Metal Content of Stream Sediments as a Tool to Assess Remediation in an Area Recovering from Historic Mining Contamination

Abstract

Lead and zinc mining was booming in the early 1900s in and near Joplin, Missouri; a town within the Tri-State Mining District, USA. After the ore became depleted, mining companies moved out, leaving a profoundly disturbed land. Presently, over 90% of the land has been remediated. We collected sediment samples along two creeks flowing through the historically contaminated area that have been identified as major contributors of metals to downstream reservoirs, Center Creek (14 samples) and Turkey Creek (30 samples). Sediment metal content was determined by aqua regia extraction, the potentially bioavailable fraction by 0.11 M acetic acid extraction, and toxicity by ΣPEC-QCd,Pb,Zn. Zinc and lead content in sediments were high in both creeks notwithstanding remediation actions; e.g., median concentrations of 521 mg/kg Pb and 5425 mg/kg Zn in Center Creek, corresponding to 19 and 52 times the background concentration. The metals’ distribution followed no discernible pattern downstream. The potentially bioavailable fraction varied between 0.36% (Pb, Center Creek) and 4.96% (Zn, Turkey Creek). High toxicity was found in 40% of the samples in Turkey Creek and 78.5% of the samples in Center Creek. While this level of toxicity would likely affect aquatic organisms, its limited mobility under alkaline conditions suggests a lesser threat to humans. On the other hand, this high toxicity will likely persist in sediments for at least a few decades, based on their high metal content and low mobility.

Matrix-Type Certified Reference Materials for Quality Control of Metal Determination From Solid Environmental and Vegetation Samples

“…The monitoring and rehabilitation studies have as a starting point the investigation of the quality of environmental factors affected by anthropogenic activities, such as: mining, metallurgical industry, machine building industry, intensive agriculture, etc. Even if some mines have been closed or abandoned, the surrounding areas remain a potential danger to fauna, flora, the aquatic environment and human health [1][2][3][4]. Different types of waste with varied metal content are stored either in specially designed landfills, which over time can produce discharges of toxic substances into the environment, or directly on the ground as long as the content of toxic substances is below certain limits imposed by laws [5,6].…”

Editorial for Special Issue “Sustainable Use of Abandoned Mines”

“…wastes were either spread-over [9] or used to fill mine cavities [10]. The former remediation method was applied to floodplain areas in Złoty Stok, a historical center of gold and arsenic mining in Poland.…”

“…Another area where phytostabilization had been used to remediate a highly disturbed area of zinc and lead mines in southwest Missouri was analyzed for metal content and metal mobility by Gutiérrez et al [10]. Sediment samples collected from streams traversing this remediated area showed that toxic concentrations persist in the sediments.…”

“…Sediment samples collected from streams traversing this remediated area showed that toxic concentrations persist in the sediments. However, metal concentrations followed no specific pattern along the stream, likely a result of the disturbance of sediments created by recent remediation procedures [10]. The results also showed that lead was less mobile than zinc and cadmium, and that cadmium with higher mobility has a greater potential to move through the food chain [10].…”