南京地区7Be沉降特征

7Be是研究大气科学与地球化学的核元素之一，对研究短期过程的地表土壤颗粒迁移具有较大价值。为了解南京地区利用7Be进行土壤侵蚀示踪研究的合适时机，于2010年1月~2011年12月收集南京地区各月的7Be沉降样品，经实验室化学实验处理和γ谱仪测量，计算7Be沉降通量，并分析7Be大气沉降的季节性变化趋势。结果表明：南京地区平均7Be沉降量为1 62178 Bq/（m2·a），沉降通量为066～1449 Bq/（m2·d），平均沉降通量为444 Bq/（m2·d）；7Be沉降通量的季节变化呈现双峰型趋势，冬末春初和夏季是两个高值区；7Be沉降的а值冬春季较大，夏季最低；降雨量大小与沉降量存在明显的正相关

DEPOSITIONAL FLUXES OF ~7BE AT NANJING REGION

7Be which is one of the most investigated radionuclides in the atmosphere has wide applications in meteorology and geochemistry.It also has been a useful tracer for documenting soil erosion rates over much shorter timescales.In order to find the suitable time of soil erosion by using 7Be tracer in Nanjing region,monthly atmospheric deposition samples of 7Be were collected from January 2010 to December 2011.Deposition samples were experimented to obtain residual samples which was followed by measurement with a HPGe detector for 7Be.Deposition fluxes and seasonal variation pattern of atmospheric deposition of 7Be were analyzed.The results showed that the depositional fluxes of 7Be ranged from 066 to 1449 Bq/(m2·d) and a mean value was 444 Bq/(m2·d),annual average depositional fluxes were 1 62178 Bq/m2.The seasonal variation of depositional fluxes of 7Be showed double peaks,higher flux value was in late winter and early spring,another higher flux value was in summer.The fractor of precipitation normalized depositional fluxes of 7Be were higher value in winter and spring,but the minimum value was in summer.Furthermore,a positive correlation between the 7Be fluxes and precipitation was observed in this study