Recreational Use of Acidic Pit Lakes—Human Health Considerations for Post Closure Planning

Pit lakes may form in mining voids that extend below groundwater level after mining ceases and many have been found to have elevated metals concentrations and low pH through acidic and metalliferous drainage (AMD). Pit lakes are often used for recreational activities including swimming, fishing and boating and poor water quality may present health risks to recreational users. Pit lakes also provide the opportunity for additional water resource uses. The Collie Coal Basin in south-western Australia currently has a number of pit lakes with moderate AMD effects which are also used for recreational pursuits. Twelve hundred questionnaires were mailed to selected addresses in the Collie shire with an additional 170 questionnaires to specific interest groups. Participants were asked about the type of activity, frequency and duration and any health symptoms experienced after use of the lakes. Two hundred and fifty questionnaires were returned, which comprised 176 returns from the random sample and 74 from the targeted sample. Three pit lakes with elevated metals concentrations and low pH were used for recreational purposes by 62% of respondents. This was mostly in summer with swimming the most common activity. Of all respondents 52% were concerned about lake water quality and 38% using the lakes reported a variety of symptoms. Recreational use of Collie pit lakes did not represent a health risk for most of the surveyed population due to the low frequency and duration of use, however health risks may be elevated in sensitive users such as children and those consuming seafood from the lakes. Comprehensive water quality monitoring for chemicals and further characterisation of recreational use of pit lakes is warranted to more comprehensively assess the potential health risks to recreational users. Post closure mine plans need to consider potential future community uses combined with assessments of water quality and physical characteristics to reduce the potential for adverse health and safety impacts.

A 60-year journey of mycorrhizal research in China:Past,present and future directions

The significance of mycorrhizas(fungal roots in 90% of land plants) in plant nutrient acquisition and growth,element biogeo-chemical cycling and maintaining of terrestrial ecosystem structures has been globally established for more than 120 years.Great progress in mycorrhizal research in the past 60 years(1950-2009,1981-2009 in particular) has also been made across China,particularly in the mainland,Hong Kong and Taiwan.For instance,a total of 20 new and ~120 records of arbuscular mycorrhizal(AM) fungal species,30 new and ~800 records of ectomycorrhizal(EM) fungal species,a dozen of new and ~100 records of orchid mycorrhizal(OM) fungal species have been isolated by morphological observation and/or molecular identification in China since the 1950s.Great accomplishment has also been made in the following area,including fungal species richness and genetic structure,relationships between species composition and plant taxa,effects of mycorrhizal fungi on plant nutrient uptake and growth,resistances to pathogens and interactions with other soil microorganisms,potential of mycorrhizal fungi in phytoremediation and/or land reclamation,alterations of enzymatic activities in mycorrhizal plants,and elevated CO2 and O3 on root colonization and species diversity.Unfortunately,the international community cannot easily appreciate almost all Chinese mycorrhizal studies since the vast majority of them have been published in Chinese and/or in China-based journals.The aim of this review is to make a comprehensive exposure of the past and present China's major mycorrhizal research to the whole world,and then to suggest potential directions for the enhancement of future mycorrhizal research within and/or between the Chinese and international mycorrhizal community.

Effect of Long-Term Potassium Fertilization on Crop Yield and Potassium Efficiency and Balance Under Wheat-Maize Rotation in China

Sustainable potassium (K) management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale.We analyzed responses of grain yield of wheat (Triticum aestivum L.) and maize (Zea mays L.),K efficiency,and partial balance (difference between K input through fertilizer and K output in the aboveground biomass) during 15-(1990-2005) or 18-year (1990-2008) K fertilizations at five distinctive agroecological zones across China.Compared to the inorganic nitrogen (N) and phosphorus (P) fertilization,the inorganic NPK fertilization significantly increased grain yields of wheat (21%) and maize (16%-72%) at Qiyang and Changping,where soils have low exchangeable and non-exchangeable K contents,but not at rmqi,Yangling and Zhengzhou,where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants.Compared to the inorganic NPK fertilization,the inorganic NPK (30% N) and organic manure (70% N) fertilization (NPKM) increased grain yields of wheat (14%-40%) and maize (9%-61%) at four sites,but not at Zhengzhou.For a productivity of wheat at 2-5 t ha-1 or maize at 3-6 t ha-1,13-26 or 9-17 kg K ha-1 were required to produce 1.0 t wheat or maize.The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha-1 year-1 less than the NPK fertilization,which accumulated 28 kg ha-1 year-1 less K than the NPKM fertilization.A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM fertilization is urgently needed to increase both crop yield and K use efficiency at different agroecological zones across China.

Environmental drivers and genomic architecture of trait differentiation in fire-adapted Banksia attenuata ecotypes

Trait divergence between populations is considered an adaptive response to different environments,but to what extent this response is accompanied by genetic differentiation is less clear since it may be phenotypic plasticity. In this study, we analyzed phenotypic variation between two Banksia attenuata growth forms, lignotuberous(shrub) and epicormic resprouting(tree), in fire-prone environments to identify the environmental factors that have driven this phenotypic divergence. We linked genotype with phenotype and traced candidate genes using differential gene expression analysis. Fire intervals determined the phenotypic divergence between growth forms in B. attenuata. A genome-wide association study identified 69 single nucleotide polymorphisms, putatively associated with growth form, whereas no growth form-or phenotype-specific genotypes were eidentified. Genomic differentiation between the two growth forms was low(F_(st)=0.024). Differential gene expression analysis identified 37 genes/transcripts that were differentially expressed in the two growth forms. A small heat-shock protein gene, associated with lignotuber presence, was differentially expressed in the two forms.We conclude that different fire regimes induce phenotypic polymorphism in B. attenuata, whereas phenotypic trait divergence involves the differential expression of a small fraction of genes that interact strongly with the disturbance regime. Thus, phenotypic plasticity among resprouters is the general strategy for surviving varying fire regimes.