Accumulation of lead and zinc by plants colonizing a metal mining area in Central Iran

The Irankouh area, located in Central Iran, is a vast mountainous region with mineralized soils and several active zinc and lead mining and smelting sites. In this study plants and soils from 5 different sites in this area were collected and analyzed for Zn and Pb. Analysis of soils from different sites showed the expected high concentrations of Zn and Pb - up to 23,000 and 18,000 μg g-1 for total, 30 and 20 μg g-1 for exchangeable, 1 and 0.6 μg g-1 for water-soluble fractions, respectively. Plants collected from these sites total 67 species from 66 genera and 29 families. Most of these are annual herbs found also on non-metalliferous soils in this region. The concentrations of Zn and Pb in the leaf dry matter of plants were variable, with up to 4800 μg g-1 for Zn and 740 μg g-1 Pb in Matthiola chenopodiifolia and Pinus elderica, respectively. A significant positive correlation was detected between the concentrations of Zn and Pb in plant dry matter and those in soils. The concentrations of Zn and Pb in the leaves of most species collected were significantly higher than for other plants from non-metalliferous soils. Some accumulator plants found in this area could have potential for soil clean-up by phytoextraction

Cadmium hyperaccumulation protects Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis)

Metal hyperaccumulation has been proposed as a plant defensive strategy. Here, we investigated whether cadmium (Cd) hyperaccumulation protected Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis). Two ecotypes differing in Cd accumulation, Ganges (high) and Prayon (low), were grown in compost amended with 0-1000 mg Cd kg(-1) in two experiments under glasshouse conditions. F-2 and F-3 plants from the Prayon x Ganges crosses were grown with 5 mg Cd kg(-1). Plants were naturally colonized by thrips and the leaf feeding damage index (LFDI) was assessed. The LFDI decreased significantly with increasing Cd in both ecotypes, and correlated with shoot Cd concentration in a log-linear fashion. Prayon was more attractive to thrips than Ganges, but the ecotypic difference in the LFDI was largely accounted for by the shoot Cd concentration. In the F-2 and F-3 plants, the LFDI correlated significantly and negatively with shoot Cd, but not with shoot zinc (Zn) or sulphur (S) concentrations. We conclude that Cd hyperaccumulation deters thrips from feeding on T. caerulescens leaves, which may offer an adaptive benefit to the plant

Geochemical assessment of metal transfer from rock and soil to water in serpentine areas of Sabah (Malaysia)

The mobility of metals in ultramafic rock–soil systems and metal contamination in serpentine soils were investigated from the Ranau area in Sabah, East Malaysia. Metal concentrations were analysed after division into seven operationally defined fractions by selective sequential extraction (SSE). Geochemical studies showed that the soils are exceptionally high in Cr (95%) residing in refractory residual fractions. Metal speciation studies will shed further light on toxicities in the Malaysian ultramafic tropical environment, reconciled against elemental metal tenure, adopted by common standards

Ultramafic vegetation and soils in the circumboreal region of the Northern Hemisphere

The paper summarizes literature on climate, soil chemistry, vegetation and metal accumulation by plants found on ultramafic substrata in the circumboreal zone (sensu Takhtajan, Floristic regions of the world, 1986) of the Northern Hemisphere. We present a list of 50 endemic species and 18 ecotypes obligate to ultramafic soils from the circumboreal region of Holarctic, as well as 30 and 2 species of Ni and Zn hyperaccumulators, respectively. The number of both endemics and hyperaccumulators are markedly lower compared to that of the Mediterranean and tropical regions. The diversity of plant communities on ultramafics soils of the circumboral region is also described. The underlying causes for the differences of ultramafic flora between arctic, cold, cool temperate and Mediterranean and tropical regions are also discussed. © 2018, The Ecological Society of Japan

Advances in aluminum powder usage as an energetic material and applications for rocket propellant

Energetic materials have been widely used for military purposes. Continuous research programs are performing in the world for the development of the new materials with higher and improved performance comparing with the available ones in order to fulfill the needs of the military in future. Different sizes of aluminum powders are employed to produce composite rocket propellants with the bases of Ammonium Perchlorate (AP) and Hydroxyl-Terminated-Polybutadiene (HTPB) as oxidizer and binder respectively. This paper concentrates on recent advances in using aluminum as an energetic material and the properties and characteristics pertaining to its combustion. Nano-sized aluminum as one of the most attractable particles in propellants is discussed particularly

Performance of copper oxide/distilled water nanofluid in evacuated tube solar collector (ETSC) water heater with internal coil under thermosyphon system circulations

In this study, the effect of CuO/distilled water nanofluid on the performance of evacuated tube solar collector (ETSC) water heater with internal coil under thermosyphon system circulations was experimentally investigated. The volume fraction of nanoparticles was considered at 0.03–0.06%. The mass flow rate of water passing through the coil was varied from 20 to 60 L/h. ASHRAE standard 86–93 was considered to calculate the efficiency of the collector. From the study, we found that the efficiency of ETSC increase when the nanofluid was used as an absorption medium. CuO nanofluids at 0.03% volume fraction in ETSC gave enhancement up to 14%, when compared to water