Biogeochemistry of Permafrosted/NonPermafrosted Watersheds in CPCRW: Summer 1995

Chemical measurements of groundwater, soil water and stream water were made in watersheds C2 and C3 in CPCRW (DOC, DON, NO3-N, NH4-N, Al, Mg, Ca, Mn, Si, K, Na, SO4 and conductivity). One watershed C3 had extensive permafrost and the other C2 had limited permafrost. Stream discharge data was collected from permanently installed flumes. Soil water retained within the rooting zone (0.3 - 0.5 m) was high in DOC, DON and DIN but low in dissolved minerals (dominantly Ca, Mg and Na) and conductivity. The reverse was true for groundwater from springs and wells. Permafrost in C3 prevented deep percolation of water and generated stormflows rich in DOC. Stormflow accounted for 24% of total streamflow in C3 but only 3% of total streamflow in C2. The presence of permafrost appears to result in higher fluxes of DOC, DON and DIN into stream water from upland soils.

本研究针对CPCRW内C2与C3两个流域的地下水、土壤水及河流水体开展化学组分测定，检测指标包括溶解有机碳（Dissolved Organic Carbon, DOC）、溶解有机氮（Dissolved Organic Nitrogen, DON）、硝态氮（Nitrate-Nitrogen, NO3-N）、铵态氮（Ammonium-Nitrogen, NH4-N）、铝（Aluminum, Al）、镁（Magnesium, Mg）、钙（Calcium, Ca）、锰（Manganese, Mn）、硅（Silicon, Si）、钾（Potassium, K）、钠（Sodium, Na）、硫酸盐（Sulfate, SO4）及电导率（Conductivity）；其中C3流域分布有大面积多年冻土，C2流域多年冻土分布有限。径流数据通过永久安装的测流槽采集获取，根系层（0.3~0.5米）内留存的土壤水溶解有机碳（DOC）、溶解有机氮（DON）与溶解无机氮（Dissolved Inorganic Nitrogen, DIN）含量较高，但溶解态矿物（以钙、镁、钠为主）及电导率较低，而泉水与井水来源的地下水则呈现完全相反的特征。C3流域的多年冻土阻碍了水分的深层入渗，进而形成富含DOC的暴雨径流，该类暴雨径流量分别占C3流域总径流量的24%、仅占C2流域总径流量的3%；多年冻土的存在似乎使得高地土壤向河流水体迁移的DOC、DON与DIN通量显著提升。