Major ion and carbonate system chemistry of a navigable freshwater canal

Abstract

1. An examination has been made of the water quality of a 50 km (Wigan toLitherland) length of the Leeds-Liverpool canal. Regular in situ measurements accompanied by sampling for laboratory analysis were made at seventeen stations over a 15-month period.2. Three principal contributory water types have been recognized, and the observations have allowed estimates to be made of their relative contributions to the total water flux in the lower reaches of the system. Linear flow rates (c. 0.6 km day"' near Litherland) are consistent with previous reports.3. The combined field and laboratory measurements have been used to obtain estimates of the partial pressure of CO2 in the water {PcoX the degree of saturation of the water with respect to calcite (Q) and the major ion speciation in the water. Because of the variable ionic compositions of the waters examined, these estimates were made using a program (WATEQ) which took account of ion-pairing.4. Diurnal andannualcycleswithrespect to pH,Pco and Q occur, these being most marked in the lower parts of the study length when, for a large proportion of the spring and summer, Pco, was below the atmospheric level and noticeable supersaturation with respect to calcite occurred. In contrast, two of the contributory water types, the River Douglas input and the Creek, showed low pH and Q values and high P(Q^ values throughout the year.

Interactive Effects of Temperature and Salinity upon Net Photosynthesis of Cladophora glomerata (L.) Kütz. and C. rupestris (L.) Kütz.

“…There is no significant seasonal variation in the salinity conditions at this freshwater site (Howard et al 1984). The temperature and salinity of water retained among emergent Cladophora rupestris plants was also measured over this period.…”

Photosynthesis and calcification of the stromatolitic freshwater cyanobacteriumRivularia

“…When ¼ 1 the water sample is at equilibrium, i.e. saturated with respect to calcite, and when 41 the sample is supersaturated with respect to calcite (Howard et al, 1984).…”

The chalk-stream environment

“…Such degassing can occur across the air-water interface under conditions of severe turbulence and this can prove a problem when water is being recirculated in experimental systems (House et al, 1986;House et al, 1988). It can also occur in the relatively static flow conditions that develop in large macrophyte beds where CO, is taken out of solution by the photosynthetic activity of the plants (Howard et al, 1984).…”