青海南部高原积雪期与生长季高寒草甸土壤CO2、CH4和N2O通量的观测

以静态箱采集气体和气相色谱分析气体浓度方法,测定分析了青海南部高原积雪期和生长季高寒草甸土壤CO_2、CH_4和N_2O通量.结果表明在积雪集中期的3月3日和4日,积雪深度为9~10 cm时,土壤CO_2通量为1.33 g·(m~2·h)-1、N_2O通量为0.21 mg·(m~2·h)-1、CH_4通量为-0.19 mg·(m~2·h)-1;在积雪末期的4月30日,积雪深度在8~9 cm时,土壤CO_2通量为4.70 g·(m~2·h)~(-1)、N_2O通量为0.24 mg·(m~2·h)-1、CH_4通量为-1.23 mg·(m~2·h)-1;积雪深度小于4 cm时,土壤CO_2和N_2O通量较低或为负值,土壤CH_4通量为负值且绝对值较小.土壤CO_2和N_2O通量与积雪深度呈正相关、土壤CH_4通量与积雪深度呈负相关(P0.05),土壤CO_2与CH_4通量及CH_4与N_2O通量间呈负相关、土壤CO_2与N_2O通量间呈正相关.土壤CO_2和N_2O通量在生长季较高、在积雪末期其次、在积雪集中期较低;土壤CH_4通量为负值,其绝对值在生长季和积雪末期较大.结果说明积雪改变将影响青藏高原高寒草甸土壤温室气体通量.

Soil CO2,CH4 and N2O Fluxes from Alpine Meadows on the Plateau of Southern Qinghai Province During Snow Cover Period and Growing Seasons

To understand the fluxes of soil greenhouse gases from Alpine meadows on the Qinghai-Tibet plateau during non-growing season, a static chamber method was used to sample gases of soil CO₂, CH₄ and N₂O from alpine meadow on the plateau of Southern Qinghai province during snow cover period, and gas chromatography was used to analyze concentrations of these gases. The results showed that soil CO₂ flux was 1.33 g·(m²·h)^-1, soil CH₄ flux was -0.19 mg·(m²·h)^-1, and soil N₂O flux was 0.21 mg·(m²·h)^-1 when the snow depth was 9-10 cm on March 3 and 4 during the prevalence period of snow cover; soil CO₂ flux was 4.70 g·(m²·h)^-1 ,and soil N₂O flux was 0.24 mg·(m²·h)^-1, and soil CH₄ flux was -1.23 mg·(m²·h)^-1 when the snow depth was 8-9 cm on April 30 during the end period of snow cover. And soil CO₂ and N₂O fluxes were low or negative, soil CH₄ flux was negative and its absolute value was low when the snow depth was less than 4 cm during snow cover period. In addition, soil CO₂ or N₂O flux was positively correlated with the snow depth, and soil CH₄ flux was negatively correlated with the snow depth (P<0.05). Additionally, soil CO₂ or N₂O flux was negatively correlated with CH₄ fluxes, and soil CO₂ was positively correlated with soil N₂O flux. In addition, soil CO₂ flux was the highest during the growing season, followed by the end period of snow cover, and it was the lowest during the prevalence period of snow cover; soil N₂O flux was high during the growing season, followed by the end period of snow cover, and it was the lowest during the prevalence period of snow cover; soil CH₄ flux was negative, and its absolute value was higher during the growing season than other seasons, and it was the lowest during the prevalence period of snow cover. The results suggested that the change in snow cover would influence the fluxes of soil greenhouse gases from alpine meadow on the Qinghai-Tibet plateau.