Pb-Zn Mining Area Research Articles

Kalimeris integrifolia Turcz. ex DC.: An accumulator of Cd

Phytoremediation is a traditional technique that uses vegetation to remediate contaminants from water, soil and sediments. This is a solar-driven, aesthetically pleasing, and cost effective technology. In a former published article, Kalimeris integrifolia Turcz. ex DC. indicated some basic properties of hyperaccumulators for cadmium (Cd). In this study, concentration gradient experiment and sample-analyzing experiments were used to assess whether this plant is a Cd-hyperaccumulator. The results showed the Cd enrichment factor (concentration in plant/soil) and Cd translocation factor (concentration in shoot/root) of K. integrifolia was basically >1 in concentration gradient experiment. Shoot biomass was not reduced significantly ( p < 0.05) compared to the control. However, the Cd concentration in K. integrifolia shoots was not higher than 100 mg kg −1, the threshold concentration for a Cd-hyperaccumulator. Thus, K. integrifolia should only be considered as a Cd-accumulator. In the sample-analyzing experiments conducted in a Pb–Zn mine area and a wastewater irrigation region, K. integrifolia also showed Cd-accumulator properties. Based on these results, K. integrifolia could be identified as a Cd-accumulator.

A newly found cadmium accumulator— Taraxacum mongolicum

Identification of hyperaccumulator and accumulator is still key step of phytoextracting-contaminated soils by heavy metals. In a former published experiment, Taraxacum mongolicum showed basic characteristics of hyperaccumulators. In order to confirm if this plant was a Cd-hyperaccumulator, concentration gradient experiment and sample-analyzing experiments were designed and performed. The results showed that Cd enrichment factor and Cd transformation factor of T. mongolicum were all higher than 1 in concentration gradient experiment. The shoot biomasses did not reduced significantly ( p < 0.05) compared with the control without Cd added under the conditions of lower than 25 mg kg −1 Cd spiked into soil. However, Cd concentration in shoot of T. mongolicum was not higher than 100 mg kg −1 the minimum a Cd-hyperaccumulator should have under the conditions of any concentration level of Cd spiked. Thus, T. mongolicum should be a Cd-accumulator. In the sample-analyzing experiments settled in a Pb–Zn mine area and Shenyang wastewater irrigation region, T. mongolicum also showed that Cd-accumulator characteristics. Based on these results, T. mongolicum could be identified as a Cd-accumulator, which may have important implication in plant physiology and gene engineering.

Hyperaccumulative Characteristics of Weed Species to Heavy Metals

Phytoremediation, which mainly employs hyperaccumulators to remove heavy metals from contaminated soils, is receiving more attention world-wide. The identification of hyperaccumulators is still a key step for phytoremediation. This research is devoted to identify some plants with hyperaccumulative characteristics from weed species. In a pot culture experiment, the hyperaccumulative characteristics of 13 weed species in 11 families to Cd, Pb, Cu and Zn were examined. The result showed that Taraxacum mongolicum and Rorippa globosa indicated some Cd hyperaccumulative properties. In a sample-analysis experiment conducted in a Pb-Zn mining area, T. mongolicum and R. globosa also displayed the same hyperaccumulative characteristics. However, in a concentration gradient experiment, Cd content in shoot of T. mongolicum was not higher than 100 mg/kg (DW, dry weight), the minimum Cd concentration for a Cd-hyperaccumulator in any treatment. The concentration of Cd in the stems and leaves of R. globosa were greater than 100 mg/kg, under the conditions of the soils spiked with 25 and 50 mg/kg Cd. The Cd accumulation factors and translocation factors in the shoots of R. globosa were higher than 1 too, and the plant biomasses did not decrease significantly (p<0.05) compared with the control. Thus, we conclude that only R. globosa showed the whole Cd-hyperaccumulator properties, which is a Cd-hyperaccumulator.

Effects of metal contamination on the activity and diversity of springtails in an ancient Pb-Zn mining area at Plombières, Belgium

Springtails were sampled monthly with pitfall traps in the ancient Pb-Zn mining area of Plombières for one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of springtails were negatively related to the total zinc concentration in the soil, the water-soluble and the calcium chloride extracted zinc fractions. However, these relationships were only significant for the calcium chloride extracted fraction. The latter fraction might therefore be a good indicator of bioavailable zinc for springtails. Despite the high total soil concentrations of zinc, springtails were still quite abundant at all sampling sites. This is probably caused by the low bioavailability of zinc to the springtails in the soils of the study sites.

High contents of rare earth elements (REEs) in stream waters of a Cu–Pb–Zn mining area

Stream waters draining an old mining area present very high rare earth element (REE) contents, reaching 928 μg/l as the maximum total value (ΣREE). The middle rare earth elements (MREEs) are usually enriched with respect to both the light (LREEs) and heavy (HREEs) elements of this group, producing a characteristic “roof-shaped” pattern of the shale Post-Archean Australian Shales-normalized concentrations. At the Fenice Capanne Mine (FCM), the most important base metal mine of the study area, the REE source coincides with the mine tailings, mostly the oldest ones composed of iron-rich materials. The geochemical history of the REEs released into Noni stream from wastes in the FCM area is strictly determined by the pH, which controls the REE speciation and in-stream processes. The formation of Al-rich and mainly Fe-rich flocs effectively scavenges the REEs, which are readily and drastically removed from the solution when the pH approaches neutrality. Leaching experiments performed on flocs and waste materials demonstrate that Fe-oxides/oxyhydroxides play a key role in the release of lanthanide elements into stream waters. The origin of the “roof-shaped” REE distribution pattern as well as the peculiar geochemical behavior of some lanthanide elements in the aqueous system are discussed.

Discovery of Miocene granitoids in eastern Fukui Prefecture, central Japan.

So-called late Cretaceous-Paleogene quartz monzodiorite stock (13 km2) and small dolerite dike in the Arashima-dake-Nakatatsu Pb-Zn mine area were dated as 18.3-20.9 Ma and 24.8 Ma, respectively. Thus, Miocene plutonic cycle should be added to the plutonic activity of eastern Fukui Prefecture, where Jurassic and late Cretaceous-Paleogene ones were recognized before. The Kadohara quartz monzodiorite is high-level portion of volcano-plutonic complex, which is a part of intense andesitic activity of the Green Tuff orogeny.