Phytoremediation of heavy metal-contaminated sites: Eco-environmental concerns, field studies, sustainability issues and future prospects

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physico-chemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metals-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches, evaluate their efficacy to remove toxic metals from our natural environment, explore current scientific progresses, field experiences and sustainability issues and revise world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in 21st century

SOME THERMODYNAMICAL PROPERTIES OF KDP-DKDP MIXED CRYSTALS

Nous étudions la chaleur spécifique, la permittivité et la polarisation spontanée de milieux mixtes KDP-DKDP (KH2(l-x)D2xPO4). Nous trouvons que la température de transition dépend d'une manière non linéaire de la concentration de deutérium. La transition de phase du premier ordre des cristaux DKDP se déplace en fonction de la concentration en deutérium vers la transition pratiquement continue du KDP. La constante de Curie et la variation d'anisotropie à la transition de phase sont d'une manière appréciable dans les cristaux à haute concentration en deutérium.The specific heat, dielectric permeability and spontaneous polarization of the mixed KDP-DKDP (KH2(1-x)D2xPO4) crystals have been studied. The deuterium concentration dependence of the transition temperature is found to be nonlinear. The first order phase transition in DKDP crystals shifts to the nearly continuous one in KDP while deuterium concentration changes. The Curie constant and surplace entropy of the phase transition increase appreciably in crystals with high deuterium concentration