Monthly resolved modelled oceanic emissions of carbonyl sulphide and carbon disulphide for the period 2000–2019

Carbonyl sulphide (OCS) is the most abundant, long-lived sulphur gas in the atmosphere and a major supplier of sulphur to the stratospheric sulphate aerosol layer. The short-lived gas carbon disulphide (CS2) is oxidized to OCS and constitutes a major indirect source to the atmospheric OCS budget. The atmospheric budget of OCS is not well constrained due to a large missing source needed to compensate for substantial evidence that was provided for significantly higher sinks. Oceanic emissions are associated with major uncertainties. Here we provide a first, monthly resolved ocean emission inventory of both gases for the period 2000–2019 (available at https://doi.org/10.5281/zenodo.4297010) (Lennartz et al., 2020a). Emissions are calculated with a numerical box model (2.8∘×2.8∘ resolution at the Equator, T42 grid) for the oceanic surface mixed layer, driven by ERA5 data from ECMWF and chromophoric dissolved organic matter (CDOM) from Aqua MODIS. We find that interannual variability in OCS emissions is smaller than seasonal variability and is mainly driven by variations in CDOM, which influences both photochemical and light-independent production. A comparison with a global database of more than 2500 measurements reveals overall good agreement. Emissions of CS2 constitute a larger sulphur source to the atmosphere than OCS and equally show interannual variability connected to variability in CDOM. The emission estimate of CS2 is associated with higher uncertainties as process understanding of the marine cycling of CS2 is incomplete. We encourage the use of the data provided here as input for atmospheric modelling studies to further assess the atmospheric OCS budget and the role of OCS in climate.

The influence of light on soil community structure and consequences for soil CO2, CO18O and COS exchange

<p>The stable oxygen isotope composition of atmospheric CO<sub>2</sub> and the mixing ratio of carbonyl sulphide (COS) are potential tracers of biospheric CO<sub>2</sub> fluxes at large scales. However, the use of these tracers hinges on our ability to understand and better predict the activity of the enzyme carbonic anhydrase (CA) in different soil microbial groups, including phototrophs. Because different classes of the CA family (α, β and γ) may have different affinities to CO<sub>2</sub> and COS and their expression should also vary between different microbial groups, differences in the community structure could impact the ‘community-integrated’ CA activity differently for CO<sub>2</sub> and COS. Four soils of different pH were incubated in the dark or with a diurnal cycle for forty days to vary the abundance of native phototrophs. Fluxes of CO<sub>2</sub>, CO<sup>18</sup>O and COS were measured to estimate CA activity alongside the abundance of bacteria, fungi and phototroph genes. The abundance of soil phototrophs increased most at higher soil pH. In the light, the strength of the soil CO<sub>2</sub> sink and the CA-driven CO<sub>2</sub>-H<sub>2</sub>O isotopic exchange rates correlated with phototroph abundance. COS uptake rates were attributed to fungi whose abundance was positively enhanced in alkaline soils but only in the presence of increased phototrophs. In addition we developed a metabarcoding approach to reveal the interactions of specific taxonomic groups incuding photosynthetic eukaryotic algae and cyanobacteria when exposed to light and their impact on flux rates. Our findings demonstrate that soil-atmosphere CO<sub>2</sub>, COS and CO<sup>18</sup>O fluxes are strongly regulated by the microbial community structure in response to changes in soil pH and light availability and support the idea that different members of the microbial community express different classes of CA, with different affinities to CO<sub>2</sub> and COS.</p>

Kuantifikasi Kandungan Volatile Organic Compounds (VOC) di Kawasan Desa Sungai Rambe untuk Memprediksi Keberadaan Minyak Bumi

Penelitian ini menggunakan metode Gore Sorber dengan menanamkan alat ke dalam tanah selama 21 hari dan pada hari ke-21 alat tersebut diambil kemudian kandungannya dianalisis dengan menggunakan GC-MS untuk mengetahui jumlah senyawa hidrokarbon yang terkandung dalam minyak bumi. Beberapa senyawa yang terdeteksi dengan metode Gore Sorber diantaranya adalah alfa pinena, dimetil sulfida, karbonil sulfide, dimetil disulfida, butana dana etana. Senyawa tersebut merupakan senyawa yang umum ditemukan pada minyak bumi dengan komposisi alfa pinena 206,34 ng; dimetil sulfida 196,65 ng; dan dimetil disulfida 205,8 ng. Tiga komponen tersebut merupakan komponen minyak bumi hidrokarbon dan non-hidrokarbon. This research uses Gore Sorber method by implanting the tool into the soil for 21 days then taken on day 21 and directly analyzed using GC-MS instrument to know the amount of hydrocarbon compound contained in petroleum. Some of the compounds detected using Gore-Sorber are alpha pinene, dimethyl sulphide, carbonyl sulphide, dimethyl disulfide, butane and ethane. These components are typical of petroleum compounds seen from the highest components of alpha pinene 206.34 ng, dimethyl sulfide 196.65 ng and dimethyl disulfide 205.8 ng. The three components are petroleum components of hydrocarbons and non-hydrocarbons.

Nitrogen Fertilization Reduces the Capacity of Soils to Take up Atmospheric Carbonyl Sulphide

Soils are an important carbonyl sulphide (COS) sink. However, they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to the available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that a one-off addition of ammonium nitrate systematically decreased the COS uptake rate whilst simultaneously increasing the COS production rate of soils from boreal and temperate sites in Europe. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass, and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how the soil–atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.

Nitrogen Fertilization Reduces the Capacity of Soils to take up Atmospheric Carbonyl Sulphide

Soils are an important COS sink. However they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that N fertilisation simultaneously decreases the COS sink strength of soils while increasing the COS production rate. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how soil-atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.

Disentangling the rates of carbonyl sulphide (COS) production and consumption and their dependency with soil properties across biomes and land use types

Soils both emit and consume the trace gas carbonyl sulphide (COS) leading to a soil-air COS exchange rate that is the net result of two opposing fluxes. Partitioning these two gross fluxes and understanding their drivers are necessary to estimate the contribution of soils to the current and future atmospheric budget of COS. Previous efforts to disentangle the gross COS fluxes from soils have used flux measurements on air-dried soils as a proxy for the COS emission rates of moist soils. However, this method implicitly assumes that COS uptake becomes negligible and COS emission remains steady while soils are drying. We tested this assumption by estimating simultaneously the soil COS sources and sinks and their temperature sensitivity (Q10) from soil-air COS flux measurements on fresh soils at different COS concentrations and two soil temperatures. Measurements were performed on 27 European soils from different biomes and land use types in order to obtain a large range of physical-chemical properties and identify the drivers of COS consumption and production rates. We found that COS production rates from moist and air-dried soils were not significantly different for a given soil and that the COS production rates had Q10 values (3.96 ± 3.94) that were larger and more variable than the Q10 for COS consumption (1.17 ± 0.27). COS production generally contributed less to the net flux that was dominated by gross COS consumption but this contribution of COS production increased rapidly at higher temperature, lower soil moisture and lower COS concentrations. Consequently, measurements at higher COS concentrations (viz. 1000 ppt) always increased the robustness of COS consumption estimates. Across the range of biomes and land use types, COS production rates co-varied with total soil nitrogen (r = 0.68, P < 0.05) and the first-order COS uptake rate co-varied most with microbial N content (r = 0.64, P < 0.05) providing new insights on how to upscale the contribution of soils to the global COS atmospheric budget.