Unprecedented evidence for high viral abundance and lytic activity in coral reef waters of the South Pacific Ocean

Despite nutrient-depleted conditions, coral reef waters harbor abundant and diverse microbes; as major agents of microbial mortality, viruses are likely to influence microbial processes in these ecosystems. However, little is known about marine viruses in these rapidly changing ecosystems. Here we examined spatial and short-term temporal variability in marine viral abundance (VA) and viral lytic activity across various reef habitats surrounding Moorea Island (French Polynesia) in the South Pacific. Water samples were collected along four regional cross-reef transects and during a time-series in Opunohu Bay. Results revealed high VA (range: 5.6 x 10(6)-3.6 x 10(7) viruses ml(-1)) and lytic viral production (range: 1.5 x 10(9)-9.2 x 10(10) viruses l(-1) d(-1)). Flow cytometry revealed that viral assemblages were composed of three subsets that each displayed distinct spatiotemporal relationships with nutrient concentrations and autotrophic and heterotrophic microbial abundances. The results highlight dynamic shifts in viral community structure and imply that each of these three subsets is ecologically important and likely to infect distinct microbial hosts in reef waters. Based on viral-reduction approach, we estimate that lytic viruses were responsible for the removal of ca. 24-367% of bacterial standing stock d(-1) and the release of ca. 1.0- 62 mu g of organic carbon l(-1) d(-1) in reef waters. Overall, this work demonstrates the highly dynamic distribution of viruses and their critical roles in controlling microbial mortality and nutrient cycling in coral reef water ecosystems

IMPACT 2002+: A new life cycle impact assessment methodology

The new IMPACT 2002+ life cycle impact assessment methodology proposes a feasible implementation of a combined midpoint/damage approach, linking all types of life cycle inventory results (elementary flows and other interventions) via 14 midpoint categories to four damage categories. For IMPACT 2002+, new concepts and methods have been developed, especially for the comparative assessment of human toxicity and ecotoxicity. Human Damage Factors are calculated for carcinogens and non-carcinogens, employing intake fractions, best estimates of dose-response slope factors, as well as severities. The transfer of contaminants into the human food is no more based on consumption surveys, but accounts for agricultural and livestock production levels. Indoor and outdoor air emissions can be compared and the intermittent character of rainfall is considered. Both human toxicity and ecotoxicity effect factors are based on mean responses rather than on conservative assumptions. Other midpoint categories are adapted from existing characterizing methods (Eco-indicator 99 and CML 2002). All midpoint scores are expressed in units of a reference substance and related to the four damage categories human health, ecosystem quality, climate change, and resources. Normalization can be performed either at midpoint or at damage level. The IMPACT 2002+ method presently provides characterization factors for almost 1500 different LCI-results, which can be downloaded at http://www.epfl.ch/impac

Environmental Impact of PV Systems: Effects of Energy Sources Used in Production of Solar Panels

http://www.eupvsec-proceedings.com/proceedings?char=E&paper=4860International audienceThe international expansion of the PV industry can affect the range of indirect environmental impacts, and mostly the CO2 equivalent emissions, of the solar electricity produced in any country. We demonstrate a clear trend towards high variation in the global warming potential of solar electricity produced in France by PV installations which use modules produced with different electricity mix. The variation is somewhat less important when looking at the Energy Payback Time (EPBT) of the PV installation. In any studied case, the transportation between countries has a low effect compared to the choice made on the source of electricity used during the different steps involved in the fabrication of modules for any technology

Espace-PV: Key Sensitive Parameters for Environmental Impacts of Grid-Connected PV Systems With LCA

http://www.eupvsec-proceedings.com/proceedings?char=E&paper=2818International audienceThe study of sensitive parameters for the life cycle analysis (LCA) of PV system showed that irradiation intensity will bring the biggest variation on environmental impact when considering regions with large difference in solar irradiation level. For example, in France a system installed in the northern region will produce electricity with more than a 100% of the impact of a southern system. Other important factors are the lifetime of the system and the associated electricity use for the different components needed for the PV system. They can bring up to 35% of variation in the production of CO2 gas and primary non-renewable energy use. This study has been developed within Espace-PV project and results have been analyzed and compared with the EcoInvent database. These results are provided for a 3 kWp multicrystalline grid connected system integrated in a slanted roof with near optimal inclination

Environmental Impacts of Large-Scale Grid-Connected Ground-Mounted PV Installations

Available on: http://www.ep.liu.se/ecp/057/vol11/007/ecp57vol11_007.pdfInternational audienceThis study characterizes the environmental performances of large-scale ground-mounted PV installations by considering a life-cycle approach. The methodology is based on the application of the existing international standards of Life Cycle Assessment (LCA). Four scenarios are compared, considering fixedmounting structures with (1) primary aluminum supports or (2) wood supports, and mobile structures with (3) single-axis trackers or (4) dual-axis trackers. Life cycle inventories are based on manufacturers' data combined with additional calculations and assumptions. Fixed-mounting installations with primary aluminum supports show the largest environmental impact potential with respect to human health, climate change and energy consumption. The climate change impact potential ranges between 37.5 and 53.5 gCO2eq/kWh depending on the scenario, assuming 1700 kWh/m².yr of irradiation on an inclined plane (30°), and multi-crystalline silicon modules with 14% of energy production performance. Mobile PV installations with dual-axis trackers show the largest impact potential on ecosystem quality, with more than a factor 2 of difference with other considered installations. Supports mass and composition, power density (in MWp/acre of land) and energy production performances appear as key design parameters with respect to large-scale ground mounted PV installations environmental performances, in addition to modules manufacturing process energy inputs

Modeling the Winter–to–Summer Transition of Prokaryotic and Viral Abundance in the Arctic Ocean

One of the challenges in oceanography is to understand the influence of environmental factors on the abundances of prokaryotes and viruses. Generally, conventional statistical methods resolve trends well, but more complex relationships are difficult to explore. In such cases, Artificial Neural Networks (ANNs) offer an alternative way for data analysis. Here, we developed ANN-based models of prokaryotic and viral abundances in the Arctic Ocean. The models were used to identify the best predictors for prokaryotic and viral abundances including cytometrically-distinguishable populations of prokaryotes (high and low nucleic acid cells) and viruses (high- and low-fluorescent viruses) among salinity, temperature, depth, day length, and the concentration of Chlorophyll-a. The best performing ANNs to model the abundances of high and low nucleic acid cells used temperature and Chl-a as input parameters, while the abundances of high- and low-fluorescent viruses used depth, Chl-a, and day length as input parameters. Decreasing viral abundance with increasing depth and decreasing system productivity was captured well by the ANNs. Despite identifying the same predictors for the two populations of prokaryotes and viruses, respectively, the structure of the best performing ANNs differed between high and low nucleic acid cells and between high- and low-fluorescent viruses. Also, the two prokaryotic and viral groups responded differently to changes in the predictor parameters; hence, the cytometric distinction between these populations is ecologically relevant. The models imply that temperature is the main factor explaining most of the variation in the abundances of high nucleic acid cells and total prokaryotes and that the mechanisms governing the reaction to changes in the environment are distinctly different among the prokaryotic and viral populations

Environmental Impacts of Solar Thermal Systems with Life Cycle Assessment

Available on: http://www.ep.liu.se/ecp/057/vol14/002/ecp57vol14_002.pdfInternational audienceSolar thermal systems are an ecological way of providing domestic hot water. They are experiencing a rapid growth since the beginning of the last decade. This study characterizes the environmental performances of such installations with a life-cycle approach. The methodology is based on the application of the international standards of Life Cycle Assessment. Two types of systems are presented. Firstly a temperate-climate system, with solar thermal collectors and a backup energy as heat sources. Secondly, a tropical system, with thermosiphonic solar thermal system and no backup energy. For temperate-climate systems, two alternatives are presented: the first one with gas backup energy, and the second one with electric backup energy. These two scenarios are compared to two conventional scenarios providing the same service, but without solar thermal systems. Life cycle inventories are based on manufacturer data combined with additional calculations and assumptions. The fabrication of the components for temperate-climate systems has a minor influence on overall impacts. The environmental impacts are mostly explained by the additional energy consumed and therefore depend on the type of energy backup that is used. The study shows that the energy pay-back time of solar systems is lower than 2 years considering gas or electric energy when compared to 100% gas or electric systems

Experimental metatranscriptomics reveals the costs and benefits of dissolved organic matter photo‐alteration for freshwater microbes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156421/2/emi15121_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156421/1/emi15121.pd