Chemical and plant tests to assess the viability of amendments to reduce metal availability in mine soils and tailings

The goal of this research was to assess the potential of several industrial wastes to immobilise metals in two polluted soils deriving from an old Pb/Zn mine. Two different approaches were used to assess the performance of different amendments: a chemical one, using extraction by ethylenediaminetetraacetic acid (EDTA), and a biological one, using Lupinus albus as a bio-indicator. Four amendments were used: inorganic sugar production waste (named ‘sugar foam’, SF), sludge from a drinking water treatment sludge (DWS), organic waste from olive mill waste (OMW) and paper mill sludge (PMS). Amendment to soil ratios ranged from 0.1 to 0.3 (w/w). All the amendments were capable of significantly decreasing (p?<?0.05) EDTA-extractable Pb, Zn and Cu concentrations in the two soils used, with decreases in ranges 21–100, 25–100 and 2–100 % for Pb, Zn and Cu, respectively. The amendments tested were also effective in reducing the bioavailability of Pb and Zn for L. albus, which gave rise to a decrease in shoot metal accumulation by the lupine plants compared to that found in the control soil. That decrease reached up to 5.6 and 2.8 times for Pb and Zn, respectively, being statistically significant in most cases. Moreover, application of the OMW, DWS and SF amendments led to higher average values of plant biomass (up to 71 %) than those obtained in the control soil. The results obtained showed the technology put forward to be a viable means of remediating mine soils as it led to a decrease in the availability and toxicity of metals and, thus, facilitated the growth of a vegetation layer.     

Response of microcrustacean communities from the surface—groundwater interface to water contamination in urban river system of the Jarama basin (central Spain)

In order to evaluate the water quality at the surface/groundwater interface (hyporheic zone), the pattern of microcrustacean assemblages in response to environmental stress caused by urban industrial contamination was studied in the Jarama River basin (central Spain) during high water discharges (March and April 2011). The clustering of biological variables and the concentration of urban contaminants in hyporheic waters showed that pristine hyporheic waters have moderate species diversity (two to seven species) and dominance of k strategist stygobites, whereas excessively contaminated sites are devoid by crustaceans. An intermediate level of disturbance in hyporheic waters is associated with a peak of species taxonomic diversity (four to nine species) and proliferation of r strategist more tolerant species. Typical species found in hyporheic zone, e.g., Paracyclops imminutus (Copepoda, Cyclopoida), Cryptocandona vavrai (Ostracoda) and Herpetocypris chevreuxi (Ostracoda), were good indicators of high concentrations of Cr, Mn, Ni, Cd, Pb and VOCs; whereas the stygobites do not show any significant correlation. The effectiveness of hyporheic crustaceans as efficient bioindicators for assessing the current ecological status of river ecosystems is emphasised.