Effects of metals and sediment particle size on the species composition of the epifauna of Pinna bicolor near a lead smelter,Spencer Gulf,South Australia

Pinna bicolor (Mollusca: Pelecypoda) were transplanted between four sites near a lead smelter. The species composition of their epifauna (sessile and mobile) was examined in relation to characteristics of both sediments and seston at the sites. Seventy-two taxa were distinguished in the epifaunal community. Substantial differences were found in the short-term sensitivity of some of the species to concentrations of Cd, Pb and Zn in sediments and to sediment particle size. The short-term sensitivity of many species to metals or sediment particle size explained their long-term distribution pattern. Twenty-three taxa were identified as significantly characterizing the faunal differences. Of these, eleven (four molluscs, four bryozoans, two barnacles and one ascidian) were affected by both sediment metal concentration and particle size, and eight (four molluscs, one bryozoan, one polychaete, one hydroid and one barnacle) were affected by metal contamination but not particle size. Of all fauna examined, the Bryozoa were the most metal-sensitive. Four species, Smittina raigii (Bryozoa), Galeolaria sp. 1 (Polychaeta), Epopella simplex (Cirripedia) and Monia ione (Pelecypoda) were identified by their short- and long-term sensitivity to metal contamination, and absence of sensitivity to sediment particle size, as suitable species for monitoring the effects of metal contamination on the epifauna. The implications of the results for toxicity-testing are discussed.     

Using micro-catchment experiments for multi-local scale modelling of nature-based solutions

The Q-natural flood management project has co-developed with the Environment Agency 18 monitored micro-catchments (~1 km²) in Cumbria, UK installing calibrated flumes aimed at quantifying the potential shift in observed flows resulting from a range of nature-based-solutions installed by local organizations. The small-scale reduces the influence of variability characterizing larger catchments that would otherwise mask any such shifts, which we attempt to relate to a shift in model parameters. This paper demonstrates an approach to applying donor-parameter-shifts obtained from modelling two of the paired micro-catchments to a much larger scale, in order to understand the potential for improved distributed modelling of nature-based solutions in the form of additional tree-planting. The models include a rainfall-runoff model, Dynamic Topmodel, and a 2D hydrodynamic model, JFlow, permitting analysis of changes in hillslope processes and channel hydrodynamics resulting from a range of distributed measures designed to emulate natural hydrological processes that evaporate, store or infiltrate flows. We report on attempts to detect shift in hydrological response using one of the paired-micro-catchment moorland versus forestry sites in Lorton using Dynamic Topmodel. A donor-parameter-shift approach is used in a hypothetical experiment to represent new woodland in a much larger catchment, although testing all combinations of spatial planting strategies, responses to multiple-extremes, failure-modes and changes to synchronization becomes intractable to support good decision making. We argue that the problem can be re-framed to use donor-parameter-shifts at multi-local-scale catchments above communities known to be at risk, commensurate with most of the evidence of NbS impacts being effective at the small scale (ca. 10 km²). This might lead to more effective modelling to help catchment managers prioritize those communities-at-risk where there is more evidence that NbS might be effective.     

Intensity and Magnetic Field Distribution of Sunspots

We study the relationship between the brightness (I) and magnetic field (B) distributions of sunspots using 272 samples observed at the San Fernando Observatory and the National Solar Observatory, Kitt Peak, whose characteristics varied widely. We find that the I – B relationship has a quadratic form for the spots with magnetic field less than about 2000 G. The slope of the linear part of the I – B curve varies by about a factor of three for different types of spots. In general the slope increases as the spot approaches disk center. The I – B slope does not have a clear dependency on the spot size but the lower limit appears to increase as a function of the ratio of umbra and penumbra area. The I – B slope changes as a function of age of the sunspots. We discuss various sunspot models using these results.     

The Upper Oligocene of Antigua: the volcanic to limestone transition in a limestone Caribbee

Antigua is a small island at the northern end of the Lesser Antilles chain. Its geology is largely limited to the Upper Oligocene and it records with unusual fidelity the transition from island arc volcanism to quiescence and limestone deposition. Despite the apparent limitation of a rock record confined to a short stratigraphical interval, Antigua has a geodiversity that ranges from thick andesites through silicified logs and freshwater snails in cherts to limestones that include both shallow and deeper water facies, and fine karstic features.     

Intercomparison of multiple statistical downscaling methods: multi-criteria model selection for South Korea

A number of statistical downscaling methodologies have been introduced to bridge the gap in scale between outputs of climate models and climate information needed to assess potential impacts at local and regional scales. Four statistical downscaling methods [bias-correction/spatial disaggregation (BCSD), bias-correction/constructed analogue (BCCA), multivariate adaptive constructed analogs (MACA), and bias-correction/climate imprint (BCCI)] are applied to downscale the latest climate forecast system reanalysis (CFSR) data to stations for precipitation, maximum temperature, and minimum temperature over South Korea. All methods are calibrated with observational station data for 19 years from 1973 to 1991 and validated for the more recent 19-year period from 1992 to 2010. We construct a comprehensive suite of performance metrics to inter-compare methods, which is comprised of five criteria related to time-series, distribution, multi-day persistence, extremes, and spatial structure. Based on the performance metrics, we employ technique for order of preference by similarity to ideal solution (TOPSIS) and apply 10,000 different weighting combinations to the criteria of performance metrics to identify a robust statistical downscaling method and important criteria. The results show that MACA and BCSD have comparable skill in the time-series related criterion and BCSD outperforms other methods in distribution and extremes related criteria. In addition, MACA and BCCA, which incorporate spatial patterns, show higher skill in the multi-day persistence criterion for temperature, while BCSD shows the highest skill for precipitation. For the spatial structure related criterion, BCCA and MACA outperformed BCSD and BCCI. From the TOPSIS analysis, we found that MACA is the most robust method for all variables in South Korea, and BCCA and BCSD are the second for temperature and precipitation, respectively. We also found that the contribution of the multi-day persistence and spatial structure related criteria are crucial to ranking the skill of statistical downscaling methods.     

High‐Precision,High‐Accuracy Oxygen Isotope Measurements of Zircon Reference Materials with the SHRIMP‐SI

Analytical protocols for SHRIMP‐SI oxygen isotope analysis (δ¹⁸O) of a suite of zircon reference materials (RMs) are presented. Data reduction involved a robust estimate of uncertainties associated with the individual spot as well as for groups where the spot data are combined. The repeatability of δ¹⁸O measurements is dependent on both the analytical conditions and the choice of the primary reference material. Under optimised conditions, repeatability was often better than 0.4‰ (2s) allowing sample uncertainties to be obtained to better than 0.2‰ (at 95% confidence limit). Single spot uncertainty combined the within‐spot precision with the scatter associated with repeated measurements of the primary zircon reference material during a measurement session. The uncertainty for individual spots measured under optimised conditions was between 0.3 and 0.4‰ (at 95% confidence). The analytical protocols described were used to assess a variety of zircon RMs that have been used for geochronology and for which laser fluorination oxygen isotope data are available (Temora 2, FC1, R33, QGNG and Ple?ovice), as well as zircons that have been used as RMs for trace element or other types of determination (Mud Tank, Monastery, 91500, AS57, AS3, KIM‐5, OG1, SL13, CZ3 and several other Sri Lankan zircons). Repeated analyses over nine sessions and seven different mounts show agreement within analytical uncertainty for Temora 2, FC1, R33, QGNG, Ple?ovice and 91500, when normalised to Mud Tank. For existing ion microprobe mounts with these materials, an appropriate δ¹⁸O can be determined. However, care should be taken when using zircons from the Duluth Complex (i.e., FC1, AS57 and AS3) as reference materials as our data indicated an excess scatter on δ¹⁸O values associated with low‐U zircon grains.     

Field Demonstration of the Horizontal Treatment Well (HRX Well®) for Passive In Situ Remediation

The horizontal reactive media treatment well (HRX Well®) uses directionally drilled horizontal wells filled with a treatment media to induce flow-focusing behavior created by the well-to-aquifer permeability contrast to passively capture proportionally large volumes of groundwater. Groundwater is treated in situ as it flows through the HRX Well and downgradient portions of the aquifer are cleaned via elution as these zones are flushed with clean water discharging from the HRX Well. The HRX Well concept is particularly well suited for sites where long-term mass discharge control is a primary performance objective. This concept is appropriate for recalcitrant and difficult-to-treat constituents, including chlorinated solvents, per- and polyfluoroalkyl substances (PFAS), 1,4-dioxane, and metals. A full-scale HRX Well was installed and operated to treat trichloroethene (TCE) with zero valent iron (ZVI). The model-predicted enhanced flow through the HRX Well (compared to the flow in and equivalent cross-sectional area orthogonal to flow in the natural formation before HRX Well installation) and treatment zone width was consistent with flows and widths estimated independently by point velocity probe (PVP) testing, HRX Well tracer testing, and observed treatment in downgradient monitoring wells. The actual average capture zone width was estimated to be between 45 and 69 feet. Total TCE mass discharge reduction was maintained through the duration of the performance monitoring period and exceeded 99.99% (%). Decreases in TCE concentrations were observed at all four downgradient monitoring wells within the treatment zone (ranging from 50 to 74% at day 436), and the first arrival of treated water was consistent with model predictions. The field demonstration confirmed the HRX Well technology is best suited for long-term mass discharge control, can be installed under active infrastructure, requires limited ongoing operation and maintenance, and has low life cycle energy and water requirements.