Plant response to mycorrhizal inoculation and amendments on a contaminated soil.

Understanding the combined effects of soil amendments and inoculation of mycorrhizal fungi on the response of different plant species during the phytostabilization process of trace elements contaminated soils is a challenge. This task is more difficult but more realistic when studied under field conditions. We assess the combined effects of two amendment doses and mycorrhizal inoculation on the response of saplings of two tree species planted in a contaminated field.

Rehabilitation of waste rock piles: Impact of acid drainage on potential toxicity by trace elements in plants and soil.

The restoration of mining areas, in particular if they are located near towns or villages, is essential to reduce their potential risks for human health and to minimize their visual impacts. In this study, we assess the rehabilitation of a waste rock pile adjacent to the town of Tharsis (SW Spain). We measured vegetation cover and its diversity, and chemical composition of plants and soil, twelve years after remediation by lime amendments, added topsoil and planted vegetation.

Soil hydraulic properties as the main driver in the establishment of biomass crops in contaminated soils.

In recent years increasing attention has been given to the potential use of contaminated lands for biofuel production, because these degraded soils cannot be used for food production. To establish these crops in Mediterranean contaminated areas, where the soil quality is usually very poor, the addition of soil amendments might be necessary to improve soil productivity. In addition, the use of crops with low water demands, adapted to these particular conditions of climate and soil contamination, is a key requirement.

Soil-plant relationships and contamination by trace elements: A review of twenty years of experimentation and monitoring after the Aznalcóllar (SW Spain) mine accident.

Soil contamination by trace elements (TE) is a major environmental problem and much research is done into its effects on ecosystems and human health, as well as into remediation techniques. The Aznalcóllar mine accident (April 1998) was a large-scale ecological and socio-economic catastrophe in the South of Spain. We present here a literature review that synthesizes the main results found during the research conducted at the affected area over the past 20years since the mine accident, focused on the soil-plant system.

Novel energy crops for Mediterranean contaminated lands: Valorization of Dittrichia viscosa and Silybum marianum biomass by pyrolysis.

Establishing energy crops could be a cost-efficient alternative towards the valorization of the plant biomass produced in contaminated lands, where they would not compete with food production for land use. Dittrichia viscosa and Silybum marianum are two native Mediterranean species recently identified as potential energy crops for degraded lands. Here, we present the first characterization of the decomposition of the biomass of these species during thermo-chemical conversion (pyrolysis).

Potential of Eucalyptus camaldulensis for phytostabilization and biomonitoring of trace-element contaminated soils.

Soil pollution by trace elements (TEs) from mining and industrial activity is widespread and presents a risk to humans and ecosystems. The use of trees to immobilize TEs (phytostabilization) is a low-cost and effective method of soil remediation. We aimed to determine the chemical composition of leaves and flower buds of Eucalyptus camaldulensis in seven sites along the Guadiamar River valley (SW Spain), an area contaminated by a mine-spill in 1998.

The potential of native species as bioenergy crops on trace-element contaminated Mediterranean lands.

The establishment of energy crops could be an option for the management of degraded and contaminated lands, where they would not compete with food production for land use. Here, we aimed to explore the potential of certain native Mediterranean species for the revegetation of contaminated lands for energy production purposes. A field survey was conducted in a trace-element (TE) contaminated area from SW Spain, where the patterns of biomass production, TE accumulation and the calorific value of some thistle species were analyzed along a soil contamination gradient.

Three-year study of fast-growing trees in degraded soils amended with composts: Effects on soil fertility and productivity.

Currently, worries about the effects of intensive plantations on long-term nutrient supply and a loss of productivity have risen. In this study two composts were added to degraded soils where this type of intensive crops were growing, to avoid the soil fertility decrease and try to increase biomass production. For the experiment, two degraded soils in terms of low organic carbon content and low pH were selected in South-West Spain: La Rábida (RA) and Villablanca (VI) sites.

Effects of soil contamination by trace elements on white poplar progeny: seed germination and seedling vigour.

Seed germination is considered a critical phase in plant development and relatively sensitive to heavy metals. White poplar (Populus alba) trees tend to accumulate Cd and Zn in their tissues. We tested if soil contamination can affect P.

Improving sustainability in the remediation of contaminated soils by the use of compost and energy valorization by Paulownia fortunei.

The plantation of fast growing trees in contaminated sites, in combination with the use of organic wastes, could partially solve a dual environmental problem: the disposal of these wastes and the improvement of soil quality in these degraded soils. This study evaluated the effects of two compost on the quantity and quality of Paulownia fortunei biomass and on syngas production by biomass gasification, produced by plants growing on trace elements contaminated soils. Compost increased biomass production to values similar to those produced in non-contaminated soils, due to the improvement in plant nutritional status.

Soil plant interactions of Populus alba in contrasting environments.

The effects of the Populus alba tree on different biochemical soil properties, growing in a contaminated area, were studied for two years under field conditions. Two types of trace element contaminated soils were studied: a neutral contaminated soil (NC) and an acid contaminated soil (AC). One neutral non-contaminated area was studied as control.

The snail Theba pisana as an indicator of soil contamination by trace elements: potential exposure for animals and humans.

Background: The ability of snails to accumulate trace elements is well known. We analysed the snail Theba pisana as an indicator of soil contamination by trace elements after a mine spill accident, to assess the exposure of animal and human consumption. Snails were collected in autumn and spring, when they are most active.

Lignite reduces the solubility and plant uptake of cadmium in pasturelands.

Repeated application of Cd-rich phosphate fertilizers can lead to the accumulation of this nonessential element in soil. This can result in increased plant uptake, with possible breaches of food or feed safety standards. We aimed to determine whether lignite (brown coal) can reduce Cd solubility and plant uptake in New Zealand pasture soils.

Natural remediation of an unremediated soil twelve years after a mine accident: trace element mobility and plant composition.

The long-term influence of a mine spill in soil was studied 12 years after the Aznalcóllar accident. Soils where the pyritic sludge was not removed, a fenced plot established for research purposes (2000 m(2)) and soils where the process of remediation was accomplished successfully were sampled and studied in detail. Soils were characterized at different depths, down to 100 cm depth, determining chemical parameters and total concentrations of major and trace elements.

Pasture composition in a trace element-contaminated area: the particular case of Fe and Cd for grazing horses.

Pasture selection by livestock is an essential topic for rangeland management, especially in trace element-contaminated soils. We have studied the composition (nutrients and trace elements) of a grass-based diet from soils affected by a mine spill at different growth stages (October 2008 to May 2009). A diet based on other plants (mainly Compositae species) was also studied (May 2009) for comparison.

Phytostabilization of semiarid soils residually contaminated with trace elements using by-products: sustainability and risks.

We investigated the efficiency of various by-products (sugarbeet lime, biosolid compost and leonardite), based on single or repeated applications to field plots, on the establishment of a vegetation cover compatible with a stabilization strategy on a multi-element (As, Cd, Cu, Pb and Zn) contaminated soil 4-6 years after initial amendment applications. Results indicate that the need for re-treatment is amendment- and element-dependent; in some cases, a single application may reduce trace element concentrations in above-ground biomass and enhance the establishment of a healthy vegetation cover. Amendment performance as evaluated by % cover, biomass and number of colonizing taxa differs; however, changes in plant community composition are not necessarily amendment-specific.

In situ remediation of metal-contaminated soils with organic amendments: role of humic acids in copper bioavailability.

The purposes of this study were to determine the Cu(II) binding behavior of humic acids (HAs) isolated from biosolid compost (BI), leonardite (LE), a metal-contaminated soil, and the soil remediated with either BI or LE in relation to their structural properties, and to explore the role exerted by the HA fractions in controlling soil Cu(II) bioavailability. Potentiometric titrations at pH 5 and ionic strength 0.1M and the Langmuir model were used to obtain the Cu(II) complexing capacity of the HAs examined and the conditional stability constant of the Cu(II)-HA complexes.

Cadmium and zinc in vegetation and litter of a voluntary woodland that has developed on contaminated sediment-derived soil.

Vegetation that develops spontaneously on metal-contaminated soils presents an opportunity to evaluate both metal bioavailability and the risks posed to biota. The behavior of Cd and Zn in the species of a spontaneously developed woodland, colonizing a canal embankment, has been investigated. Nitric-acid-extractable metal concentrations in the sediment-derived substrate ranged between 5.

Arsenic in soils and plants of woodland regenerated on an arsenic-contaminated substrate: a sustainable natural remediation?

Plant As accumulation at three As-polluted sites where spontaneous re-vegetation has taken place is examined. Each site had a different source of soil As (coal fly ash, LeBlanc process waste, canal dredging). Plant analysis indicates that soil-plant As transfer is poor at each site.

In defence of plants as biomonitors of soil quality.

Biomonitors are organisms that provide quantitative information on environmental quality. There are some constraints and limitations for the use of plants as biomonitors of soil pollution, as pointed out recently by some authors in this journal. However, we defend the use of plants as biomonitors, and argue that they have important advantages over soil analyses as indicators of soil quality, particularly when investigations are made on a large scale.

Biomonitoring of trace elements in the leaves and fruits of wild olive and holm oak trees.

Biomonitoring of trace elements is essential to assess ecosystem health, in particular in landscapes influenced by human activity. The Guadiamar Valley (SW Spain) was polluted in 1998 by a spill from an open-pit pyrite mine affecting about 55 km2. In this paper, we used two common species of tree, namely wild olive and holm oak, to biomonitor the concentration of nine trace elements-As, Cd, Cu, Fe, Mn, Ni, Pb, Tl and Zn-in this spill-affected area over the 3-year period 1999-2001.

White poplar (Populus alba) as a biomonitor of trace elements in contaminated riparian forests.

Trees can be used to monitor the level of pollution of trace elements in the soil and atmosphere. In this paper, we surveyed the content of eight trace elements (As, Cd, Cu, Fe, Mn, Ni, Pb and Zn) in leaves and stems of white poplar (Populus alba) trees. We selected 25 trees in the riparian forest of the Guadiamar River (S.