ABSTRACT

The concentration and spatial distribution of three naturally occurring radionuclides, ²³⁸U, ²³²Th and ⁴⁰K, has been determined in stream sediments from six left side tributaries of Bistricioara river (Bistriței Mountains, Eastern Carpathians, Romania). Historically, several mining works were undertaken in the area, with a view of exploring its’ potential regarding mineral resources. The aim of this study is to serve as a reference point for future environmental monitoring, in the event of resuming the mining activities in this area, which accommodates a major uranium deposit. Stream sediment samples were collected from the riverbed and the concentration of naturally occurring radionuclides was determined using gamma-ray spectrometry with a high purity germanium (HPGe) detector. The average activity concentration of ²³⁸U, ²³²Th and ⁴⁰K was found to be 27.84, 41.08 and 511.27 Bq·kg⁻¹. Based on radionuclides’ activity concentrations, radiological hazard parameters were estimated in order to assess any radiation risk which may be associated with the riverbed sediments. The radiological hazard parameters, such as radium equivalent activity (Ra_eq.), absorbed gamma dose rates in air (D_R), annual gonadal dose equivalent (AGDE), representative level index (RLI), annual effective dose equivalent (AEDE), external hazard index (H_ex) and internal hazard index (H_in), were all calculated and later compared with international safety limits. Generally, all radiological hazard parameters have values lower than world average excepting AGDE and RLI values that exceed the UNSCEAR thresholds.

摘要

三种天然放射性核素²³⁸ U，²³² Th和⁴⁰的浓度和空间分布在Bistricioara河的六个支流（Bistriței山，东喀尔巴阡山，罗马尼亚）的河流沉积物中测定了K。历史上，该地区曾进行过几次采矿工作，以发掘其在矿产资源方面的潜力。本研究的目的是在恢复该地区的采矿活动（可容纳大量铀矿床）的情况下，为将来的环境监测提供参考。从河床采集河流沉积物样品，并使用带有高纯度锗（HPGe）检测器的伽马射线光谱法测定自然存在的放射性核素的浓度。平均活动浓度为²³⁸ U，²³² Th和⁴⁰发现K为27.84、41.08和511.27Bq·kg ^-1。根据放射性核素的活动浓度，估算了放射性危害参数，以评估可能与河床沉积物有关的任何辐射风险。的放射性危害参数，如镭相当的活性（RA_当量），在空气中（d吸收伽马剂量率_{- [R} ），一年生性腺剂量当量（AGDE），代表电平指数（RLI），年有效剂量当量（AEDE），外部危险指数（H _ex）和内部危险指数（H _in），然后进行计算，然后与国际安全限值进行比较。通常，除AGDE和RLI值超过UNSCEAR阈值外，所有放射危害参数值均低于世界平均水平。