Underway pH measurements in upwelling conditions: The California Current

This paper reports the use of underway spectrophotometric pH as part of a series of measurements (together with underway salinity, temperature and some discrete measurements of chlorophyll a) made in the California Current coastal upwelling area. The values of pH obtained (measured at 25ºC) ranged f...

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Author: Del-Valls, TA
Format: Article
Status:Published version
Publication date:1999
Country:México
Institution:UABC
Repository:Ciencias Marinas
Language:English
OAI Identifier:oai:cienciasmarinas.com.mx:article/719
Online Access:https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/719
Access Level:Open access
Keyword:spectrophotometric pH
CO2
biogeochemical processes
upwelling
California Current
pH espectrofotométrico
procesos biogeoquímicos
afloramiento
Corriente de California
Summary:This paper reports the use of underway spectrophotometric pH as part of a series of measurements (together with underway salinity, temperature and some discrete measurements of chlorophyll a) made in the California Current coastal upwelling area. The values of pH obtained (measured at 25ºC) ranged from 7.6 near the coastline (in the centre of the upwelling) to 8.3 at the western boundary of the study area (close to the oceanic environment); pH values were more uniform away from the influence of upwelling. Variations in the pH, temperature and chlorophyll a were all approximately in phase. In particular, higher pH values –indicative of photosynthetic activity– were well correlated with the chlorophyll a measurements. These results illustrate the need to consider both small and mesoscale processes when investigating carbon dioxide exchange across the air-sea interface in such systems, and also show that spectrophotometric pH measurements are sufficiently sensitive (and can be measured sufficiently rapidly) to describe various biogeochemical processes in such systems.

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