Shallow marine sediments characterisation of the Bagnoli brownfield site, Pozzuoli Bay (Italy)

We adopted a combined geophysical-stratigraphic approach to identify grain size anomalies in sediment distribution of the Bagnoli coastal brownfield site. A large industrial plant occupied this area during most of the 20th Century. We used 18 core logs to identify macroscopic variation in sediment stratigraphy, and 72 supplemental cores to mark changes between sandy- and silt-dominated intervals. The stratigraphy evidenced the presence of anomalous lens of silt within a sandy coastal sector inside the Bagnoli industrial harbour. Cores description helped us to calibrate the interpretation of 4 subbottom profiles, that we used to obtain information on geometries of silty deposits. The spatial layout of sediments revealed that silt intervals are present in the area bounded by the old industrial wharfs. We suggest that these silty sediments are likely the result of uncontrolled discharge occurred during the last century. Once calibrated, high-resolution mono-channel seismic profiles helped us to define the shape as well as the real extent and thicknesses of silty deposits, resulted to be ca. 515.000 m², with an overall volume of 480.000 m³. These results are a first attempt to define the amount of polluted sediments in the area facing the Bagnoli industrial harbour.

我们采用联合地球物理-地层学方法，识别巴尼奥利沿海棕地（brownfield）场地沉积物分布中的粒度异常。该区域在20世纪绝大部分时段内均被一座大型工业厂房占用。我们借助18组岩心录井（core logs）识别沉积物地层的宏观变化，并通过72根补充岩心标记砂质层段与粉砂质主导层段之间的界面转换。地层分析结果证实，巴尼奥利工业港内部的砂质海岸区域内存在异常粉砂透镜体。岩心描述结果帮助我们校准了4条海底剖面（subbottom profiles）的解译结果，借此获取了粉砂质沉积物的几何形态信息。沉积物的空间分布格局显示，粉砂质层段分布于旧工业码头围限的区域内。我们推测，此类粉砂质沉积物大概率是上个世纪无管控排放活动的产物。经校准后的高分辨率单道地震剖面（mono-channel seismic profiles）帮助我们明确了粉砂质沉积物的形态、实际分布范围与厚度：其分布面积约为515000 m²，总体积达480000 m³。本研究成果为首次界定巴尼奥利工业港邻近区域内污染沉积物的总量做出了初步尝试。