Tissue culture tools for selenium hyperaccumulator Neptunia amplexicaulis for development in phytoextraction

Neptunia amplexicaulis is an herbaceous legume endemic to the Richmond area in central Queensland,Australia and is one of the strongest known Selenium hyperaccumulators on earth,showing significant potential to be utilised in Se phytoextraction applications.Here a protocol was established for in vitro micropropagation of Se hyperaccumula-tor N.amplexicaulis using nodal segments from in vitro-germinated seedlings.Shoot multiplication was achieved on Murashige and Skoog(MS)basal media supplemented with various concentrations of 6-Benzylaminopurine(BA)(1.0,2.0,3.0 mg L^(−1))alone or in combination with low levels of Naphthaleneacetic acid(NAA)(0.1,0.2,0.3 mg L^(−1)),with 2.0 mg L^(−1) BA+0.2 mg L^(−1) NAA found to be most effective.Elongated shoots were rooted in vitro using NAA,with highest root induction rate of 30%observed at 0.2 mg L^(−1) NAA.About 95%of the in vitro rooted shoots survived acclimatization.Clonally propagated plantlets were dosed with selenate/selenite solution and assessed for Se tissue concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES)and found to retain their ability to hyperaccumulate.The protocol developed for this study has potential to be optimised for generating clonal plants of N.amplexicaulis for use in research and phytoextraction industry applications.

Adopting novel ecosystems as suitable rehabilitation alternatives for former mine sites

The nature and extent of environmental disturbance associated with mining commonly entails completely new and challenging combinations of climate,lithology and landform.Consequently,the outcomes of ecological processes associated with the recovery or restoration of ecosystems cannot be predicted reliably from previously known associations between their physical and biological components.For radically disturbed sites,we propose that it is not practicable to aim for the restoration of historical ecosystems.However,hybrid(reversibly different)or novel(irreversibly different)ecosystems comprising new combinations of physical and biological components,including both native and non-native species,could provide levels of stability and functionality acceptable to all stakeholders and within feasible management regimes.We propose that limiting physical conditions of the landscape can be identified and managed,and that alternative species combinations for introduction to these new landscapes may be considered with cautious optimism.

Alkalinity stabilization behavior of bauxite residue:Ca-driving regulation characteristics of gypsum

Alkaline anions,include CO3^2–,HCO3^–,Al(OH)4^–,OH^–,continuously released from bauxite residue(BR),will cause a potential disastrous impact on surrounding environment.The composition variation of alkaline anions,alkaline phase transformation pathway,and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior.Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%,whilst pH and alkalinity were reduced from 10.47 to 8.15,47.39 mmol/L to 2 mmol/L,respectively.During the alkalinity stabilization,chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions(CO3^2–,HCO3^–,Al(OH)4^–,OH^–),with calcium carbonate(CaCO3))being the most prevalent among the transformed alkaline phases.In addition,XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca^2+from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure.These findings will be beneficial for effectively regulating strong alkalinity of BR.

Improvement of alkaline electrochemical characteristics of bauxite residue amendment with organic acid and gypsum

Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.

Ecotoxicological assessment of diffuse pollution using biomonitoring tool for sustainable land use in Thailand

As a developing country, Thailand has a significant issue with diffuse pollution of the soil ecosystem due to an indiscriminate use of agrichemicals and poorly regulated disposal of a wide variety of hazardous wastes. Practical risk assessment tools based on locallyoccurring species are needed to assess the effects of diffuse pollutants on the soil ecosystem in Thailand because reliance on soil criteria developed for overseas conditions may provide inadequate protection. Native soil organisms in Thailand may be more or less sensitive to contaminants compared to overseas test species. This article described a biological indicator approach for ecological risk assessment of diffuse pollution in the soil ecosystem of Thailand from pesticide application with the aim of developing standardized protocols using native species and locally generated data to better evaluate the ecological risks of non-point source soil pollution. It was found that ecotoxicological assessment provided a better understanding of the ecological impacts that diffuse pollution induced on Thai environmental conditions. Thai soil biota species were more sensitive to soil contaminants than similar species overseas. Soil series also had an influence on the ecotoxicology of contaminants to soil biota. Collembolan, Cyphoderus sp., was demonstrated as a useful alternative test species to Folsomia candida （international test species） for terrestrial ecotoxicological testing of Thai soils. In addition, the soil biota activities such as soil respiration and earthworm avoidance including soil biodiversity and the litter bag decomposition technique are also good tools to assess the effects of diffuse pollution by pesticides on the soil ecosystem of Thailand.

Growth rates of Eucalyptus and other Australian native tree species derived from seven decades of growth monitoring

There is widespread interest in estimating and forecasting individual tree and forest growth rates for restoration and carbon sequestration objectives. Outside intensively managed forests, past attempts have been limited by the lack of accurate long-term monitoring in multi-age mixed native forests to provide estimates of both expected mean diameter increments and the statistical variation in those estimates. A dataset from Eucalyptus-dominated native forests in subtropical Queensland, Australia offers an opportunity to provide accurate estimates of tree and forest growth rates. Over 86,400 trees from 155 native species were identified and remeasured between 1936 and 2011 in 641 permanent sample plots across a 500-2000 mm mean annual rainfall gradient. Individual tree diameter at breast height （DBH） increments observed for all species ranged mainly from 0.01 to 0.5 cm yr-1 （94 % of values）, with consistentdifferences between rainfall zones （mean of 500- 2000 mm yr-1）, and varying differences between species （155） and stem diameter class （10-100 cm）. For some spe- cies, diameter increment increased progressively with rain- fall （e.g. Eucalyptus siderophloia, Eucalyptus propinqua, and Lophostemon confertus）, but in others （e.g. Corymbia citriodora subsp, variegata, Corymbia intermedia, and Eucalyptus biturbinata） the greatest diameter increments were recorded between 1200 and 1600 mm yr-1. Where there were sufficient data, most species exhibited a quadratic relationship between DBH increment and DBH class, but two species （ Callitris glaucophylla and Eucalyptus crebra） native to the 500-800 mm annual rainfall zone showed lin- ear increases in DBH increment with increasing DBH. Continued monitoring of these plots would add to their already great value.

The rhizospheric microbiome becomes more diverse with maize domestication and genetic improvement

Domestication and genetic improvement of maize improve yield and stress tolerance due to changes in morphological and physiological properties, which likely alter rhizosphere microbial diversity. Understanding how the evolution of maize germplasm impacts its rhizobacterial traits during the growth stage is important for optimizing plant-microbe associations and obtaining yield gain in domesticated germplasms. In this study, a total of nine accessions representing domestication and subsequent genetic improvement were selected. We then sequenced the plant DNA and rhizobacterial DNA of teosinte, landraces and inbred lines at the seedling, flowering and maturity stages in a field trial. Moreover, the soil chemical properties were determined at the respective stages to explore the associations of soil characteristics with bacterial community structures. The results showed that domestication and genetic improvement increased the rhizobacterial diversity and substantially altered the rhizobacterial community composition. The core microbiome in the rhizosphere differed among germplasm groups. The co-occurrence network analysis demonstrated that the modularity in the bacterial network of the inbred lines was greater than those of teosinte and the landraces. In conclusion, the increased diversity of the rhizobacterial community with domestication and genetic improvement may improve maize resilience to biotic stresses and soil nutrient availability to plants.

Assessment of pesticide contaminated sediment using biological response of tropical chironomid,Chironomus javanus Kiffer as biomarker

To investigate the use of a biomarker for assessment of the effects on the tropical chironomid, Chironomus javanus (C. javanus), Kiffer of sediment contaminated with an insecticide (chlorpyrifos).MethodsA wide range of biological responses to the tropical chironomid exposed were measured, including survival, growth rate and Acetylcholinesterase (AChE) activity.ResultsThe measured median lethal concentration (96 h LC50) of chlorpyrifos to C. javanus was 0.056 (95% CI 0.024-0.124) μg/kg. For sub-chronic levels of chlorpyrifos between 0.001 and 0.25 μg/kg administered for 10 days, the effects on the growth of C. javanus were reduced (larva size, head structure width and dry weight) at the significance level (P < 0.01) and the effects were concentration dependent. Following exposure to chlorpyrifos at the level of 0.001 μg/kg for 48 and 96 h, the AChE activity in C. javanus was inhibited compared with control samples (P < 0.05).ConclusionsThis study demonstrated that C. javanus was sensitive when exposed to chlorpyrifos. This species could serve as a potential biomarker for assessing pesticide contamination at low environmental persistence and provides limited effects data on the sensitivity of tropical biota to contaminants for ecological risk assessment of organophosphate pesticides in the tropical aquatic ecosystem.

Artificial intelligence optimization and controllable slow-release iron sulfide realizes efficient separation of copper and arsenic in strongly acidic wastewater

Iron sulfide(FeS)is a promising material for separating copper and arsenic from strongly acidic wastewater due to its S^(2-)slow-release effect.However,uncertainties arise because of the constant changes in wastewater composition,affecting the selection of operating parameters and FeS types.In this study,the aging method was first used to prepare various controllable FeS nanoparticles to weaken the arsenic removal ability without affecting the copper removal.Orthogonal experiments were conducted,and the results identified the Cu/As ratio,H_(2)SO_(4) concentration,and FeS dosage as the three main factors influencing the separation efficiency.The backpropagation artificial neural network(BP-ANN)model was established to determine the relationship between the influencing factors and the separation efficiency.The correlation coefficient(R)of overall model was 0.9923 after optimizing using genetic algorithm(GA).The BP-GA model was also solved using GA under specific constraints,predicting the best solution for the separation process in real-time.The predicted results show that the high temperature and long aging time of FeS were necessary to gain high separation efficiency,and the maximum separation factor can reached 1,400.This study provides a suitable sulfurizing material and a set of methods and models with robust flexibility that can successfully predict the separation efficiency of copper and arsenic from highly acidic environments.

Arbuscular mycorrhizal fungi regulate plant mineral nutrient uptake and partitioning in iron ore tailings undergoing eco-engineered pedogenesis

Excess available K and Fe in Fe ore tailings with organic matter amendment and water-deficiencies may restrain plant colonization and growth,which hinders the formation of eco-engineered soil from these tailings for sustainable and cost-effective mine site rehabilitation.Arbuscular mycorrhizal(AM)fungi are widely demonstrated to assist plant growth under various unfavorable environments.However,it is still unclear whether AM symbiosis in tailings amended with different types of plant biomass and under different water conditions could overcome the surplus K and Fe stress for plants in Fe ore tailings,and if so,by what mechanisms.Here,host plants(Sorghum sp.Hybrid cv.Silk),either colonized or noncolonized by the AM fungi(Glomus spp.),were cultivated in lucerne hay(LH,C:N ratio of 18)-or sugarcane mulch(SM,C:N ratio of 78)-amended Fe ore tailings under well-watered(55%water-holding capacity(WHC)of tailings)or water-deficient(30%WHC of tailings)conditions.Root mycorrhizal colonization,plant growth,and mineral elemental uptake and partitioning were examined.Results indicated that AM fungal colonization improved plant growth in tailings amended with plant biomass under water-deficient conditions.Arbuscular mycorrhizal fungal colonization enhanced plant mineral element uptake,especially P,both in the LH-and SM-amended tailings regardless of water condition.Additionally,AM symbiosis development restrained the translocation of excess elements(i.e.,K and Fe)from plant roots to shoots,thereby relieving their phytotoxicity.The AM fungal roles in P uptake and excess elemental partitioning were greater in LH-amended tailings than in SM-amended tailings.Water deficiency weakened AM fungal colonization and functions in terms of mineral element uptake and partitioning.These findings highlighted the vital role AM fungi played in regulating plant growth and nutrition status in Fe ore tailings technosol,providing an important basis for involvement of AM fungi in the eco-engineered pedogenesis of Fe ore tailings.

Novel ecosystems created by coal mines in central Queensland’s Bowen Basin

Introduction:Open-cut coal mining began in central Queensland’s Bowen Basin approximately 50 years ago.Over this period of time,mine rehabilitators have used a variety of tree,shrub,and groundcover species to create‘novel ecosystems’to stabilise soils and provide vegetative cover for pre-supposed final end-land uses.We examine post-mining rehabilitation from multiple soil and vegetation monitoring activities in the Bowen Basin to assess the similarity of landforms,plant composition,and trends in plant diversity compared to unmined reference communities.Methods:Rehabilitated spoil dumps and reference sites were assessed using soil and vegetation data contained in compliance monitoring reports from Goonyella Riverside,Moura,Oaky Creek,Rolleston,and Blackwater mines.Slopes,soil chemistry,and plant species mixes of rehabilitation aged from 2 to 22 years were compared to selected reference communities.Results:Mines in this region have generally proposed one of two post-rehabilitation end-land uses:either pasture for cattle grazing or reconstructed native communities which potentially provide native fauna habitat.Landform data from a selection of these mine sites suggest that when their rehabilitation was compared to nearby reference sites median slope values were between 2.5 and 7 times steeper and soil pH,electrical conductivity,and phosphorus levels were significantly higher.The steeply sloped landforms,poor soil characteristics,depauperate native species pool,and uniform presence of exotic pasture grasses in the rehabilitation indicate that most of these newly created ecosystems should not be used for cattle grazing and also have few natural values.Conclusions:Legislative and community expectations have changed progressively over time and,although much of the rehabilitation is currently dominated by an assemblage of exotic buffel grass(Cenchrus ciliaris)and Acacia spp.,recent environmental authorities suggest these‘novel ecosystems’will be judged against native reference sites.Upon completion of mining activities the resilience of these new ecosystems to drought,fire,and grazing will need to be demonstrated prior to lease relinquishment.

Novel ecosystems in ecological restoration and rehabilitation:Innovative planning or lowering the bar?

Stemming from a special symposium at the 2012 inaugural meeting of the Society for Ecological Restoration Australasia in Perth,Western Australia,this special issue editorial addresses novel ecosystems in ecological restoration and the inherent challenges of maintaining the highest standards of environmental stewardship and biological conservation in the face of increasing urbanization,agricultural expansion,and industrialization.Echoing others,we(the Guest Editors)view novel ecosystems as offering opportunities for conservation and restoration in the coming years and a pragmatic recognition that it may not always be possible,or desirable,to overcome adverse consequences of environmental degradation to reinstate historical systems.Being mindful of hubris and taking into account difficulties with identification,novel ecosystems may be viewed as a temporary or interim stage on the way towards the evolution of other future ecosystems able to supply a variety of ecosystem services,while attempting to maintain and enhance biodiversity,function and resilience.Here,a concise summary of contributions to the special issue and their significance to the field of restoration ecology is provided noting that authors were tasked to answer whether novel ecosystems are innovative planning or lowering the bar in ecological restoration.Core themes shared by the manuscripts are elucidated leading to guiding principles and,more importantly,an assessment of how and why restoration priorities are changing in the 21^(st)century.

Structural development of vegetation on rehabilitated North Stradbroke Island:Above/belowground feedback may facilitate alternative ecological outcomes

Introduction:This study depicts broad-scale revegetation patterns following sand mining on North Stradbroke Island,south-eastern Queensland,Australia.Methods:Based on an ecological timeline spanning 4–20 years post-rehabilitation,the structure of these ecosystems(n=146)was assessed by distinguishing between periods of‘older’(pre-1995)and‘younger’(post-1995)rehabilitation practices.Results:The general rehabilitation outlook appeared promising,whereby an adequate forest composition and suitable levels of native biodiversity(consisting of mixed-eucalypt communities)were achieved across the majority of rehabilitated sites over a relatively short time.Still,older sites(n=36)appeared to deviate relative to natural analogues as indicated by their lack of under-storey heath and simplified canopy composition now characterised by mono-dominant black sheoak(Allocasuarina littoralis)reaching up to 60%of the total tree density.These changes coincided with lower soil fertility parameters(e.g.,total carbon,total nitrogen,and nutrient holding capacity)leading us to believe that altered growth conditions associated with the initial mining disturbance could have facilitated an opportunistic colonisation by this species.Once established,it is suspected that the black sheoak’s above/belowground ecological behaviour(i.e.,relating to its leaf-litter allelopathy and potential for soil-nitrogen fixation)further exacerbated its mono-dominant distribution by inhibiting the development of other native species.Conclusions:Although rehabilitation techniques on-site have undergone refinements to improve site management,our findings support that putative changes in edaphic conditions in combination with the competitive characteristics of some plant species can facilitate conditions leading to alternative ecological outcomes among rehabilitated ecosystems.Based on these outcomes,future studies would benefit from in depth spatio-temporal analyses to verify these mechanisms at finer investigative scales.

Diversity of As Metabolism Functional Genes in Pb-Zn Mine Tailings

Microbial activities impact arsenic （As） transformation in mine tailings substantially, yet little is understood on the functional diversity of As metabolism genes. This study explored this issue using a metagenomic approach coupled by a local BLASTN procedure established in our recent studies. An assembled metagenome, recovered from hypersaline and sulfidic mine tailings, was screened for As metabolism genes aioA, arrA, arsC and arsM. This was done using a local BLASTN procedure against databases of the As metabolism genes built in this study. Putative As metabolism genes detected in the assembled metagenome included 11 arsM, 20 arsC and 1 arrA full-length sequences. Together with the rRNA-based phylogenetic profiling results, a picture depicting microbial As cycling in the tailings to the genus level was obtained. It was found that most of the dominant genera in the tailings potentially harboured the genes for As reduction and/or methylation. In particular, a typical pyrite-eater present in the tailings, Thioalkalivibrio sp., was found to harbour not only arsC and arsM, but also arrA. These results highlight the unexpected diversity of As metabolism genes in the tailings, especially considering the extremely low species diversity therein. The microbial As cycling picture established here has potential use for guiding the purposeful manipulation of As biogeochemistry in the railings.

An Attempt to Quantify Cu-Resistant Microorganisms in a Paddy Soil from Jiaxing, China

Understanding the mechanisms of Cu pollution-induced community tolerance (PICT) in soil requires the characterization of Cu-resistant microorganisms at a community level using modern molecular tools. A primer pair (copAF2010 (5 -TGCAC CTGAC VGGSC AYAT-3 )/copAR2333 (5 -GVACT TCRCG GAACA TRCC-3 )) tentatively targeting Pseudomonas-like Cu-resistant microorganisms was designed in this study. The specification of the primers was tested through conventional polymerase chain reaction (PCR) and the construction of a Pseudomonas-like copA gene fragment library, and then the primers were used to quantify the Cu-resistant microorganisms using quantitative PCR technique. A significant increase of Cu-resistant microorganisms targeted by the primers was observed in a paddy soil from Jiaxing, China which has been exposed to one-year Cu contamination. The results provided direct evidence for Cu PICT in the soil, and the quantification method developed in this study has the potential to be used as a molecular assay for soil Cu pollution.