Role of rhizosphere and soil properties for the phytomanagement of a salt marsh polluted by mining wastes

Abstract

The goal of this study was to evaluate the soil properties and their modifications within the rhizosphere of spontaneous vegetation as key factors to assess the phytomanagement of a salt marsh polluted by mining wastes. A field survey was performed based on a plot sampling design. The results provided by the analyses of rhizospheric soil (pH, electrical conductivity (EC), organic carbon, total nitrogen, etc.) and metal(loid)s' phytoavailability (assessed by EDTA) were discussed and related to plant metal uptake. The averages of pH and EC values of the bulk soil and rhizospheric samples were in the range of neutral to slightly alkaline (pH 7-8) to saline ([2 dS m -1 ), respectively. Heavy metal and As concentrations (e.g. *600 mg kg -1 As, *50 mg kg -1 Cd, *11,000 mg kgPb) were higher in the rhizosphere for both total and EDTA-extractable fraction. Phragmites australis uptaked the highest concentrations in roots (e.g. *66 mg kg -1 As, *1,770 mg kg -1 Zn) but not in shoots, for which most of plant species showed low values for Zn (\300 mg kg -1 ) but not for Cd ([0.5 mg kg -1 ) or Pb (*20-40 mg kg -1 ). Vegetation distribution in the studied salt marsh looked to be more affected by salinity than by metal pollution. The free availability of water for plants and the incoming nutrient-enriched effluents which flow through the salt marsh may have hindered the metal(loid)s' phytotoxicity. The phytomanagement of these polluted areas employing the spontaneous vegetation is a good option in order to improve the ecological indicators and to prevent the transport of pollutants to nearby areas.

Biological Flora of the British Isles:Phragmites australis

“…), and Pb 15·9 g kg −1 and Cu 275 mg kg −1 in a saltmarsh polluted by mining effluent (Conesa et al . ). The tolerance of Al and B can also be high: Al up to 19·4 g kg −1 , B up to 8·4 mg kg −1 in sand (Morari, Dal Ferro & Cocco ), or 30 mg L −1 in water (Allende, McCarthy & Fletcher ) of constructed wetlands.…”

“…Phragmites australis can perform well under rather high levels of iron and heavy metals (Table ), such as Fe of 89 mg L −1 in experimental water (Allende, McCarthy & Fletcher ) and Cd up to 44 mg kg −1 in soil of saltmarshes polluted by mining wastes (Conesa et al . ), Hg 130 μg kg −1 in a mercury‐contaminated coastal lagoon (Anjum et al . ), and Pb 15·9 g kg −1 and Cu 275 mg kg −1 in a saltmarsh polluted by mining effluent (Conesa et al .…”

Effects of two plant growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate deaminase on oat growth in petroleum-contaminated soil

“…Common soil cleanup technologies are often beyond financial possibilities, especially if large areas or volumes of soil are contaminated. Furthermore, soil structure and biology can be dramatically disturbed or even destroyed making the land useless for agricultural purposes (Conesa et al 2014;Merkl et al 2006). In contrast, phytoremediation, the use of higher plants for decontamination of soil, water, and sediments, is a cost-effective technique that, at the same time, is nondestructive and even has a rehabilitating effect on soil structure and ecology (Marinescu et al 2010).…”

Crude oil and bioproducts of castor bean (Ricinus communis L.) plants established naturally on metal mine tailings

“…Optimization of plant growth under these marginal soil conditions in these metal-polluted sites does need to be improved through agronomical management in order to obtain sustainable crop productivity in the long term. Phytomanagement of metal-polluted areas such employing natural vegetation is a good option to improve the ecological indicators and avoid transport of metals to nearby areas as pointed by Conesa et al (2013).…”