Correspondence of biological condition models of California streams at statewide and regional scales

We used boosted regression trees (BRT) to model stream biological condition as measured by benthic macroinvertebrate taxonomic completeness, the ratio of observed to expected (O/E) taxa. Models were developed with and without exclusion of rare taxa at a site. BRT models are robust, requiring few assumptions compared with traditional modeling techniques such as multiple linear regression. The BRT models were constructed to provide baseline support to stressor delineation by identifying natural physiographic and human land use gradients affecting stream biological condition statewide and for eight ecological regions within the state, as part of the development of numerical biological objectives for California’s wadeable streams. Regions were defined on the basis of ecological, hydrologic, and jurisdictional factors and roughly corresponded with ecoregions. Physiographic and land use variables were derived from geographic information system coverages. The model for the entire state (n?=?1,386) identified a composite measure of anthropogenic disturbance (the sum of urban, agricultural, and unmanaged roadside vegetation land cover) within the local watershed as the most important variable, explaining 56 % of the variance in O/E values. Models for individual regions explained between 51 and 84 % of the variance in O/E values. Measures of human disturbance were important in the three coastal regions. In the South Coast and Coastal Chaparral, local watershed measures of urbanization were the most important variables related to biological condition, while in the North Coast the composite measure of human disturbance at the watershed scale was most important. In the two mountain regions, natural gradients were most important, including slope, precipitation, and temperature. The remaining three regions had relatively small sample sizes (n?≤?75 sites) and had models that gave mixed results. Understanding the spatial scale at which land use and land cover affect taxonomic completeness is imperative for sound management. Our results suggest that invertebrate taxonomic completeness is affected by human disturbance at the statewide and regional levels, with some differences among regions in the importance of natural gradients and types of human disturbance. The construction and application of models similar to the ones presented here could be useful in the planning and prioritization of actions for protection and conservation of biodiversity in California streams.     

Using Resource Economics to Anticipate Forest Land Use Change in the U.S. Mid-Atlantic Region

Demands for forest, farm, and developed land are evolving in the U.S. mid-Atlantic region. The demand for land in developed uses, as well as demands for various forest and farm products are changing in response to population growth, demographic shifts, and market forces. As demand factors change so do relative land values. Land area in future forest, farm, and developed uses may shift as landowners re-evaluate relative net benefits from land use alternatives. This study examines the effects of various land demand and supply factors on the determination of land use patterns in the mid-Atlantic region. Driving variables include costs and benefits from various uses, population density, and measures of land quality. Model parameters are estimated using a binomial logit procedure. Results from the study are used to estimate proportions of forest area on a county by county basis. Simulated forest landscapes under hypothetical future conditions are prepared and illustrated using geographic information system (GIS) techniques.     

Relations of Habitat-Specific Algal Assemblages to Land Use and Water Chemistry in the Willamette Basin, Oregon

Benthic algal assemblages, water chemistry, and habitat were characterized at 25 stream sites in the Willamette Basin, Oregon, during low flow in 1994. Seventy-three algal samples yielded 420 taxa — mostly diatoms, blue-green algae, and green algae. Algal assemblages from depositional samples were strongly dominated by diatoms (76% mean relative abundance), whereas erosional samples were dominated by blue-green algae (68% mean relative abundance).Canonical correspondence analysis (CCA) of semiquantitative and qualitative (presence/absence) data sets identified four environmental variables (maximum specific conductance, % open canopy, pH, and drainage area) that were significant in describing patterns of algal taxa among sites. Based on CCA, four groups of sites were identified: streams in forested basins that supported oligotrophic taxa, such as Diatoma mesodon;small streams in agricultural and urban basins that contained a variety of eutrophic and nitrogen-heterotrophic algal taxa; larger rivers draining areas of mixed land use that supported planktonic, eutrophic, and nitrogen-heterotrophic algal taxa; and streams with severely degraded or absent riparian vegetation (> 75% open canopy) that were dominated by other planktonic, eutrophic, and nitrogen-heterotrophic algal taxa. Patterns in water chemistry were consistent with the algal autecological interpretations and clearly demonstrated relationships between land use, water quality, and algal distribution patterns.     

Lead forms in urban turfgrass and forest soils as related to organic matter content and pH

Identification of reference streams and human disturbance gradients are crucial steps in assessing the effects of human disturbances on stream health. We describe a process for identifying reference stream reaches and assessing disturbance gradients using readily available, geo-referenced stream and human disturbance databases. We demonstrate the utility of this process by applying it to wadeable streams in Michigan, USA, and use it to identify which human disturbances have the greatest impact on streams. Approximately 38% of cold-water and 16% of warm-water streams in Michigan were identified as being in least-disturbed condition. Conversely, approximately 3% of cold-water and 4% of warm-water streams were moderately to severely disturbed by landscape human disturbances. Anthropogenic disturbances that had the greatest impact on moderately to severely disturbed streams were nutrient loading and percent urban land use within network watersheds. Our process for assessing stream health represents a significant advantage over other routinely used methods. It uses inter-confluence stream reaches as an assessment unit, permits the evaluation of stream health across large regions, and yields an overall disturbance index that is a weighted sum of multiple disturbance factors. The robustness of our approach is linked to the scale of disturbances that affect a stream; it will be less robust for identifying less degraded or reference streams with localized human disturbances. With improved availability of high-resolution disturbance datasets, this approach will provide a more complete picture of reference stream reaches and factors contributing to degradation of stream health.     

The Use of Indoor Air Measurements To Evaluate Intrusion of Subsurface VOC Vapors into Buildings

ABSTRACT

The implementation of a risk-based corrective action approach often requires consideration of soil vapor migration into buildings and potential inhalation exposure and risk to human health. Due to the uncertainty associated with models for this pathway, there may be a desire to analyze indoor air samples to validate model predictions, and this approach is followed on a somewhat frequent basis at sites where risks are considered potentially significant. Indoor air testing can be problematic for a number of reasons. Soil vapor intrusion into buildings is complex, highly dependent on site-specific conditions, and may vary over time, complicating the interpretation of indoor air measurements when the goal is to deduce the subsurface-derived component. An extensive survey of indoor air quality data sets highlights the variability in indoor volatile organic compound (VOC) concentrations and numerous sources that can lead to elevated VOC levels. The contribution from soil vapor is likely to be small relative to VOCs from other sources for most sites. In light of these challenges, we discuss how studies that use indoor air testing to assess subsurface risks could be improved. To provide added perspective, we conclude by comparing indoor air concentrations and risks arising from subsurface VOCs, predicted using standard model equations for soil vapor fate and intrusion into buildings, to those associated with indoor sources.     

Edible Protein Energy Return on Investment Ratio (ep-EROI) for Spanish Seafood Products

Life cycle assessment (LCA) has developed into a useful methodology to assess energy consumption of fishing fleets and their derived seafood products, as well as the associated environmental burdens. In this study, however, the life cycle inventory data is used to provide a dimensionless ratio between energy inputs and the energy provided by the fish: the edible protein energy return on investment (ep-EROI). The main objective was to perform a critical comparison of seafood products landed in Galicia (NW Spain) in terms of ep-EROI. The combination of energy return on investment (EROI) with LCA, the latter having standardized mechanisms regarding data acquisition and system boundary delimitation, allowed a reduction of uncertainties in EROI estimations. Results allow a deeper understanding of the energy efficiency in the Galician fishing sector, showing that small pelagic species present the highest ep-EROI values if captured using specific fishing techniques. Finally, results are expected to provide useful guidelines for policy support in the EU’s Common Fisheries Policy.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-013-0426-2) contains supplementary material, which is available to authorized users.     

Diagnosis of dissolved organic matter removal by GAC treatment in biologically treated papermill effluents using advanced organic characterisation techniques

Granular activated carbon (GAC) exhaustion rates on pulp and paper effluent from South East Australia were found to be a factor of three higher (3.62 cf. 1.47 kg m⁻³) on Kraft mills compared to mills using Thermomechanical pulping supplemented by Recycled Fibre (TMP/RCF). Biological waste treatment at both mills resulted in a final effluent COD of 240 mg L⁻¹. The dissolved organic carbon (DOC) was only 1.2 times higher in the Kraft effluent (70 vs. 58 mg L⁻¹), however, GAC treatment of Kraft and TMP/RCF effluent was largely different on the DOC persisted after biological treatment. The molecular mass (636 vs. 534 g mol⁻¹) and aromaticity (5.35 vs. 4.67 L mg⁻¹ m⁻¹) of humic substances (HS) were slightly higher in the Kraft effluent. The HS aromaticity was decreased by a factor of 1.0 L mg⁻¹ m⁻¹ in both Kraft and TMP/RCF effluent. The molecular mass of the Kraft effluent increased by 50 g mol⁻¹ while the molecular mass of the TMP/RCF effluent was essentially unchanged after GAC treatment; the DOC removal efficiency of the GAC on Kraft effluent was biased towards the low molecular weight humic compounds. The rapid adsorption of this fraction, coupled with the slightly higher aromaticity of the humic components resulted in early breakthrough on the Kraft effluent. Fluorescence excitation-emission matrix analysis of the each GAC treated effluent indicated that the refractory components were higher molecular weight humics on the Kraft effluent and protein-like compounds on the TMP/RCF effluent. Although the GAC exhaustion rates are too high for an effective DOC removal option for biologically treated pulp and paper mill effluents, the study indicates that advanced organic characterisation techniques can be used to diagnose GAC performance on complex effluents with comparable bulk DOC and COD loads.     

Influence of organic waste and residue mud additions on chemical,physical and microbial properties of bauxite residue sand

Background, aim and scope  

In an alumina refinery, bauxite ore is treated with sodium hydroxide at high temperatures and pressures and for every tonne of alumina produced, about 2 tonnes of alkaline, saline bauxite processing waste is also produced. At Alcoa, a dry stacking system of disposal is used, and it is the sand fraction of the processing waste that is rehabilitated. There is little information available regarding the most appropriate amendments to add to the processing sand to aid in revegetation. The purpose of this study was to investigate how the addition of organic wastes (biosolids and poultry manure), in the presence or absence of added residue mud, would affect the properties of the residue sand and its suitability for revegetation.     

Potential environmental influence of amino acids on the behavior of ZnO nanoparticles

The fate of nanomaterials when they enter the environment is an issue of increasing concern and thus it is important to know how they interact with natural organic molecules since this may have a significant impact on the particles' behavior. Because of our poor knowledge in this regard, the interaction of ZnO nanoparticles with amino acids of contrasting surface charge, including Histidine (HIS), Glycine (GLY), Aspartic acid (ASP) and Glutamic acid (GLU) which occur commonly in natural habitats, such as the plant root zone, was investigated over a range of pH conditions and concentrations. The addition of the individual amino acid led to significant changes in nanoparticle colloidal zeta potential stability, particle size distribution and the extent of agglomeration. Variations in pH resulted in considerable changes in nanoparticle surface charge and hydrodynamic size. In general, the particle size distribution decreased as the amino acid concentration increased, with more acidic conditions exacerbating this effect. In addition, increased concentrations of amino acids resulted in more stable nanoparticles in aqueous suspensions. Histidine had the greatest effect on colloidal stability, followed by Glycine, Aspartic acid and finally Glutamic acid. This study illustrates how nanoparticle behavior may change in the presence of naturally occurring amino acids, an important consideration when assessing the fate of nanoparticles in the environment. Additionally, utilization of amino acids in industrial processes could reduce particle agglomeration and it could lead to a way of employing more sustainable reagents.