Water Quality Mixing Model (WQMM) for Environmental Flow Release Monitoring

<p>Environmental Flow Release monitoring can be an expensive undertaking in active watercourses normally suitable for run-of-river hydropower projects.  In order to attain acceptable (<10%) uncertainty in the derived flow series, it is necessary for a Qualified Professional (QP) to make several site visits to measure a range of flows in order to calibrate a stage-discharge (rating) curve.  With climate change, the need to measure drought conditions and respond appropriately is crucial for habitat health and to prevent fish stranding.  The current study employs a Water Quality Mixing Model (WQMM) to estimate flows at a downstream site from an existing hydropower plant using a modified constant rate mixing model.  This is an independent estimate of flow entirely distinct from the stage-discharge curve.  The method can be employed anywhere there is a sufficient mixing length and sufficiently distinct WQ traits.  The method can reduce both maintenance costs and flow uncertainty where Environmental Flow Release Monitoring is required.</p>

Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition

The ocean is the main source of thermal inertia in the climate system. Ocean heat uptake during recent decades has been quantified using ocean temperature measurements. However, these estimates all use the same imperfect ocean dataset and share additional uncertainty due to sparse coverage, especially before 2007. Here, we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2) – levels of which increase as the ocean warms and releases gases – as a whole ocean thermometer. We show that the ocean gained 1.29 ± 0.79 × 1022 Joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.80 ± 0.49 W watts per square metre of Earth’s surface. We also find that the ocean-warming effect that led to the outgassing of O2 and CO2 can be isolated from the direct effects of anthropogenic emissions and CO2 sinks. Our result – which relies on high-precision O2 atmospheric measurements dating back to 1991 – leverages an integrative Earth system approach and provides much needed independent confirmation of heat uptake estimated from ocean data.

James Bradley, Sailing on the Thames

The story of the astronomical observations of James Bradley in the eighteenth century, whose measurements of the small movements of a star throughout the year provided an independent estimate of the speed of the Earth around the Sun relative to the speed of light. His work provided the first experimental evidence in support of Copernicus’s theory that the earth is in motion, and against the idea that it is stationary at the center of the universe. His simple telescope at home, his brilliant idea and perseverance, and his life’s work and influence. The importance of his result for the development of Einstein’s theory of relativity and for theories of the Aether in the following centuries.

The Crafts–Harley view of German industrialization: an independent estimate of the income side of net national product, 1851–1913

Novel information on land rent is used to estimate the income side of German net national product (NNP) in 1851–1913 without recourse to output side aggregates. The new series shows higher values during the initial part of the period of observation, which narrows the wedge that opens up between existing estimates of NNP before the 1880s. The results support a modified Crafts–Harley view of the first phase of German industrialization: despite rapid catch-up growth of industrial leading sectors from the 1840s to the 1870s, the pace of aggregate growth accelerated only gradually. The initially small size of the modern sector and the simultaneity of the first phase of industrialization and the first wave of globalization account for this paradox. The labor share remained largely constant; the decline of the land share in NNP was compensated by a rise of the capital share.

Decline towards extinction of Mexico's vaquita porpoise ( Phocoena sinus )

The vaquita ( Phocoena sinus ) is a small porpoise endemic to Mexico. It is listed by IUCN as Critically Endangered because of unsustainable levels of bycatch in gillnets. The population has been monitored with passive acoustic detectors every summer from 2011 to 2018; here we report results for 2017 and 2018. We combine the acoustic trends with an independent estimate of population size from 2015, and visual observations of at least seven animals in 2017 and six in 2018. Despite adoption of an emergency gillnet ban in May 2015, the estimated rate of decline remains extremely high: 48% decline in 2017 (95% Bayesian credible interval (CRI) 78% decline to 9% increase) and 47% in 2018 (95% CRI 80% decline to 13% increase). Estimated total population decline since 2011 is 98.6%, with greater than 99% probability the decline is greater than 33% yr −1 . We estimate fewer than 19 vaquitas remained as of summer 2018 (posterior mean 9, median 8, 95% CRI 6–19). From March 2016 to March 2019, 10 dead vaquitas killed in gillnets were found. The ongoing presence of illegal gillnets despite the emergency ban continues to drive the vaquita towards extinction. Immediate management action is required if the species is to be saved.

Quantification of leakage in batch biogas assays

Avoiding leaks is essential for accurate measurement of biogas production by batch assays. Here we present a simple method for detecting leaks and correcting results, based on the change in bottle mass during incubation. Three experiments were carried out using pure chemicals, wastewater sludge, and other complex substrates to test and demonstrate the method, and leaks were detected in all three. The frequency and magnitude of leakage was related to headspace pressure and the number of times bottle septa had been punctured. Comparison to an independent estimate of leakage in two experiments showed that the proposed method is accurate. This mass-based approach can generally be used to detect leaks as small as 20% of total biogas or methane production, or lower when biogas production is high relative to the precision of mass measurements. Additional research is needed to improve the sensitivity of the method and to better understand the causes of leakage. Given the potential importance of leaks and the simplicity of leakage measurements, we recommend that this method is always used in batch biogas assays.