Sulfate Reduction and Sulfur Cycles at Two Seagrass Beds Inhabited by Cold Affinity <Emphasis Type="Italic">Zostera marina</Emphasis> and Warm Affinity <Emphasis Type="Italic">Halophila nipponica</Emphasis> in Temperate Coastal Waters

To evaluate the impact of invading seagrass on biogeochemical processes associated with sulfur cycles, we investigated the geochemical properties and sulfate reduction rates (SRRs) in sediments inhabited by invasive warm affinity Halophila nipponica and indigenous cold affinity Zostera marina. A more positive relationship between SRR and below-ground biomass (BGB) was observed at the H. nipponica bed (SRR = 0.6809 × BGB ? 4.3162, r ² = 0.9878, p = 0.0006) than at the Z. marina bed (SRR = 0.3470 × BGB ? 4.0341, r ² = 0.7082, p = 0.0357). These results suggested that SR was more stimulated by the dissolved organic carbon (DOC) exuded from the roots of H. nipponica than by the DOC released from the roots of Z. marina. Despite the enhanced SR in spring-summer, the relatively lower proportion (average, 20%) of acid-volatile sulfur (AVS) in total reduced sulfur and the strong correlation between total oxalate-extractable Fe (Fe_(oxal)) and chromium-reducible sulfur (CRS = 0.2321 × total Fe_(oxal) + 1.8180, r ² = 0.3344, p = 0.0076) in the sediments suggested the rapid re-oxidation of sulfide and precipitation of sulfide with Fe. The turnover rate of the AVS at the H. nipponica bed (0.13 day^?1) was 2.5 times lower than that at the Z. marina bed (0.33 day^?1). Together with lower AVS turnover, the stronger correlation of SRR to BGB in the H. nipponica bed suggests that the extension of H. nipponica resulting from the warming of seawater might provoke more sulfide accumulation in coastal sediments.     

Effect of connecting rain barrels on the storage size reduction

In this article, the possibility of sharing rain barrels and the potential benefit of reducing storage size through physical and non‐physical connections of rain barrels in a community are investigated. Using the concepts of homogeneous/heterogeneous users in rainwater harvesting systems (RWHS), two simple cases of a community composed of four prospective users are examined. The first is performed with the users who have the same mean and variance in water demands (homogeneous users), and the second is with the users with different means and variances (heterogeneous users). To take account for the rainfall characteristics in different places, historical records from six cities in the USA are used for storage–reliability–yield analysis. The result indicates that required total storage can be reduced by connecting multiple rain barrels. In addition, a significant difference is found between homogeneous and heterogeneous user groups. Homogeneous users do not achieve a substantial benefit from connecting their rain barrels; these users may even be disadvantaged by sharing. In contrast, heterogeneous users receive benefit by reducing the total required storage. Most benefit is expected between users with maximum difference in mean water demands. The reduction in storage size was as considerable as 37% in this study. The quantity of storage reduction depends on locations and target reliabilities. Knowledge of the benefits and limitations of rain barrel connections can improve RWHS performance through ability to customize a network plan for individual users. Copyright © 2011 John Wiley & Sons, Ltd.     

Let-It-Rain: a web application for stochastic point rainfall generation at ungaged basins and its applicability in runoff and flood modeling

We present a web application named Let-It-Rain that is able to generate a 1-h temporal resolution synthetic rainfall time series using the modified Bartlett–Lewis rectangular pulse (MBLRP) model, a type of Poisson stochastic rainfall generator. Let-It-Rain, which can be accessed through the web address http://www.LetItRain.info, adopts a web-based framework combining ArcGIS Server from server side for parameter value dissemination and JavaScript from client side to implement the MBLRP model. This enables any desktop and mobile end users with internet access and web browser to obtain the synthetic rainfall time series at any given location at which the parameter regionalization work has been completed (currently the contiguous United States and Republic of Korea) with only a few mouse clicks. Let-It-Rain shows satisfactory performance in its ability to reproduce observed rainfall mean, variance, auto-correlation, and probability of zero rainfall at hourly through daily accumulation levels. It also shows a reasonably good performance in reproducing watershed runoff depth and peak flow. We expect that Let-It-Rain can stimulate the uncertainty analysis of hydrologic variables across the world.     

Geological and geotechnical aspects of underground coal mining methods within Australia

About one quarter of the coal produced in Australia is by underground mining methods. The most commonly used underground coal mining methods in Australia are longwall, and room and pillar. This paper provides a detailed review of the two methods, including their advantages and disadvantages, the major geotechnical and operational issues, and the factors that need to be considered regarding their choice, including the varying geological and geotechnical conditions suited to a particular method. Factors and issues such as capital cost, productivity, recovery, versatility and mine safety associated with the two methods are discussed and compared. The major advantages of the longwall mining method include its suitability for mining at greater depth, higher recovery, and higher production rate compared to room and pillar. The main disadvantages of the room and pillar method are the higher risks of roof and pillar collapse, higher capital costs incurred as well as lower recovery rate.     

Classifying coastal waters: Current necessity and historical perspective

Coastal ecosystems are ecologically and commercially valuable, productive habitats that are experiencing escalating compromises of their structural and functional integrity. The Clean Water Act (USC 1972) requires identification of impaired water bodies and determination of the causes of impairment. Classification simplifies these determinations, because estuaries within a class are more likely to respond similarly to particular stressors. We reviewed existing classification systems for their applicability to grouping coastal marine and Great Lakes water bodies based on their responses to aquatic stressors, including nutrients, toxic substances, suspended sediments, habitat alteration, and combinations of stressors. Classification research historically addressed terrestrial and freshwater habitats rather than coastal habitats. Few efforts focused on stressor response, although many well-researched classification frameworks provide information pertinent to stressor response. Early coastal classifications relied on physical and hydrological properties, including geomorphology, general circulation patterns, and salinity. More recent classifications sort ecosystems into a few broad types and may integrate physical and biological factors. Among current efforts are those designed for conservation of sensitive habitats based on ecological processes that support patterns of biological diversity. Physical factors, including freshwater inflow, residence time, and flushing rates, affect sensitivity to stressors. Biological factors, such as primary production, grazing rates, and mineral cycling, also need to be considered in classification. We evaluate each existing classification system with respect to objectives, defining factors, extent of spatial and temporal applicability, existing sources of data, and relevance to aquatic stressors. We also consider classification methods in a generic sense and discuss their strengths and weaknesses for our purposes. Although few existing classifications are based on responses to stressors, may well-researched paradigms provide important information for improving our capabilities for classification, as an investigative and predictive management tool.     

Geochemistry and sediment in the main stream of the Ca River basin,Vietnam: weathering process,solute-discharge relationships,and reservoir impact

Acta Geochimica - In this study, we investigated the chemical composition of dissolved solids in the Ca River basin, North-Central Vietnam. Water samples were collected from August 2017 to July...     

On the observational determination of climate sensitivity and its implications

We estimate climate sensitivity from observations, using the deseasonalized fluctuations in sea surface temperatures (SSTs) and the concurrent fluctuations in the top-of-atmosphere (TOA) outgoing radiation from the ERBE (1985–1999) and CERES (2000–2008) satellite instruments. Distinct periods of warming and cooling in the SSTs were used to evaluate feedbacks. An earlier study (Lindzen and Choi, 2009) was subject to significant criticisms. The present paper is an expansion of the earlier paper where the various criticisms are taken into account. The present analysis accounts for the 72 day precession period for the ERBE satellite in a more appropriate manner than in the earlier paper. We develop a method to distinguish noise in the outgoing radiation as well as radiation changes that are forcing SST changes from those radiation changes that constitute feedbacks to changes in SST. We demonstrate that our new method does moderately well in distinguishing positive from negative feedbacks and in quantifying negative feedbacks. In contrast, we show that simple regression methods used by several existing papers generally exaggerate positive feedbacks and even show positive feedbacks when actual feedbacks are negative. We argue that feedbacks are largely concentrated in the tropics, and the tropical feedbacks can be adjusted to account for their impact on the globe as a whole. Indeed, we show that including all CERES data (not just from the tropics) leads to results similar to what are obtained for the tropics alone — though with more noise. We again find that the outgoing radiation resulting from SST fluctuations exceeds the zerofeedback response thus implying negative feedback. In contrast to this, the calculated TOA outgoing radiation fluxes from 11 atmospheric models forced by the observed SST are less than the zerofeedback response, consistent with the positive feedbacks that characterize these models. The results imply that the models are exaggerating climate sensitivity.