Fabrication of graphene oxide-based pretreatment filter and Electrochemical-CRISPR biosensor for the field-ready cyanobacteria monitoring system

Microcystis aeruginosa (M. aeruginosa) cause the eutrophication of lakes and rivers. To effectively control the overgrowth of M. aeruginosa, a suitable measurement method should be required in the aquatic fields. To address this, we developed a field-ready cyanobacterial pretreatment device and an electrochemical clustered regularly interspaced short palindromic repeats (EC-CRISPR) biosensor. The cyanobacterial pretreatment device consists of a syringe, glass bead, and graphene oxide (GO) bead. Then, the M. aeruginosa dissolved in the freshwater sample was added to fabricated filter. After filtration, the purified gene was loaded onto a CRISPR-based electrochemical biosensor chip to detect M. aeruginosa gene fragments. The biosensor was composed of CRISPR/Cpf1 protein conjugated with MXene on an Au microgap electrode (AuMGE) integrated into a printed circuit board (PCB). This AuMGE/PCB system maximizes the signal-to-noise ratio, which controls the working and counter electrode areas requiring only 3 μL samples to obtain high reliability. Using the extracted M. aeruginosa gene with a pre-treatment filter, the CRISPR biosensor showed a limit of detection of 0.089 pg/μl in fresh water. Moreover, selectivity test and matrix condition test carried out using the EC-CRISPR biosensor. These handheld pre-treatment kit and biosensors can enable field-ready detection of CyanoHABs.

Evaluating temporal patterns of metals concentrations in floodplain lakes of the Athabasca Delta (Canada) relative to pre-industrial baselines

Sediment quality monitoring is widely used to quantify extent of river pollution, but requires knowledge of pre-disturbance conditions in the potentially altered landscape. This has long been identified as a critical aspect to develop for addressing concerns of river pollution in the Alberta Oil Sands Region. Here, we use analyses of sediment cores from eight floodplain lakes spanning a 67 river-km transect across the Athabasca Delta to define pre-1920 (pre-industrial) baseline concentrations for vanadium and five primary pollutants. We then evaluate if sediment metals concentrations have become enriched above baseline since onset of oil sands development and other industrial activities. Results demonstrate no enrichment of metals concentrations (except zinc at one lake) and absence of consistent temporal increases above pre-industrial baselines. Thus, natural processes continue to dominate metal deposition in floodplain lakes of the Athabasca Delta -- an important finding to inform stewardship decisions. The pre-1920 metals concentrations baselines offer a useful tool for ongoing sediment monitoring in aquatic ecosystems of the Athabasca Delta.

Use of pre-industrial baselines to monitor anthropogenic enrichment of metals concentrations in recently deposited sediment of floodplain lakes in the Peace-Athabasca Delta (Alberta, Canada)

Well-designed monitoring approaches are needed to assess effects of industrial development on downstream aquatic environments and guide environmental stewardship. Here, we develop and apply a monitoring approach to detect potential enrichment of metals concentrations in surficial lake sediments of the Peace-Athabasca Delta (PAD), northern Alberta, Canada. Since the ecological integrity of the PAD is strongly tied to river floodwaters that replenish lakes in the delta, and the PAD is located downstream of the Alberta oil sands, concerns have been raised over the potential transport of industry-supplied metals to the PAD via the Athabasca River. Surface sediment samples were collected in September 2017 from 61 lakes across the delta, and again in July 2018 from 20 of the same lakes that had received river floodwaters 2 months earlier, to provide snapshots of metals concentrations (Be, Cd, Cr, Cu, Ni, Pb, V, and Zn) that have recently accumulated in these lakes. To assess for anthropogenic enrichment, surficial sediment metals concentrations were normalized to aluminum and compared to pre-industrial baseline (i.e., reference) metal-aluminum linear relations for the Athabasca and Peace sectors of the PAD developed from pre-1920 measurements in lake sediment cores. Numerical analysis demonstrates no marked enrichment of these metals concentrations above pre-1920 baselines despite strong ability (> 99% power) to detect enrichment of 10%. Measurements of river sediment collected by the Regional Aquatics- and Oil Sands-Monitoring Programs (RAMP/OSM) also did not exceed pre-1920 concentrations. Thus, results presented here show no evidence of substantial oil sands-derived metals enrichment of sediment supplied by the Athabasca River to lakes in the PAD and demonstrate the usefulness of these methods as a monitoring framework.