住宅室内降尘中邻苯二甲酸酯的污染特征及传输途径

Characterization of phthalates in residential house dust and their transfer routes

本文分别于夏季和冬季在北京市40户家庭的客厅和卧室采集降尘样品,研究降尘中邻苯二甲酸酯(PAEs)的污染特征.结果表明,室内降尘中主要的PAEs(及其浓度)为DIBP (39.6 ng·mg-1,几何平均浓度,下同)、DBP (38.7 ng·mg-1)和DEHP (418.5 ng·mg-1).降尘中PAEs的浓度与温度、相对湿度和换气次数均呈显著正相关(P<0.005).这是由于室温升高和换气次数增高加快PAEs的源排放速率,促进室内空气中PAEs积累并通过气相媒介传输使得降尘PAEs浓度增高;湿度升高促进空气中PAEs向降尘的传质,增大降尘中PAEs浓度.3种因素共同影响使得夏季降尘中3种PAEs的浓度均显著高于冬季(P<0.0001).研究还发现,源材料中PAEs至降尘的传输途径包括以气相为媒介的间接传输和源至降尘的直接转移,因此降尘PAEs浓度与采集平面材料相关;降尘PAEs浓度还受降尘在室内的停留时间影响.因此,相关研究需指明降尘的类型、采集位置和平面材料,便于利用测量数据进行准确的暴露评估.

House dust samples were collected in the living room and bedroom of forty residences in Beijing in both summer and winter. The concentrations of 7 phthalates in these samples were characterized. The results showed that the major phthalates in house dust were DIBP(39.6 ng·mg-1, geometric mean concentration, thereafter), DBP(38.7 ng·mg-1) and DEHP(418.5 ng·mg-1). The concentrations of dust-borne DIBP, DBP and DEHP were positively associated with temperature, relative humidity and ventilation rate(P<0.005). Elevated temperature and improved ventilation could accelerate the source emission rates of phthalates, resulting in the accumulation of airborne phthalates, and ultimately increase the concentration of dust-borne phthalates through the air-mediated transfer;whereas higher humidity could expedite the mass transfer of phthalates from air to dust, leading to the higher concentration of dust-borne phthalates. Due to the combined effects of above factors, significantly higher concentrations of dust-borne phthalates were found in the summer(P<0.0001). The results also suggested that phthalates transport from source materials to house dust via two routes: air-mediated indirect transfer and direct transfer from source to dust on source surface. As a result, the concentrations of dust-borne phthalates were closely associated with surface material. The residence time of dust was also found to impact the concentrations of dust-borne phthalates. Therefore, it is necessary to specify the type of dust, collection location and surface material, so that accurate exposure assessment can be conducted using measurement data.