Gendered spaces of payment for environmental services: A critical look

This article investigates the paradoxical outcomes of a mechanism to promote women's participation in payment for ecosystem services (PES). Focusing specifically on the Legal Representative position, I examine how gendered and generational power dynamics become reinscribed through this position and the various ways that this position is conceptualized, performed, and negotiated. To do this, I combine theoretical insights from feminist theories of subjectivity, political ecology, and forest governance with empirical evidence from a small case study of PES in Jalisco, Mexico. I find that the subjectivity of women within the case study both produce and are produced by gendered and generational differences that simultaneously both challenge and also maintain social‐spatial exclusions. Although this study is limited by its focus on the Legal Representative and a small sample size, such a focused case study sheds light on the social and spatial ways in which PES runs the risk of exacerbating already existing inequities.     

Natural hazards,disaster management and simulation: a bibliometric analysis of keyword searches

Natural Hazards - Disasters affect millions of people annually, causing large numbers of fatalities, detrimental economic impact and the displacement of communities. Policy-makers, researchers and...     

Characterization and Source History Modeling Using Low‐k Zone Profiles at Two Source Areas

Like tree rings, high‐resolution soil sampling of low‐permeability (low‐k) zones can be used to evaluate the style of source history at contaminated sites (i.e., historical pattern of concentration and composition vs. time since releases occurred at the interface with the low‐k zone). This is valuable for the development of conceptual site model (CSM) and can serve as an important line of evidence supporting monitored natural attenuation (MNA) as a long‐term remedy. Source histories were successfully reconstructed at two sites at Naval Air Station Jacksonville using a simple one‐dimensional (1D) model. The plume arrival time and historical composition were reconstructed from the time initial releases that were suspected to occur decades earlier. At the first site (Building 106), the source reconstructions showed relatively constant source concentrations, but significant attenuation over time in the downgradient plume in the transmissive zone, suggesting MNA may not be an appropriate remedy if source control is a requirement, but attenuation processes are clearly helping to maintain plume stability and reduce risk. At the second site (Building 780), source concentrations in the transmissive zone showed an approximately a one order of magnitude over time, but apparently less attenuation in the downgradient plume. The source reconstruction method appeared to reflect site remediation efforts (excavation, soil vapor extraction) implemented in the 1990s. Finally, a detailed analysis using molecular biological tools, carbon isotopes, and by‐products suggests that most degradation activity is associated with high‐k zones but not with low‐k zones at these source areas. Overall, the source reconstruction methodology provided insight into historical concentration trends not obtainable otherwise given the limited long‐term monitoring data.     

Visible–near infrared spectral indices for mapping mineralogy and chemistry with OSIRIS‐REx

The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping of Bennu as part of sample site selection and characterization, we tested 95 spectral indices on visible to near infrared laboratory reflectance data from minerals and carbonaceous meteorites. Our aim was to determine which indices reliably identify spectral features of interest. Most spectral indices had high positive detection rates when applied to spectra of pure, single‐component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral indices. Indices targeting absorptions at 0.7 and 2.7–3 μm, which are attributable to hydrated minerals, were most successful for the meteorites. Based on these results, we identified a set of 17 indices that are most likely to be useful at Bennu. These indices detect olivines, pyroxenes, carbonates, water/OH‐bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on interpretive success with spectral indices. Preliminary analysis of the disk‐integrated Bennu spectrum with these indices is consistent with expectations given the observed absorption near 3 μm. Our study prioritizes spectral indices to be used for OSIRIS‐REx spectral analysis and mapping and informs the reliability of all index‐derived data products, including a science value map for sample site selection.     

The role of land surface versus drainage network characteristics in controlling water quality and quantity in a small urban watershed

The processes that control run‐off quantity and quality in urban watersheds are complex and not well understood. Although impervious surface coverage has traditionally been used to examine altered hydrologic response in urban watersheds, several studies suggest that other elements of the urban landscape, particularly those associated with urban infrastructure and the drainage system, play an equally important role. The relative importance of impervious surfaces, stormwater ponds, expansion of the drainage network, and drainage network structures in controlling hydrologic response was examined in the subwatersheds of the Kromma Kill, an urban watershed located in Albany County, NY. In this study, geographic information systems was used to compute geospatial land surface and drainage network properties of 5 Kromma Kill subwatersheds. In these same subwatersheds, water quantity (rainfall and run‐off) and quality (macroinvertebrates, nitrate, total nitrogen, dissolved oxygen, total dissolved solids, and nonpurgable organic carbon) parameters were measured. Strong and significant correlations were identified between land surface and drainage network properties and field observations. Causal relationships were then tested using the Environmental Protection Agency's Stormwater Management Model. Field and model analyses suggest that whereas percent imperviousness is a dominant control on water quality, drainage density and slope are equally important. However, for water quantity, whereas imperviousness is positively correlated with increased run‐off volumes, drainage network properties and slope are the dominant controls on run‐off volumes. Results have important implications for stormwater management plans, especially those aimed at reducing the effective impervious surface coverage of urban watersheds. Reducing the percentage of effective imperviousness in a watershed is not a “one size fits all” solution and can help to meet some management objectives, such as reducing nitrogen concentrations and improving water quality, but may not serve as the most effective, and therefore economical, solution for every management objective including reducing run‐off volumes.     

Middle to late Holocene initiation of the annual flood pulse in Tonle Sap Lake,Cambodia

Tonle Sap Lake, Cambodia, possesses one of the most productive inland fisheries in the world and is a vital natural resource for the country. The lake is connected to the Mekong River via the Tonle Sap River. Flow in the Tonle Sap River reverses seasonally, with water exiting the lake in the dry season and entering the lake during the summer monsoon. This flood pulse drives the lake’s biological productivity. We used Sr, Nd, and Pb isotopes and elemental concentrations in lake sediment cores to track changes in the provenance of deposits in Tonle Sap Lake. We sought to determine when the lake first began to receive water and sediment input via the Mekong River, which initiated flood pulse processes. The transition from a non-pulsing lake to the Mekong-connected system is marked by shifts to values of ⁸⁷Sr/⁸⁶Sr, ε_Nd, and ²⁰⁷Pb/²⁰⁴Pb that are characteristic of Mekong River sediments. In addition, magnetic susceptibility increased and sediment elemental composition changed. Elemental (P) measures point to enhanced phosphorus loading and C/N and isotope ratios of bulk organic matter indicate a shift to greater relative contribution of organic material from aquatic versus terrestrial environments, coinciding with the initiation of flood pulse processes. On the basis of radiocarbon dating in two cores, we estimate the initiation of the annual flood pulse occurred between ~4,450 and 3,910 cal year BP.     

Differential kinetics and temperature dependence of abiotic and biotic processes controlling the environmental fate of TNT in simulated marine systems

This work seeks to understand how the balance of abiotic and biotic kinetic processes in sediments control the residual concentration of TNT in marine systems after release from ocean-dumped source. Kinetics of TNT disappearance were followed using marine sediments at different temperatures and under both biotic and presumably abiotic conditions (through sodium azide addition). Sediments exhibiting the highest rate of TNT disappearance under biotic conditions also exhibited the highest sorption affinity for TNT under abiotic conditions. Significant temperature dependence in the abiotic processes was observed in the diffusion coefficient of TNT and not sediment sorption affinity. At higher temperature, kinetics of biotic processes outpaced abiotic processes, but at low temperature, kinetics of abiotic processes were much more significant. We concluded that the differential influence of temperature on the kinetics of abiotic and biotic processes could provide distinguishing predictions for the potential residual concentration of TNT contamination in marine-sediment systems.     

Absence of seasonal patterns in MBT-CBT indices in mid-latitude soils

The degree of methylation and cyclization of bacteria-derived branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in soils depends on temperature and soil pH. Expressed in the methylation index of branched tetraethers (MBT) and cyclization ratio of branched tetraethers (CBT), these relationships are used to reconstruct past annual mean air temperature (MAT) based on the distribution of branched GDGTs in ancient sediments; the MBT-CBT proxy. Although it was shown that the best correlation of this proxy is with annual MAT, it remains unknown whether a seasonal bias in temperature reconstructions could occur, such as towards a seasonal period of ‘optimal growth’ of the, as yet, unidentified soil bacteria which produce branched GDGTs. To investigate this possibility, soils were sampled from eight different plots in the USA (Minnesota and Ohio), The Netherlands (Texel) and the UK (Devon) in time series over 1 year and analyzed for their branched GDGT content. Further analyses of the branched GDGTs present as core lipids (CLs; the presumed fossil pool) and intact polar lipids (IPLs; the presumed extant pool) were undertaken for two of the investigated soil plots. The amount of IPL-derived branched GDGTs is low relative to the branched GDGT CLs, i.e. only 6-9% of the total branched GDGT pool. In all soils, no clear change was apparent in the distribution of branched GDGT lipids (either core or IPL-derived) with seasonal temperature change; the MBT-CBT temperature proxy gave similar temperature estimates year-round, which generally matched the mean annual soil temperature. In addition to a lack of coherent changes in relative distributions, concentrations of the branched GDGTs did not show clear changes over the seasons. For IPL-derived GDGTs these results suggest that their turnover time in soils is in the order of 1 year or more. Thus, our study does not provide evidence for seasonal effects on the distribution of branched GDGTs in soils, at least at mid-latitudes, and therefore, no direct evidence for a bias of MBT-CBT reconstructed temperatures towards a certain season of optimal growth of the source bacteria. If, however, there is a slight seasonal preference of branched GDGT production, which can easily be obscured by natural variability due to the heterogeneity of soils, then a seasonal bias may potentially still develop over time due to the long turnover time of branched GDGTs.     

Tidal river sediments in the Washington,D.C. area. I. Distribution and sources of trace metals

Thirty-three bottom sediments were collected from the Potomac and Anacostia rivers, Tidal Basin, and Washington Ship Channel in June 1991 to define the extent of trace metal contamination and to elucidate source areas of sediment contaminants. In addition, twenty-three sediment samples were collected directly in front of and within major storm and combined sewers that discharge directly to these areas. Trace metals (e.g., Cu, Cr, Cd, Hg, Pb, and Zn) exhibited a wide range in values throughout the study area. Sediment concentrations of Pb ranged from 32.0 μg Pb g^?1 to 3,630 μg Pb g^?1, Cd from 0.24 μg Cd g^?1 to 4.1 μg Cd g^?1, and Hg from 0.13 μg Hg g^?1 to 9.2 μg Hg g^?1, with generally higher concentrations in either outfall or sewer sediments compared to river bottom-sediments. In the Anacostia River, concentration differences among sewer, outfall, and river sediments, along with downriver spatial trends in trace metals suggest that numerous storm and combined swers are major sources of trace metals. Similar results were observed in both the Tidal Basin and Washington Ship Channel. Cadminum and Pb concentrations are higher in specific sewers and outfalls, whereas the distribution of other metals suggests a more diffuse source to the rivers and basins of the area. Cadmium and Pb also exhibited the greatest enrichment throughout the study area, with peak values located in the Anacostia River, near the Washington Navy Yard. Enrichment factors decrease in the order: Cd>Pb>Zn>Hg>Cu>Cr. Between 70% and 96% of sediment-bound Pb and Cd was released from a N₂-purged IN HCl leach. On average, ≤40% of total sedimentary Cu was liberated, possibly due to the partial attack of organic components of the sediment. Sediments of the tidal freshwater portion of the Potomac estuary reflect a moderate to highly components area with substantial enrichments of sedimentary Pb, Cd, and Zn. The sediment phase that contains these metals indicates the potential mobility of the sediment-bound metals if they are reworked during either storm events or dredging.