Impact of Herbicide Treatments on the Construction Materials in the Roman Wall of Lugo, Spain (UNESCO World Heritage Site)

Herbicide treatments applied to the Roman Wall of Lugo were found to have minimal mineralogical impact on its construction materials. A 20-year study involving glyphosate, sulphosate, glufosinate–ammonium, oxyfluorfen (Goal Supreme®), and essential oils from Origanum vulgare, Thymus zygis, and Thymus vulgaris revealed that only glyphosate and physical treatments (infrared and burning) altered vermiculite clay minerals in schist. Oxyfluorfen increased chloride, nitrate, and sulphate contents in granite but caused no significant mineralogical changes. The most recent study found that Thymus zygis essential oil slightly lightened granite. These findings highlight the need for cautious herbicide use to preserve the integrity of historic structures.

Prieto, B., Sanmartín, P., Cancelo-González, J., Torres, L., & Silva, B. (2021). Impact of Herbicide Treatments on the Construction Materials in the Roman Wall of Lugo, Spain (UNESCO World Heritage Site). Applied Sciences, 11(11), 5276. https://doi.org/10.3390/app11115276