Tonnes Year Research Articles

Measurement of solar pp neutrino flux using electron recoil data from PandaX-4T commissioning run* *This project is supported in part by the grants from the National Science Foundation of China (12090060, 12090063, 12105052, 12005131, 11905128, 11925502), the Office of Science and Technology, Shanghai Municipal Government (22JC1410100), and the National Science Foundation of Sichuan Province, China (2024NSFSC1371). We are grateful for

The proton-proton ( ) fusion chain dominates the neutrino production in the Sun. The uncertainty of the predicted neutrino flux is at the sub-percent level, whereas that of the best measurement is (10%). In this study, for the first time, we measure solar neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne year exposure. The neutrino flux is determined as , which is consistent with the Standard Solar Model and existing measurements, corresponding to an upper flux limit of at 90% C.L..

Geolocation and immersion loggers reveal year‐round residency and facilitate nutrient deposition rate estimation of adult red‐footed boobies in the Chagos Archipelago, tropical Indian Ocean

Bio‐logging has revealed much about high‐latitude seabird migratory strategies, but migratory behaviour in tropical species may differ, with implications for understanding nutrient deposition. Here we use combined light‐level and saltwater immersion loggers to study the year‐round movement behaviour of adult red‐footed boobies Sula sula rubripes from the Chagos Archipelago, tropical Indian Ocean, to assess migratory movements and estimate nutrient deposition rates based on the number of days they spent ashore. Light levels suggest that red‐footed boobies are resident in the Chagos Archipelago year‐round, although there are large latitudinal errors this close to the equator. Immersion data also indicate residency with tracked birds returning to land every one or two days. Spending an average of 79.86 ± 2.80 days and 280.84 ± 2.64 nights per year on land allows us to estimate that the 21 670 pairs of red‐footed boobies deposit 37.34 ± 0.56 tonnes year−1 of guano‐derived nitrogen throughout the archipelago. Our findings have implications for tropical seabird conservation and phylogenetics, as well as for assessing the impact of seabird nutrients on coral reef ecosystems.

Social, economic and environmental benefits of organic waste home composting in Iran

Organic waste management is challenging in low-middle income countries. Environmental impacts and high management costs affect the sustainable development of cities, an issue that is exacerbated by the lack of social involvement. The research conducted in Iran aims to assess the benefits of organic waste home composting in Shiraz to improve solid waste management (SWM) sustainability. The introduction of a pilot project to assess home composting systems was described, together with an economic, social and environmental analysis. The current SWM system (S0) has been compared with the new strategy proposed (S1), where home composting is considered to be introduced to collect about 10% of the municipal solid waste generated in a 10-year horizon. An economic balance related to the capital costs and operational costs of both systems was introduced, in parallel with a life cycle assessment (LCA) of the SWM system, and a questionnaire survey of the local population. Results showed that S1 leads to around 5% economic savings for the municipality due to the avoidance of organic waste transportation and disposal. Environmental benefits include a lowering of CO2-Eq emissions of about 19,076 tonnes year−1. In addition, about 28% of the interviewed ( n = 319) agreed to employ the home composting system at home (CI 5.5%, 95% of confidence level) supporting the theory that about 10% of the organic waste can be segregated and home-composted. The research underlines that home composting can contribute to improve the sustainability of SWM systems in developing countries.

Search for Solar ^{8}B Neutrinos in the PandaX-4T Experiment Using Neutrino-Nucleus Coherent Scattering.

A search for interactions from solar ^{8}B neutrinos elastically scattering off xenon nuclei using PandaX-4T commissioning data is reported. The energy threshold of this search is further lowered compared with the previous search for dark matter, with various techniques utilized to suppress the background that emerges from data with the lowered threshold. A blind analysis is performed on the data with an effective exposure of 0.48 tonne year, and no significant excess of events is observed. Among the results obtained using the neutrino-nucleus coherent scattering, our results give the best constraint on the solar ^{8}B neutrino flux. We further provide a more stringent limit on the cross section between dark matter and nucleon in the mass range from 3 to 9 GeV/c^{2}.

Trends in Indian Ocean marine fisheries since 1950: synthesis of reconstructed catch and effort data

Context Contrary to other ocean basins, Indian Ocean catches have increased consistently since 1950, although reported data are known to be incomplete. Fish is a crucial food source in the Indian Ocean; however, ineffective management often empowers over-exploitation. Aims We synthesised and reviewed Indian Ocean reconstructed catch and effort data by fishing sector and fishing country at the ocean-basin scale. Methods We aggregated reported and reconstructed unreported catch and effort data for the Indian Ocean and derived catch-per-unit-effort (CPUE) time-series by sector. Key results Indian Ocean rim country catches dominated in the Indian Ocean. Small-scale catches in the Indian Ocean have grown continuously by over 300% from 1.9 × 106 tonnes (Mg) year−1 in 1950 to 6.5 × 106 tonnes year−1 by 2018. By contrast, total industrial catches from the Indian Ocean have reached a plateau at ~8.5 × 106 tonnes year−1 since the late 1990s, after having steadily risen from very low levels in the early 1960s. Unreported catches declined from 45 to 25% of total catches. Total fishing effort, driven by the industrial sector, has increased 30-fold since 1950 from 0.4 × 109 to 11 × 109 kW-days by 2010, whereas CPUE has declined 78%, with steeper declines in the small-scale (>80% since 1950) than in the industrial sector (65% from its 1981 peak). Conclusions The different sectoral patterns in the Indian Ocean compared with other ocean basins are likely to be due to the region’s high dependence on small-scale fisheries and the later onset but swift growth of industrial fishing. The declining CPUE suggests strong decreases in stock biomass caused by strongly increasing fishing effort, especially in the industrial sector. Implications Indian Ocean countries should prioritise lower-impact well-managed domestic small-scale fisheries to maximise long-term, sustainable nutrient supply for local livelihoods.

Direct Detection of Dark Matter with DarkSide-20k

DarkSide run since mid 2015 a 50-kg-active-mass dual phase Liquid Argon Time Projection Chamber (TPC), filled with low radioactivity argon from an underground source and produced world class results for both the low mass (< 20 GeV/c2) and high mass ( > 100 GeV/c2) direct detection search for dark matter. The next stage of the DarkSide program will be a new generation experiment involving a global collaboration from all the current Argon based experiments. DarkSide-20k, is designed as a 20-tonne fiducial mass dual phase Liquid Argon TPC with SiPM based cryogenic photosensors, and is expected to be free of any instrumental background for an exposure of >100 tonne year. Like its predecessor, DarkSide-20k will be housed at the INFN Gran Sasso (LNGS) underground laboratory, and it is expected to attain a WIMP-nucleon cross section exclusion sensitivity of 7.4 × 10−48 cm2 for a WIMP mass of 1 TeV/c2 in a 200 t yr run. DarkSide-20k will be installed inside a membrane cryostat containing more than 700 t of liquid Argon and be surrounded by an active neutron veto based on a Gd-loaded acrylic shell. The talk will give the latest updates of the ongoing R&D and prototype tests validating the initial design. A subsequent objective, towards the end of the next decade, will be the construction of the ultimate detector, ARGO, with a 300 t fiducial mass to push the sensitivity to the neutrino floor region for high mass WIMPs.

Formal and informal solid waste management in Kutaisi, Georgia: A status quo report based on material flow analysis.

The goal of this study is a qualitative and quantitative evaluation of processes and flows within the solid waste management (WM) system in Kutaisi, Georgia, and the wider Imereti region. The applied methodology based upon data collected through customized questionnaires enabled both the formal and informal sectors (IS) to be characterized. Moreover, waste composition studies in the region's rural and semi-urban areas revealed that the share of recyclables is higher in urban areas and commercial centres. A material flow analysis was used to transparently consolidate the collected data, showing that dumping and landfilling still play a major role within the Georgian WM system. The total amount of waste landfilled on 'Nikea' landfill in 2019 equals 58,000 tonnes year-1, from where around 55,500 tonnes year-1 is formally collected municipal solid waste, and 2,503 tonnes year-1 is commercial and industrial waste. According to the findings, the size of the IS in Kutaisi is 0.07-0.15% of the city's population, whose supposed cumulative income is estimated GEL 0.57-1.13 million (EUR 180-360 thousand) in 2019. Informally collected recyclables are estimated 870-1,750 tonnes year-1, comprising 6-11% of recyclables landfilled in Kutaisi in 2019. The study provides a basis for decision-makers. Replicating the applied methodologies and approaches to create this sound database could support the WM system across whole Georgia. The study further reveals the importance of the need to stop neglecting the IS and recognizes the importance of its role in the WM system of Kutaisi and the wider Imereti region, respectively.

Search for Light Fermionic Dark Matter Absorption on Electrons in PandaX-4T.

We report a search on sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the 0.63 tonne year exposure collected by the PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background. The data are interpreted into limits to the effective couplings between such dark matter and the electron. For axial-vector or vector interactions, our sensitivity is competitive in comparison to existing astrophysical bounds on the decay of such a dark matter candidate into photon final states. In particular, we present the first direct detection limits for a vector (axial-vector) interaction which are the strongest in the mass range from 35 to 55 (25 to 45) keV/c^{2} in comparison to other astrophysical and cosmological constraints.

Marine mammal consumption and fisheries removals in the Nordic and Barents Seas

AbstractIn this study, we assess prey consumption by the marine mammal community in the northeast Atlantic [including 21 taxa, across three regions: (I) the Icelandic shelf, Denmark Strait, and Iceland Sea (ICE); (II) the Greenland and Norwegian Seas (GN); and (III) the Barents Sea (BS)], and compare mammal requirements with removals by fisheries. To determine prey needs, estimates of energetic requirements were combined with diet and abundance information for parameterizing simple allometric scaling models, taking uncertainties into account through bootstrapping procedures. In total, marine mammals in the ICE, GN, and BS consumed 13.4 [Confidence Interval (CI): 5.6–25.0], 4.6 (CI: 1.9–8.6), and 7.1 (CI: 2.8–13.8) million tonnes of prey year–1. Fisheries removed 1.55, 1.45, and 1.16 million tonnes year–1 from these three areas, respectively. While fisheries generally operate at significantly higher trophic levels than marine mammals, we find that the potential for direct competition between marine mammals and fisheries is strongest in the GN and weakest in the BS. Furthermore, our results also demonstrate significant changes in mammal consumption compared to previous and more focused studies over the last decades. These changes likely reflect both ongoing population recoveries from historic whaling and the current rapid physical and biological changes of these high-latitude systems. We argue that changing distributions and abundances of mammals should be considered when establishing fisheries harvesting strategies, to ensure effective fisheries management and good conservation practices of top predators in such rapidly changing systems.

Using life-history traits to predict the vulnerability to overexploitation in soldier striped shrimps

The global overfishing scenario of the historically exploited marine stocks have generated concern and encouraged the search for new potentially exploitable fisheries resources. In this sense, shrimps are potential alternative resources to be exploited, given their high diversity and stock resilience. This study had an objective to estimate life-history traits and analyse yield and abundance fishing levels to see whether Plesionika edwardsii shrimp is vulnerable to overexploitation or not in the mid-North Atlantic (Azores region, ICES Subdivision 10a2). The females showed larger L∞ (asymptotic length) and k (coefficient of growth; L∞ = 27.3 mm, k = 0.75 year−1) than did males (L∞ = 24.58 mm, k = 0.73 year−1). The mortality rates of males (Z = 1.00 year−1; M = 0.84 year−1) and females (Z = 0.92 year−1; M = 0.85 year−1) were very similar. In terms of longevity, the males (3.47 year−1) survived longer than did females (3.34 year−1). Depletion experiments showed a fast and straight-forward decline of CPUEs (3, 5 and 9 days), confirming a low mobility and vulnerability to high fishing efforts. The maximum sustainable yield (MSY) estimates (5.4–10.7 tonnes (Mg) year−1) showed a low annual sustainable catch. These values combined with the life-history characteristics indicated that this stock is less resilient and highly vulnerable to overfishing.

A financial analysis of four carbon offset accounting protocols for a representative afforestation project (southern Ontario, Canada)

Forestry projects participate in carbon markets by sequestering carbon dioxide equivalent (CO2e) and producing carbon offsets. The creation of forest-based offsets is guided by protocols that dictate how sequestered CO2e is converted into marketable offsets. Existing protocol designs aim to produce offsets that meet sustainability requirements, while providing financial incentives for landowner participation. However, limited Canadian uptake implies that current financial incentives are insufficient to encourage the production of carbon offsets via private landowners. Here we consider various design features of four protocols and their financial implications for an illustrative afforestation project in southern Ontario, Canada. We explore the protocols (two tonne–tonne protocols and two tonne–year protocols) under two afforestation project management systems (“no-harvest” and “harvest” management scenarios). Results indicate that a project that terminates in a harvest is not economically attractive at current CO2e prices under any protocol design at a scale likely to be undertaken in southern Ontario, Canada. Projects that do not conclude in harvest are generally more attractive. Tonne–tonne protocols that pay upfront for sequestered CO2e improve the economic attractiveness of afforestation projects, but the delayed realization of the value of offset credits under tonne–year protocols reduces the economic attractiveness of these projects. We discuss these results in light of the choices facing afforestation project proponents and offset protocol designers (including governments) in general, and provide detailed insights into the financial dynamics of the Canadian case.

Effects of extrinsic abiotic factors on induction of gametogenesis and efficacy of a device for the segregation of non-fused gametes and zygotes in the green alga Ulva lactuca

ABSTRACT Seaweed aquaculture is one of the fastest growing marine sectors with 31.2 million tonnes year–1 of harvest worth over 11.7 billion USD. Commercial operations still rely on traditional techniques but innovative strategies are essential for future expansion. The present paper reports on a simple device that could effectively segregate non-fused haploid gametes from diploid zygotes in the green alga Ulva lactuca. The differential phototactic behaviour of gametes and zygotes was used for their separation. Approximately 56.2% non-fused haploid gametes and 5.3% diploid zygotes were separated after 5 min and after 1 hr and 2 hr, the composition of gametes was 26.6 and 8.8%, respectively while that of zygotes 32.7 and 57.4%, respectively. The effects of extrinsic abiotic factors, including light, temperature, salinity, photoperiod, dehydration and thallus fragmentation, on the induction of gametogenesis was found to be limited at 35°C (13.33 ± 5.77%) and a short day 9:15 h light:dark photoperiod (20 ± 4.08%), while dehydration treatments enhanced spore induction. This study demonstrated the efficient and cost-effective utilisation of locally available materials in producing a simple, small, precise, durable and easy to use system, which also saved on energy. The effective segregation of non-fused gametes from zygotes aids in cytological preparation, bio-chemical characterisation investigations as well as breeding and hybridisation all of which have direct implications on the future farming of Ulva and other species of seaweeds with similar life phases.

An experiment revealing the ability of a side‐scan sonar to detect CO2 bubbles in shallow seas

AbstractWith the aim of using side‐scan sonar (SSS) in marine monitoring at offshore CO2 storage sites, an experiment was conducted in a bay with a flat seabed, approximately 32 m deep. CO2 bubbles released at regulated rates between 500 and 5000 mL min−1 were searched for with SSS to elucidate the detection limit, which depends on the towing speed and the altitude of SSS, and the horizontal distance between the release point and SSS. When the towing speed was less than 6 knots, SSS was able to detect CO2 bubbles released at 1000 mL min−1 (approximately 4 tonnes year−1), which is an extremely small rate compared with injection rates in commercial scale storage, O(106) tonnes year−1. The time required for searching an area of 1 km2 with SSS was estimated to be between 1.7 and 3.4 hours, assuming that SSS was towed at an altitude of 27 m. Thus, SSS was demonstrated to be serviceable for marine monitoring. pH measured at 5 m away from the release point dropped by larger than 0.05 four times during the experiment. Only one of them might have been due to the CO2 release, and the others were due to intrusion of water from deeper layers because temperature, salinity and dissolved oxygen simultaneously changed. This indicates that bubble searching with SSS could detect smaller‐scale CO2 leakages than locating anomalous carbonate values, although the latter is still important in case all or most of CO2 dissolve before the emission to the sea. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

Effect of Long-Term Nutrient Management on Soil Organic Carbon Sequestration in Rice–Rice–Fallow Rotation

A study was conducted on long-term (for 31 years) rice–rice–fallow cropping sequence to determine the effect of balanced chemical fertilizer and integrated nutrient management (INM; chemical fertilizer + poultry manure 2 tonne ha –1 ) on soil organic carbon (SOC) sequestration. C mineralization rate (k), microbial population, SOC and C content in the mean water stable soil aggregate (MWDw) were measured from field soil. The C dynamics was described using DSSAT crop and DNDC models. INM increased soil bacteria and improved SOC stock by 27.98%, although C loss was higher with this treatment. A decreasing trend of bacterial population and SOC was observed in the balanced chemical fertilizer (15%) and fertilizer control (46%) treatments compared to initial soil. A positive correlation (r = 0.94) was found between C content of MWDw and soil bacteria population, which provided evidence of vital contribution of soil bacteria for SOC sequestration. In INM treatment, k (incubation study) was 0.011 tonne year –1 , and it was less than DNDC- and DSSAT-generated data. However, k value (0.010 tonne year –1 ) obtained in the incubation study of the balanced chemical fertilizer was similar to DNDC model data. An increasing trend of paddy yield (10 years) was observed in INM compared to balanced chemical fertilizer. In conclusion, microbial population, SOC sequestration and crop yield were high with INM. For sustainable rice production and C sequestration, INM is superior to balanced chemical fertilizer. Between two models used, DNDC is better for prediction of SOC balance.

Techno-economic analysis of producing liquid fuels from biomass via anaerobic digestion and thermochemical conversion

This paper discusses a preliminary design and a techno-economic analysis of a process that produces liquid hydrocarbon fuels from biomass through a combined biochemical and thermochemical process. The biochemical component involves anaerobic digestion (AD) of the biomass's biodegradable portion to produce biogas. Biogas is purified by removing contaminants and upgraded to liquid hydrocarbon fuel in a biogas to liquid facility (BGTL) via thermochemical conversion route. The BGTL process involves two major steps: tri-reforming to produce syngas (a mixture of CO and H2), and, Fischer-Tropsch Synthesis (FTS) to convert the syngas to a spectrum of hydrocarbons (synthetic crude). Separation and upgrading of the produced hydrocarbon mixture allows production of transportation fuels such as gasoline, jet fuel, and diesel.In order to evaluate the economics of the combined process a detailed process modelling was carried out using Aspen Plus® software. Bench-scale experimental results served as the basis of modelling the BGTL section of the plant, while the AD portion of the plant is based on empirical models selected from the literature validated by comparison with experimental results. Recent bench scale tests in our lab were used to determine processing parameters (yield, temperature, and pressure) for the reforming and FTS conversion.A plant capable of processing 90,000 tonne year−1 of wet biomass feed was designed and analyzed using the model. Results of the economic analysis estimate that a breakeven cost of diesel of $1.30 L-1 is achievable without the consideration of charging tipping fees to accept the biomass feedstock. Sensitivity study shows that the economics are significantly affected by the fixed capital investment (FCI) and less so by the operating expenses and interest rate. In addition, tipping fees and biomass feedstock cost have a substantial effect on the breakeven price of diesel.

European solvent VOC emission inventories based on industry-wide information

The European Solvents Industry Group (ESIG) has established volatile organic compound emission inventories for solvents for individual countries or groups of countries within the European Union for 2008, 2009, 2013 and 2015. A top-down approach has been adopted starting with EU-wide solvents industry sales data as supplied by solvent manufacturers, to which atmospheric release factors were applied for each solvent use sector. ESIG total solvent emissions for the EU ranged from 2159 thousand tonnes year−1 in 2008 to 1981 thousand tonnes year−1 in 2015. Comparison with internationally-agreed solvent emissions suggests that official estimates of total solvent emissions across the EU are over 30% too high by comparison with ESIG estimates and showed too high a trend with time. Using official statistics on chemical exports and imports for each country, ESIG has been able to compile solvent emissions for each European country or groups of countries. The over-estimation by the internationally-agreed solvent emissions compared with the ESIG estimates for Europe as a whole was mirrored in the individual country estimates for 2008, 2009, 2013 and 2015. No simple, uniform relationship between national solvent emissions and per capita population for either total or domestic sector solvent emissions was found. Assumption of uniform solvents emission factors on a per-head of population basis, has led to the introduction of inaccuracies in internationally-agreed solvent emission inventories. More detailed work with Member States has shown that non-solvents are also being included in the official solvent VOC inventories-indeed these VOC inventories are for ‘solvents and other product use’.

Waste Management and Treatment of Copper Slag BCL, Selebi Phikwe Botswana: Review

The production of copper bears both viable product and by product know as slag which is a challenge to dispose and poses a problem to the environment. BCL holds copper slag is seen as waste which is iron - opulent containing heavy metals which can seep into ground water and affect environment. These metal accumulate in millions of tonnes year after year posing as a threat to the environment and need to be managed to avoid them being harmful. This paper explores metallurgical ways of treating the slag and utilizing it in different ways. Extracting metals such as iron is one way of managing the slag, as previous research and present indicate that iron can be recovered from copper slag. This will help manage the waste slag and rehabilitate land sustainably. The copper slag can also be used in cement and concrete production and provides potential environmental and economic benefits for all parties involved. The BCL dump will be regarded as raw material rather than waste hence igniting management and treatment of waste to sustainability.

A perspective for reducing environmental impacts of mussel culture in Algeria

In Algeria, the Ministry of Fisheries and Halieutic Resources has designed a strategic plan for the development of marine aquaculture for the years 2015–2025, which aims at expanding the annual production of Mediterranean mussel from less than 150 metric tonnes year−1 in 2013 to 7600 metric tonnes year−1 in 2025. We used Life Cycle Assessment (LCA) for evaluating the environmental impact of suspended mussel culture in Algeria and suggest management practices which could reduce it. In order to estimate the current and perspective impact of this industry, we (1) applied LCA to one of the few farms currently operating in Algeria and (2) investigated two management scenarios for the farms to be established in the future in the same coastal area. The first scenario (Comp_S) represents the continuity with the current situation, in which each farm is competing with the other ones and is therefore managing the production cycle independently. In the second scenario (Coop_S), mussel farms are grouped in an aquaculture management area and shared the same facilities for post-processing harvested mussels before sending them to the market. The midpoint-based CML-IA method baseline 2000 V 3.01 was employed using SimaPro software. Furthermore, we carried out a Monte Carlo simulation, in order to assess the uncertainty in the results. The analysis focused on impact categories related to acidification and global warming potential. We took into account the energy consumptions (electricity and vessel fuel), the rearing infrastructure, including longlines, and a building for stabling, grading, and packing the mussel. Electricity contributes with 38.1 and 31.8 % respectively to global warming potential (GWP) and acidification, while fuel consumption contributes with 19.5 % to GWP and 31.8 % to acidification. Results of this work are compared with other LCA studies recently carried out in France (Aubin and Fontaine 2014) and in Spain (Iribarren et al. 2010c). The LCA results show that important reductions in environmental impacts could be attained if the mussel farming activity would be operated according to the cooperative scenario here proposed. In this case, the environmental benefits will be a reduction of 3150 MJ and 156 kg CO2 eq per metric tonne of mussel produced, compared with the alternative scenario. The results of this study suggest that LCA should be applied to the seafood production sector in Algeria, in order to identify best management practices.

Overview and Perspectives on Emissions of Polybrominated Diphenyl Ethers on a Global Basis: Evaporative and Fugitive Releases from Commercial PBDE Mixtures and Emissions from Combustion Sources

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants, but are of concern due to their potential health risks. PBDEs are ubiquitous in the environment and their occurrence in polar regions highlights the importance of atmospheric transport. As yet, most researches emphasized evaporative and fugitive releases of PBDEs during production, use and waste management phases. However, the recent studies have uncovered the importance of the combustion sources when considering the release of PBDEs into the atmosphere. Nevertheless, complete PBDE emission inventories are lacking, and no global PBDE emissions from combustion sources have been estimated. Therefore, this study estimated the global PBDE emissions from combustion sources and illegal open burning of waste electrical and electronic equipment (WEEE) and e-waste, as well as evaporative and fugitive releases from commercial PBDE mixtures. We found that combustion sources and illegal open burning of e-waste globally emit PBDEs at 6.75 and 0.255–5.56 tonnes year–1, and are important PBDE emitters. The effectiveness of reducing human exposure to PBDEs will be minimized and delayed if mitigation of PBDE emissions from combustion sources is ignored. Control of PBDE emissions from combustion sources should be taken along with the ban of commercial PBDE mixtures.

Greenhouse gas emissions from municipal solid waste management in Vientiane, Lao PDR.

Municipal solid waste (MSW) is one of the major environmental problems throughout the world including in Lao PDR. In Vientiane, due to the lack of a collection service, open burning and illegal dumping are commonly practised. This study aims to estimate the greenhouse gas (GHG) emission from the current situation of MSW management (MSWM) in Vientiane and proposes an alternative solution to reduce the GHG emission and environmental impacts. The 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories (IPCC 2006 model) are used for the estimation of GHG emission from landfill and composting. For the estimation of GHG emission from open burning, the Atmospheric Brown Clouds Emission Inventory Manual (ABC EIM) is used. In Vientiane, a total of 232, 505 tonnes year(-1) of MSW was generated in 2011. Waste generation in Vientiane is 0.69 kg per capita per day, and about 31% of the total MSW generated was directly sent to landfill (71,162 tonnes year(-1)). The total potential GHG emission from the baseline scenario in 2011 was 110,182 tonnes year(-1) CO2-eq, which is 0.15 tonne year(-1) CO2-eq per capita. From the three MSWM scenarios proposed, scenario S3, which includes recycling, composting and landfilling, seems to be an effective solution for dealing with MSW in Vientiane with less air pollution, and is environmentally friendly. The total GHG emission in scenario S3 is reduced to 91,920 tonnes year(-1) CO2-eq (47% reduction), compared with the S1 scenario where all uncollected waste is diverted to landfill.