Seasonal and inter-annual patterns of sediment-water nutrient and oxygen fluxes in Mobile Bay, Alabama (USA): Regulating factors and ecological significance.

Sediment oxygen and nutrient fluxes were measured monthly for 2 yr in Mobile Bay, Alabama, USA. Rates of sediment oxygen consumption (0.1 to 1.25 gO2 m-2 d-1), ammonium flux (-22 to 181 µmol m-2 h-1), nitrate flux (-14 to 67 µmol m-2 h-1), phosphate flux (-2 to 20.4 µmol m-2 h-1), and dissolved silicate flux (-15 to 342 µmol m-2 h-1) were moderate to high compared to values for other estuaries. A step-wise regression analysis revealed that dissolved oxygen concentration and temperature in bottom-waters explained much of the variance in fluxes. This is presumably because of their influence on rates of microbial and physico-chemical processes. Organic matter availability was not found to be an important factor in regulating temporal (month to month) variability of fluxes, possibly because frequent resuspension of the sediments in this shallow system rendered indices of sediment organic matter nearly constant with time. However, warm season-averaged sediment nutrient releases were correlated with sediment chlorophyll a. This relationship in Mobile Bay is in strong agreement with similar relationships found in other estuarine systems, and suggests that the availability of labile organic matter ultimately regulates the maximum rate of nutrient release by the sediments. Annually averaged sediment fluxes supplied 36% of the nitrogen (N) and 25% of the phosphorus (P) required by phytoplankton in Mobile Bay. While this is not particularly high compared to other estuaries, monthly estimates show that the sediments can supply from 0 to 94% of the N, and 0 to 83% of the P required by phytoplankton. In addition, flux ratios show that N and P are released from sediments at N:P ratios that rapidly switch from above (maximum 98) to below (minimum 1.2) that required for phytoplankton growth. This pattern is different from cooler temperate systems, where such switching is seasonally base

Review: Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution

Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution. 2000. Committee on the Causes and Management of Coastal Eutrophication, National Research Council. National Academy Press, Washington, D.C. 405 pages. ISBN 0-309-06948-3. US $54.9

Review: Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution

Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution. 2000. Committee on the Causes and Management of Coastal Eutrophication, National Research Council. National Academy Press, Washington, D.C. 405 pages. ISBN 0-309-06948-3. US $54.9

Nanoscale Hafnium Metal-organic Frameworks Enhance Radiotherapeutic Effects by Upregulation of Type I Interferon and TLR7 Expression

Recent preclinical and clinical studies have highlighted the improved outcomes of combination radiotherapy and immunotherapy. Concurrently, the development of high-Z metallic nanoparticles as radiation dose enhancers has been explored to widen the therapeutic window of radiotherapy and potentially enhance immune activation. In this study, we evaluate folate-modified hafnium-based metal-organic frameworks (HfMOF-PEG-FA) in combination with imiquimod, a TLR7 agonist, as a well-defined interferon regulatory factor (IRF) stimulator for local antitumor immunotherapy. The enhancement of radiation dose deposition by HfMOF-PEG-FA and subsequent generation of reactive oxygen species (ROS) deregulates cell proliferation and increases apoptosis. HfMOF-PEG-FA loaded with imiquimod (HfMOF-PEG-FA@IMQ) increases DNA double-strand breaks and cell death, including apoptosis, necrosis, and calreticulin exposure, in response to X-ray irradiation. Treatment with this multipronged therapy promotes IRF stimulation for subsequent interferon production within tumor cells themselves. We report the novel observation that, HfMOF itself increased TLR7 expression, unexpectedly pairing immune agonist and receptor up-regulation in a tumor intrinsic manner, and supporting the synergistic affect observed with the γH2AX assay. T cell analysis of CT26 tumors following intratumoral administration of HfMOF-PEG-FA@IMQ with radiotherapy reveals a promising antitumor response, characterized by an increase in CD8+ and proliferative T cells

Estimating Future Costs of Emerging Wave Energy Technologies

The development of new renewable energy technologies is generally perceived as a critical factor in the fight against climate change. However, significant difficulties arise when estimating the future performance and costs of nascent technologies such as wave energy. Robust methods to estimate the commercial costs that emerging technologies may reach in the future are needed to inform decision-making. The aim of this paper is to increase the clarity, consistency, and utility of future cost estimates for emerging wave energy technologies. It proposes a novel three-step method: (1) using a combination of existing bottom-up and top-down approaches to derive the current cost breakdown; (2) assigning uncertainty ranges, depending on the estimation reliability then used, to derive the first-of-a-kind cost of the commercial technology; and (3) applying component-based learning rates to produce the LCOE of a mature technology using the upper bound from (2) to account for optimism bias. This novel method counters the human propensity toward over-optimism. Compared with state-of-the-art direct estimation approaches, it provides a tool that can be used to explore uncertainties and focus attention on the accuracy of cost estimates and potential learning from the early stage of technology development. Moreover, this approach delivers useful information to identify remaining technology challenges, concentrate innovation efforts, and collect evidence through testing activities

Contribution of ephemeral wetlands to annual nitrous oxide flux from an agricultural landscape

Non-Peer ReviewedMeasurement of soil nitrous oxide emissions from soil in the Canadian Prairie Region rarely includes uncultivated ephemeral wetlands (UW) within agricultural landscapes. Accurate inventories and a better understanding spatial and temporal variability for soil N2O in agricultural terrains requires flux measurements from non-agricultural areas of the field. The purpose of this study was to measure soil nitrous oxide flux from an agricultural landscape that includes UW. Measurements were taken weekly and bi-weekly from July to October of 2003 and from March to October of 2004 and 2005. Cumulative emissions were highest from concave elements (cultivated ephemeral wetlands) (CV) elements in 2003 and 2004 and highest from the basin centers (BC) of UW in 2005. High flux events were associated with rainfall in 2003, and the recession of standing water at CV and BC elements in 2004 and 2005. However, there are differences between ephemeral wetlands in their emission response to water recession. Accounting for aerial extent of landscape units reveals that CV elements make greatest contribution to total yearly flux. Beneficial management practices intended to reduce annual emissions from this site should be designed to reduce emission from CV elements and UW should not be cleared for crop production. Sampling designs for measurement of emissions from UW need not distinguish between riparian grass and riparian tree elements within the UW