Mercury (Hg) emissions from domestic biomass combustion for space heating

Three mercury (Hg) species (gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and fine particulate-bound mercury (PBM_2.5)) were measured in the stack of a small scale wood combustion chamber at 400 °C, in the stack of an advanced wood boiler, and in two areas influenced by wood combustion. The low temperature process (lab-scale) emitted mostly GEM (∼99% when burning wood pellets and ∼95% when burning unprocessed wood). The high temperature wood boiler emitted a greater proportion of oxidized Hg (approximately 65%) than the low temperature system. In field measurements, mean PBM_2.5 concentrations at the rural and urban sites in winter were statistically significantly higher than in warmer seasons and were well correlated with Delta-C concentrations, a wood combustion indictor measured by an aethalometer (UV-absorbable carbon minus black carbon). Overall the results suggest that wood combustion may be an important source of oxidized mercury (mostly in the particulate phase) in northern climates in winter.     

Environmental monitoring study of selected veterinary antibiotics in animal manure and soils in Austria

LC-MS/MS was used for determination of selected tetracyclines, sulfonamides, trimethoprim, and fluoroquinolones in manure samples of pig, chicken and turkey, as well as arable soils fertilized with manure. Recoveries from spiked samples ranged from 61 to 105%. Method quantification limits were set to 100 microg/kg for all substances. Analysis of 30 pig manure, 20 chicken and turkey dung, and 30 lyophilized soil samples taken in Austria revealed that in pig manure up to 46 mg/kg chlortetracycline, 29 mg/kg oxytetracycline and 23 mg/kg tetracycline could be detected. As representatives of the group of sulfonamides, sulfadimidine in pig manure and sulfadiazine in chicken and turkey dung were detected in significant amounts (maximum concentration, 20 and 91 mg/kg, respectively). Enrofloxacin was particularly observed in chicken and turkey samples. Positive detection of chlortetracycline, enrofloxacin, and ciprofloxacin, in soil samples should be outlined as most important results of this study.     

HPLC determination of chlorate metabolism in bovine ruminal fluid

Salmonella and Escherichia coli are two bacteria that are important causes of human and animal disease worldwide. Chlorate is converted in the cell to chlorite, which is lethal to these bacteria. An HPLC procedure was developed for the rapid analysis of chlorate (ClO(3)(-)), nitrate (NO(3)(-)), and nitrite (NO(2)(-)) ions in bovine ruminal fluid samples. Standard curves for chlorite, nitrite, nitrate, and chlorate were well defined linear curves with R(2) values of 0.99846, 0.99106, 0.99854, and 0.99138, respectively. Concentrations of chlorite could not be accurately determined in bovine ruminal fluid because chlorite reacts with or binds a component(s) or is reduced to chloride in bovine ruminal fluid resulting in low chlorite measurements. A standard curve ranging from 25 to 150 ppm ClO(3)(-) ion was used to measure chlorate fortified into ruminal fluid. The concentration of chlorate was more rapidly lowered (P < 0.01) under anaerobic compared to aerobic incubation conditions. Chlorate alone or chlorate supplemented with the reductants sodium lactate or glycerol were bactericidal in anaerobic incubations. In anaerobic culture, the addition of sodium formate to chlorate-fortified ruminal fluid appeared to decrease chlorate concentrations; however, formate also appeared to moderate the bactericidal effect of chlorate against E. coli. Addition of the reductants, glycerol or lactate, to chlorate-fortified ruminal fluid did not increase the killing of E. coli at 24 h, but may be useful when the reducing equivalents are limiting as in waste holding reservoirs or composting systems required for intense animal production.     

The IMPROVE_A temperature protocol for thermal/optical carbon analysis: maintaining consistency with a long-term database

Thermally derived carbon fractions including organic carbon (OC) and elemental carbon (EC) have been reported for the U.S. Interagency Monitoring of PROtected Visual Environments (IMPROVE) network since 1987 and have been found useful in source apportionment studies and to evaluate quartz-fiber filter adsorption of organic vapors. The IMPROVE_A temperature protocol defines temperature plateaus for thermally derived carbon fractions of 140 degrees C for OC1, 280 degrees C for OC2, 480 degrees C for OC3, and 580 degrees C for OC4 in a helium (He) carrier gas and 580 degrees C for EC1, 740 degrees C for EC2, and 840 degrees C for EC3 in a 98% He/2% oxygen (O2) carrier gas. These temperatures differ from those used previously because new hardware used for the IMPROVE thermal/optical reflectance (IMPROVE_TOR) protocol better represents the sample temperature than did the old hardware. A newly developed temperature calibration method demonstrates that these temperatures better represent sample temperatures in the older units used to quantify IMPROVE carbon fractions from 1987 through 2004. Only the thermal fractions are affected by changes in temperature. The OC and EC by TOR are insensitive to the change in temperature protocol, and therefore the long-term consistency of the IMPROVE database is conserved. A method to detect small quantities of O2 in the pure He carrier gas shows that O2 levels above 100 ppmv also affect the comparability of thermal carbon fractions but have little effect on the IMPROVE_TOR split between OC and EC.     

Dilution-based emissions sampling from stationary sources: Part 2--Gas-fired combustors compared with other fuel-fired systems

With the recent focus on fine particle matter (PM2.5), new, self-consistent data are needed to characterize emissions from combustion sources. Such data are necessary for health assessment and air quality modeling. To address this need, emissions data for gas-fired combustors are presented here, using dilution sampling as the reference. The dilution method allows for collection of emitted particles under conditions simulating cooling and dilution during entry from the stack into the air. The sampling and analysis of the collected particles in the presence of precursor gases, SO2 nitrogen oxide, volatile organic compound, and NH3 is discussed; the results include data from eight gas fired units, including a dual-fuel institutional boiler and a diesel engine powered electricity generator. These data are compared with results in the literature for heavy-duty diesel vehicles and stationary sources using coal or wood as fuels. The results show that the gas-fired combustors have very low PM2.5 mass emission rates in the range of approximately 10(-4) lb/million Btu (MMBTU) compared with the diesel backup generator with particle filter, with approximately 5 x 10(-3) lb/MMBTU. Even higher mass emission rates are found in coal-fired systems, with rates of approximately 0.07 lb/MMBTU for a bag-filter-controlled pilot unit burning eastern bituminous coal. The characterization of PM2.5 chemical composition from the gas-fired units indicates that much of the measured primary particle mass in PM2.5 samples is organic or elemental carbon and, to a much less extent, sulfate. Metal emissions are quite low compared with the diesel engines and the coal- or wood-fueled combustors. The metals found in the gas-fired combustor particles are low in concentration, similar in concentration to ambient particles. The interpretation of the particulate carbon emissions is complicated by the fact that an approximately equal amount of particulate carbon (mainly organic carbon) is found on the particle collector and a backup filter. It is likely that measurement artifacts, mostly adsorption of volatile organic compounds on quartz filters, are positively biasing "true" particulate carbon emission results.     

A schematic sampling protocol for contaminant monitoring in raptors

Birds of prey, owls and falcons are widely used as sentinel species in raptor biomonitoring programmes. A major current challenge is to facilitate large-scale biomonitoring by coordinating contaminant monitoring activities and by building capacity across countries. This requires sharing, dissemination and adoption of best practices addressed by the Networking Programme Research and Monitoring for and with Raptors in Europe (EURAPMON) and now being advanced by the ongoing international COST Action European Raptor Biomonitoring Facility. The present perspective introduces a schematic sampling protocol for contaminant monitoring in raptors. We provide guidance on sample collection with a view to increasing sampling capacity across countries, ensuring appropriate quality of samples and facilitating harmonization of procedures to maximize the reliability, comparability and interoperability of data. The here presented protocol can be used by professionals and volunteers as a standard guide to ensure harmonised sampling methods for contaminant monitoring in raptors.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01341-9) contains supplementary material, which is available to authorized users.     

Distribution and partitioning of depleted uranium (DU) in soils at weapons test ranges - investigations combining the BCR extraction scheme and isotopic analysis

Depleted uranium (DU) has become a soil contaminant of considerable concern in many combat zones and weapons-testing sites around the world, including locations in Europe, the Middle East and the USA, arising from its dispersion via the application of DU-bearing munitions. Once DU is released into the environment its mobility and bioavailability will, like that of other contaminants, largely depend on the type of associations it forms in soil and on the nature of the soil components to which it binds. In this study we used the BCR sequential extraction scheme to determine the partitioning of DU amongst soil fractions of texturally varying soils from locations affected by weapons-testing activities. Isotopic analyses (MC-ICP-MS and alpha-spectrometry) were performed to verify the presence of DU in whole soils and soil fractions and to determine any preferential partitioning of the contaminant. Results identified soil organic matter as being consistently the most important component in terms of DU retention, accounting for 30-100% of DU observed in the soils examined. However, at greater distances from known contamination points, DU was also found to be largely associated with the exchangeable fraction, suggesting that DU can be mobilised and transported by surface and near-surface water and does remain in an exchangeable (and thus potentially bioavailable) form in soils.     

Evaluation of solid particle number and black carbon for very low particulate matter emissions standards in light-duty vehicles

To reliably measure at the low particulate matter (PM) levels needed to meet California’s Low Emission Vehicle (LEV III) 3- and 1-mg/mile particulate matter (PM) standards, various approaches other than gravimetric measurement have been suggested for testing purposes. In this work, a feasibility study of solid particle number (SPN, d50 = 23 nm) and black carbon (BC) as alternatives to gravimetric PM mass was conducted, based on the relationship of these two metrics to gravimetric PM mass, as well as the variability of each of these metrics. More than 150 Federal Test Procedure (FTP-75) or Supplemental Federal Test Procedure (US06) tests were conducted on 46 light-duty vehicles, including port-fuel-injected and direct-injected gasoline vehicles, as well as several light-duty diesel vehicles equipped with diesel particle filters (LDD/DPF). For FTP tests, emission variability of gravimetric PM mass was found to be slightly less than that of either SPN or BC, whereas the opposite was observed for US06 tests. Emission variability of PM mass for LDD/DPF was higher than that of both SPN and BC, primarily because of higher PM mass measurement uncertainties (background and precision) near or below 0.1 mg/mile. While strong correlations were observed from both SPN and BC to PM mass, the slopes are dependent on engine technologies and driving cycles, and the proportionality between the metrics can vary over the course of the test. Replacement of the LEV III PM mass emission standard with one other measurement metric may imperil the effectiveness of emission reduction, as a correlation-based relationship may evolve over future technologies for meeting stringent greenhouse standards.

Implications: Solid particle number and black carbon were suggested in place of PM mass for the California LEV III 1-mg/mile FTP standard. Their equivalence, proportionality, and emission variability in comparison to PM mass, based on a large light-duty vehicle fleet examined, are dependent on engine technologies and driving cycles. Such empirical derived correlations exhibit the limitation of using these metrics for enforcement and certification standards as vehicle combustion and after-treatment technologies advance.     

A model for interprovincial air pollution control based on futures prices

Based on the current status of research on tradable emission rights futures, this paper introduces basic market-related assumptions for China’s interprovincial air pollution control problem. The authors construct an interprovincial air pollution control model based on futures prices: the model calculated the spot price of emission rights using a classic futures pricing formula, and determined the identities of buyers and sellers for various provinces according to a partitioning criterion, thereby revealing five trading markets. To ensure interprovincial cooperation, a rational allocation result for the benefits from this model was achieved using the Shapley value method to construct an optimal reduction program and to determine the optimal annual decisions for each province. Finally, the Beijing–Tianjin–Hebei region was used as a case study, as this region has recently experienced serious pollution. It was found that the model reduced the overall cost of reducing SO₂ pollution. Moreover, each province can lower its cost for air pollution reduction, resulting in a win–win solution. Adopting the model would therefore enhance regional cooperation and promote the control of China’s air pollution.

Implications: The authors construct an interprovincial air pollution control model based on futures prices. The Shapley value method is used to rationally allocate the cooperation benefit. Interprovincial pollution control reduces the overall reduction cost of SO₂. Each province can lower its cost for air pollution reduction by cooperation.