Natural revegetation of coal fly ash in a highly saline disposal lagoon in Hong Kong

Abstract

Question: What is the relationship of the naturally colonizing vegetation and substrate characteristics in fly ash lagoons? Location: West lagoon, Deep Bay, a 13-ha coastal lagoon in Hong Kong in subtropical Southeast Asia. Methods: Vegetation establishment was examined in a coal fly ash lagoon two years after its abandonment to investigate the distribution of vegetation in relationship to the chemical properties of the fly ash in the lagoon. A greenhouse experiment assessed the limits imposed on plant growth in fly ash. Results: The fly ash was saline, slightly alkaline and very poor in organic matter and nitrogen. Ash from bare and vegetated areas differed significantly in their salinity and extractable concentrations of inorganic nitrogen and various metals. Bare ash had a significantly higher conductivity and extractable sodium, aluminum, manganese, potassium, and lead. In total 11 plant species that belonged to seven families were found growing on the fly ash; all species except the shrub Tamarix chinensis were herbaceous. Using discriminant analysis, the most important factors in distinguishing bare and vegetated ashes were conductivity and sodium. Cluster analysis of bare samples gave two distinct groups, one from the periphery of the lagoon, which had lower sodium, conductivity, organic carbon, potassium and copper, and the other from a second group that contained ashes from the central region of the lagoon. Results of the greenhouse experiment showed that the inhibition of plant growth was significantly correlated with the presence of soluble toxic elements in ash. Conclusion: Toxicity and salinity seem to be the major limiting factors to plant establishment in fly ash, and these factors must be ameliorated for the successful reclamation of these fly ash lagoons.

Meadow species in the early stages of succession on the ash settler of power plant EDF Toruń SA in Toruń, Poland

“…The number of species naturally found on fly-ash landfill in our work was similar to that research i.e. 58 in India (Pandey et al 2015), 125 in Kosovo (Mustafa et al 2012) and 11 find in China (Chu 2008). Among them the most richest groups were characteristic for disturbed habitats and represented the Artemisietea vulgaris and Stellarietea mediae class of plant associations.…”

“…400 milion tons of fly-ash is left in landfills (Szczygielski 2010). The ability of fly-ash deposits revegetation has been investigated in many countries over the world: in USA (Bilski et al 2011), in India (Raj & Mohan 2008Babu & Reddy 2011;Pandey et al 2015), China (Chu 2008), Australia (Jusaitis & Pillman 1997) and Kosovo in Europe (Mustafa et al 2012). Some of that research was focused on natural revegetation.…”

Ecological Potential of Plants for Phytoremediation and Ecorestoration of Fly Ash Deposits and Mine Wastes

“…Furthermore, in India different plant herbaceous species colonize fly ash deposits: Amaranthus deflexus, Calotropis procera, Cannabis sativa, Cassia tora, Chenopodium album, Croton bonplandium, Cynodon dactylon, Eclipta alba, Limnanthe, Ipomea carnea, Parthenium hysterophorus, Saccharum bengalense, Sacharum munja, Saccharum spontaneum, Sida cordifolia, Solanum nigrum, Thelypteris dentate, Typha latifolia (Dwivedi et al, 2008;Gupta and Sinha, 2008;Maiti and Jaiswal, 2008;Pandey, 2015;Pandey et al, 2015bPandey et al, , 2016aKumari et al, 2016) ( Table 2). In Hong Kong, plant species that can grow on fly ash deposits are Eleusine indica, Neyraudia reynaudiana, Tamarix chinensis, Chenopodium acuminatum, Fimbristylis polytrichoides, Pteridium aquiilinum, Panicum repens (Chu, 2008) whereas, in Australia plants with high ecological potential to grow on fly ash deposits are Atriplex, Enchylaena tomentosa, Halosarcia, Mesembryanthemum, Nitraria billardieri and Scaevola colloris (Jusaitis and Pillman, 1997) ( Table 2). Vegetation surveys on fly ash deposits in South Africa showed the following plant species: Amaranthus hybridus, Chamaecrista bienis, Chloris gayana, Cynodon dactylon, Cyperus esculentus, Digitaria eriantha, Eragrostis sp., Hyparrhenia hirta, Lepidium bonariensis, Lespedeza cunea, Brachiaria serrata, Heteropogon contortus, Tristachya leucothrix, Setaria sphacelata (Morgenthal et al, 2001;Van Rensburg et al, 2003) (Table 2).…”

Plant Recruitment in Early Development Stages on Rehabilitated Quarries in Hong Kong

“…A major function of these restorations is to establish a vegetation layer for erosion control and visual improvement. This may also promote successful invasion and establishment of native species (Lugo 1997;Parrotta et al 1997;Zhuang & Yau 1999;Chu 2008), although poor vegetation growth is frequently reported, probably attributable to adverse edaphic conditions like high temperature, drought and poor physical properties (Wong & Yu 1989;Lugo 1992;Chan et al 1998;Jim 2001;Clemente et al 2004;Hutchings et al 2006).…”