在黑龙江省帽儿山地区对经过不同强度采伐1 a 后的次生林,采用PVC 管原位培养法测定土壤净氮矿化速率和净氮硝化速率的变化,结果表明,0～10 cm 土层的土壤平均净氮矿化速率和净氮硝化速率从大到小依次为皆伐后造林、皆伐后农作、50%强...在黑龙江省帽儿山地区对经过不同强度采伐1 a 后的次生林,采用PVC 管原位培养法测定土壤净氮矿化速率和净氮硝化速率的变化,结果表明,0～10 cm 土层的土壤平均净氮矿化速率和净氮硝化速率从大到小依次为皆伐后造林、皆伐后农作、50%强度采伐、25%强度采伐和对照,各采伐处理的0～12 cm 土层土壤质量含水量均显著高于对照（P〈0. 05）,净氮矿化速率和净氮硝化速率与土壤质量含水量呈显著正相关（P〈0. 05）,同时采伐亦增加了土壤中的有机碳含量,这说明采伐引起土壤含水量和有机碳含量增加是导致净氮矿化速率和净氮硝化速率升高的主要原因.此外,采伐还引起了土壤无机氮含量的变化,在生长季各采伐处理土壤硝态氮平均含量均显著高于对照（P〈0. 05）,而土壤铵态氮平均含量则显著低于对照（P〈0. 05）,各采伐处理土壤无机氮以硝态氮为主,对照则以铵态氮为主.上述结果表明该地区的森林经过采伐干扰后,可导致土壤硝态氮含量增加,土壤氮素流失风险亦增加.展开更多
Using the closed-top tube incubation method, we examined the soil nitrogen (N) mineralizationand nitrification in the primary Lithocarpus xylocarpus forest, a secondary oak forest and a tea plantationin the Ailao Moun...Using the closed-top tube incubation method, we examined the soil nitrogen (N) mineralizationand nitrification in the primary Lithocarpus xylocarpus forest, a secondary oak forest and a tea plantationin the Ailao Mountain, Yunnan Province, China. This study was conducted in the dry season fromNovember 20, 1998 to May 15, 1999. Results showed that there were significant differences among thethree vegetation types in both net N mineralization and nitrification rates, and they also demonstratedtemporal variation. The net ammonification rate (RA) was much higher than net nitrification rate (RN), andthe latter was about 0.5%-10% of the former. Our results indicated that incubation period, vegetation typeand the location of plot all interactively affected RA, RN and net mineralization rate (RM). We providedevidence that anthropogenic disturbances could result in changes of ecosystems processes such as Nmineralization and nitrification rates. It is obvious that tea plantation and secondary growth forest havemore physically (mainly temperature and moisture) controlled N transformation processes than thewell-preserved primary L. xylocarpus forest, implying that the conservation of primary forest ecosystemsin the Ailao Mountain region should be emphasized.展开更多
Carbon foam—a kind of new engineering material as packing material was adopted in three biofilters with different pore dimensions and adapted autotrophic nitrite nitrobacteria to investigate the purification of nitri...Carbon foam—a kind of new engineering material as packing material was adopted in three biofilters with different pore dimensions and adapted autotrophic nitrite nitrobacteria to investigate the purification of nitric oxide (NO) in a gas stream. The biofilm was developed on the surface of carbon foams using nitrite as its only nitric source. The moisture in the filter was maintained by ultrasonic aerosol equipment which can minimize the thickness of the liquid film. The liquid phase nitrification test was conducted to determine the variability and the potential of performance among the three carbon foam biofilters. The investigation showed that during the NO2^-—N inlet concentration of 200 g·L^-1·min^-1 to 800 g·L^-1·min^-1, the 24PPC (pores per centimeter) carbon foam biofilter had the greatest potential, achieving the NO2^-—N removal efficiency of 94% to 98%. The 8PPC and 18PPC carbon foam biofilters achieved the NO2^-—N removal efficiency of 15% to 21% and of 30% to 40%, respectively. The potential for this system to remove NO from a gas stream was shown on the basis of a steady removal efficiency of 41% to 50% which was attained for the 24PPC carbon foam biofilter at specified NO inlet concentration of 66.97 mg·m^-3 to 267.86mg·m^-3 and an empty-bed residence time of 3.5 min.展开更多
文摘在黑龙江省帽儿山地区对经过不同强度采伐1 a 后的次生林,采用PVC 管原位培养法测定土壤净氮矿化速率和净氮硝化速率的变化,结果表明,0～10 cm 土层的土壤平均净氮矿化速率和净氮硝化速率从大到小依次为皆伐后造林、皆伐后农作、50%强度采伐、25%强度采伐和对照,各采伐处理的0～12 cm 土层土壤质量含水量均显著高于对照（P〈0. 05）,净氮矿化速率和净氮硝化速率与土壤质量含水量呈显著正相关（P〈0. 05）,同时采伐亦增加了土壤中的有机碳含量,这说明采伐引起土壤含水量和有机碳含量增加是导致净氮矿化速率和净氮硝化速率升高的主要原因.此外,采伐还引起了土壤无机氮含量的变化,在生长季各采伐处理土壤硝态氮平均含量均显著高于对照（P〈0. 05）,而土壤铵态氮平均含量则显著低于对照（P〈0. 05）,各采伐处理土壤无机氮以硝态氮为主,对照则以铵态氮为主.上述结果表明该地区的森林经过采伐干扰后,可导致土壤硝态氮含量增加,土壤氮素流失风险亦增加.
文摘Using the closed-top tube incubation method, we examined the soil nitrogen (N) mineralizationand nitrification in the primary Lithocarpus xylocarpus forest, a secondary oak forest and a tea plantationin the Ailao Mountain, Yunnan Province, China. This study was conducted in the dry season fromNovember 20, 1998 to May 15, 1999. Results showed that there were significant differences among thethree vegetation types in both net N mineralization and nitrification rates, and they also demonstratedtemporal variation. The net ammonification rate (RA) was much higher than net nitrification rate (RN), andthe latter was about 0.5%-10% of the former. Our results indicated that incubation period, vegetation typeand the location of plot all interactively affected RA, RN and net mineralization rate (RM). We providedevidence that anthropogenic disturbances could result in changes of ecosystems processes such as Nmineralization and nitrification rates. It is obvious that tea plantation and secondary growth forest havemore physically (mainly temperature and moisture) controlled N transformation processes than thewell-preserved primary L. xylocarpus forest, implying that the conservation of primary forest ecosystemsin the Ailao Mountain region should be emphasized.
基金Supported by the National Natural Science Foundation of China (No. 20276070)the National 863 Project of China (No. 2002AA649310) the Natural Science Foundation of Zhejiang Province (No. 202084).
文摘Carbon foam—a kind of new engineering material as packing material was adopted in three biofilters with different pore dimensions and adapted autotrophic nitrite nitrobacteria to investigate the purification of nitric oxide (NO) in a gas stream. The biofilm was developed on the surface of carbon foams using nitrite as its only nitric source. The moisture in the filter was maintained by ultrasonic aerosol equipment which can minimize the thickness of the liquid film. The liquid phase nitrification test was conducted to determine the variability and the potential of performance among the three carbon foam biofilters. The investigation showed that during the NO2^-—N inlet concentration of 200 g·L^-1·min^-1 to 800 g·L^-1·min^-1, the 24PPC (pores per centimeter) carbon foam biofilter had the greatest potential, achieving the NO2^-—N removal efficiency of 94% to 98%. The 8PPC and 18PPC carbon foam biofilters achieved the NO2^-—N removal efficiency of 15% to 21% and of 30% to 40%, respectively. The potential for this system to remove NO from a gas stream was shown on the basis of a steady removal efficiency of 41% to 50% which was attained for the 24PPC carbon foam biofilter at specified NO inlet concentration of 66.97 mg·m^-3 to 267.86mg·m^-3 and an empty-bed residence time of 3.5 min.
