Post - Mining soil as carbon storehouse under polish conditions.

The main aim of these studies was to determine the potential for carbon sequestration in brown coal open-cast mine by phytoremediation using scots pine (Pinus sylvestris L.) and giant miscanthus (Miscanthus x giganteus) plants. This paper presents relationships between soil organic carbon (SOC) sequestration and carbon phytosequestration in waste dump associated with open-cast lignite mine in Central Poland. The research is the continuation of previously carried out experiments, but was conducted in field conditions. In reclamation of post-mining landscapes, during field experiment, an effect of sewage sludge, compost and lake chalk amendments and in combination of plants was investigated. The impact of soil amendments on carbon stock, CO2 emission reduction, plant biomass production and carbon content in shoots and roots was studied. The highest SOC stock was found in soil treated with sewage sludge (33 Mg*ha-1) and compost (45 Mg*ha-1) stabilized by lake chalk. These fertilizer combinations also contributed the most in relation to CO2 emission reduction through SOC stock (83 Mg*ha-1 and 127 Mg*ha-1 respectively). In addition, greater amounts (60-100%) of soil organic matter was converted into humic acids fraction. This phenomenon could be the initial stage of the progressive process of organic matter deposition and carbon sequestration in post-mining area. Carbon phytosequestration was determined through carbon bound in plant tissues. The highest carbon content (60%) in both plant species was recorded in treatments with sewage sludge and compost with lake chalk. Stabilization of compost by lake chalk application was good method to improve the efficiency of carbon sequestration in soil and carbon phytosequestration. Improving the efficiency of these two processes, through skillfully selected soil additives and plant species, may be used on a larger scale in the future as an alternative to the storage of carbon dioxide, especially in degraded areas.

Sewage sludge disposal strategies for sustainable development.

The main objective of the present review is to compare the existing sewage sludge management solutions in terms of their environmental sustainability. The most commonly used strategies, that include treatment and disposal has been favored within the present state-of-art, considering existing legislation (at European and national level), characterization, ecotoxicology, waste management and actual routs used currently in particular European countries. Selected decision making tools, namely End-of-waste criteria and Life Cycle Assessment has been proposed in order to appropriately assess the possible environmental, economic and technical evaluation of different systems. Therefore, some basic criteria for the best suitable option selection has been described, in the circular economy "from waste to resources" sense. The importance of sewage sludge as a valuable source of matter and energy has been appreciated, as well as a potential risk related to the application of those strategies.

Antimony (Sb) and lead (Pb) in contaminated shooting range soils: Sb and Pb mobility and immobilization by iron based sorbents, a field study.

Small-arm shooting ranges often receive a significant input of lead (Pb), copper (Cu) and antimony (Sb) from ammunition. The goal of the present study was to investigate the mobility, distribution and speciation of Pb and Sb pollution under field conditions in both untreated and sorbent-amended shooting range soil. Elevated Sb (19-349µgL(-1)) and Pb (7-1495µgPbL(-1)) concentrations in the porewater of untreated soil over the four-year test period indicated a long-term Sb and Pb source to the adjacent environment in the absence of remedial measures. Mixing ferric oxyhydroxide powder (CFH-12) (2%) together with limestone (1%) into the soil resulted in an average decrease of Sb and Pb porewater concentrations of 66% and 97%, respectively. A similar reduction was achieved by adding 2% zerovalent iron (Fe°) to the soil. The remediation effect was stable over the four-year experimental period indicating no remobilization. Water- and 1M NH4NO3-extractable levels of Sb and Pb in field soil samples indicated significant immobilization by both treatments (89-90% for Sb and 89-99% for Pb). Results from sequential extraction analysis indicate fixation of Sb and Pb in less accessible fractions like amorphous iron oxides or even more crystalline and residual mineral phases, respectively. This work shows that amendment with Fe-based sorbents can be an effective method to reduce the mobility of metals both in cationic and anionic form in polluted shooting range soil.

Speciation of Cd and Zn in contaminated soils assessed by DGT-DIFS, and WHAM/Model VI in relation to uptake by spinach and ryegrass.

A pot experiment was carried out to investigate the impact of Cd and Zn extractability in soil and speciation in pore water of industrial contaminated soils, on metal concentration in a metal sensitive species like spinach (Spinacia oleracea) and a more metal tolerant species like Italian ryegrass (Lolium multiflorum). For chemical speciation of Cd and Zn in pore water, WHAM/Model VI version 6.0 was used. The DGT technique was used to determine the effective concentration, C(E), of Cd and Zn in soils. The free ion activity in pore water correlated well with the contents in plants, and there was a linear relationship between the C(E) values and the concentration of Cd and Zn in both spinach and ryegrass in the non-toxic range. However, the C(E) values usually overestimated the plant contents when plants, particularly the spinach plants, were subjected to toxic concentration in the pore water. Metal uptake decreased in plants affected by toxicity, whereas metal binding to the Chelex resin did not. Thus, we found no linear relationship between the C(E) and metal contents in spinach, whereas a linear relationship was found between C(E)-Zn and the Zn concentration in ryegrass (r2=0.96, p<0.001). For Cd in ryegrass this relationship was weak (r2=0.53, p=0.18). This study indicates that the transport of metals from labile metal pools to the DGT-resin is linearly related to plant uptake only when plants are growing well, and that the applicability of DGT as an indicator for plant uptake seems species dependent.

Trace metal exposure of soil bacteria depends on their position in the soil matrix.

Micropores and biofilms of soils may protect bacteria against chemical stress, predation, and competition phenomena, explaining the great diversity and robustness of soil microbial communities and functions. We used sequential dispersion/density gradient centrifugation to separate free and loosely attached cells (FLA) from strongly attached cells (SA). The two fractions of the soils communities were investigated along a Zn and Cd pollution gradient, and the pollution-induced trace metal community tolerance (PICT) for SA and FLA was analyzed. FLA had developed a strong PICT in response to the 80 years of Zn and Cd pollution, whereas SA was virtually unaffected. It appears that the position of SA in biofilms and micropores has effectively protected them against toxic metal concentrations. The estimated free ion activity showed that the Cd activity was too low to reach toxic levels (PICT(cd) was probably caused by Zn). In contrast, the estimated Zn ion activity was close to a critical level, and could have caused the observed PICT(Zn) in FLA, at least if temporal/ spatial fluctuations of soil pH are taken into account. Such fluctuations could also explain the protection of SA as a result of diffusion constraints; which would be of little help under constant conditions because chemical equilibrium would be reached throughout.