Recent Ogallala Aquifer Region Drought Conditions as Observed by Terrestrial Water Storage Anomalies from GRACE

Recent severe drought events have occurred over the Ogallala Aquifer region (OAR) during the period 2011–2015, creating significant impacts on water resources and their use in regional environmental and economic systems. The changes in terrestrial water storage (TWS), as indicated by the Gravity Recovery and Climate Experiment (GRACE), reveals a detailed picture of the temporal and spatial evolution of drought events. The observations by GRACE indicate the worst drought conditions occurred in September 2012, with an average TWS deficit of ~8 cm in the northern OAR and ~11 cm in the southern OAR, consistent with precipitation data from the Global Precipitation Climatology Project. Comparing changes in TWS with precipitation shows the TWS changes can be predominantly attributable to variations in precipitation. Power spectrum and squared wavelet coherence analysis indicate a significant correlation between TWS change and the El Nino‐Southern Oscillation, and the influence of equatorial Pacific sea surface temperatures on TWS change is much stronger in the southern OAR than the northern OAR. The results of this study illustrate the value of GRACE in not just the diagnosis of significant drought events, but also in possibly improving the predictive power of remote signals that are impacted by nonregional climatic events (El Nino), ultimately leading to improved water resource management applications on a regional scale. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

Condition of the Mid-Atlantic Estuaries: Production of a State of the Environment Report

The U.S. Environmental Protection Agency has released a report entitled Condition of the Mid-Atlantic Estuaries. That report summarizes the findings of several studies conducted by federal and state agencies and academic institutions in Chesapeake Bay, Delaware Estuary, and the coastal bays of Delaware, Maryland, and Virginia, and simultaneously addresses two distinct audiences: environmental managers and the general public. This paper documents the process of preparing the Estuaries Report, emphasizing the lessons learned in merging information from a wide-variety of sources and in reporting the results to multiple audiences. The major difficulties in preparing the report included: 1) choosing a format and topics that adequately addressed both environmental managers and the public, 2) resolving spatial and temporal disparities in the assembled data sets, and 3) establishing threshold values that distinguished between acceptable and unacceptable conditions in indicators. Our solutions to these challenges and alternatives are discussed. We conclude that a small team of knowledgeable scientists can effectively merge the information of diverse sources into a document that is useful to both environmental managers and the interested public. However, considerable interaction between the team and other scientists was necessary to resolve ambiguities and assure relevancy and accuracy. These findings support the proposition that the vast sources of existing environmental information can be easily and effectively used to assess the ecological condition across large regions.     

Land managers’ behaviours modulate pathways to visions of future land systems

Regional Environmental Change - Attempts to influence the development of land systems are often based on detailed scenarios that constrain relevant factors, describe a range of divergent but...     

Levels and transfer of Po and Pb in Nordic terrestrial ecosystems

Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides ²¹⁰Po and ²¹⁰Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell exhibited an approximately exponential fall in ²¹⁰Pb activity concentrations from elevated levels in humus/surface soils to “supported” levels at depth. Activity concentrations of ²¹⁰Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123 Bq kg⁻¹ d.w. and in plants and lichens between 20 and 138 Bq kg⁻¹ d.w. The results showed that soil humus is an important reservoir for ²¹⁰Po and ²¹⁰Pb and that fauna in close contact with this media may also exhibit elevated levels of ²¹⁰Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of ²¹⁰Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of ²¹⁰Po in this system.     

Patterns of organic osmolytes in two marine bivalves, Macoma balthica, and Mytilus spp., along their European distribution

Patterns of nine intracellular free amino acids (FAA), which are utilized as organic osmolytes for salinity-induced cell volume regulation in marine osmoconformers, were compared in five Macoma balthica populations and seven Mytilus spp. populations along their European distribution. Three types of FAA patterns were classified within both taxa: a northern Baltic type, a southern Baltic type and an Atlantic/Mediterranean type which mainly differ regarding the share of alanine and taurine. Differences are discussed in relation to habitat salinity and population genetics. Along a salinity gradient, the total size of the intracellular FAA pool did not differ between sympatric M. balthica and Mytilus spp., and was significantly correlated with habitat osmolality in a range from 70 to 600 mmol kg⁻¹ H₂O (oligohaline to mesohaline) in both bivalves. In M. balthica, this correlation was mainly based on significant correlations of alanine (15–100 mmol kg⁻¹ DW), glycine (30–100 mmol kg⁻¹ DW) and taurine (0–70 mmol kg⁻¹ DW) with habitat osmolality. In Mytilus spp., only glycine (25–100 mmol kg⁻¹ DW) and taurine (4–180 mmol kg⁻¹ DW) were significantly correlated with habitat osmolality. The concentration of alanine was three times lower in Mytilus spp. than in M. balthica and did not correlate with habitat osmolality. Within a habitat osmolality range from 600 to 1,100 mmol kg⁻¹ H₂O (mesohaline to marine) the concentration of FAA remained constant in both taxa. It is suggested that under marine conditions additional organic osmolytes must become more important for cell volume regulation in Macoma and Mytilus.     

Perils of using speed zone data to assess real-world compliance to speed limits

Objective: Real-world driving studies, including those involving speeding alert devices and autonomous vehicles, can gauge an individual vehicle's speeding behavior by comparing measured speed with mapped speed zone data. However, there are complexities with developing and maintaining a database of mapped speed zones over a large geographic area that may lead to inaccuracies within the data set. When this approach is applied to large-scale real-world driving data or speeding alert device data to determine speeding behavior, these inaccuracies may result in invalid identification of speeding. We investigated speeding events based on service provider speed zone data.

Methods: We compared service provider speed zone data (Speed Alert by Smart Car Technologies Pty Ltd., Ultimo, NSW, Australia) against a second set of speed zone data (Google Maps Application Programming Interface [API] mapped speed zones).

Results: We found a systematic error in the zones where speed limits of 50–60 km/h, typical of local roads, were allocated to high-speed motorways, which produced false speed limits in the speed zone database. The result was detection of false-positive high-range speeding. Through comparison of the service provider speed zone data against a second set of speed zone data, we were able to identify and eliminate data most affected by this systematic error, thereby establishing a data set of speeding events with a high level of sensitivity (a true positive rate of 92% or 6,412/6,960).

Conclusions: Mapped speed zones can be a source of error in real-world driving when examining vehicle speed. We explored the types of inaccuracies found within speed zone data and recommend that a second set of speed zone data be utilized when investigating speeding behavior or developing mapped speed zone data to minimize inaccuracy in estimates of speeding.     

Derivation of transfer parameters for use within the ERICA Tool and the default concentration ratios for terrestrial biota

An ability to predict radionuclide activity concentrations in biota is a requirement of any method assessing the exposure of biota to ionising radiation. Within the ERICA Tool fresh weight whole-body activity concentrations in organisms are estimated using concentration ratios (the ratio of the activity concentration in the organism to the activity concentration in an environmental media). This paper describes the methodology used to derive the default terrestrial ecosystem concentration ratio database available within the ERICA Tool and provides details of the provenance of each value for terrestrial reference organisms. As the ERICA Tool considers 13 terrestrial reference organisms and the radioisotopes of 31 elements, a total of 403 concentration ratios were required for terrestrial reference organisms. Of these, 129 could be derived from literature review. The approaches taken for selecting the remaining values are described. These included, for example, assuming values for similar reference organisms and/or biogeochemically similar elements, and various simple modelling approaches.