Affecting factors on the concentration and amount of forest run-off waterchemicals.

1.森林生态系统中水化学物质的垂直分布每月采集降水、森林穿透雨、凋落物层、5、10、20、30、50、70 cm土层和溪流径流水2~4次，并对其中的水化学物质进行研究。将内径19.5 cm的塑料管垂直插入每一土层采集水样。在穿透雨中，降水中各矿物质的浓度均有所增加。NH4-N、有机N、P、K、Cl、SO4浓度在渗入各土层时均呈下降趋势。另一方面，硝态氮、钙、镁在各土层均有所增加，并在70 cm左右达到最大。降水和溪流径流中水化学成分的季节变化。冬季降水中的钠和氯由于西北季风带携带的海盐而增加。氯浓度的增加对溪水中的浓度有影响。溪水中NO_3-N含量从4月份开始随土壤生化活性的增加而增加，在秋末达到最大。在冬季减少之后，在积雪融化季节又出现了冲刷。溪水中的SO4、Ca、Mg在夏季径流增加时有下降的趋势。PH、SiO_2、NH_4-N、org-N和Na.3没有明显的季节变化。洪水中水化学物质浓度的变化：溪水中NO_3-N浓度随着径流水量的增加而增加，在径流水量达到最大时达到最大值，并随着水量的减少而降低。Na、Mg、SO4随水分的增加呈下降趋势。氯的变化与汛期有关，钙、钾的变化与流域有关。

1. Vertical distribution of waterchemicals in a forest ecosystem.Precipitation, forest throughfall, a litter layer, 5, 10, 20, 30, 50, 70 cm soil layers, and stream run-off water were collected vertically 2-4 times per month, and the waterchemicals therein were studied. Plastic pipes with an inside diameter of 19.5cm were inserted vertically into each soil layer to collect the water samples. The concentration of each mineral in the precipitation increased in the throughfall. While infiltrating through each soil layer, the concentration of NH_4-N, organic-N, P, K, Cl, So_4 decreased. On the other hand, NO_3-N, Ca, and Mg increased in each soil layer and reached a maximum at around 70cm in depth.2. Seasonal change of waterchemicals in precipitation and stream run-off water.Na and Cl in precipitation increased in the winter due to sea salt which wascarried by the north-west monsonn. The increase of Cl affected the concentration in stream water. NO_3-N in stream water incresed from April with the increase of biochemical activity in the soil, reaching a maximum late in the autumn. After the decrease in winter, it was flushed again during the snow melting season. SO_4, Ca, Mg in stream water tended to decrease in the summer when run-off water increased. Seasonal change was not detected in pH, SiO_2, NH_4-N, org-N, or Na.3. Change of the concentration of waterchemicals in floodwater.NO_3-N concentration in stream water increased with the increase in run-off water and reached a maximum when run-off water reached a maximum, and decreased with the decrease in water. Na, Mg, and SO_4 tended to decrease with the increase in water. The change of Cl depended on the season of floods, and those of Ca and K depended on the watersheds.