Water Total Alkalinity Research Articles

Dietary supplementation of Spirulina platensis enhances body colouration of shubunkin gold fish, Carassius auratus (Linn.) even in high‐alkalinity rearing water

The study was conducted to determine whether dietary supplementation of Spirulina platensis (S. platensis), a natural carotenoid source, could enhance body (skin) colouration of shubunkin gold fish, Carrasius auratus (Linn.) even in high-alkalinity rearing water. This was done with the objective of utilizing vast inland saline water for the culture of high-value low-volume ornamental fishes. The 40% S. platensis diet caused highest total carotenoid content (TCC), and maximum growth. The lower S. platensis levels (10% and 20%) also resulted in higher TCC than the reference diet, and the diet without S. platensis. The level of rearing water total alkalinity (RWTA) at which S. platensis could be effectively used for body colour enhancement was 300 mgl−1 as it resulted in maximum TCC (38.25 ± 0.33 µg/g wet body weight). At higher RWTA (450 mgl−1 and 600 mgl−1), the TCC considerably reduced and was minimum (32.66 + 0.15 µg/g wet body weight) at 600 mgl−1. At lower RWTA (150 mgl−1), TCC was 36.03 ± 0.2 µg/g wet body weight. Better growth of the fish was also obtained at 300 mgl−1 of RWTA.

Effects of near-bottom water oxygen concentration on biogeochemical cycling of C, N and S in sediments of the Gulf of Gdansk (southern Baltic)

Sediments from four sampling sites in the Gulf of Gdansk were sampled to test how different oxygen concentrations in near-bottom water affects biogeochemical cycling of C, N and S. Vertical distributions of content of organic carbon (OC), total nitrogen (TN) and total sulfur (TS) and number of sulfate-reducing bacteria (SRB) in sediments were determined. Pore water total alkalinity (TA), dissolved inorganic carbon (DIC), sulfate, hydrogen sulfide, ammonium and phosphate were analyzed and benthic fluxes of DIC, hydrogen sulfide and ammonium were calculated.Concentrations of OC and TN decreased and concentration of TS increased with sediment depth. Highest concentrations of OC, TN and TS were observed in silty clay sediments from hypoxic and anoxic sediments below the permanent halocline. Organic matter (OM) accumulation in sediments and oxygen deficiency in near-bottom water stimulate preservation of OC and burial of TS in this area.Concentrations of TA, DIC, hydrogen sulfide, ammonium and phosphate in pore water increased, while concentration of sulfate decreased with sediment depth. Hydrogen sulfide, ammonium and phosphate was a significant additional source of TA in pore water under hypoxic and anoxic conditions.Mineralization of OM at oxygen concentrations <2 ml l−1 occurred mainly via bacterial sulfate reduction. Diurnal hydrogen sulfide fluxes under hypoxic conditions ranged from 400 to 1240 µmol m−2 d−1. Ammonium fluxes were estimated on 534 – 924 µmol m−2 d−1. Corresponding fluxes measured under anoxic conditions were 266 µmol m−2 d−1 and 106 µmol m−2 d−1.Sediments under oxic conditions became a place of the intensive regeneration of carbon - DIC flux from sediment reached 2775 µmol m−2 day−1. Sediment-water DIC fluxes under hypoxic and anoxic conditions were much lower and ranged from 1015 to 1208 µmol m−2 d−1.

Corrosion loss of mild steel in high temperature hard freshwater

This paper presents an interpretation of corrosion loss data for mild steel coupons exposed for up to 2.6 years to freshwater under a range of dissolved oxygen levels and temperatures 50–60 °C. The water total alkalinity was 0.5–0.6 mmol/l and pH 8.7–9.2. It is shown herein that the data is consistent with the early stages of the corrosion loss model proposed earlier for steel exposed to seawater, brackish water or freshwaters in the usual environmental range of 0–30 °C. The new data was found to be consistent with the effect of dissolved oxygen and the effect of water hardness on the model.

Air–sea CO 2 exchange in a subtropical estuarine-coral reef system, Kaneohe Bay, Oahu, Hawaii

The present study represents the first time-series evaluation of air–sea CO 2 exchange for a coastal marine system of a subtropical high island of the Pacific. From September 2003 through September 2004, surface water total alkalinity (TA) and dissolved inorganic carbon (DIC) data were collected bimonthly throughout the Kaneohe Bay estuarine-coral reef system. The partial pressure of carbon dioxide ( pCO 2) and the air–sea CO 2 exchange flux were calculated using TA, DIC, atmospheric CO 2 at sea level, and five wind speed relationships for gas transfer velocity. pCO 2 values were above the atmospheric level (average: 378 μatm) throughout Kaneohe Bay (400–500 μatm) and Kaneohe Stream waters (600–1300 μatm) during baseline conditions. pCO 2 levels above atmospheric in bay water were driven mainly by calcification while pCO 2 levels above atmospheric in stream water were driven mainly by remineralization of terrestrial organic matter. pCO 2 values above the atmospheric level were observed in surface water that extended almost 4 km beyond the boundary of the bay indicating that processes inside the bay such as calcification affect the inorganic carbon properties of the surrounding near shore open ocean. Precipitation from storm events in the Kaneohe watershed increases stream and land runoff that brings excess nutrients to bay waters. These excess nutrients stimulate phytoplankton blooms which draw down CO 2 in Kaneohe Bay water through photosynthesis. Despite the significant effects of the storms, Kaneohe Bay was a net annual source of CO 2 to the atmosphere of − 0.046 Gmol C year − 1 (− 0.55 kton C year − 1 ) with an area-specific flux of − 1.45 mol C m − 2 year − 1 (− 17.4 g C m − 2 year − 1 ). The source of CO 2 in Kaneohe Bay could be stronger on a long-term basis since dry years may be stronger net annual sources than wet years such as this study period. As shown by Kaneohe Bay data, the dynamic nature of estuarine systems makes closely spaced time-series data imperative for characterizing accurately the inorganic carbon system and the net annual air–sea exchange flux of CO 2.

Spectrophotometric procedures for determination of sea water alkalinity using bromocresol green

Spectrophotometric procedures are presented for the determination of sea water total alkalinity over a range of temperatures and salinities. One-step volumetric acid addition with prompt spectrophotometric measurement of excess acid provides total alkalinities precise to ± 2 micromolal. Excess acid concentrations are quantified using the sulfonephthalein indicator. bromocresol green. Measurements of bromocresol green absorbance ratios [ R ( t) = 616 A/ 444A] at temperature t (°C) and salinity S provide molal scale total hydrogen ion concentrations ([H +] T = [H +] + [HSO 4 −] + [HF]) through the equation ▪