除渗沥液中氨氮的反应机制及主要影响因素,并通过实验找出了最佳的操作条件：入水初始 pH值为9.0;流速为0.01－0.10cm/s;CI加入量2000mg/L;电流密度 32.3mA/cm²．在此条件下,经过 6h电解后,UASB反应器出水中NH_－N和COD的去除率分别达到100％和87％．对该电化学氧化过程的运行成本进行了评估．     

Distribution and fractionation of phosphorus, cadmium, nickel, and lead in calcareous soils amended with composts

Composts improve organic carbon content and nutrients of calcareous soils but the accumulation and distribution of phosphorus and heavy metals among various fractions in soil may vary under the south Florida conditions. The accumulation of P, Cd, Ni, and Pb with depth and the distribution of water soluble, exchangeable, carbonate, Fe-Mn oxides, organic and residual forms of each element were investigated in soils amended with municipal solid waste (MSW) compost, co-compost and biosolids compost and inorganic fertilizer (as control). Total concentrations of P, Cd, Ni, and Pb were higher in the 0-22 cm soil layers and decreased considerably in the rock layers. These elements were in the decreasing order of P > Pb > Ni > Cd. Amounts of water soluble and exchangeable forms of P, Cd, Ni and Pb were negligible at 0-22 cm soil depths except for Cd in the 10-22 cm depth. Amending calcareous soil with either organic or inorganic amendments rendered phosphorus, nickle and lead in the residual form followed by Fe-Mn oxides form in the 0-10 and 10-22 cm soil layers. Cadmium was predominantly in the Fe-Mn oxides fraction followed by the residual and carbonate forms in both soil layers. A significant positive correlation was found between various organic carbon fractions and organic forms of P, Cd and Pb in the surface soil layer. Soil amended with MSW compost had higher concentration of Cd in the organic fraction whereas, co-compost and MSW compost amended soil had higher concentrations of organic Ni fraction in the 0-10 cm soil layer.     

Assessing risk and adaptation options to fires and windstorms in European forestry

Risks can generally be described as the combination of hazard, exposure and vulnerability. Using this framework, we evaluated the historical and future development of risk of fire and wind damage in European forestry at the national level. Fire risk is expected to increase, mainly as a consequence of an increase in fire hazard, defined as the Fire Weather Index in summer. Exposure, defined as forest area, is expected to increase slightly as a consequence of active afforestation and abandonment of marginal agricultural areas. Adaptation options to fire risk should therefore aim to decrease the vulnerability, where a change in tree species from conifers to broadleaves had most effect. Risk for wind damage in forests is expected to increase mainly as a consequence of increase in exposure (total growing stock) and vulnerability (defined by age class and tree species distribution). Projections of future wind climate indicate an increase in hazard (storminess) mainly over Western Europe. Adaptation options should aim to limit the increase in exposure and vulnerability. Only an increase in harvest level can stop the current build-up of growing stock, while at the same time it will lower vulnerability through the reduction of the share of old and vulnerable stands. Changing species from conifers to broadleaves helps to reduce vulnerability as well. Lowering vulnerability by decreasing the rotation length is only effective in combination with a high demand for wood. Due to data limitations, no forecast of future fire area or damaged timber amount by storms was possible.