A Roman provincial city and its contamination legacy from artisanal and daily-life activities

Abstract

Roman metal use and related extraction activities resulted in heavy metal pollution and contamination, in particular of Pb near ancient mines and harbors, as well as producing a global atmospheric impact. New evidence from ancient Gerasa (Jerash), Jordan, suggests that small-scale but intense Roman, Byzantine and Umayyad period urban, artisanal, and everyday site activities contributed to substantial heavy metal contamination of the city and its hinterland wadi, even though no metal mining took place and hardly any lead water pipes were used. Distribution of heavy metal contaminants, especially Pb, observed in the urban soils and sediments within this ancient city and its hinterland wadi resulted from aeolian, fluvial, cultural and post-depositional processes. These represent the contamination pathways of an ancient city-hinterland setting and reflect long-term anthropogenic legacies at local and regional scales beginning in the Roman period. Thus, urban use and re-use of heavy metal sources should be factored into understanding historical global-scale contaminant distributions.

Urban gardens in Antiquity

“…5 and 6) are highly suggestive of soil manuring and cultivation (Wouters et al, 2017;Simpson et al, 1998;Simpson et al, 2000;Vissac, 2005). Furthermore, enhanced levels of P, an indicator of organic amendment, found in some of the RMS relative to average within-city sediments despite the fact that RMS had a lower average (2070 vs. 2450 mg P/kg, respectively, See Appendix A, Table S4), but significantly higher P levels than any soil or sediment found upstream of the city (Holdridge et al, 2021). This also supports the view that these soils were part of an ancient agricultural system.…”

“…In present day studies of heavy metal distribution in urban soils, it was found that increased metal concentrations in surface horizons may have resulted from irrigating soils with waste water containing contaminants (Van Oort et al, 2008). In summary, the urban RMS at Jerash, like contemporary urban soils, served as sinks of contaminants including Pb, Cu, and P, the sources of which resulted from urban industrial, farming and artisanal activities (Holdridge et al, 2021). Novel methods are nevertheless needed for future studies of ancient gardening on RMS in the region, e.g.…”

“…Previously reported soil parameters include 1) effective cation exchange capacity (ECEC) measurements summarized by Holdridge et al (2020), 2) optically stimulated luminescence (OSL) quartz ages of some RMS materials examined offsite Holdridge et al, 2021), 3) soil geochemistry of profiles within the ancient city (Holdridge et al, 2021) and 4) off-site and within ancient city particle size and geochemical analyses reported by Holdridge (submitted) and Holdridge et al, (2021), respectively. Evidence here revealed that the on-site red horizons are either intact pedogenic or moved by human endeavor to create a placed red horizon.…”

“…The elemental concentrations of the sediments within the city and the RMS material is shown in Appendix A Supplementary Data Table S4. The heavy metals of the sediments in the wadi are discussed in more detail in Holdridge et al (2021). The within city RMS material had an average P content of 2000 (range 940-2930 mg/kg, n = 5), while the inner-city non-RMS sediments had 2060 mg/kg (range 1080-3430 mg/ kg, n = 19).…”

Concentrations of Potentially Toxic Elements in Topsoils of Urban Agricultural Areas of Rome

“…A study on volcanic agricultural soils in southwestern Italy reveals elevated concentrations of chromium and copper due to irrigation with contaminated water, suggesting a potential risk of metal-rich sediment transfer during water movement [57]. Roman industrial mining and smelting have had a lasting impact on atmospheric contamination, with lead and copper used in water supply networks causing significant contamination in adjacent city harbors [58][59][60][61][62]. Investigations of abandoned sites in northern Italy with extractive wastes indicate elevated concentrations of Co, Cu, Ni, Cd, and Zn, posing significant risks to the environment and living organisms [63].…”