ALBERT

Description: Peatlands store and emit large amounts of greenhouse gases. With the climate changing due to global warming, measuring these emissions helps to get a better understanding of the role of peatlands in the global carbon cycle. Measurements at a bog site of the Siikaneva peatland show that the emissions vary along the different microtopographies shaped by their vegetation and ground water level. To upscale these measurements, a supervised classification of the study area was implemented in this study by testing a method that uses high-resolution multispectral aerial imagery, captured by a UAV (Uncrewed Aerial Vehicle), and a Random Forest classifier. A cohesive orthomosaic of the study area was produced, training data were generated to adjust the Random Forest model, and the study area was classified. The results show that the applied methods were successful in generating a multispectral orthomosaic as well as a classified raster of the study area. A mean classification accuracy of 75.7 % was achieved, which can be considered as a good result. Misclassification rates of neighboring microtopographies with similar vegetation could be mitigated by utilizing a LiDAR (Light Detection and Ranging) sensor in further studies.

Description: The oxidation of hydrocarbons, including methane, is part of interrelated hydrogeochemical reactions affecting the carbon budget in Earth’s crust. To investigate these processes in deep siliciclastic strata, we analyzed core samples from Lower Triassic red beds in the Mahu Sag (Junggar Basin, northwest China) by coupling petrological observations with high-resolution in situ secondary ion mass spectroscopy stable carbon and oxygen isotope analyses and clumped isotopes (Δ47) of authigenic calcite. The strata contain variable oil and gas content as well as abundant high-valence Fe and/or Mn oxides. Three sequential generations of cement occur, which are characterized as (1) non-luminescent, early diagenetic calcite (MnO 〈0.3%, δ13CVPDB [Vienna Peedee belemnite] = −5.6‰ to −4.1‰); (2) bright-orange luminescent late-stage I calcite (0.75%−5.23% MnO, δ13C = −51.4‰ to −25.8‰); and (3) dull-orange late-stage II calcite (4.10%−12.93% MnO, δ13C = −91.4‰ to −30.9‰). Clumped isotopic thermometry reveals that the calcite precipitation temperature increases successively from 〈40 °C, to 81−107 °C, to finally 107−132 °C, corresponding to three precipitation time periods: before the Late Triassic, from the Early Jurassic to the Early Cretaceous, and from the Early Cretaceous to the present, respectively. δ13C values of −55.7‰ to −25.8‰ indicate that late-stage I calcite is the final product of oxidation of both methane and C2+ hydrocarbons, whereas δ13C values as low as −91‰ indicate that late-stage II calcite is mainly derived from the thermochemical oxidation of methane (δ13C = −46.8‰ to −39.3‰) induced by high-valence Mn and/or Fe oxides. For late-stage I calcite, hydrocarbon oxidation was most likely promoted by high temperatures, although microbial oxidation cannot be completely ruled out. The higher precipitation temperature of late-stage II calcite demonstrates that the oxidation of methane requires higher activation energies than oxidation of C2+ hydrocarbons. We provide reliable geochemical evidence for thermally induced sequential oxidation of hydrocarbons within deep siliciclastic strata.

Description: Understanding the spatiotemporal dynamics of river water chemistry from its source to sinks is critical for constraining the origin, transformation, and “hotspots” of contaminants in a river basin. To provide new spatiotemporal constraints on river chemistry, dissolved trace element concentrations were measured at 17 targeted locations across the Ramganga River catchment. River water samples were collected across three seasons: pre-monsoon, monsoon, and post-monsoon between 2019 and 2021. To remove the dependency of trace element concentrations on discharge, we used molar ratios, as discharge data on Indian transboundary rivers are not publicly available. The dataset reveals significant spatiotemporal variability in dissolved trace element concentrations of the Ramganga River. Samples collected upstream of Moradabad, a major industrial city in western Uttar Pradesh, are characterized by ~ 1.2–2.5 times higher average concentrations of most of the trace elements except Sc, V, Cr, Rb, and Pb, likely due to intense water–rock interactions in the headwaters. Such kind of enrichment in trace metal concentrations was also observed at sites downstream of large cities and industrial centers. However, such enrichment was not enough to bring a major change in the River Ganga chemistry, as the signals got diluted downstream of the Ramganga-Ganga confluence. The average river water composition of the Ramganga River was comparable to worldwide river water composition, albeit a few sites were characterized by very high concentrations of dissolved trace elements. Finally, we provide an outlook that calls for an assessment of stable non-traditional isotopes that are ideally suited to track the origin and transformation of elements such as Li, Mg, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Sr, Ag, Cd, Sn, Pt, and Hg in Indian rivers.

Description: The southwest monsoon rainfall not only provides water and food security over the Indo-Gangetic Basin, it also plays an important role in reducing atmospheric pollution by removing ambient particles via wet deposition processes. In addition to rainfall, aerosol loading and its removal from ambient air are also governed by other meteorological parameters, such as the temperature, humidity, wind speed, and wind direction. To understand the effect of southwest monsoon withdrawal on aerosol loading over the Indo-Gangetic Basin, airborne particles (PM10 size fraction) and meteorological parameters, including the temperature, humidity, rainfall, wind speed, and wind direction data were collected between July and October 2015 at Kanpur, India, which is a large industrial city in the central part of the Indo-Gangetic Basin. The study shows that withdrawal of the southwest monsoon since July 2015 increased the aerosol loading in the ambient air by up to 28, 43 and 152% during August, September, and October, respectively. The aerosol loading exceeded the ambient Indian National Air Quality Standard limit of 100 μg/m–3 just within 3 months. In addition to increased aerosol mass loading, the concentration of heavy metals (Cr, Ni, Cu, and Cd) in the aerosols also increased with monsoon withdrawal. The only heavy metal that did not show an increasing trend was Pb, which indicates that Pb is either coming from local source(s) or that Pb was not efficiently scavenged by wet deposition processes. In general, Cd, Pb, and Cu concentrations were 10–1500 times higher when compared to the upper continental crust and were mostly derived from coal-burning products. The study shows that southwest monsoon strongly influence the physiochemical properties of aerosols over the Indo-Gangetic Basin.

Description: latinum group element (PGE) is among the emerging airborne contaminants mainly emitting from automobile catalysts. The ambient PGE concentration in Asia is expected to rise due to an increase in vehicle sales over the last two decades. Of all the Asian countries, the automobile industry in India has grown at a spectacular rate (〉 50% in the last 10 years) and is expected to become a hotspot of global PGE contamination. However, the Indian subcontinent can be regarded as a “white spot” on the global PGE contamination map, indicating the presence of very limited field data. Here, we report the annual time-series record of PGE concentrations of the airborne particulate matter 〈10-micron-sized (PM10) collected from a high-altitude remote site in the central Himalaya that draws a significant fraction of air mass from the heavily polluted Indo-Gangetic Plain (IGP). The time-series record reveals that the PGE concentrations in PM10 are amongst the lowest recorded levels globally, lack seasonal variability, and are derived from aged catalyst and coal combustion products. We conclude that the annual average Pt, Pd, Rh, and Ru concentrations of 0.88 ± 0.57, 2.07 ± 1.75, 0.14 ± 0.1, and 0.16 ± 0.08 pg m−3, respectively, would serve as a baseline concentration in PM10 to judge the future magnitude of PGE contamination in the Indian subcontinent.

Description: he Indo-Gangetic Plain (IGP) is one of the most highly polluted regions of the world, yet the temporal pattern of transport of anthropogenic aerosols from this region to the Himalayas is poorly constrained. On the basis of the seasonal variation of planetary boundary layer heights, air mass back trajectory analysis, and year-long time-series data for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb, and 143Nd/144Nd from aerosols collected over a high-altitude station, we demonstrate that anthropogenic Pb transport to the glacierized catchment has a seasonal pattern. The Pb isotope data reveal that during winter, the thinned boundary layer traps up to 10 ± 7% more coal-derived Pb in the IGP. In contrast, in nonwinter months, a thicker boundary layer and enhanced subtropical westerly winds result in efficient Pb transport to the Himalayas. As Pb isotope ratios are robust conservative chemical tracers and Pb is predominantly derived from anthropogenic sources, these observations suggest that enhanced transport of anthropogenic aerosols to the glacierized catchment of the Himalayas coincides with higher near-surface temperatures in the summer, creating positive feedback that enhances melting. Our results further suggest that 〉50% of Pb in the Himalayan aerosols originates from the resuspension of historic Pb derived from phased out leaded gasoline, highlighting the importance of legacy Pb stored in the Indo-Gangetic Plains.