The alkalinity of the deep Pacific

The distribution of alkalinity obtained by the GEOSECS Pacific expedition provides implications for the ocean circulation and for the dissolution of CaCO₃. Alkalinity has a maximum in the deep water at all stations occupied north of the Circumpolar. The distribution of alkalinity at its maximum suggests a cyclonic circulation in the deep water. The bottom water in the North Pacific gains alkalinity primarily by vertical mixing with deep water and the deep water loses most of its alkalinity by mixing with Circumpolar and Antarctic Intermediate Water in the South Pacific. The alkalinity distribution can be explained only by local sources in the water column. Calcium carbonate, like silicate, seems to dissolve primarily in the deep water.     

Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program

Approximately 6000 determinations of the alkalinity and total carbon dioxide content of seawater have now been made in the Atlantic, Pacific and Indian Oceans as part of the GEOSECS program by a computer-controlled potentiometric titration technique. The equations used to locate the equivalence points of the carbonic acid system on this titration curve were developed in 1971 but have not previously been published. These functions may be represented by:$\begin{array}{l}{F}_1=\frac{\left(V_2?V\right)}{V_0}N\left[H^{+}\right]/K_{1C}+\frac{\left(V_0+V\right)}{V_0}\left(\left[H^{+}\right]+\left[HS{O}_4^{?}\right]+\left[HF\right]?\left[B{\left(OH\right)}_4^{?}\right]\right)\\ \times \left(1+\left[H^{+}\right]/K_{1C}\right)\\ F_2=\frac{\left(V_0+V\right)}{V_0}\left(\left[H^{+}\right]+\left[HS{O}_4^{?}\right]+\left[HF\right]?\left[HC{O}_3^{?}\right]\right)\end{array}$Upon inspection, these functions are analogous to the modified Gran functions of Hansson and Jagner [25] with the omission of the contributions of [OH^?] and [CO₃^2?], and with the contribution of B(OH)₄^? being assessed at a chlorinity of 19‰ for all samples. Reprocessing the original titration e.m.f.-volume data with appropriate corrections and modified Gran functions reveals an error of about +12 μmol/kg in the GEOSECS total carbon dioxide data. In addition, the protonation of dissolved phosphate species during the titration results in a contribution to measured total carbon dioxide equal to the total phosphate concentration. Differences in the application of the GEOSECS functions between the Atlantic and the Pacific-Indian Oceans expeditions are also to be found so that the error deriving from this source for the Atlantic expedition was only +5 μmol/kg. The application of the correct functions increases precision enabling smaller differences, such as those attributable to fossil fuel carbon dioxide, potentially to be observed, and increases accuracy so that the error in titrator total carbon dioxide previously diagnosed by Takahashi [14] can be logically accounted for.     

碱度增加对蛋白核小球藻光合活性与胞外多糖的影响

本文研究了不同重碳酸盐(HCO3)碱度2.3mmol/L(ALK2.3)和12.4mmoFL(ALK12.4)条件对蛋白核小球藻光合活性、色素组成、丙二醛(MDA)含量与胞外多糖的影响.实验结果表明,碱度增加对蛋白核小球藻光合活性呈促进一抑制一促进效应,ALK2.3对光合活性影响的强度.高于ALK12.4.碱度增加提高叶绿素b/叶绿素a(Chl.b/Chl.a)的值,降低类胡萝卜素/叶绿素(Caro/TChl)的值,并且ALKl24条件下对藻细胞的作用程度强于ALK2.3.此外碱度增加刺激蛋白核小球藻胞外多糖分泌,ALK2.3在培养初期提高MDA含量,ALK12.4下细胞MDA含量显著降低.说明碱度增加会促进蛋白核小球藻光合活性,促进光合产物的积累与分泌.暗示胞外多糖的分泌可能是细胞适应高碱度的一种自我保护机制.     

Internal elemental cycles affecting the long-term alkalinity status of lakes: implications for lake restoration

Although the major processes affecting the acid-base balance of a lake are directly linked to reactions involving nitrogen and sulphur they are also influenced by the carbon cycle which is regulated by the supply of phosphorus. Changes in the long-term alkalinity of a lake are brought about by redox reactions in solution and through interactions with the atmosphere and sediments. Adding organic material or nutrients may help to restore acidified lakes, by generating base and by the increased carbon turnover creating a self-regulating ecosystem which is resistant to change.     

Linkage of liquid conductivity of glacier ice with its alkalinity over the north Qinghai-Xizang (Tibet) Plateau

Liquid conductivity (EC) measurement was conducted for the samples collected from several snow pits and ice cores over the Qinghai-Xizang (Tibet) Plateau, with their time range covering seasonal, decadal and centennial scales. Unlike the previous attention mostly focused on the acidity (H⁺) responding to the solid conductance (ECM) of glacial ice, we introduce the alkalinity (OH⁻) of snow and ice to show how it responds to EC. Strong linear relationship was established between EC and OH⁻ for these snow pits and ice cores. Positive correlation is also established between EC and major cations (Ca²⁺, Mg²⁺, Na⁺ and K⁺). Since the cations are known as the proxies for the intensity of mineral dust influx onto glaciers of the northern Qinghai-Xizang Plateau, we believe that EC could be used as an indicator for the history of dust input in deep ice core study. In fact, records in Guliya ice core since the Little Ice Age (LIA) indicate that dust load in glacier may depend on the combination of temperature and humidity. “Cold-dry” combination favors the dust arising, and results in higher EC and OH⁻ values, while “warm-wet” combination prevents dust form and EC and OH⁻ values are lower. In the past century, with the atmospheric warming and precipitation increasing over the northern plateau, which means an atmospheric condition of dust decreasing, both EC and OH⁻ displayed rapid decline.     

Evaluation of a probabilistic approach to simulation of alkalinity and electrical conductivity at a river bank filtration site

In river bank filtration, impurities present in the river water travel with the bank filtrate towards the pumping well. During this passage, certain types of impurities, such as turbidity, total coliform, and so forth, may get attenuated; however, it is interesting to note that some of the instant raw river water quality parameters, such as alkalinity and electrical conductivity, increase after the passage of water through the porous medium. This occurs because water, when passing through the soil pores, absorbs many of the solutes that cause an increase in alkalinity and electrical conductivity. Measurements at a river bank filtration site for a year showed that alkalinity of 116–32 mg l^?1 in river water increased to 222.4–159.9 mg l^?1 in the river bank filtered water. Likewise, the electrical conductivity increased from 280–131 μS cm^?1 to 462–409.6 μS cm^?1. This study uses a probabilistic approach for investigating the variation of alkalinity and electrical conductivity of source water that varies with the natural logarithm of the concentration of influent water. The probabilistic approach has the potential of being used in simulating the variation of alkalinity and electrical conductivity in river bank filtrate. Copyright © 2011 John Wiley & Sons, Ltd.     

Linkage of liquid conductivity of glacier ice with its alkalinity over the north Qinghai-Xizang (Tibet) Plateau--Implication to the past dust recovery

Liquid conductivity (EC) measurement was conducted for the samples collected from several snow pits and ice cores over the Qinghai-Xizang (Tibet) Plateau, with their time range covering seasonal, decadal and centennial scales. Unlike the previous attention mostly focused on the acidity (H+) responding to the solid conductance (ECM) of glacial ice, we introduce the alkalinity (OH?) of snow and ice to show how it responds to EC. Strong linear relationship was established between EC and OH? for these snow pits and ice cores. Positive correlation is also established between EC and major cations (Ca2+, Mg2+, Na+ and K+). Since the cations are known as the proxies for the intensity of mineral dust influx onto glaciers of the northern Qinghai-Xizang Plateau, we believe that EC could be used as an indicator for the history of dust input in deep ice core study. In fact, records in Guliya ice core since the Little Ice Age (LIA) indicate that dust load in glacier may depend on the combination of temperature and humidity. "Cold-dry" combination favors the dust arising, and results in higher EC and OH- values, while "warm-wet" combination prevents dust form and EC and OH- values are lower. In the past century, with the atmospheric warming and precipitation increasing over the northern plateau, which means an atmospheric condition of dust decreasing, both EC and OH- displayed rapid decline.