Marine Submicron Aerosols from the Gulf of Mexico: Polluted and Acidic with Rapid Production of Sulfate and Organosulfates.

We measured submicron aerosols (PM1) at a beachfront site in Texas in Spring 2021 to characterize the "background" aerosol chemical composition advecting into Texas and the factors controlling this composition. Observations show that marine "background" aerosols from the Gulf of Mexico were highly processed and acidic; sulfate was the most abundant component (on average 57% of total PM1 mass), followed by organic material (26%). These chemical characteristics are similar to those observed at other marine locations globally. However, Gulf "background" aerosols were much more polluted; the average non-refractory (NR-) PM1 mass concentration was 3-70 times higher than that observed in other clean marine atmospheres. Anthropogenic shipping emissions over the Gulf of Mexico explain 78.3% of the total measured "background" sulfate in the Gulf air. We frequently observed haze pollution in the air mass from the Gulf, with significantly elevated concentrations of sulfate, organosulfates, and secondary organic aerosol associated with sulfuric acid. Analysis suggests that aqueous oxidation of shipping emissions over the Gulf of Mexico by peroxides in the particles might potentially be an important pathway for the rapid production of acidic sulfate and organosulfates during the haze episodes under acidic conditions.

Targeting Atmospheric Oxidants Can Better Reduce Sulfate Aerosol in China: H2O2 Aqueous Oxidation Pathway Dominates Sulfate Formation in Haze.

Particulate sulfate is one of the most important components in the atmosphere. The observation of rapid sulfate aerosol production during haze events provoked scientific interest in the multiphase oxidation of SO2 in aqueous aerosol particles. Diverse oxidation pathways can be enhanced or suppressed under different aerosol acidity levels and high ionic strength conditions of atmospheric aerosol. The importance of ionic strength to sulfate multiphase chemistry has been verified under laboratory conditions, though studies in the actual atmosphere are still limited. By utilizing online observations and developing an improved solute strength-dependent chemical thermodynamics and kinetics model (EF-T&K model, EF is the enhancement factor that represents the effect of ionic strength on an aerosol aqueous-phase reaction), we provided quantitative evidence that the H2O2 pathway was enhanced nearly 100 times and dominated sulfate formation for entire years (66%) in Tianjin (a northern city in China). TMI (oxygen catalyzed by transition-metal ions) (14%) and NO2 (14%) pathways got the second-highest contributions. Machine learning supported the result that aerosol sulfate production was more affected by the H2O2 pathway. The collaborative effects of atmospheric oxidants and SO2 on sulfate aerosol production were further investigated using the improved EF-T&K model. Our findings highlight the effectiveness of adopting target oxidant control as a new direction for sustainable mitigation of sulfate, given the already low SO2 concentrations in China.

A top-down approach of sources and non-photosynthetic sinks of carbonyl sulfide from atmospheric measurements over multiple years in the Paris region (France).

Carbonyl sulfide (COS) has been proposed as a proxy for carbon dioxide (CO2) taken up by plants at the leaf and ecosystem scales. However, several additional production and removal processes have been identified which could complicate its use at larger scales, among which are soil uptake, dark uptake by plants, and soil and anthropogenic emissions. This study evaluates the significance of these processes at the regional scale through a top-down approach based on atmospheric COS measurements at Gif-sur-Yvette (GIF), a suburban site near Paris (France). Over a period of four and a half years, hourly measurements at 7 m above ground level were performed by gas chromatography and combined with 222Radon measurements to calculate nocturnal COS fluxes using the Radon-Tracer Method. In addition, the vertical distribution of COS was investigated at a second site, 2 km away from GIF, where a fast gas analyzer deployed on a 100 m tower for several months during winter 2015-2016 recorded mixing ratios at 3 heights (15, 60 and 100 m). COS appears to be homogeneously distributed both horizontally and vertically in the sampling area. The main finding is that the area is a persistent COS sink even during wintertime episodes of strong pollution. Nighttime net uptake rates ranged from -1.5 to -32.8 pmol m-2 s-1, with an average of -7.3 ± 4.5 pmol m-2 s-1 (n = 253). However, episodes of biogenic emissions happened each year in June-July (11.9 ± 6.2 pmol m-2 s-1, n = 24). Preliminary analyses of simulated footprints of source areas influencing the recorded COS data suggest that long-range transport of COS from anthropogenic sources located in Benelux, Eastern France and Germany occasionally impacts the Paris area during wintertime. These production and removal processes may limit the use of COS to assess regional-scale CO2 uptake in Europe by plants through inverse modeling.

Air Pollution in Kazakhstan and Its Health Risk Assessment.

Background: Air pollution in Kazakhstan is caused by many factors and poses serious threats to public health. Ambient air in the cities of Kazakhstan is polluted due to mining and processing of mineral resources, oil and gas production, gasoline and diesel fuel motor vehicles, industrial enterprises. Objective: The study aim is to assess the air pollution degree in most significant settlements of Kazakhstan and define risk levels for the population health. Ambient air monitoring was conducted in 26 cities. Air pollution severity was assessed by the analysis results and processing of air samples taken at the stationary observation posts. Health risk assessment due to chemical factors was calculated according to the approved risk assessment methodology. Findings: There is high risk of acute adverse effects risk from suspended particles, oxides and dioxides of nitrogen and sulfur in almost all of the studied cities. The most unfavorable situation is in Ust-Kamenogorsk. Also, there is the adverse chronic effects risk caused by suspended particles exposure in majority of the studied cities. Extremely high chronic effects risk as a result of heavy metals exposure was detected in Ust-Kamenogorsk, Shymkent, Almaty, Taraz and Balkhash. Unacceptable carcinogenic risk levels have been determined for professional groups and the whole population with respect to cadmium in Shymkent, Almaty, Balkhash; arsenic in Shymkent, Almaty, Balkhash; lead in Taraz; chromium - in Shymkent, Aktobe, Almaty and Balkhash. Thus, the values of the hazard quotients and indices for acute and chronic exposure in most of the studied cities of Kazakhstan exceed the permissible level equal to 1.0. Conclusion: Due to the unacceptable risk levels in the cities it is strongly recommended to conduct a detailed study of the health status of the population depending on the air pollution.

Impact of emission control areas on atmospheric pollutant emissions from major ocean-going ships entering the Shanghai Port, China.

Ocean-going ships are mostly driven by high­sulfur heavy fuel oil, which poses public health and environmental concerns. Emission control areas (ECA) have been developed for the regulatory control of the sulfur content in fuel. We tracked 28 sample vessels that entered and exited Shanghai Port, to understand how air pollutants, including oxysulfides (SOx), nitric oxide (NOx), and particulate matter smaller than 10 µm (PM10), would change under the ECA regulations. Emission reductions vary with the types and sizes of the ships. In our sample pool, oil/chemical tankers and container ships have the highest decline rates of SOx emissions at 26.8%-56.4% and 17.4%-56.6%, respectively. Cruise ships, container ships, and liquefied gas carriers occupy the highest share ratios of pollutant emissions in the sample pool because of the higher average gross tonnage and correspondingly higher-rated power of the ships' main engines. As expected, SOx and PM10 emissions under hoteling conditions (operations while stationary at dock) can be considerably reduced by switching to low-sulfur fuel. Using fuel with the much lower sulfur content of 0.1% m/m in the ECA, the SOx and PM10 emissions of our sample pool could be reduced considerably by up to 94.4% and 78.3%, respectively, compared to the 0.5% m/m sulfur content used during ship hoteling.

Research on sulfur oxides and nitric oxides released from coal-fired flue gas and vehicle exhaust: a bibliometric analysis.

A bibliometric method was used to evaluate the global scientific publications about sulfur oxides and nitric oxides released by coal-fired flue gas and vehicle exhaust from 1995 to 2018 and to provide insights into the characteristics of the articles and tendencies that may exist in the publications. Performance of publications, research tendency, and hotspots were analyzed. The article number had an explosive growth in 2004 and, then, began to grow steadily. China had an absolutely advantage in publication quantities; however, America had a leading position considering publication cited times. The simultaneous removal of mercury, particulate matter, and CO2 was a research hotpot in sulfur oxide and nitric oxide control process; oxidation, absorption, and catalytic reduction were the central control methods that had the most strength in relation with sulfur dioxide and nitric oxide. Considering the study of traditional flue gas pollutant control method (limestone-gypsum method, selective catalytic reduction, etc.) was perfection, it was speculated that adsorption by ionic liquid, electricity charging, advanced oxidation progress, and multi-pollutant removal, simultaneously, would be the new research orientation in flue gas pollutant control. One of the hot points of controlling the vehicle exhaust was the application of the "green energy" biodiesel; lots of keywords concerning human health suggested that quite a lot studies were focused on the health hazard brought by sulfur oxides and nitric oxide.

Carbonyl sulfide (COS) and carbon disulfide (CS2) exchange fluxes between cotton fields and the atmosphere in the arid area in Xinjiang, China.

Due to the important roles of carbonyl sulfide (COS) and carbon disulfide (CS2) in atmospheric chemistry, this study was designed to determine different proportions of COS and CS2 fluxes contributed from different sources, i.e., vegetation, soil and roots, at monthly and hourly timescales in the arid area in Xinjiang, China. Results indicated that the seasonal net uptake of COS by vegetation was predominant in the growing season. The CS2 fluxes from vegetation and soils had no significant seasonal variations compared with COS. The exchange rates of COS and CS2 have been found to be stimulated by the addition of nutrients in the form of urea fertilizer. Compared with the results of plots that were treated only with nitrogen, the treatments with both nitrogen and sulfur displayed no significant difference in the exchange fluxes. The results of compartment experiments indicated that the aboveground plants had the highest uptake of COS and had a vital role in the uptake of COS during the main growth period. The shares of COS emissions from the soil and roots increased to 6-17% and 55-58%, respectively, in the total COS fluxes when conditions, such as drought and senescence, were unfavorable for the developmental of vegetation. Observations of the preliminary diurnal fluxes indicated that the fluxes that occurred at night, with contributions from soils and plants, accounted for 27% of the total daily uptake of COS uptake. These quantitative results may be reasonably accounted for the use of COS as a promising tracer to obtain independent constraints on terrestrial carbon exchange at regional to global scales for their response to special environmental conditions in semiarid area.

Emission inventory of carbonyl sulfide (COS) from primary anthropogenic sources in China.

An emission inventory of carbonyl sulfide (COS) from primary anthropogenic sources in China was compiled from 2010 to 2015. The national total emission was estimated at 174 Gg S yr-1 in 2015, with an annually average sustainable growth rate of 7.2% from 2010 to 2015. Industrial sources, biomass burning, coal combustion, agricultural sources and vehicle exhaust contributed 68.2%, 22.0%, 6.1%, 2.2%, and 1.5%, respectively, of total COS emissions in 2015. Aluminum production, carbon black production, titania production, coke production, pulp and paper industry, were the main industrial sources of COS, with the emission about 118 Gg S yr-1 COS in 2015, accounting for 98.5% of total direct emissions from the Chinese industry. The distribution of COS emissions in China showed significant differences at the provincial level. In Shandong and Xinjiang province, they were much bigger than other provinces, with total emissions of 31 and 15 Gg S yr-1, respectively. Uncertainty analysis of COS emission inventories showed that the emission range was 70-267 Gg S yr-1 at a 95% confidence interval. In this study, COS emissions in China were much higher than prior underestimated estimations, even for Asian and global emissions, which could be resolved part of missing sources in the global COS budget.

Physical, chemical and biological behaviour of fumigants on cottonseed.

Fumigation is required to protect cottonseed in storage and pre-shipment from insect pests and/or microorganisms. Fumigation of cottonseed with carbon disulphide (CS2), carbonyl sulphide (COS), ethanedinitrile (C2N2), ethyl formate (EF), methyl bromide (MB) and phosphine (PH3) showed that >85% of the fumigants disappeared within 5 h of exposure. COS maintained >20 mg L-1 for 24 h. After 1 day of aeration, 75%-85% of the absorbed COS and MB and 20%-40% of the absorbed CS2, EF and PH3 were released from treated cottonseed. The fumigant residues were reduced by 80% for COS, 50% for EF or MB and 25% for CS2 after 1 day of aeration. After 13 days of aeration, fumigant residues were reduced by 95% for MB, 65% for EF, 55% for CS2 and to natural levels in the COS residue. Carbon disulphide, COS, PH3, EF and C2N2 had no effect on the germination of cottonseed, but germination was reduced to 50% by MB. COS has potential as a fumigant for control of insect pests in cottonseed because it dissipates quickly and does not negatively impact germination. On the other hand, MB appears to strongly absorb and requires an extended period for residues to dissipate, and it negatively impacts germination.

Recent spatial gradients and time trends in Dhaka, Bangladesh, air pollution and their human health implications.

Dhaka, the capital of Bangladesh, is among the most polluted cities in the world. This research evaluates seasonal patterns, day-of-week patterns, spatial gradients, and trends in PM2.5 (<2.5 µm in aerodynamic diameter), PM10 (<10 µm in aerodynamic diameter), and gaseous pollutants concentrations (SO2, NO2, CO, and O3) monitored in Dhaka from 2013 to 2017. It expands on past work by considering multiple monitoring sites and air pollutants. Except for ozone, the average concentrations of these pollutants showed strong seasonal variation, with maximum during winter and minimum during monsoon, with the pollution concentration of PM2.5 and PM10 being roughly five- to sixfold higher during winter versus monsoon. Our comparisons of the pollutant concentrations with Bangladesh NAAQS and U.S. NAAQS limits analysis indicate particulate matter (PM2.5 and PM10) as the air pollutants of greatest concern, as they frequently exceeded the Bangladesh NAAQS and U.S. NAAQS, especially during nonmonsoon time. In contrast, gaseous pollutants reported far fewer exceedances throughout the study period. During the study period, the highest number of exceedances of NAAQS limits in Dhaka City (Darus-Salam site) were found for PM2.5 (72% of total study days), followed by PM10 (40% of total study days), O3 (1.7% of total study days), SO2 (0.38% of total study days), and CO (0.25% of total study days). The trend analyses results showed statistically significant positive slopes over time for SO2 (5.6 ppb yr-1, 95% confidence interval [CI]: 0.7, 10.5) and CO (0.32 ppm yr-1, 95% CI: 0.01, 0.56), which suggest increase in brick kilns operation and high-sulfur diesel use. Though statistically nonsignificant annual decreasing slopes for PM2.5 (-4.6 µg/m3 yr-1, 95% CI: -12.7, 3.6) and PM10 (-2.7 µg/m3 yr-1, 95% CI: -7.9, 2.5) were observed during this study period, the PM2.5 concentration is still too high (~ 82.0 µg/m3) and can cause severe impact on human health. Implications: This study revealed key insights into air quality challenges across Dhaka, Bangladesh, indicating particulate matter (PM) as Dhaka's most serious air pollutant threat to human health. The results of these analyses indicate that there is a need for immediate further investigations, and action based on those investigations, including the conduct local epidemiological PM exposure-human health effects studies for this city, in order to determine the most public health effective interventions.

Soil exchange rates of COS and CO18O differ with the diversity of microbial communities and their carbonic anhydrase enzymes.

Differentiating the contributions of photosynthesis and respiration to the global carbon cycle is critical for improving predictive climate models. Carbonic anhydrase (CA) activity in leaves is responsible for the largest biosphere-atmosphere trace gas fluxes of carbonyl sulfide (COS) and the oxygen-18 isotopologue of carbon dioxide (CO18O) that both reflect gross photosynthetic rates. However, CA activity also occurs in soils and will be a source of uncertainty in the use of COS and CO18O as carbon cycle tracers until process-based constraints are improved. In this study, we measured COS and CO18O exchange rates and estimated the corresponding CA activity in soils from a range of biomes and land use types. Soil CA activity was not uniform for COS and CO2, and patterns of divergence were related to microbial community composition and CA gene expression patterns. In some cases, the same microbial taxa and CA classes catalyzed both COS and CO2 reactions in soil, but in other cases the specificity towards the two substrates differed markedly. CA activity for COS was related to fungal taxa and ß-D-CA expression, whereas CA activity for CO2 was related to algal and bacterial taxa and α-CA expression. This study integrates gas exchange measurements, enzyme activity models, and characterization of soil taxonomic and genetic diversity to build connections between CA activity and the soil microbiome. Importantly, our results identify kinetic parameters to represent soil CA activity during application of COS and CO18O as carbon cycle tracers.

Evaluation of sulfur trioxide detection with online isopropanol absorption method.

Measurement of the SO3 concentration in flue gas is important to estimate the acid dew point and to control corrosion of downstream equipment. SO3 measurement is a difficult question since SO3 is a highly reactive gas, and its concentration is generally two orders of magnitude lower than the SO2 concentration. The SO3 concentration can be measured online by the isopropanol absorption method; however, the reliability of the test results is relatively low. This work aims to find the error sources and to evaluate the extent of influence of each factor on the measurement results. The test results from a SO3 analyzer showed that the measuring errors are mainly caused by the gas-liquid flow ratio, SO2 oxidation, and the side reactions of SO3. The error in the gas sampling rate is generally less than 13%. The isopropanol solution flow rate decreases 3% to 30% due to the volatilization of isopropanol, and accordingly, this will increase the apparent SO3 concentration. The amount of SO2 oxidation is linearly related to the SO2 concentration. The side reactions of SO3 reduce the selectivity of SO42- to nearly 73%. As sampling temperature increases from 180 to 300°C, the selectivity of SO42- decreases from 73% to 50%. The presence of H2O in the sample gas helps to reduce the measurement error by inhibiting the volatilization of the isopropanol and weakening side reactions. A formula was established to modify the displayed value, and the measurement error was reduced from 25%-54% to less than 15%.

Molecular Detection for Unconcentrated Gas With ppm Sensitivity Using 220-to-320-GHz Dual-Frequency-Comb Spectrometer in CMOS.

Millimeter-wave/terahertz rotational spectroscopy of polar gaseous molecules provides a powerful tool for complicated gas mixture analysis. In this paper, a 220-to-320-GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection sensitivity, etc. Our comb spectrometer, based on a high-parallelism architecture, probes gas sample with 20 comb lines simultaneously. It does not only improve the scanning speed by 20, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In the measurements, state-of-the-art total radiated power of 5.2 mW and single sideband noise figure of 14.6-19.5 dB are achieved, which further boost the scanning speed and sensitivity. Finally, spectroscopic measurements for carbonyl sulfide (OCS) and acetonitrile (CH CN) are presented. With a path length of 70 cm and 1 Hz bandwidth, the measured minimum detectable absorption coefficient reaches  cm. For OCS that enables a minimum detectable concentration of 11 ppm. The predicted sensitivity for some other molecules reaches ppm level (e.g., 3 ppm for hydrogen cyanide), or 10 ppt level if gas preconcentration with a typical gain of 10 is used.

A Global Perspective on Sulfur Oxide Controls in Coal-Fired Power Plants and Cardiovascular Disease.

Sulfur oxides (SOx), particularly SO2 emitted by coal-fired power plants, produce long-term risks for cardiovascular disease (CVD). We estimated the relative risks of CVD and ischemic heart disease (IHD) attributable to SOx emission globally. National SOx reduction achieved by emissions control systems was defined as the average SOx reduction percentage weighted by generating capacities of individual plants in a country. We analyzed the relative risk of CVD incidence associated with national SOx reduction for 13,581 coal-fired power-generating units in 79 countries. A 10% decrease in SOx emission was associated with 0.28% (males; 95%CI = -0.39%~0.95%) and 1.69% (females; 95%CI = 0.99%~2.38%) lower CVD risk. The effects on IHD were > 2 times stronger among males than females (2.78%, 95%CI = 1.99%~3.57% vs. 1.18%, 95%CI = 0.19%~2.17%). Further, 1.43% (males) and 8.00% (females) of CVD cases were attributable to suboptimal SOx reduction. Thus, enhancing regulations on SOx emission control represents a target for national and international intervention to prevent CVD.

Pollutants identification of ambient aerosols by two types of aerosol mass spectrometers over southeast coastal area, China.

Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer (AMS) and Single Particle Aerosol Mass Spectrometer (SPAMS) were deployed to identify the aerosol pollutants over Xiamen, representing the coastal urban area. Five obvious processes were classified during the whole observation period. Organics and sulfate were the dominant components in ambient aerosols over Xiamen. Most of the particles were in the size range of 0.2-1.0µm, accounting for over 97% of the total particles measured by both instruments. Organics, as well as sulfate, measured by AMS were in good correlation with measured by SPAMS. However, high concentration of NH4+ was obtained by AMS, while extremely low value of NH4+ was detected by SPAMS. Contrarily, high particle number counts of NO3- and Cl- were given by SPAMS while low concentrations of NO3- and Cl- were measured by AMS. The variations of POA and SOA obtained from SPAMS during event 1 and event 2 were in accordance with the analysis of HOA and OOA given by AMS, suggesting that both of AMS and SPAMS can well identify the organic clusters of aerosol particles. Overestimate or underestimate of the aerosol sources and acidity would be present in some circumstances when the measurement results were used to analyze the aerosol properties, because of the detection loss of some species for both instruments.

A ratiometric fluorogenic probe for the real-time detection of SO32- in aqueous medium: application in a cellulose paper based device and potential to sense SO32- in mitochondria.

A new water soluble and fluorogenic probe (L) that can demonstrate a specific ratiometric detection of a SO2 derivative (SO32-) in 100% aqueous medium and live cells has been designed and synthesized. The detection process can be visualized by the naked eye, as the orange-red fluorescence of L turns into a strong blue fluorescence upon interaction with SO32-. L displayed several beneficial attributes such as detection in complete aqueous medium, extremely fast response time along with high selectivity and sensitivity. The ratiometric sensing was attributed to the selective nucleophilic addition reaction of SO32- with L. The probe was further used to develop a low cost microfluidic sensor device (µPAD). The probe was biocompatible and its potential to sense SO32- in mitochondria was captured in live HeLa cells.

Large historical growth in global terrestrial gross primary production.

Growth in terrestrial gross primary production (GPP)-the amount of carbon dioxide that is 'fixed' into organic material through the photosynthesis of land plants-may provide a negative feedback for climate change. It remains uncertain, however, to what extent biogeochemical processes can suppress global GPP growth. As a consequence, modelling estimates of terrestrial carbon storage, and of feedbacks between the carbon cycle and climate, remain poorly constrained. Here we present a global, measurement-based estimate of GPP growth during the twentieth century that is based on long-term atmospheric carbonyl sulfide (COS) records, derived from ice-core, firn and ambient air samples. We interpret these records using a model that simulates changes in COS concentration according to changes in its sources and sinks-including a large sink that is related to GPP. We find that the observation-based COS record is most consistent with simulations of climate and the carbon cycle that assume large GPP growth during the twentieth century (31% ± 5% growth; mean ± 95% confidence interval). Although this COS analysis does not directly constrain models of future GPP growth, it does provide a global-scale benchmark for historical carbon-cycle simulations.

Persistent sulfate formation from London Fog to Chinese haze.

Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.

Self-Immolative Thiocarbamates Provide Access to Triggered H2S Donors and Analyte Replacement Fluorescent Probes.

Hydrogen sulfide (H2S) is an important biological signaling molecule, and chemical tools for H2S delivery and detection have emerged as important investigative methods. Key challenges in these fields include developing donors that are triggered to release H2S in response to stimuli and developing probes that do not irreversibly consume H2S. Here we report a new strategy for H2S donation based on self-immolation of benzyl thiocarbamates to release carbonyl sulfide, which is rapidly converted to H2S by carbonic anhydrase. We leverage this chemistry to develop easily modifiable donors that can be triggered to release H2S. We also demonstrate that this approach can be coupled with common H2S-sensing motifs to generate scaffolds which, upon reaction with H2S, generate a fluorescence response and also release caged H2S, thus addressing challenges of analyte homeostasis in reaction-based probes.

Micromorphological and ultramicroscopic aspects of buried remains: Time-dependent markers of decomposition and permanence in soil in experimental burial.

A buried body not only determines an environmental response at the deposition site but it is also affected by the soil. The experiment was performed using eleven swine carcasses buried in an open site (Northern Italy). Changes occurring in bone tissue at different post-burial intervals were evaluated observing thin sections of bones through micromorphological and ultramicroscopic (SEM-EDS) techniques. These methods allowed the identification of: (a) magnesium phosphate (Mg3(PO4)2) crystallizations, probably linked to decomposition of bones and soft tissues; (b) significant sulphur levels which seem to be related to hydrogen sulphide (H2S) fixation in bone tissue; (c) metal oxide concentrations in the form of unusual violet-blue colorations, which probably are evidence of the soil's action and penetration in bones, also testified by (d) the presence of mineral grains enclosed in the osseous tissue. The results underline the possibility of identifying both time-dependent markers of decomposition and indicators of permanence in soil in buried bones.