scholarly journals Dispersion and Intersection of Hydrothermal Plumes in the Manus Back-Arc Basin, Western Pacific

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Zhigang Zeng ◽  
Xiaoyuan Wang ◽  
Bramley J. Murton ◽  
Haiyan Qi ◽  
Berit Lehrmann ◽  
...  
Keyword(s):  
Water Column ◽  
Ph Value ◽  
Chemical Properties ◽  
Hydrothermal Systems ◽  
Pacmanus Hydrothermal Field ◽  
Different Depths ◽  
Hydrothermal Plumes ◽  
Back Arc ◽  
Physical And Chemical ◽  
Fluid Sources

The composition of hydrothermal plumes reflects the physical and chemical characteristics of seafloor hydrothermal fluids, which in turn reflects the host rock and subseafloor reaction conditions as well as the water column processes that act to alter the plumes as they disperse and age. Here, we show that the turbidity, current, pH value, dissolved Fe (dFe), and dissolved Mn (dMn) compositions of hydrothermal plumes can be used to understand the spatial distribution and source of hydrothermal systems in the submarine geological environment. Data were obtained from 18 hydrocast stations, among which the water column samples were collected at 8 stations during the MANUS cruise of R/V KEXUE in 2015. The results showed that the Satanic Mills plume and Fenway plume rose approximately 140 m and 220 m above the seafloor, respectively. In the Satanic Mills plume, dFe remained longer than dMn during lateral plume dispersal. There was a clear intersection of the Satanic Mills plume and Fenway plume between 1625 m and 1550 m in the PACMANUS hydrothermal field, and the varied dispersion trends of the mixed plumes were affected by current velocities at different depths. The physical and chemical properties of the seawater columns in the Manus Basin were affected by the input of high-Mn, high-Fe, and low-Mg vent fluids. The turbidity and dFe, dMn, and dissolved Mg concentrations in the sections of the plumes proximal to the Satanic Mills, Fenway, and Desmos vent sites were generally higher (turbidity, Mn, and Fe) and lower (Mg) than those in the sections of the plumes that were more distal from the vent sites. This implied that the plumes proximal to their vent fluid sources, which were interpreted to have relatively young ages, dispersed chemically over time, and their concentrations became more similar to those of the plumes that were more distal from their vent fluid sources.

scholarly journals Effects of Continuous Cropping of Dictyophora on Soil Physical and Chemical Properties, Microbial Biomass and Enzyme Activity

2021 ◽  
Vol 8 (7) ◽  
pp. 214-220
Author(s):  
Long Tong ◽  
◽  
Hongyan Li ◽  
Xiaoming Liu ◽  
Bin Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Ph Value ◽  
Chemical Properties ◽  
Available Phosphorus ◽  
Continuous Cropping ◽  
Physical And Chemical Properties ◽  
Factors Affecting ◽  
The One ◽  
Physical And Chemical ◽  
And Chemical Properties

The continuous obstacle of Dictyophora indusiata has become the one of the main factors affecting the healthy development of D. indusiata industry. In order to study the effects of continuous cropping of D. indusiata on the soil environment, four treatments were used in this study: no planted (CK), planted for 1 years (1Y), continuous cropping for 2 years (2Y) and continuous cropping for 3 years (3Y), to determined of the yield of D. indusiata, soil physical and chemical properties, microbial content and enzyme activity. The results showed that the yield and soil pH value decreased with the increase of continuous cropping years, and the contents of organic matter, total nitrogen, total phosphorus and total potassium, C/N and C/P also increased with the increase of continuous cropping years. Soil availability decreased with the increase of continuous cropping years, the content of alkaline nitrogen, available phosphorus and available potassium decreased by 12.25%, 28.91% and 24.86% at 3Y compared with 1Y, respectively. The biomass of bacteria, actinomycetes and fungi and the total amount of microorganism in soil increased at 1Y compared with CK, but with the increase of continuous cropping years, the biomass of bacteria and actinomycetes and the total amount of microorganism decreased significantly, while the biomass of fungi increased significantly; the continuous cropping of D. indusiata also decreased the value of bacteria/fungi in soil. The enzyme activities of the soil were higher than those of the unplanted plots, however, the activities of urease, catalase, peroxidase, sucrase, phosphatase and protease decreased with the increase of continuous cropping years. In a word, with the increase of continuous cropping, the acidity of rhizosphere soil increased, the availability of soil nutrients and the activity of soil enzymes decreased, the biomass of soil microorganisms, bacteria and actinomycetes decreased. However, the increase of fungal biomass led to the decline of soil texture.

scholarly journals Plankton and Macrobiota Composition and Diversity of Three Tropical Freshwaters Rivers in Ogun and Ondo States, Southwest Nigeria

2016 ◽  
Vol 8 (2) ◽  
pp. 246-255
Author(s):  
Taofikat Abosede ADESALU ◽  
Olakunbi Anike KUNRUNMI ◽  
Muyideen Owonire LAWAL
Keyword(s):  
Ph Value ◽  
Chemical Properties ◽  
Common Species ◽  
Water Bodies ◽  
Dominant Group ◽  
Ogun State ◽  
Tropical Freshwaters ◽  
Southwest Nigeria ◽  
Ondo State ◽  
Physical And Chemical

Three different rivers in Ogun and Ondo states were investigated for both micro and macro-biota of the water bodies. Several physical and chemical properties of these rivers were determined. The pH value of the studied water bodies was essentially neutral with salinity values between 0.02 - 4.0‰. Microalgae communities were represented by three divisions: Cyanophyta, Bacillariophyta and Chlorophyta at Oluwa and Ifara Rivers (Ondo state), while at Ibefun River (Ogun state), five divisions: Cyanophyta, Bacillariophyta, Chlorophyta, Euglenophyta and Pyrrhophyta were identified. Diatoms dominated these water bodies, with Navicula radiosa Kutz. at Ifara River, Fragilaria sp. in Oluwa River, while out of 90 algal taxa identified in Ibefun river, 64 were diatoms species belonging to 26 genera, with Melosira sp. and Synedra sp. recording the highest numbers of cell count. Dinoflagellates recorded only Peridinium sp. while Phacus orbicularis Hubner and Trachelomonas sp. dominated the euglenoids. For the zooplankton composition at Ibefun, rotifers (75.95%) were represented by Brachionus sp., which recorded 62.03%, and Gastropus sp. with 13.92% of the total zooplankton, thus dominated the spectrum, while the copepod recorded 22.78% of the total organisms, with Copilia sp. and Euchirella sp. having 8.86% each. The macrobenthic invertebrates were represented by 3 taxa, belonging to 3 groups, with the dominant group Insecta accounted for 57% of the total individuals (7 individuals/m2), while Oligochaeta and Hirudinea accounted for 29% and 14% respectively of the total individuals at Oluwa and Ifara Rivers. At Ibefun River, the macrobenthic invertebrates were represented by 5 taxa, belonging to 3 groups, Bivalves, Oligochaeta and Insecta, with bivalves being the dominant group (51.7% of the total individuals, as 64 individuals/m2), while Oligochaeta and Insecta accounted for 26.6% and 21.9% respectively of the total individuals. The dominant taxon, Macoma cumana, accounted for 42.2%. A total of seventeen (17) finfish and shellfish species comprised of thirteen (13) finfish and four (4) shellfish species were recorded, being representative of freshwater and brackish water species; Clarias anguillaris (Clariidae), Tilapia zilli (Cichlidae), Chrysichthys nigrodigitatus (Bagridae), Alestes spp. and Macrobrachium vollenhovenii (Palaemonidae) were the most common species observed.

Validating the Use of Radiotracers as Analogs of Stable Metal Behaviour in Enclosed Aquatic Ecosystem Experiments

1987 ◽  
Vol 44 (S1) ◽  
pp. s251-s259 ◽  
Author(s):  
Robert F. Anderson ◽  
Peter H. Santschi ◽  
Urs P. Nyffeler ◽  
Sherry L. Schiff
Keyword(s):  
Trace Metal ◽  
Water Column ◽  
Metal Removal ◽  
Chemical Properties ◽  
Ionic Form ◽  
Experimental Lakes Area ◽  
Suspended Particulate ◽  
Area North ◽  
Exchange Resins ◽  
Physical And Chemical

Radiotracer experiments were carried out in enclosures in two lakes at the Experimental Lakes Area, North-western Ontario, to study the pathways of trace metal removal from the shallow water columns to the sediments of these lakes. As part of the larger experiment, stable carriers of Fe, Mn, and Zn were added individually to each of three enclosures. Rates of removal to sediments at pH 6.3 and backdiffusion after HCl addition to pH 4.8 of radiotracer 59Fe, 54Mn, and 65Zn were compared to the respective rates of their stable counterparts. Tracer removal and backdiffusion rates in enclosures which received stable carrier additions were further compared with the tracer behaviour in enclosures which received no carrier additions. Radiotracers and stable carriers were removed from the water column at similar rates at pH 6.3, and were remobilized at similar rates from the sediments when the pH of the water column was lowered to 4.8. The presence of the added stable carriers had no effect on the removal or remobilization of Mn or Zn. However, the removal of 59Fe from the water column was slowed slightly by the addition of Fe(III) carrier compared to removal in the other tubes, possibly due to the formation of colloidal phases. These results show that information on the rates of trace metal transport obtained using radiotracers is applicable to stable metal behavior in these freshwater systems. The use of radiotracers to study trace metal geochemistry under natural conditions is preferred to the addition of stable metals which may alter the physical and chemical properties of the suspended particulate matter as occurred after the addition of stable iron. Speciation studies showed that adsorption to ion exchange resins does not provide a reliable indication of the ionic form of metals in lake water.

scholarly journals Diel vertical migration of Cladocera in a compartment of a tropical reservoir

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Erika dos Santos Silva ◽  
Odete Rocha ◽  
Maria José dos Santos-Wisniewski
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Chlorophyll A ◽  
Vertical Migration ◽  
Variable Temperature ◽  
Chemical Properties ◽  
Migration Pattern ◽  
Limiting Factor ◽  
Tropical Reservoir ◽  
Physical And Chemical

Abstract Aim This study seeks to analyze the vertical migration pattern of Cladocera species as related with the physical and chemical parameters of the water. Methods Samplings were carried out at 3-h intervals for 24 h in January 15 on the Sapucaí River compartment of Furnas reservoir, Minas Gerais State, Brazil. These samples were taken at five depths, from the surface to the near-bottom layer (0, 2, 4, 6, 8, and 9 m) totalizing 54 samplings for each limnological variable (temperature, pH, dissolved oxygen, electrical conductivity, chlorophyll-a content, Index of Trophic State, water transparency and Cladocera populations abundance). The samplings were performed at the limnetic region at a point with total depth of 9 meters. Results Water column thermal and chemical stratifications and thermocline occurrences were registered in the middle of the day. Among the 14 Cladocera species, only Ceriodaphnia cornuta and C. silvestrii displayed a significant migration pattern, which was mainly related to chlorophyll-a and dissolved oxygen concentrations. Diaphanosoma birgei and D. spinulosum are found at high densities near the surface and low ones in depth. The migration of Diaphanosoma was directly related to the concentration of chlorophyll a and pH, thus acting as a limiting factor. Feeding at high temperatures in the surface layer and assimilating at lower ones in depth, usually confer metabolic advantages to the vertically migratory species. Conclusions In this study, a well-defined pattern of vertical migration was found for two Cladocera species and its possible causes were hypothesized. To the species with less locomotory capacity, thermal and chemical stratifications can act as barriers to migration and distribution through the water column. This pattern may probably be found for zooplankton species in other compartments of Furnas reservoir, with similar physical and chemical properties.

scholarly journals Factors Affecting the Setting Time of Fly Ash-Based Geopolymer

2016 ◽  
Vol 841 ◽  
pp. 90-97 ◽  
Author(s):  
Antoni ◽  
Stephen Wibiatma Wijaya ◽  
Djwantoro Hardjito
Keyword(s):  
Fly Ash ◽  
Initial Temperature ◽  
Ph Value ◽  
Setting Time ◽  
Chemical Properties ◽  
Curing Temperature ◽  
Factors Affecting ◽  
Ph Values ◽  
Physical And Chemical ◽  
And Chemical Properties

Fly ash is a waste from coal burning, that are generated with fluctuation both in its physical and chemical characteristics. This characteristics of fly ash when used in the making of geopolymer concrete will greatly affect the final products obtained. The pH value measured in fly ash, according previous research, can influence the setting time of geopolymer and fly ash with high pH values can cause flash-setting in the concrete. Understanding more clearly about the factors that affect the setting time of fly ash based geopolymer is important for further progress and development of the material. It was found that factors that influence the setting time of geopolymer was not only from the physical and chemical properties of the fly ash itself. Other factors such as composition and mix design, manufacturing process and environmental conditions can also affect its setting time. The experimental results showed that fly ash particle size, CaO and MgO content, in addition to ratio of sodium silicate and sodium hydroxide in the alkali solution, molarity of NaOH, initial temperature of the mixture, curing temperature, and mix volume could potentially influence the setting time of the geopolymer mixture.

scholarly journals Effect of Co-Surfactants and Pasteurization for Preservation of Natural Rubber

2021 ◽  
Author(s):  
Sittiporn Punyanity ◽  
Rungsarit Koonawoot ◽  
Anucha Raksanti ◽  
Sakdiphon Thiansem ◽  
Somchai Thamsutiwat ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Ph Value ◽  
Chemical Properties ◽  
Time Range ◽  
Linear Alkylbenzene ◽  
Linear Alkylbenzene Sulfonates ◽  
Short And Long Term ◽  
Acid Producing Bacteria ◽  
Physical And Chemical

This research was a study of the effect of addition linear alkylbenzene sulfonates (LAS), NaHCO3, and NaCl and pasteurization on the preservation of natural rubber (NR). The samples were collected from rubber plantations of Chiang Rai province which were added with three surfactants in samples already. Physical and chemical properties were evaluated using pH, deterioration, viscosity, color, and odor. Then, the samples were stored at 28-30°C periods times of 0, 15, 30, 45, and 60 days. The experiment found that the color, viscosity, odor, and texture of NR samples were not spoiled after being preserved for 30 days but after 45 and 60 days found some coagulation of NR. In the case of non-preserved NR was found that spoiled NR in every period time range of 15-60 days. The pH testing found that increasing period times affect decreased pH value and increased viscosity due to salt of sulfate, carbonate, chloride, and thermal treatment of pasteurization which kill microorganisms and evaporated water. It concluded that the reagents were the process of cosurfactants with heat and frozen for increased effectiveness of anti-acid-producing bacteria and can use as short and long-term preservation of NR under the planting area condition of Thailand.

scholarly journals Influence of the Addition of Calcium Hydroxide Powder on Some Physical and Chemical Properties of the Sealer MTA Fillapex

2012 ◽  
Vol 3 (2) ◽  
pp. 180-183
Author(s):  
Marcelo Ferrarezi de Andrade ◽  
Renato de Toledo Leonardo ◽  
Edson Alves de Campos ◽  
Milton Carlos Kuga ◽  
Marco Antonio Hungaro Duarte ◽  
...  
Keyword(s):  
Calcium Hydroxide ◽  
Calcium Release ◽  
Ph Value ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Ph Values ◽  
The One ◽  
Physical And Chemical ◽  
The Impact ◽  
And Chemical Properties

ABSTRACT Objective This study evaluated the flow, pH and calcium release of MTA Fillapex (G1) or Fillapex plus 10% in weight of calcium hydroxide powder (G2), compared to AH Plus (G3) and Sealapex (G4). Materials and methods The flow test was performed according to ISO 6876:2001 requirements. The sealers were placed into plastic tubes and immersed in deionized water. After 24 hours, 7, 14 and 28 days, the water of each tube was removed and tested to evaluate the pH values and the level of released calcium. Calcium release values were analyzed statistically by Kruskal Wallis and Dunn tests and pH values analyzed by ANOVA and Tukey tests (α = 5%). Results G1 presented higher flow among all sealers. The addition of 10% calcium hydroxide into MTA Fillapex reduced the flow (p < 0.05) but, in a level, that is lower than the one recommended for ISO norms. G2 and G4 presented pH values and calcium release higher than G3 (p < 0.05) in all periods. G1 presented pH value higher than G3 (p < 0.05), except in 7 days period (p > 0.05). G4 presented higher pH values than G1 and G2, but the calcium release was similar for all periods (p > 0.05). G3 presented lower calcium release among all groups (p < 0.05). Conclusion The addition of 10% calcium hydroxide in MTA Fillapex caused reduction in flow and no negative interference in pH and/or calcium release. However, the obtained flow is different from ISO requirements. Clinical relevance MTA Fillapex presents levels of flow above the ISO norms. The addition of calcium hydroxide is a suggestion for solving this problem, but the impact of these procedures should be carefully evaluated. How to cite this article Keine KC, Guiotti FA, Leonardo RT, Kuga MC, Duarte MAH, de Campos EA, de Andrade MF. Influence of the Addition of Calcium Hydroxide Powder on Some Physical and Chemical Properties of the Sealer MTA Fillapex. World J Dent 2012;3(2):180-183.

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