三峡库区澎溪河消落带落干期土壤硝化强度及影响因素

研究了三峡库区澎溪河落干期消落带不同地点、不同高程段、不同土地利用方式下土壤硝化强度及影响因素。结果表明,研究区域消落带硝化强度范围为0.76~9.76 mg/kg·d,平均值为3.76±0.76 mg/kg·d,明显低于国内其他研究区域土壤硝化强度。澎溪河消落带从上游汉丰湖到下游黄石,土壤硝化强度呈现递减的趋势。随着高程的增加,消落带土壤硝化强度逐渐降低,但没有显著差异（P >0.05）。消落带不同土地利用方式中,河滩地土壤硝化强度显著高于耕地土壤硝化强度（P<0.05）,是耕地土壤硝化强度的1.82倍。消落带土壤硝化强度与土壤pH值呈显著正相关（P<0.05）,与有机质含量及亚硝化菌数量呈极显著正相关（P<0.01）,周期性的淹水影响了消落带土壤pH值和有机质含量,从而影响了消落带土壤硝化强度。     

The influencing factors of N2O emission and denitrification in the soil of water-level-fluctuation zone in the Three Gorges Reservoir area

In order to study the influences of water filled pore space (WFPS), temperature, the addition of nitrate (NO -3) and carbon source on N2O emission and denitrification in the soil of water-level-fluctuation zone in the Three Gorges Reservoir area, C2H2 in hibition incubation experiments are applied. Results from experiments in laboratory and in situ field are analyzed. Results show that the WFPS is a main factor determining N2O emission and denitrification. Denitrification rate increases while the WFPS increases, and the maximum denitrification rate and the maximum N2O emission rate appear when the WFPS is 100% and 60%, respectively. In addition, while the temperature is between 10 ℃ and 40 ℃, the increase of temperature contributes to the increase of the N2O emission and denitrification rates. Furthermore, it is found that the N2O emission and denitrification rates are significantly and positively correlated with temperature. The addition of carbon source could increase denitrification performance in soil. However, the addition of nitrate has a negative impact on the denitrification performance, because nitrogen source is not the main factor determining denitrification performance and excessive nitrate could inhibit the denitrification in these experiments. The addition of glucose, which is a carbon source easily be utilized by denitrifying bacteria, could significantly increase the denitrification rate in soil, and the maximum denitrification rate takes place while the carbon content in per kilogram soil is 240 mg.     

Urban Design for Continuity of the Urban Context: A Case Study of Landscape Conceptual Design on Both Banks of the Tuojiang River in Luzhou, P. R. China

Luzhou is a famous wine country and a historical city in P. R. China. Insuring the continuity of urban context is an effective method for creating a distinctive image of a city. Considering the authenticity, sustainable development, enforceability and regional differences of urban contexts, it is an appropriate way to extract the original urban context and adopt a proper design method that combines humanized nature, material culture, and intangible culture to form an area with cultural atmosphere on both banks of the Tuojiang River.