Monitoring the levels of particle matter-bound manganese: an intensive campaign in an urban/industrial area

Abstract

The aim of this work is to monitor the manganese levels in the particulate matter throughout the Santander Bay, an urban/industrial area located in the region of Cantabria (northern Spain). Previous studies developed in the region have shown high concentrations of manganese in ambient air according to the World Health Organization (WHO) criteria, most likely due to the presence of a ferromanganese alloy plant in the area. An intensive PM10 sampling campaign has been carried out for a year in nine monitoring sites (one per month) by means of a low volume sequential sampling device (2.3 m3 /h) equipped with a 15 filter cartridge. 28 samples have been collected in each location onto 47 mm quartz fiber filters. The filters were subjected to microwave assisted acid digestion (HNO3:H2O2 with a mixture of 8:2 ml) based on UNE-EN 14902:2006. Inductively coupled plasma mass spectrometry (ICP-MS) was then used for metal analysis. In addition to Mn, also Ti, V, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb and Pb were analyzed. According to the results obtained in the present sampling campaign, the highest daily manganese level at Santander Bay reached 3200 ng/m3 with a monthly average higher than the 150 ng/m3 established by the WHO as an annual average guideline value in six monitoring sites (up to 713.9 ng/m3 ). The highest manganese levels were found at N-NE of the ferroalloy plant, which agrees with the prevailing winds (S/SW). Although monthly samplings have been carried out in each location, these results suggest that manganese concentrations in ambient air in some sites of the Santander Bay would exceed the WHO recommendation. In addition, the strong linear relationship found between Mn and V, Fe, As, Cd and Pb in the vicinities of the plant suggests that the presence of some of these metals in the area may be also related to this activity.