Mining 4500 Years Ago in Europe Resulted in Watershed-Scale Metal Contamination - 100 Times Background Levels

4,500-YEAR-OLD MINING POLLUTION IN SOUTHWESTERN SPAIN: LONG-TERM IMPLICATIONS FOR MODERN MINING POLLUTION

The Tinto river drains the Rio Tinto mining district, which comprises the world’s largest known massive sulfide deposits; these orebodies have been mined from the third millenium BC to the present. The Tinto river is strongly acidic (pH, 1.5–2.5); during flood events, it transports a sandy material, including abundant detrital pyrite grains. A core drilled in the Holocene sediments of the Tinto estuary allows for investigation of recent and historical mining pollution. Two anomalous horizons have been recognized (0–1.3 m; 3–4 m). Both are characterized by very high metal content (100 times over the background) and by the presence of abundant clastic pyrite grains. The metal association (Pb, Ba, As, Cu, Zn, Sn, Tl, Cd, Ag, Hg, Au) is typical of that of the Rio Tinto pyritic ore. The upper horizon corresponds to the modern mining activity; the lower horizon has been dated at 2530 BC (14C AMS calibrated age).

We show here that active mining occurred early (Copper Age) in the Rio Tinto area, resulting in a watershed-scale metal contamination. We also show that anthropogenic input of metals may be accumulated and immobilized during thousands of years in estuarine sediments.

M. Leblanc (corresponding author)
Hydrosciences, UMR CNRS-Université Montpellier 2, 34095, Montpellier, France

J. A. Morales and J. Borrego

GIGC, Departamiento de Geología, Universidad Huelva, 21819 Huelva, Spain

F. Elbaz-Poulichet

Hydrosciences, UMR CNRS-Université Montpellier 2, 34095, Montpellier, France

Economic Geology; May 2000; v. 95; no. 3; p. 655-662; DOI: 10.2113/95.3.655
© 2000 Society of Economic Geologists

Here is the full citation.

Mining of Massive Sulfide Deposits in Spain During the Copper and Bronze Ages has Resulted in the Pollution of the Rio Tinto River Estuary

Rio Tinto estuary (Spain) : 5000 years of pollution

Résumé / Abstract
Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus' departure for the New World in 1492. Additional sources of potential pollution include the large industrial complex at Huelva near the lower portion of the estuary. Extensive analysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co. These data have, however, demonstrated that tidal flux within the estuary carries phosphorus and perhaps other elements from the industrial complex at Huelva to the tidal limit of the system, several kilometers upstream from the discharge site. Radiometric analysis of short cores shows that sedimentation rates over at least the past couple of centuries have been about 0.3 cm/ year. These data and that from a single deep core demonstrate that the estuary was polluted from mining activity long before the large-scale operations began in the late nineteenth century.

Auteur(s) / Author(s)
DAVIS R. A. (1) ; WELTY A. T. (1) ; BORREGO J. (2) ; MORALES J. A. (2) ; PENDON J. G. (2) ; RYAN J. G. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Department of Geology, University of South Florida, 4202 E. Fowler Ave, SCA 203, Tampa, FL 33620, ETATS-UNIS

(2) Departmento de Geologia, University de Huelva, 21819 Huelva, ESPAGNE

Revue / Journal Title
Environmental geology (Environ. geol.) ISSN 0943-0105

Source / Source
2000, vol. 39, no10, pp. 1107-1116 (18 ref.)

Here is the full citation.

Toxic Metal Pollution From Medieval Mining Persists 800 Years Later

Study looks at patterns of heavy-metal contamination of a site in southern France

Scientists have tracked down the source of high levels of heavy metal pollution at a site in southern France: medieval metallurgical workshops. Sandrine Baron, Jean Carignan, and Alain Ploquin of the Center for Petrographic and Geochemical Research in Nancy, France, report that the lead, antimony, arsenic, copper, and zinc residues left behind there more than 800 years ago still pose a potential health threat (Environ. Sci. Technol., DOI: 10.1021/es0606430). Mont-Lozère Massif, the site of medieval workshop remnants that they studied, is in the Cévennes National Park, where people fish, hunt, farm, and camp.

Heavy metals are distributed in the environment because of natural and anthropogenic mechanisms. The trick for Baron's team was to figure out to what extent each mechanism contributed. While it's not surprising that large quantities of heavy metals have staying power in soil and rocks, this study is one of the first to systematically attribute present-day pollution levels to an ancient source of man-made pollution. The study "certifies the responsibilities of the polluters and the origin of the toxicity," Baron points out.

The team examined leftover slag—the by-product of smelting ore to purify mined metals—and the background content of the metals in surrounding soil and granite. By comparing the lead-isotope ratios found in the slag to those found in rock and soil, Baron's team illustrated that binary mixing between slag and granite was the primary method of dispersion and verified that the medieval pollution contributed at least 40% of the lead found in the granite.

Studies of old metallurgical pollution allow the understanding of modern pollution because we can observe the long-term effect of heavy metals in the environment.

Here is the full article.