scholarly journals Review of the analysis of 234Th in small volume (2–4 L) seawater samples: improvements and recommendations

2021 ◽  
Author(s):  
Samantha J. Clevenger ◽  
Claudia R. Benitez-Nelson ◽  
Jessica Drysdale ◽  
Steven Pike ◽  
Viena Puigcorbé ◽  
...  
Keyword(s):  
Small Volume ◽  
Recovery Process ◽  
Chemical Recovery ◽  
Wait Times ◽  
Upper Ocean ◽  
Beta Counting ◽  
Particle Scavenging ◽  
Seawater Samples

AbstractThe short-lived radionuclide 234Th is widely used to study particle scavenging and transport from the upper ocean to deeper waters. This manuscript optimizes, reviews and validates the collection, processing and analyses of total 234Th in seawater and suggests areas of further improvements. The standard 234Th protocol method consists of scavenging 234Th from seawater via a MnO2 precipitate, beta counting, and using chemical recoveries determined by adding 230Th. The revised protocol decreases sample volumes to 2 L, shortens wait times between steps, and simplifies the chemical recovery process, expanding the ability to more rapidly and safely apply the 234Th method.

scholarly journals Small Volume (1-3l) Filtration of Coastal Seawater Samples

10.3791/1163 ◽  
2009 ◽  
Author(s):  
David A. Walsh ◽  
Elena Zaikova ◽  
Steven J. Hallam
Keyword(s):  
Small Volume ◽  
Coastal Seawater ◽  
Seawater Samples

The Dow Stretford chemical recovery process

1986 ◽  
Vol 5 (1) ◽  
pp. 1-4 ◽  
Author(s):  
C. Alan Hammond
Keyword(s):  
Recovery Process ◽  
Chemical Recovery

Removal of silicon from green liquor with carbon dioxide in the chemical recovery process of wheat straw soda pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 35-40 ◽  
Author(s):  
XINXING XIA ◽  
MINGZHU DU ◽  
XIUJUAN GENG
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Wheat Straw ◽  
Reaction Temperature ◽  
Recovery Process ◽  
Chemical Recovery ◽  
Step Process ◽  
Green Liquor ◽  
One Step ◽  
The One

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon by a one-step process and a seeding process to address problems caused by high silicon content. The total silicon removal, the particle size, and the sedimentation performance of silica were investigated. The results showed that the pH of green liquor decreased with increasing amounts of carbon dioxide, becoming stable after the pH decreased to 8.2. Reaction temperature had no significant effect on the removal of silicon. About 99% of silicon removal was achieved at a pH of 9.2 at room temperature. In the one-step process, the particle size increased and the silica sedimentation performance improved with decreasing pH. The particle size decreased and the sedimentation performance improved with increasing reaction temperature. At a pH of 9.5 and reaction temperature of 80°C, the particle size was 10.43 μm. In the seeding process, 40% green liquor was treated with carbon dioxide at 80°C until the pH was about 10.5, then the 40% treated green liquor was mixed with the remaining 60% of green liquor. The mixture was then treated with carbon dioxide at a reaction temperature of 80°C until the pH reached 9.5. In that situation, the particle size reached 14.11 μm. Compared with the one-step process, the particle size of silica generated by the seeding process was bigger and the sedimentation performance was improved.

scholarly journals Quantifying 210Po/210Pb Disequilibrium in Seawater: A Comparison of Two Precipitation Methods With Differing Results

2021 ◽  
Vol 8 ◽  
Author(s):  
Montserrat Roca-Martí ◽  
Viena Puigcorbé ◽  
Maxi Castrillejo ◽  
Núria Casacuberta ◽  
Jordi Garcia-Orellana ◽  
...  
Keyword(s):  
Water Column ◽  
Methodological Issue ◽  
Deep Ocean ◽  
Future Research ◽  
Upper Ocean ◽  
Deep Waters ◽  
Poc Export ◽  
Particle Export ◽  
Seawater Samples ◽  
Lead 210

The disequilibrium between lead-210 (210Pb) and polonium-210 (210Po) is increasingly used in oceanography to quantify particulate organic carbon (POC) export from the upper ocean. This proxy is based on the deficits of 210Po typically observed in the upper water column due to the preferential removal of 210Po relative to 210Pb by sinking particles. Yet, a number of studies have reported unexpected large 210Po deficits in the deep ocean indicating scavenging of 210Po despite its radioactive mean life of ∼ 200 days. Two precipitation methods, Fe(OH)3 and Co-APDC, are typically used to concentrate Pb and Po from seawater samples, and deep 210Po deficits raise the question whether this feature is biogeochemically consistent or there is a methodological issue. Here, we present a compilation of 210Pb and 210Po studies that suggests that 210Po deficits at depths >300 m are more often observed in studies where Fe(OH)3 is used to precipitate Pb and Po from seawater, than in those using Co-APDC (in 68 versus 33% of the profiles analyzed for each method, respectively). In order to test whether 210Po/210Pb disequilibrium can be partly related to a methodological artifact, we directly compared the total activities of 210Pb and 210Po in four duplicate ocean depth-profiles determined by using Fe(OH)3 and Co-APDC on unfiltered seawater samples. While both methods produced the same 210Pb activities, results from the Co-APDC method showed equilibrium between 210Pb and 210Po below 100 m, whereas the Fe(OH)3 method resulted in activities of 210Po significantly lower than 210Pb throughout the entire water column. These results show that 210Po deficits in deep waters, but also in the upper ocean, may be greater when calculated using a commonly used Fe(OH)3 protocol. This finding has potential implications for the use of the 210Po/210Pb pair as a tracer of particle export in the oceans because 210Po (and thus POC) fluxes calculated using Fe(OH)3 on unfiltered seawater samples may be overestimated. Recommendations for future research are provided based on the possible reasons for the discrepancy in 210Po activities between both analytical methods.

Fundamental of the KP Chemical Recovery Process

2017 ◽  
Vol 71 (10) ◽  
pp. 1128-1143
Author(s):  
Makoto Iwasaki
Keyword(s):  
Recovery Process ◽  
Chemical Recovery

scholarly journals CHEMICAL RECOVERY PROCESS FOR HIGH SULFIDITY SPENT COOKING LIQUOR

1970 ◽  
Vol 24 (10) ◽  
pp. 515-521
Author(s):  
Saburo Fukui ◽  
Masao Ono ◽  
Tooru Yoshii ◽  
Hiroshi Matsuura ◽  
Hitoshi Sotobayashi
Keyword(s):  
Recovery Process ◽  
Chemical Recovery ◽  
Cooking Liquor

scholarly journals Improved biodiversity detection using a large-volume environmental DNA sampler with in situ filtration and implications for marine eDNA sampling strategies

2022 ◽  
Author(s):  
Annette F. Govindarajan ◽  
Luke McCartin ◽  
Allan Adams ◽  
Elizabeth Allan ◽  
Abhimanyu Belani ◽  
...  
Keyword(s):  
Large Volume ◽  
Small Volume ◽  
Deep Ocean ◽  
Environmental Dna ◽  
Marine Biodiversity ◽  
Robotic Vehicle ◽  
Seawater Samples ◽  
Biodiversity Changes ◽  
Collection Strategies

Metabarcoding analysis of environmental DNA samples is a promising new tool for marine biodiversity and conservation. Typically, seawater samples are obtained using Niskin bottles and filtered to collect eDNA. However, standard sample volumes are small relative to the scale of the environment, conventional collection strategies are limited, and the filtration process is time consuming. To overcome these limitations, we developed a new large-volume eDNA sampler with in situ filtration, capable of taking up to 12 samples per deployment. We conducted three deployments of our sampler on the robotic vehicle Mesobot in the Flower Garden Banks National Marine Sanctuary in the northwestern Gulf of Mexico and collected samples from 20 to 400 m depth. We compared the large volume (~40-60 liters) samples collected by Mesobot with small volume (~2 liters) samples collected using the conventional CTD-mounted Niskin bottle approach. We sequenced the V9 region of 18S rRNA, which detects a broad range of invertebrate taxa, and found that while both methods detected biodiversity changes associated with depth, our large volume samples detected approximately 66% more taxa than the CTD small volume samples. We found that the fraction of the eDNA signal originating from metazoans relative to the total eDNA signal decreased with sampling depth, indicating that larger volume samples may be especially important for detecting metazoans in mesopelagic and deep ocean environments. We also noted substantial variability in biological replicates from both the large volume Mesobot and small volume CTD sample sets. Both of the sample sets also identified taxa that the other did not; although the number of unique taxa associated with the Mesobot samples was almost four times larger than those from the CTD samples. Large volume eDNA sampling with in situ filtration, particularly when coupled with robotic platforms, has great potential for marine biodiversity surveys, and we discuss practical methodological and sampling considerations for future applications.

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