The frequency and severity of drought are expected to increase due to climate change; therefore, drought tolerance of tree species should be considered before planting for maximal survival in the ...field. In this study, we examined the response of drought stress in two of the most popular plantation species: Sargent cherry (Prunus sargentii) and Japanese larch (Larix kaempferi) based on the morphological and physiological characteristics. These plantation species are widely planted in central and northern Asia, especially in Japan and Korea, and also widely used for plantation purpose in northern Europe. Three different irrigation regimes of control (CT; 100% precipitation (P)), light drought (LD; 40% reduction of P), and heavy drought (HD; 80% reduction of P) were applied at the experimental site of Mt. Jiri, the Republic of Korea. For morphological responses, both species experienced a significant decrease in leaf size in drought conditions; however, Sargent cherry and Japanese larch experienced reduced leaf width and length, respectively. On the other hand, leaf mass area (LMA, g cm−2) increased and branch growth decreased in both species under drought conditions. As physiological responses, drought stress significantly decreased maximum photosynthesis rate (Amax) and electron transfer rate (Jmax) for both species, while stomatal conductance (Gs) at Amax significantly decreased only in Sargent cherry. Drought significantly reduced predawn (ΨPD), midday leaf water potential (ΨMD), and transpiration in Sargent cherry but not in Japanese larch. In mid-summer, carbon isotopic composition (δ13C) significantly decreased in Sargent cherry but only showed a reduction tendency in Japanese larch. However, the changes of δ13C were not significant in early summer or mid-fall. In the present study, both species showed isohydric and anisohydric characteristics, but Sargent cherry showed greater anisohydric behavior with a steeper slope (Y = 2.132X) and Japanese larch showed more isohydric behavior with a shallower slope (Y = 1.722X). Our results highlight that both species altered their morphological and physiological responses under drought stress; however, the Japanese larch showed greater resistance and resilience in morphological and physiological responses, and in plant-water relations. Therefore, Japanese larch would be more beneficial for plantations in water deficit regions than Sargent cherry.
Species-specific responses of plant intrinsic water-use efficiency (iWUE) to multiple environmental drivers associated with climate change, including soil moisture (θ), vapor pressure deficit (D), ...and atmospheric CO2 concentration (c
a), are poorly understood.
We assessed how the iWUE and growth of several species of deciduous trees that span a gradient of isohydric to anisohydric water-use strategies respond to key environmental drivers (θ, D and c
a). iWUE was calculated for individual tree species using leaf-level gas exchange and tree-ring δ13C in wood measurements, and for the whole forest using the eddy covariance method.
The iWUE of the isohydric species was generally more sensitive to environmental change than the anisohydric species was, and increased significantly with rising D during the periods of water stress. At longer timescales, the influence of c
a was pronounced for isohydric tulip poplar but not for others.
Trees’ physiological responses to changing environmental drivers can be interpreted differently depending on the observational scale. Care should be also taken in interpreting observed or modeled trends in iWUE that do not explicitly account for the influence of D.
•The soil δ13C showed a moderate spatial heterogeneity in an alpine-gorge region.•The GWR model was a useful tool for mapping the isoscapes of soil δ13C.•Soil C/N and NDVI were the main factors ...influencing the spatial variation of soil δ13C.
Soil stable carbon isotope (soil δ13C) can reflect soil carbon metabolic processes and record environmental and vegetation change information, so mapping the spatial distribution of soil δ13C (isoscapes of soil δ13C) can help us better understand the spatial variability of ecosystem carbon cycles. However, efficient approaches for obtaining the isoscapes of soil δ13C remain challenging, especially in mountainous areas with complex terrain. A total of 150 soil samples were collected and their soil δ13C was measured to investigate the spatial variation of soil δ13C in an alpine-gorge region on the eastern Qinghai-Tibetan Plateau which is characterized by complex terrain. Four prediction methods included ordinary kriging interpolation, multiple linear regression, random forest regression, and geographically weighted regression (GWR) were selected and compared to find the best prediction model for mapping the isoscapes of soil δ13C. The pathways of vegetation, topography, soil, and spatial factors influencing the spatial variability of soil δ13C were explored using variance partitioning analysis and structural equation model. The soil δ13C was significantly different among vegetation types, and ranged from −27.155‰ to −9.647‰. The spatial heterogeneity of soil δ13C showed moderate variation, and was dominated by spatial structural factors. The GWR model had higher prediction accuracy in the modeling soil δ13C in comparison to other models. Soil carbon to nitrogen ratio and normalized difference vegetation index were the main factors determining the spatial variability of soil δ13C, and other topographic and soil factors indirectly regulated the spatial distribution of soil δ13C by influencing these two factors. Our results provided a useful tool (GWR model) for mapping the isoscapes of soil δ13C and explored the factors controlling the spatial variability of soil δ13C in the alpine-gorge region on the eastern Qinghai-Tibetan Plateau, which are important for an in-depth understanding of soil carbon cycling in mountain ecosystems.
Oil spill events in the marine environment can have a deleterious impact on the affected ecosystems, such as coral reefs, with direct consequences for their socioeconomic value. The mutualistic ...relationship between tropical corals and their dinoflagellate symbionts (Symbiodiniaceae) provide structural and nutritional basis for a high local biodiversity in oligotrophic waters. Here, we investigated effects of crude oil water-accommodated fraction on the competitive fitness of the model zooxanthellae species Symbiodinium glynnii. Results of laboratory essays demonstrate that crude oil carbon is incorporated into the cellular biomass with a concomitant change of δ13C isotopic value. Carcinogenic/mutagenic polycyclic aromatic hydrocarbons were identified in the culture media and were responsible for a linear reduction in population growth of S. glynnii, presumably related to energy relocation for DNA repair. Additionally, the experiments revealed that physiological effects induced by crude oil compounds are genetically inherited by the following generations under non-contaminated growth conditions, and induce a reduction in the competitive fitness to cope with other environmental parameters, such as low salinity. We suggest that the effects of crude oil contamination represent an imparing factor for S. glynnii coping with anthropogenic drivers (e.g. warming and acidification) and interfere with the delicate symbiont-host relationship of tropical corals. This is especially relevant in the coastal areas of northeastern Brazil where an oil spill event deposited crude oil on shallow water sediments with the potential to be resuspended to the water column by physical and/or biological activity, enhancing the risk of future coral bleaching events.
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•Crude oil exposure reduces population growth rates of Symbiodinium glynnii.•Phenotypic fitness reduction is inherited by the succeeding generations.•Crude oil carbon uptake is reflected in the cellular δ13C isotopic signature.•The competitive fitness to cope with other environmental drivers is reduced.
This review aims to update our understanding on molecular distributions of water-soluble dicarboxylic acids and related compounds in atmospheric aerosols with a focus on their geographical ...variability, size distribution, sources and formation pathways. In general, molecular distributions of diacids in aerosols from the continental sites and over the open ocean waters are often characterized by the predominance of oxalic acid (C2) followed by malonic acid (C3) and/or succinic acid (C4), while those sampled over the polar regions often follow the order of C4≥C2 and C3. The most abundant and ubiquitous diacid is oxalic acid, which is principally formed via atmospheric oxidation of its higher homologues of long chain diacids and other pollution-derived organic precursors (e.g., olefins and aromatic hydrocarbons). However, its occurrence in marine aerosols is mainly due to the transport from continental outflows (e.g., East Asian outflow during winter/spring to the North Pacific) and/or governed by photochemical/aqueous phase oxidation of biogenic unsaturated fatty acids (e.g., oleic acid) and isoprene emitted from the productive open ocean waters. The long-range atmospheric transport of pollutants from mid latitudes to the Arctic in dark winter facilitates to accumulate the reactants prior to their intense photochemical oxidation during springtime polar sunrise. Furthermore, the relative abundances of C2 in total diacid mass showed similar temporal trends with downward solar irradiation and ambient temperatures, suggesting the significance of atmospheric photochemical oxidation processing. Compound-specific isotopic analyses of oxalic acid showed the highest δ13C among diacids whereas azelaic acid showed the lowest value, corroborating the significance of atmospheric aging of oxalic acid. On the other hand, other diacids gave intermediate values between these two diacids, suggesting that aging of oxalic acid is associated with 13C enrichment.
Hollow-core antiresonant fiber can simultaneously act as a miniature gas cell and the light guidance with broad wavelength range, introducing an powerful tool to photothermal spectrosocpy and ...sensitive gas detection. Photothermal interferometry (PTI) is a spectroscopic tehcnique that employs an interferometer to finely measure the photothermal signal of trace gas. By splicing the HC-ARF between solid core fibers, a Fabry-Pérot (F-P) cavity is formed and enables PTI with a brief in-line design. However, the previous structure commonly adopted single-mode solid core fibers and might introduce large optical loss due to mode field mismatch, particularly for MIR pump laser. This could lead to significant decrease in sensitivity. Besides, the gas pressure effect on the HC-ARF-based PTI gas sensor had not been fully studied. In this work, we demonstrated the PTI for 13CO2 detection at 4.35 µm by employing an HC-ARF with a 100-µm core. An InF3 multimode fiber was utilized for the efficient delivery of MIR pump beam and successfully enhanced the pump power by a factor of 6.7. The limit of detection was determined to be 0.4 ppb at the integration time of 240 s. Finally, the relationship between gas pressure and photothermal signal was experimentally studied and compared with theoretical results.
•A Fabry-Pérot cavity was formed by splicing the HC-ARF between two solid core fibers.•An InF3 multimode fiber enhanced the MIR pump beam delivery, boosting the power in HC-ARF by a factor of 6.7.•The limit of detection for 13CO2 gas was 0.4 ppb at the integration time of 240 s.•Gas pressure affacted photothermal signals through thermal diffusivity and gas refractive index.
Mangrove ecosystems are an important natural carbon sink that accumulate and store large amounts of organic carbon (Corg), in particular in the sediment. However, the magnitude of carbon stocks and ...the rate of carbon accumulation (CAR) vary geographically due to a large variation of local factors. In order to better understand the blue carbon sink of mangrove ecosystems, we measured organic carbon stocks, sources and accumulation rates in three Indonesian mangrove ecosystems with different environmental settings and conditions; (i) a degraded estuarine mangrove forest in the Segara Anakan Lagoon (SAL), Central Java, (ii) an undegraded estuarine mangrove forest in Berau region, East Kalimantan, and (iii) a pristine marine mangrove forest on Kongsi Island, Thousand Islands, Jakarta. In general, Corg stocks were higher in estuarine than in marine mangroves, although a large variation was observed among the estuarine mangroves. The mean total Corg stock in Berau (615 ± 181 Mg C ha−1) is twice as high as that in SAL (298 ± 181 Mg C ha−1). However, the Segara Anakan Lagoon displayed large within-system variation with a much higher Corg stock in the eastern (483 ± 124 Mg C ha−1) than in the central lagoon (167 ± 36 Mg C ha−1). The predominant accumulation of autochthonous mangrove organic matter likely contributed to the higher Corg stocks in Berau and the eastern SAL. Interestingly, the CAR distribution pattern in SAL is opposite to that of its Corg stocks. The central SAL that receives high sediment inputs from the hinterland has a much higher CAR than the eastern SAL (658 ± 311 g C m−2 yr−1 and 194 ± 46 g C m−2 yr−1, respectively), while Berau has one of the highest CAR (1722 ± 183 g C m−2 yr−1) ever measured. It appears that these large differences are driven by the environmental setting and conditions, mainly sediment dynamics and hydrodynamics, landform, and vegetation conditions. It is inferred that quantifying carbon accumulation in sediments is a useful tool in estimating the present-day carbon storage of mangrove ecosystems. This is a precondition for taking measures under REDD+ (Reducing Emissions from Deforestation and Forest Degradation and the role of conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries) schemes.
In order to fully understand the carbon emission from different fuels in rural villages of China, especially in the typical atmospheric pollution areas. The characteristics of carbonaceous aerosols ...and carbon dioxide (CO2) with its stable carbon isotope (δ13C) were investigated in six households, which two households used coal, two households used wood as well as two households used biogas and liquefied petroleum gas (LPG), from two rural villages in Fenwei Plain from March to April 2021. It showed that the fine particulate matter (PM2.5) emitted from biogas and LPG couldn't be as lower as expected in this area. However, the clean fuels could relatively reduce the emissions of organic carbon (OC) and element carbon (EC) in PM2.5 compare to the solid fuels. The pyrolyzed carbon (OP) accounted more total carbon (TC) in coal than the other fuels use households, indicating that more water-soluble OC existed, and it still had the highest secondary organic carbon (SOC) than the other fuels. Meantime, the coal combustions in the two villages had the highest CO2 concentration of 527.6 ppm and 1120.6 ppm, respectively, while the clean fuels could effectively reduce it. The average δ13C values (−26.9‰) was much lighter than almost all the outdoor monitoring and similar to the δ13C values for coal combustion and vehicle emission, showing that they might be the main contributors of the regional atmospheric aerosol in this area. During the sandstorm, the indoor PM2.5 mass and CO2 were increasing obviously. The indoor cancer risk of PAHs for adults and children were greater than 1 × 10−6, exert a potential carcinogenic risk to human of solid fuels combustion in rural northern China. It is important to continue concern the solid fuel combustion and its health impact in rural areas.
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•Biogas and liquefied petroleum gas (LPG) emitted high PM2.5 as unexpected.•Biogas and LPG emitted lower PM2.5 bounded PAHs and CO2.•The CO2 produced by coal burning was greater than other fuels, with lighter δ13C.•Sandstorm could aggravate the accumulation of indoor atmospheric CO2.•Solid fuel users might face more serious cancer risks than biogas and LPG.
Isotopic analysis of specific compounds in aerosols can be a useful tool when studying atmospheric processes. Here, we present the results of stable carbon isotope ratio (δ13C) measurements performed ...on a one-year set (n = 96, Sep. 2013–Aug. 2014) of dicarboxylic acids and related compounds in PM1 at a rural Central European background site, Košetice (Czech Republic).
The most 13C enriched acid was oxalic (C2, annual average = −16.6 ± 5.0‰) followed by malonic (C3, avg. = −19.9 ± 6.6‰) and succinic (C4, avg. = −21.3 ± 4.6‰) acids. Thus, δ13C values decreased with an increase in carbon numbers. Azelaic acid (C9, avg. = −27.2 ± 3.6‰) was found to be the least 13C enriched.
A comparison of δ13C of dicarboxylic acids from other background sites, especially in Asia, shows similar values to those from the European site. This comparison also showed that C2 is more 13C enriched at background sites than at urban ones. In general, we did not observe significant seasonal differences in δ13C values of dicarboxylic acids at the Central European station. We observed statistically significant differences (p value < 0.05) between winter and summer δ13C values solely for C4, glyoxylic acid (ωC2), glutaric acid (C5) and suberic acid (C8).
The only significant correlations between δ13C of C2 and δ13C of C3 were found in spring and summer, suggesting that the oxidation of C3 to C2 is significant in these months with a strong contribution from biogenic aerosols. The strongest season-independent annual correlation was observed in δ13C values between C2 and C4, the two dominant dicarboxylic acids. Therefore, C4 appears to be the main intermediate precursor of C2 throughout the whole year.
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•Seasonal differences (winter vs. summer) are significant for C4, ωC2, C5 and C8.•Strong correlation was found between δ13C of oxalic and succinic acids.•Correlation between δ13C of C2 and C3 was significant in spring and summer.•δ13C values of dicarboxylic acids are similar to those from Southeast Asia.•Background aerosols provide more 13C enriched C2 compared to urban aerosols.
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