Establishing a soil monitoring network to assess the environmental exposure to PAHs and PCBs in the province of Mayabeque, Cuba (Soil-Q)

Cuba is a country in transition, with strongly growing population and industrial activities. Such development usually goes along with increasing emissions of pollutants into the environment, and eventually puts environmental and human health at risk. Therefore, and to comply with the Stockholm Convention on Persistent Organic Pollutants (POP), the Cuban government set up a National Implementation Plan (NIP) concerning POPs in the environment. However, suitable monitoring tools to assess environmental and human exposure are not yet established in Cuba.

The overarching goal in this Cuban – Swiss r4d project was to set the ground for a Cuban soil monitoring network. More specifically, the aims of Soil-Q were to:

• define appropriate sample locations in the province of Mayabeque to capture the expected pollution gradients from urban/industrial (high) to rural (low)
• To establish analytical methods for PAHs and PCBs in Cuba
• establish analytical methods for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the laboratories of the Cuban partner, incl. quality assurance and control
• gather corresponding soil samples and quantitatively determine total and bioavailable fractions of PAHs, PCBs, as well as total organic carbon (TOC) and black carbon (BC) contents therein
• evaluate the data, and compile a first database for an integrative assessment of POPs exposure in soils of Cuba
• initiate remediation of highly contaminated areas (if any) using AC/biochar amendment.

Soil-Q provides the basis for environmental and human exposure assessment of a range of priority pollutants in Cuba, currently, and as a reference point in the future. Scientifically, we adapted and tested various chemical proxies for bioavailability in soil monitoring for a more realistic exposure assessment and to facilitate prioritization of limited resources for soil remediation. More generally, Soil-Q successfully served as a vehicle for knowledge transfer and capacity building in the areas of analytical and environmental chemistry.

Soil-Q delivered for the first time monitoring data of important pollutants including PAH, PCB, and heavy metals in soils of Cuba. While contents were generally low in the rural province of Mayabeque, elevated concentrations were observed in some locations in urban Havana. In several cases, pollution gradients for point sources could be identified. With the “sorption capacity ratio” concept that assures fully depletive passive sampling conditions, Soil-Q also introduced important and often neglected quality assurance/quality control measures into passive sampling and bioavailability methodology. Moreover, we expanded and tested the applicability of such methods to soils, going all the way from saturated ex situ, to unsaturated in situ conditions. Bioaccessible fractions of PAHs in polluted soils were shown to be largely determined by the type of pollution source, rather than intrinsic soil properties. Specifically, equal total concentrations of PAHs originating from pyrogenic sources proofed less accessible than those from petrogenic ones. Quantification of bioaccessible fractions of PAHs served as a complementary tool to total content analysis, and helped to prioritize locations for remediation. Based on this, a petroleum contaminated soil in the greater Havana area was selected as a field study site to test, probably for the first time in the Caribbean region, biochar amendment for soil remediation.

• Cuba

• Link to proje ct ​ on SNSF research