Use of response surface methodology to optimise the growth of the aquatic moss Taxiphyllum barbieri (Cardot & Copp.) Z.Iwats.

This paper presents the results of a study on the dynamics in the concentrations of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in water samples collected from the Styr River between 2019 and 2022. The concentrations of DIC and DOC were measured using an Elementar liqui TOC II analyzer. The study methodology involved analyzing the changes in DIC and DOC concentrations and their relationship with flow rates, temperature, seasonality, and other indicators such as hydrogen pH levels, total alkalinity (TA), and total dissolved solids (TDS). The purpose of this article is to identify patterns in the formation and changes of DIC and DOC concentrations in the Styr River. The concentrations of DIC and DOC in the samples ranged from 1.55 to 4.93mM and 0.49 to 1.43mM, respectively, with DOC accounting for an average of 22% of the total dissolved carbon content. The highest DOC concentrations were observed in summer, while the highest DIC concentrations were observed in winter. Based on the results, it can be concluded that water flow and temperature have an impact on DOC concentration, while flow, temperature, and pH affect DIC concentration. There was no correlation between DIC and DOC concentrations, but a strong positive relationship (r = 0.9056, p < 0.001) was found between DIC and TA concentrations. Therefore, the main factors influencing DIC in the Styr River are those that affect the carbonate equilibrium, such as leaching of carbonate and silicate rocks, CO2 absorption from the atmosphere, and changes in pH. Additionally, the concentration of DOC is influenced by biological activity and is higher during the warm season. These findings can be used to develop a strategy for managing water resources in the Styr River basin and to assess and predict the ecological state of the river.

Assessing the temporal evolution of dissolved inorganic carbon in waters exposed to atmospheric CO2(g): A laboratory approach

Seasonal variations of dissolved inorganic carbon and δ13C of surface waters: application of a modified gas evolution technique

Isotopic compositions of δ 13 C DIC , sources and abundance of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC), and their response to hydrologic regimes were examined from Lianjiang River stream in rainy (DIC and DOC) and dry seasons (DOC and POC). Lianjiang River was recharged by groundwater in dry season, the abundance of DIC was higher than DOC. Apart from DIC concentrations in dry season, DIC and DOC concentrations, and δ 13 C DIC showed on spatial variation from upstream to downstream. DIC concentrations in rainy season was higher than those in dry season, while δ 13 C DIC in dry season was higher than those in rainy season because of increasing contributions from karst groundwater. Carbonate-sourced DIC contributed from 37.1% to 47.8% with an average of 42.6% of the riverine DIC in rainy season, and contributed from 44.6% to 54.5% with an average of 49.9% of the riverine DIC in dry season. Similar carbonate-sourced and soil CO 2 sourced DIC to Lianjiang River in dry season also indicates that Lianjiang River was recharged by groundwater in dry season. Total n-alkanes concentrations in POM were higher than those in DOM, and anthropogenic n-alkanes concentrations were higher than those in biogenic n-alkanes concentrations. Algae and floating/submerged aquatic plants were the major biogenic sources POM and DOM, but part sampling sites with DOM source from terrestrial plants, aquatic macrophytes sources. Light petroleum input and incomplete fossil fuel burning at high temperature and heavy oil emission were the major source of DOM and POM in Lianjiang River, but the contribution of incomplete fossil fuel burning or heavy oil emission in POM was higher than those in DOM. The results shed light on the characteristics and dynamics of different carbons in typical karstic river.

Fucus vesiculosus from the northern Baltic Sea (5 psu) and from the Irish Sea (35 psu) were cultivated at different temperatures, salinities and dissolved inorganic carbon (DIC) concentrations with the addition of different nutrient concentrations. The influence of these abiotic factors was assessed by measuring photosynthesis as electron transport rate (ETR) and growth as relative growth rate (RGR). The maximal ETR and the RGR of the Irish Sea plants in their natural seawater (50.8 µmol electrons m−2 s−1; 0.024 g g−1 day−1) were significantly higher than those of the Baltic plants in their natural seawater (21.9 µmol electrons m−2 s−1; 0.007 g g−1 day−1). When Baltic F. vesiculosus was cultivated at a DIC concentration similar to that of the Irish Sea, the ETR as well as RGR increased, but never equalled the rates of the marine F. vesiculosus from the Irish Sea. Cultivation at different salinities showed that F. vesiculosus from the Baltic has a higher ETRmax and RGR at low salinities (5–10 psu) than F. vesiculosus from the Irish Sea, whose ETR and RGR decreased sharply in salinities below 20 psu. Plants from both sites grown at high nutrient concentrations, however, performed better at low salinities than those grown under low nutrient conditions. Salinity had the greatest impact on differences in ETR and RGR between the two populations, followed by differences in DIC and nutrient concentrations. There was a highly significant correlation between ETRmax and RGR in plants from both sites and across the full range of culture conditions, indicating that the same amount of energy from photosynthesis is used for growth in both varieties of the species at different salinities. The photosynthesis of F. vesiculosus in the northern Baltic is close to the minimum demand for growth, which may account for their small size. The temperature optimum for F. vesiculosus from the Baltic was 4–10°C, while that for F. vesiculosus from the Irish Sea was 15–20°C. The photosynthesis of Irish Sea plants was less strongly affected by exposure to high irradiances than that of plants from the Baltic.

A two-step Random Forest algorithm for deriving dissolved inorganic carbon in lakes from Landsat satellite data.

The objective of this study was to determine the dissolved inorganic carbon (DIC) and pCO2 concentrations in two third order streams in southwestern Amazonia, Brazil. From May 2004 to June 2005 water dissolved oxygen, pH, electrical conductivity, temperature were measured to stream water chemical and physical description. DIC and pCO2 measurements were made by headspace extraction and gas samples for pCO2 and DIC extractions were run on an infrared gas analyzer (IRGA, LI-COR Instruments model LI-820). Results indicate a relationship between soil type and water chemistry, where sandy soil stream presented lower pH than silty soil stream – consequently DIC and pCO2 concentrations also varied with soil type. Mean DIC concentration for sitly soil stream was 403±130 ?M month-1, while sandy soil stream DIC concentration was 170±59 ?M month-1. Free CO2 was the dominant form of DIC in both streams. Nevertheless, HCO3- contribuition to DIC was greater for the silty soil stream. DIC contentration also varied seasonally with greater values in the drier period. Absolute pCO2 values were greater for silty soil stream, mean 3067±1228 µatm month-1 and 2321±1020 µatm month-1 for sandy soil stream. Seasonality, pCO2 was higher in the dry season in both streams. Our findings have important implications on the role of soil type in water chemistry and carbon dynamics and also are used in other studies on carbon balance at the landscape level.

The cycling of dissolved inorganic carbon (DIC) and the role of tidal marshes in estuarine DIC dynamics were studied in a Virginia tidal freshwater marsh and adjacent estuary. DIC was measured over diurnal cycles in different seasons in a marsh tidal creek and at the junction of the creek with the adjacent Pamunkey River. In the creek, DIC concentrations around high tide were controlled by the same processes affecting whole‐estuary DIC gradients. Near low tide, DIC concentrations were 1.5–5‐fold enriched relative to high tide concentrations, indicating an input of DIC from the marsh. Similar patterns (although dampened in magnitude) were observed at the creek mouth and indicated that DIC was exported from the marsh. Marsh pore‐water DIC concentrations were up to 5 mmol L−1 greater than those in the creek and suggested a significant input of sediment pore water to the creek. A model of tidal marsh DIC export showed that, on a seasonal basis, DIC export rates were influenced by water temperature. The composition of exported DIC averaged 19% dissolved CO2 and 81% HCO3− and CO32−. Although CO2 can be lost to the atmosphere during transit through the estuary, DIC in the form of carbonate alkalinity is subject to export from the estuary to the coastal ocean. When extrapolated to an estuarywide scale, the export of marsh‐derived DIC to the York River estuary explained a significant portion (47 ± 23%) of excess DIC production (i.e., DIC in excess of that expected from conservative mixing between seawater and freshwater and equilibrium with the atmosphere) in this system. Therefore, CO2 supersaturation, by itself, does not indicate that an estuary is net heterotrophic.

Concentrations and carbon isotope composition of dissolved inorganic carbon (DIC) and isotope composition (δD, δ18O) of waters were studied in the eastern East Siberian Sea, along two submeridional sections extending from the Indigirka and Kolyma mouths to the edge of perennial ice. Estimated contents of river waters, sea ice meltwater, and modified waters showed that the eastern part of the shelf of the East Siberian Sea in summer, 2017 was globally freshened by riverine waters (6–57%). A slight contribution of sea ice meltwater (2–3%) was found only in the surface waters of the Kolyma section. The waters of the Indigirka section experienced intense modification, which is related to the ice formation and reaches 20% ice extraction from water. The concentration and δ13C values of DIC are controlled by mixing between sea water and river runoff. Their shift relative to the values determined by conservative mixing suggests that shelf waters contain an excess of DIC with an isotopically light carbon. Main processes leading to these shifts are the decomposition of organic matter and water modification. The rate of the latter is 3–4 times higher than that of organic matter oxidation. The isotope composition and concentrations of DIC could partially reflect the influence of Pacific seawaters coming through the Bering Strait and the Chukchi Sea.

The Na(+) requirement for photosynthesis and its relationship to dissolved inorganic carbon (DIC) concentration and Li(+) concentration was examined in air-grown cells of the cyanobacterium Synechococcus leopoliensis UTEX 625 at pH 8. Analysis of the rate of photosynthesis (O(2) evolution) as a function of Na(+) concentration, at fixed DIC concentration, revealed two distinct regions to the response curve, for which half-saturation values for Na(+) (K((1/2))[Na(+)]) were calculated. The value of both the low and the high K((1/2))(Na(+)) was dependent upon extracellular DIC concentration. The low K((1/2))(Na(+)) decreased from 1000 micromolar at 5 micromolar DIC to 200 micromolar at 140 micromolar DIC whereas over the same DIC concentration range the high K((1/2))(Na(+)) decreased from 10 millimolar to 1 millimolar. The most significant increases in photosynthesis occurred in the 1 to 20 millimolar range. A fraction of total photosynthesis, however, was independent of added Na(+) and this fraction increased with increased DIC concentration. A number of factors were identified as contributing to the complexity of interaction between Na(+) and DIC concentration in the photosynthesis of Synechococcus. First, as revealed by transport studies and mass spectrometry, both CO(2) and HCO(3) (-) transport contributed to the intracellular supply of DIC and hence to photosynthesis. Second, both the CO(2) and HCO(3) (-) transport systems required Na(+), directly or indirectly, for full activity. However, micromolar levels of Na(+) were required for CO(2) transport while millimolar levels were required for HCO(3) (-) transport. These levels corresponded to those found for the low and high K((1/2))(Na(+)) for photosynthesis. Third, the contribution of each transport system to intracellular DIC was dependent on extracellular DIC concentration, where the contribution from CO(2) transport increased with increased DIC concentration relative to HCO(3) (-) transport. This change was reflected in a decrease in the Na(+) concentration required for maximum photosynthesis, in accord with the lower Na(+)-requirement for CO(2) transport. Lithium competitively inhibited Na(+)-stimulated photosynthesis by blocking the cells' ability to form an intracellular DIC pool through Na(+)-dependent HCO(3) (-) transport. Lithium had little effect on CO(2) transport and only a small effect on the size of the pool it generated. Thus, CO(2) transport did not require a functional HCO(3) (-) transport system for full activity. Based on these observations and the differential requirement for Na(+) in the CO(2) and HCO(3) (-) transport system, it was proposed that CO(2) and HCO(3) (-) were transported across the membrane by different transport systems.

The availability of dissolved inorganic carbon (DIC) may have a considerable impact on species competition in phytoplankton communities. The growth, photosynthetic characteristics and competition of three strains, the toxic Microcystis aeruginosa FACHB 912, nontoxic M. aeruginosa FACHB 469 and Chlamydomonas microsphaera FACHB 52, were investigated under two different DIC concentrations (0.365 and 7.658 mmol l−1 KHCO3). In monoculture, DIC concentration did not affect the specific growth rates of any of the three strains. However, when grown in mixed culture with C. microsphaera, both toxic and nontoxic Microcystis strains showed increased percentages under low DIC concentration but decreased percentages under high DIC concentration. After 12 days’ mixed culture, the percentage of M. aeruginosa FACHB 912 or FACHB 469 decreased by 9−22% in high DIC medium, but increased by 6–11% in low DIC medium. Low DIC concentration decreased the cell size, cellular chlorophyll fluorescence and photosynthetic capacity of C. microsphaera, but it had little effect on those of M. aeruginosa FACHB 912 and FACHB 469. The apparent photosynthetic affinities for DIC were significantly higher in the two M. aeruginosa strains than in C. microsphaera. From the higher DIC affinity, more efficient photosynthetic capacity and increased percentages in competition experiments under low DIC concentration, it can be concluded that the bloom-forming M. aeruginosa possesses a competitive advantage in DIC-limited conditions.

Carbon cycle is one of the focuses of climate change, river carbon is an important part, while dissolved inorganic carbon (DIC) has a high proportion of river carbon flux. In this study, we did the research on the Lancang River, an important international river in the southwest of China. Water samples were obtained from 16 sections of the middle and lower reaches of the Lancang River in 2016 (11 months), then we monitored some water quality indicators and DIC content, finally analyzed the temporal-spatial distribution characteristics of DIC and the relationship between DIC content and water environment factors. The results showed that: (1) DIC contents in the middle and lower reaches of the Lancang River varied from 1.1840 mmol/L to 3.1440 mmol/L, with a mean value of about 2.2155 mmol/L. (2) At a time scale, DIC contents of dry season (spring, autumn and winter) were higher than rainy season (summer). At a space scale, DIC contents of the middle and lower reaches of the Lancang River gradually decreased from north to south, and each reservoir had the same characteristics, that is, DIC contents at upstream of the dam was lower than those at downstream of the dam. Compared to other rivers with cascade dams around the world, DIC contents within studied river were at similar level. And the reservoir’s effect of the Lancang River were not obvious, however, DIC contents in the water sampled upstream the dams had a slight stratification. (3) Water temperature, conductivity, turbidity were important factors affecting DIC content of water, and the effect of oxidation and reduction potential (ORP) and pH on DIC was relatively small.

Carbon Dioxide Removal (CDR) technologies are imperative for achieving net zero emissions, a crucial feat to meet the 2&amp;#186; target set in the Paris Agreement. Ocean Alkalinity Enhancement (OAE) is a marine CDR technology that consists of increasing the Total Alkalinity (TA) of the ocean by depositing alkaline minerals to ocean surface waters. The increase in TA reduces the sea surface partial pressure of CO2 (pCO2), thereby enhancing oceanic CO2 uptake or reducing oceanic CO2 outgassing. Despite the potential of OAE to reduce atmospheric CO2 concentrations, the realistic implementation of OAE faces substantial impediments, including logistical feasibility and the lack of international ocean governance for its deployment in open waters. To address these obstacles and incentivize the development of a policy framework for OAE, we set forward optimal conditions that maximize the efficiency of OAE in the North Pacific Ocean, leveraging natural climatic variability induced by the Pacific Decadal Oscillation (PDO). The addition of TA at high Dissolved Inorganic Carbon (DIC) concentrations has the potential to induce a stronger decrease in pCO2 than at lower DIC concentrations. Therefore, natural temporal increases in surface DIC concentrations could potentially predispose the system for enhanced OAE efficiency. The PDO induces multi-decadal variations in the carbonate system, with the potential to influence the spatiotemporal variability in OAE efficiency. PDO phases have been shown to be predictable up to a decade ahead, thereby providing a practical indication for logistical planning of OAE deployment. We analyze the influence of the PDO on OAE efficiency in the North Pacific Ocean through four Earth System Model simulations under a high emission scenario (RCP8.5) spanning from 2020 to 2100. Using theoretical CO2 uptake efficiencies, as defined by Tyka et al. (2022) and Renforth and Henderson (2017), we describe how PDO states modulate variability in uptake efficiency via their control on DIC and TA concentrations. Subsequently, we analyze the realized uptake efficiency by contrasting oceanic air-water CO2 fluxes (FCO2) in simulations with continuous and homogenous global OAE deployment against simulations without CDR intervention per unit of added TA. Early results show regional differences in OAE efficiency rates during different PDO phases. During positive PDO phases, theoretical CO2 uptake efficiencies decrease in the Northeast Pacific while increasing in the central Western Pacific, corresponding to respectively lower and higher DIC concentrations. The inverse responses are observed during negative PDO phases. We discern differences between theoretical and realized CO2 uptake efficiencies, indicating the role of additional influential variables. Our study provides new insights into the impact of the PDO on OAE efficiency and the potential to optimize CDR strategies by aligning them with natural climatic variations.

Carbon plays a vital role in karst ecosystem.A proportion of carbon dioxide produced by microbial activities and respiration of roots can be dissolved and carried by the infiltration water and then dissolve carbonate materials in the karst soil system.This process can produce a lot of dissolved inorganic carbon(DIC) into the soil water and groundwater.The stable carbon composition of DIC(δ13CDIC) can be used as a tracer for studying biogeochemical processes in soil water because the potential biogenic,atmospheric and geologic sources of C have distinct δ13C signatures.In order to reveal the characteristics of temporal and spatial variations of DIC fluxes,which can help us to get an insight into the carbonate dissolution and its related carbon cycling,and evaluate the carbon isotopic evolution of soil water in karst areas,soil water derived from different vegetations in Qingmuguan karst areas,Chongqing,SW China,were collected monthly from July,2010 to July,2011,and the DIC concentrations and δ13CDIC values of soil water were analyzed.The results show that:(1) DIC concentrations and δ13CDIC of soil water showed distinct temporal and spatial variations in the study area.DIC concentrations and δ13CDIC values of soil water varied from 21.56 mg/L to 265.35 mg/L,and from-7.73‰ to-20.68‰,respectively.(2) Soil water derived from grass and coniferous forest land had lower DIC concentrations and δ13CDIC values,with a mean value of 59.12 mg/L and-17.22‰,31.47 mg/L and-16.37‰,respectively.The δ13CDIC indicated that these DIC were mainly derived from the dissolution of soil CO2.(3) Soil water derived from the dry land,shrub land and afforestation land had higher DIC concentrations and δ13CDIC values,with the averages of 153.88 mg/L and-12.2‰,221.82 mg/L and-11.9‰,97.30 mg/L and-11.23‰,respectively.Meanwhile,these δ13CDIC values of soil water were generally 4‰—5‰ higher in the rainy season than those in the dry season.Moreover,these δ13CDIC values showed positive correlations with corresponding DIC concentrations.These indicated that DIC in these soil water were primarily derived from dissolution of carbonate materials by soil CO2,suggesting that great carbonate dissolution occurs in the karst soil system which could contributes to the reduction of soil CO2 released to the atmosphere to some extent.Nevertheless,our research also indicated the carbonate was dissolved partly by sulphuric acid which derived from the atmospheric acid precipitation in the rainy season,supported by the stoichiometric analysis,elevated δ13CDIC and δ34S of sulfate in the soil water.Besides,organic acids in the soil system could also facilitate the dissolution of carbonate materials,and result in the elevated δ13CDIC of soil water.Hydrion produced by oxygenation of inorganic nitrogenous fertilizers from agricultural activities also probably participated in the dissolution of carbonate and elevated δ13CDIC of soil water.This study revealed the variations of DIC concentrations and δ13CDIC values in the karst soil water and their influencing factors,which will aid in understanding of the migration and transformation of soil CO2 in karst soil system,especially the reduction effects of soil CO2 released to the atmosphere.However,the accurate estimation of soil CO2 reduction requires further research.

Deciphering the dynamics of inorganic carbon export from intertidal salt marshes using high-frequency measurements