\u3ci\u3eSenecio Conrathii\u3c/i\u3e N.E.Br. (Asteraceae), a New Hyperaccumulator of Nickel from Serpentinite Outcrops of the Barberton Greenstone Belt, South Africa

Five nickel hyperaccumulators belonging to the Asteraceae are known from ultramafic outcrops in South Africa. Phytoremediation applications of the known hyperaccumulators in the Asteraceae, such as the indigenous Berkheya coddii Roessler, are well reported and necessitate further exploration to find additional species with such traits. This study targeted the most frequently occurring species of the Asteraceae on eight randomly selected serpentinite outcrops of the Barberton Greenstone Belt. Twenty species were sampled, including 12 that were tested for nickel accumulation for the first time. Although the majority of the species were excluders, the known hyperaccumulators Berkheya nivea N.E.Br. and B. zeyheri (Sond. & Harv.) Oliv. & Hiern subsp. rehmannii (Thell.) Roessler var. rogersiana (Thell.) Roessler hyperaccumulated nickel in the leaves at expected levels. A new hyperaccumulator of nickel was discovered, Senecio conrathii N.E.Br., which accumulated the element in its leaves at 1695 ± 637 µg g−1 on soil with a total and exchangeable nickel content of 503 mg kg−1 and 0.095 µg g−1, respectively. This makes it the third known species in the Senecioneae of South Africa to hyperaccumulate nickel after Senecio anomalochrous Hilliard and Senecio coronatus (Thunb.) Harv., albeit it being a weak accumulator compared with the latter. Seven tribes in the Asteraceae have now been screened for hyperaccumulation in South Africa, with hyperaccumulators only recorded for the Arctoteae and Senecioneae. This suggests that further exploration for hyperaccumulators should focus on these tribes as they comprise all six species (of 68 Asteraceae taxa screened thus far) to hyperaccumulate nickel

Biogeochemistry, grain size and mineralogy of the Central and Southern Adriatic Sea sediments: a review.

Volume 26 Supplement 1, January 2010

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

Comparison of techniques for ammonia emission mitigation during storage of livestock manure and assessment of their effect in the management chain

The reduction of ammonia (NH3) emissions associated with manure management requires identification and implementation of effective techniques. The objective of this study was to measure potential ammonia emissions from animal manure and evaluate emission reductions for five mitigation techniques (straw, sawdust, clay, oil and sulphuric acid). Although numerous studies have evaluated individual mitigation techniques, the variability of their effect with different types of slurries has not been fully investigated. Furthermore, the assessment of ammonia emissions from the subsequent land application of stored manure (or slurry) using different techniques would indicate the practical consequences of the entire slurry management chain. The effects of mitigation techniques were evaluated using a model to simulate field application of slurry. Three techniques were compared: broadcast spreading, band spreading and closed-slot injection. Simulations utilised data from experiments conducted at a controlled temperature on six slurries of three different types: pig, cattle and digestate. Ammonia emissions from the raw slurries (i.e., untreated slurry) were determined using the dynamic chamber technique and compared with those from the slurries treated using each of five mitigation techniques. A subsample of one 1 L of each slurry was transferred into 2 L plastic bottles. An airflow of 1 L min\u20131 across the headspace was established and then emissions were measured over a period of 24 h. The air outlet was connected to two serial acids traps filled with 1% boric acid. The quantity of NH3 trapped was determined by titration. Acidification and oil addition were the most effective techniques, reducing ammonia emission from raw slurries by more than 95% and 80%, respectively. The mitigation effects of straw and sawdust were higher for cattle slurry and digestate than for pig slurry, while clay had an opposite effect. The overall assessment of ammonia emissions from storage and subsequent field application showed that acidification followed by closed-slot injection emitted at most 12% of the emissions from the reference system, while emissions from acidification followed by band spreading were between 14% and 22% of those from the reference system. The latter appears to be both more effective than broadcast spreading and technically more easily operated than a closed-slot injector