Hexachlorocyclohexane phytoremediation using <i>Eucalyptus dunnii</i> of a contaminated site in Argentina

In 1996, a diagnostic study performed in a 16-ha field located in Buenos Aires Province (Argentina), where a chemical industry produced 1,2,3,4,5,6-hexachlorocyclohexane (HCH) from 1960 to 1978, showed contamination with HCH ranging from 10 to 20,000 mg kg⁻¹dry soil (706.4 mg kg⁻¹ average). For remediation purposes, a forestation plan was put into practice in 1997 employing approximately 12,300 <i>Eucalyptus dunnii</i> seedlings which by 2016 where fully grown into trees that formed a forest where local fauna can be found. Midterm analysis done in 2005, when <i>E. dunnii</i> trees had developed into 8–10 m high trees, indicated that HCH was incorporated into leaves and logs and soil phytoremediation was progressing. Final quantitation analysis of HCH in soil performed in 2016 demonstrated that the 97.2% of the field area was effectively decontaminated with 98.1% overall average efficiency. Thus, this work is the first global example of a successful employment of <i>E. dunnii</i> trees for HCH phytoremediation purposes at field scale. These results may encourage other researchers to test the ability of <i>E. dunnii</i> to phytoremediate soils contaminated with other chlorinated compounds like polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).