Dynamics And Critical Load Of Sulfur And Nitrogen Under Acid Deposition In Shaoshan Forest

In the thesis, the dynamic process of S and N are analyzed and the critical load is investigated under acid deposition basing on the monitoring data during 2001 and 2002 in Shaoshan forest. The results showed that the ion concentrations of all elements were negative correlation with rain water, which was due to the accumulation of the dry deposition during the relatively long dry period in winter and the dilution of ion concentrations the rainfall was plentiful in summer.The ratios of SO₄^2-/NO3- range from 2.66 to 15.53. SO₄^2- is the predominant anion in bulk precipitation in Shaoshan forest. However, the impact of NOx is also important to the formation of acid rain in Shaoshan forest. As we know, Shaoshan is a show-place and is with more than 1 million tourists come here for sightseeing every year and the emission of vehicle tail gas aggravate the pollution of NO3-.The input of SO₄^2- is less than the output but the input of NO3- is more than the output of NO3- by reason of some of S element is taken away and N element is remained in soil in liquid cycling. Also we analyzed the influencing source of the bulk precipitation and concluded that agriculture source have the biggest impact on the bulk precipitation, earth source to the next, again sea source, the last industry source. The regression analyses of pH and SO₄^2-, NO3- as well as Ca2+ show that the correlation of SO₄^2- and pH is more significant than that of other ions indicating that the origins of H+ and SO₄^2- are identical and both of them come from industry sources.Combining the acid deposition dynamic model MAGIC model and SMART model for critical load, we simulate and work out that the S deposition critical load is 1.76keq·hm-2·a-1.