Metal removal efficiency and ecotoxicological assessment of field-scale passive treatment biochemical reactors.

Anaerobic biochemical reactors (BCRs) are useful for removing metals from mining-impacted water at remote sites. Removal processes include sorption and precipitation of metal sulfides, carbonates, and hydroxides. A question of interest is whether BCRs remove aquatic toxicity. Influent and effluent samples from the Luttrell Repository and Peerless Jenny King, both in Montana, USA; Park City, Utah, USA; and Standard Mine, Colorado, USA, were examined and compared for removal of metals and aquatic toxicity. Effluent samples from Standard Mine included those having solely BCR treatment and those having BCR treatment followed by aeration in a polishing cell. Metal removal for all sites was >90%. All influent samples were acutely toxic to Ceriodaphnia dubia and Pimephales promelas; toxicity was removed following treatment, except in the Luttrell Repository and Standard Mine BCR samples. Laboratory aeration of undiluted samples eliminated (Standard Mine BCR) or significantly reduced (Luttrell Repository, 65% survival) acute toxicity, most likely through removal of hydrogen sulfide. A toxicity identification evaluation suggested that metals also might be contributing to toxicity in the Luttrell Repository effluent samples; metals other than Mn were either not detected or very low (Fe and Pb) in the Standard Mine BCR samples. Field-aerated samples were not acutely toxic, and only the Luttrell Repository and Standard Mine samples showed short-term subchronic toxicity. Overall, results indicated BCR treatment had high metal removal efficiency and that inclusion of in-field aeration was beneficial in removal of acute and short-term subchronic toxicity.

Accurate whole human genome sequencing using reversible terminator chemistry.

DNA sequence information underpins genetic research, enabling discoveries of important biological or medical benefit. Sequencing projects have traditionally used long (400-800 base pair) reads, but the existence of reference sequences for the human and many other genomes makes it possible to develop new, fast approaches to re-sequencing, whereby shorter reads are compared to a reference to identify intraspecies genetic variation. Here we report an approach that generates several billion bases of accurate nucleotide sequence per experiment at low cost. Single molecules of DNA are attached to a flat surface, amplified in situ and used as templates for synthetic sequencing with fluorescent reversible terminator deoxyribonucleotides. Images of the surface are analysed to generate high-quality sequence. We demonstrate application of this approach to human genome sequencing on flow-sorted X chromosomes and then scale the approach to determine the genome sequence of a male Yoruba from Ibadan, Nigeria. We build an accurate consensus sequence from >30x average depth of paired 35-base reads. We characterize four million single-nucleotide polymorphisms and four hundred thousand structural variants, many of which were previously unknown. Our approach is effective for accurate, rapid and economical whole-genome re-sequencing and many other biomedical applications.