Effect Of Forested Riparian Buffer Width On Nitrogen Attenuation Efficiency

As industry and agriculture development, Water Eutrophication caused by nitrogen,phosphorus and other nutrient elements accumulating excessively has become a severelyworld-wide environmental problem. Nitrogen bound on the contamination containing whichcame from cropland drainage and township drainage was retained and transformated byriparian buffer zone effectively when it attempted to flow through the riparian buffer, but thedeterminate riparian buffer width which can remove nitrogen effectively has not been reportedyet. Identificating the relationship between riparian buffer width and nitrogen removalefficiency could offer theory basis for water pollution controlling, riparian buffer constructingand land resource using. Experimental site was conducted on forest riparian buffer along a 2ndstream of Ash river in the Jianlagou silviculture experiment station, Maoershan Township,Shangzhi City, Heilongjiang Province. Fertilizer was using in this experimental site beforeevery sampling strips and 25 cm-depth and 50 cm-depth soil water was collected and analyzedperiodically. Result shown that:1). Nitrate(NO₃^--N) in 25 cm-depth soil, Ammonium (NH₄⁺-N) in 25 cm-depth and 50cm-depth were 100% removed in a short distance(width≦10m);2). NO₃^--N 50 cm-depth soil was removed effectively by riparian buffer, and its removalefficiency were significant difference with riparian buffer width: average removal rate in 3 m,10 m, 20 m distance were 18.36%, 54.78% and 92.72% respectively (P＜0.001) in 30 msampling strip, average removal rate in 3 m, 10 m distance were 82.01%, 93.65% respectively(P＜0.01) in 20 m sampling strip, average removal rate in 3 m, 5 m distance were 74.28%,91.17% respectively (P=0.271) in 10 m sampling strip;3). Nitrate removal rate were significant difference with distance between sampling spotsand stream, and removal rate in the initiative 3 m of 30 m, 20 m and 10 m were 18.36%, 82.01%, 74.27% respectively (P=0.002), removal rate in the initiative 10 m of 30 m, 20 mwere 54.78% and 93.65% respectively (P＜0.001), removal rate in the middle 7 m of 30 m,20 m were 43.85%, 64.75%, respectively (P=0.002);4). and nitrogen removal occurred in initiative 10 m of riparian buffer zone, removal rate54.78% in the initiative 5 m in every sampling strips. Basing on this experiment result, 10 mwidth riparian buffer zone can retain and transform 91,17% nitrogen enter stream in thisdistrict if riparian buffer zone was constructed scientifically.