Habitat suitability modelling to improve understanding of seagrass loss and recovery and to guide decisions in relation to coastal discharge.

Habitat suitability modelling was used to test the relationship between coastal discharges and seagrass occurrence based on data from Adelaide (South Australia). Seven variables (benthic light including epiphyte shading, temperature, salinity, substrate, wave exposure, currents and tidal exposure) were simulated using a coupled hydrodynamic-biogeochemical model and interrogated against literature-derived thresholds for nine local seagrass species. Light availability was the most critical driver across the study area but wave exposure played a key role in shallow nearshore areas. Model validation against seagrass mapping data showed 86 % goodness-of-fit. Comparison against later mapping data suggested that modelling could predict ~745 ha of seagrass recovery in areas previously classified as 'false positives'. These results suggest that habitat suitability modelling is reliable to test scenarios and predict seagrass response to reduction of land-based loads, providing a useful tool to guide (investment) decisions to prevent loss and promote recovery of seagrasses.

Web-based internet searches for digital health products in the United Kingdom before and during the COVID-19 pandemic: a time-series analysis using app libraries from the Organisation for the Review of Care and Health Applications (ORCHA).

OBJECTIVES: To explore if consumer interest in digital health products (DHPs), changed following the COVID-19 pandemic and the lockdown measures that ensued. DESIGN: Retrospective time-series analysis of web-based internet searches for DHPs in the UK, split over two periods, pre-COVID-19 lockdown (January 2019-23 March 2020) and post-COVID-19 lockdown (24 March 2020-31 December 2020). SETTING: The UK. PARTICIPANTS: Members of the UK general population using health-app libraries provided by the Organisation for the Review of Care and Health Applications. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was volume of searches for DHPs. Secondary outcomes considered search volumes for 25 different therapeutic areas. Outcomes were assessed for significance using a two-stage Poisson test. RESULTS: There were 126 640 searches for DHPs over the study period. Searches for DHPs increased by 343% from 2446 per month prior to COVID-19 lockdown measures being introduced to 8996 per month in the period following the first COVID-19 lockdown in the UK. In total, 23/25 (92%) of condition areas experienced a significant increase in searches for DHPs, with the greatest increases occurring in the first 2 months following lockdown. Musculoskeletal conditions (2.036%), allergy (1.253%) and healthy living DHPs (1.051%) experienced the greatest increases in searches compared with pre-lockdown. Increased search volumes for DHPs were sustained in the 9 months following the introduction of lockdown measures, with 21/25 (84%) of condition areas experiencing monthly search volumes at least 50% greater than pre-lockdown levels. CONCLUSIONS: The COVID-19 pandemic has profoundly disrupted the routine delivery of healthcare, making face-to-face interaction difficult, and contributing to unmet clinical needs. This study has demonstrated significant increases in internet searches for DHPs by members of the UK population since COVID-19, signifying an increased interest in this potential therapeutic medium. Future research should clarify whether this increased interest has resulted in increased acceptance and utilisation of these technologies also.

Fate and dynamics of metal precipitates arising from acid drainage discharges to a river system.

Neutralisation of acid drainage creates metal-rich precipitates that may impact receiving water bodies. This study assessed the fate of over seven years of acid drainage discharges on the sediments of the lower River Murray (Australia), including the potential for periodic water anoxia to enhance risk via reductive dissolution of amorphous (Fe, Mn and co-precipitated and bound metal) oxide phases. With the exception of one site with restricted water exchange, elevated reducible/reactive metal(oid) (Fe, Ni, As, Co, Zn) concentrations were only observed in the localised wetland-riparian area within approximately 100 m of the discharges. Only a minor exceedance of national sediment quality guideline values occurred for Ni. In the main river channel, elevated reactive metal (Fe, Mn, Ni, Zn) concentrations were also only observed less than approximately 100 m from the drainage discharge point. This appears due to (a) rapid neutralisation of pH leading to metal precipitation and deposition in the localised discharge area, and/or (b) dilution of any metal precipitates entering the main channel with natural river sediments, and/or (c) flushing of precipitates downstream during higher flow conditions. The influence of deoxygenation on metal release was profound with large increases in the concentration of dissolved Fe, Mn, Zn, Ni, and As in the overlying water during laboratory experimental simulations. However, given in situ sediment metal contamination is very localised, it appears on a river reach scale that the acid drainage precipitates will not significantly contribute, over and above, the background release of these metals during these conditions.

Chlorination of Microcystis aeruginosa: toxin release and oxidation, cellular chlorine demand and disinfection by-products formation.

Direct chlorination of toxic cyanobacteria cells can occur at various stages of treatment. The objectives of this work are to determine and model the extent of Microcystis aeruginosa cells lysis, toxins and organic compounds release and oxidation, and quantify the subsequent disinfection by-products formation. Chlorine exposure (CT) values of 296 and 100 mg min/L were required to obtain 76% cell lysis and oxidation of released cell-bound toxins at levels below the provisional World Health Organisation guideline value (1 µg/L MC-LR). Toxin oxidation rates were similar or faster than cell lysis rates in ultrapure water. This work presents much needed unit M. aeruginosa cellular chlorine demand (5.6 ± 0.2 pgCl(2)/cell) which could be used to adjust the chlorination capacity to satisfy the total chlorine demand associated with the presence of cells. Furthermore, a novel successive reaction kinetics model is developed using the kinetics of the chlorine reaction with cyanobacterial cells and cell-bound toxins. Chlorination of dense cell suspensions (500,000 cells/mL) in ultrapure water at CT up to 3051 mg min/L resulted in modest concentrations of trihalomethanes (13 µg/L) and haloacetic acids (below detection limit).