Isotopic Evidence for Sources of Dissolved Carbon and the Role of Organic Matter Respiration in the Fraser River Basin, Canada

Sources of dissolved and particulate carbon to the Fraser River system vary significantly in space and time. Tributaries in the northern interior of the basin consistently deliver higher concentrations of dissolved organic carbon (DOC) to the main stem than other tributaries. Based on samples collected near the Fraser River mouth throughout 2013, the radiocarbon age of DOC exported from the Fraser River does not change significantly across seasons despite a spike in DOC concentration during the freshet, suggesting modulation of heterogeneous upstream signals during transit through the river basin. Dissolved inorganic carbon (DIC) concentrations are highest in the Rocky Mountain headwater region where carbonate weathering is evident, but also in tributaries with high DOC concentrations, suggesting that DOC respiration may be responsible for a significant portion of DIC in this basin. Using an isotope and major ion mass balance approach to constrain the contributions of carbonate and silicate weathering and DOC respiration, we estimate that up to 29% of DIC is derived from DOC respiration in some parts of the Fraser River basin. Overall, these results indicate close coupling between the cycling of DOC and DIC, and that carbon is actively processed and transformed during transport through the river network.

Landscape, Soil, Lithology, Climate and Permafrost Control on Dissolved Carbon, Major and Trace Elements in the Ob River, Western Siberia

Assuming that climate warming in the WSL will lead to a northward shift of the forest and permafrost boundaries, a “substituting space for time” approach predicts an increase in concentration of DIC and labile major and trace elements and a decrease of the transport of DOC and low soluble trace metals in the form of colloids in the main stem of the Ob River. However, an unknown factor is the change in hydrochemistry of the largest southern tributary, the Irtysh River, which is impacted by permafrost-free steppe and forest-steppe zone. Overall, seasonally-resolved transect studies of large riverine systems of western Siberia are needed to assess the hydrochemical response of this environmentally-important territory to on-going climate change.

Scale Squeeze Inhibitor as Preventive Treatment in Brani Wells, Offshore North West Java

The Brani-Field is located offshore Northwest Java and currently produces hydrocarbons from a sandstone reservoir with an average watercut of 83%. Some high watercut wells are prone to scale problems and need repetitive clean outs to overcome production decline. In 2019, downhole scale inhibitor treatment was evaluated and planned for application in these wells. Scale inhibitors are able to prevent the formation of scale so the well is able to deliver higher average oil production with lower intervention cost. In Brani wells, scale deposits are formed in perforations, downhole completion equipment, and flowlines depending on the water composition, temperature, and a reduction in dissolved carbon dioxide partial pressure. These scales deposits restrict the fluid flow causing significant production loss. In extreme conditions, the production tubing was blocked completely with the scale deposits and cease the production. Normally, the scale restriction problem in Brani wells were handled by a combination of mechanical and acidizing treatment using Coiled Tubing (CT) for downhole completion and acidizing treatment for flowline restrictions. These treatment were performed periodically every 2-4 months depending on well conditions with scaling becoming more severe in higher watercut wells. From an economic standpoint, current scale treatment methods lead to very high well intervention costs due to expensive liftboat and CT unit daily rates. The economics of these conventional treatments is further deterred by low yearly average oil production. Evaluation for scale inhibitor treatment started with the candidate selection, fluids compatibility test, core re-gain permeability test, and economic evaluation. BRG-10 well was selected as first candidate due to scale problem severity and low oil production rate. This well normally delivers 140 bopd with 90% watercut, but scale build up in the tubing and flowline prevented the fluids flow and lowered the production to 30 bopd in just two months. Laboratory test results demonstrated that the core regained permeability with the main pill fluids to a relatively high, 77.96% without any fluids compatibility issues. Deployment of a scale inhibitor squeeze treatment in BRG-10 well was executed in Jan 2020 by bullheading 657 bbl inhibitor fluids into the formation. The well was then shut in for 24 hours of soaking time. The post treatment results showed a very promising result with much more stable oil production after 11 months treatment, welltest on December 2020 showed the well was still producing 130 bopd with 90% watercut. Following the successful application in BRG-10, the scale inhibitor treatment was applied in other wells, BRK-7 in June 2020 and BRG-5L in August 2020. So far, those two wells show good production performance with 93 bopd with 85% watercut for BRK-7 and 264 bopd with 76% for BRG-5L.

A Fiber-Integrated CRDS Sensor for In-Situ Measurement of Dissolved Carbon Dioxide in Seawater

Research on carbon dioxide (CO2) geological and biogeochemical cycles in the ocean is important to support the geoscience study. Continuous in-situ measurement of dissolved CO2 is critically needed. However, the time and spatial resolution are being restricted due to the challenges of very high submarine pressure and quite low efficiency in water-gas separation, which, therefore, are emerging the main barriers to deep sea investigation. We develop a fiber-integrated sensor based on cavity ring-down spectroscopy for in-situ CO2 measurement. Furthermore, a fast concentration retrieval model using exponential fit is proposed at non-equilibrium condition. The in-situ dissolved CO2 measurement achieves 10 times faster than conventional methods, where an equilibrium condition is needed. As a proof of principle, near-coast in-situ CO2 measurement was implemented in Sanya City, Haina, China, obtaining an effective dissolved CO2 concentration of ~950 ppm. The experimental results prove the feasibly for fast dissolved gas measurement, which would benefit the ocean investigation with more detailed scientific data.

Safe in My Garden: Reduction of Mainstream Flow and Turbulence by Macroalgal Assemblages and Implications for Refugia of Calcifying Organisms From Ocean Acidification

Macroalgae, with their various morphologies, are ubiquitous throughout the world’s oceans and provide ecosystem services to a multitude of organisms. Water motion is a fundamental physical parameter controlling the mass transfer of dissolved carbon and nutrients to and from the macroalgal surface, but measurements of flow speed and turbulence within and above macroalgal canopies are lacking. This information is becoming increasingly important as macroalgal canopies may act as refugia for calcifying organisms from ocean acidification (OA); and the extent to which they act as refugia is driven by water motion. Here we report on a field campaign to assess the flow speed and turbulence within and above natural macroalgal canopies at two depths (3 and 6 m) and two sites (Ninepin Point and Tinderbox) in Tasmania, Australia in relation to the canopy height and % cover of functional forms. Filamentous groups made up the greatest proportion (75%) at both sites and depth while foliose groups were more prevalent at 3 than at 6 m. Irrespective of background flows, depth or site, flow speeds within the canopies were <0.03 m s–1 – a ∼90% reduction in flow speeds compared to above the canopy. Turbulent kinetic energy (TKE) within the canopies was up to two orders of magnitude lower (<0.008 m2 s–2) than above the canopies, with higher levels of TKE within the canopy at 3 compared to 6 m. The significant damping effect of flow and turbulence by macroalgae highlights the potential of these ecosystems to provide a refugia for vulnerable calcifying species to OA.

IMPORTANCE OF HUMIC SUBSTANCES FOR STABILIZING SOIL AGGREGATES AND CENTRAL REACTIONS EXPLANATION IN SOIL: A REVIEW

Humic substances have an essential function in soil fertility and are viewed as being of prime importance for soil aggregation stability. Humic substances as part of humus-soil organic matter are chemicals generated from the biomolecules physically, chemical and microbiologically (humifying). It is essential since it is the most pervasive biological material source, which nature knows. Roughly 80 percent of total carbon is produced with terrestrial humic compounds and 60 percent of the water dissolved carbon. During the last three decades there have been challenges in two major approaches, the concept of soil humic substances. Much of the organic aromatic soil originates from the carbon that is frequently known as black carbon (black carbon). However, the detection of benzene polycarboxylic acid markers and the UV technique in soil with two commonly used methods is not trustworthy. Polymerisation of phenolic compounds produced from the breakdown and synthesis of lignin microorganisms may result in a wide number of humic chemicals and components including organic molecules and inorganic molecules. The addition of e.g., triazines or tensile compounds that cause to bound residues in the humic matrix demonstrates that humic substances are crucial for clarifying critical soil processes. Plant nutrients, comprising p, fe and cu, are available in soil this is equally essential to understand and can directly influence the growth of higher plants in the soil.