中文摘要：

采用ICP-MS分析了北京石花洞地区连续12个月大气沉降样品中稀酸可溶态稀土元素,计算了其沉降通量,分析了其分布模式及可能来源。结果显示:(1)各稀土元素沉降通量均表现出显著的季节变化特征,高值出现在春季(4月、5月)和秋季(10月),可能主要受大气粉尘活动的影响;从冬季的12月、1月到春季的4月、5月以及从夏季的6月到秋季的10月呈现阶梯上升过程。(2)球粒陨石标准化的稀土元素分布模式与洛川黄土及2006年北京特大降尘的一致,均表现为轻稀土元素相对于重稀土元素明显富集和较明显的Eu负异常,表明北京石花洞地区大气沉降物可溶态稀土元素主要来源于大气粉尘物质。

英文摘要：

Monthly atmospheric deposition was collected at the Shihua Cave,Beijing during the period fromNovember2012to October2012and dilute-acid soluble rare earth elements(REEs)was determined by means ofICP-MS.The monthly flux of each REE was calculated and it was found that the monthly fluxes of the solublefraction of REEs display notable seasonal variations.Higher fluxes are found in spring(April and May)andautumn(October),which may be affected by atmospheric dust activities and precipitation.Lower values are foundin December,January and June.An increasing trend can be observed from December-January to April-May andfrom June to October.The chondrite-normalized REEs patterns show a significant enrichment in light REEsrelative to heavy REEs and a remarkable negative Eu anomaly.These patterns are almost identical to those of theaeolian sediments deposited at Luochuan and the wind-blown sediments deposited at Beijing during the heavy dustevent in the year of2006,suggesting that the soluable REEs may be derived mainly from wind-blown dust.