Saline intrusion

Fig. 4 Maximum salinity intrusions into the Delta at five year time intervals from 1945 to 1990 are shown. Drought conditions and rising sea level from climate change are predicted to increase salinity intrusions eastward into the Delta in the future...

Delta irrigation channels (Faria, personal communication) indicate a saline water intrusion in the irrigation channels of the Delta. This saline intrusion may cause a dilution of mercury pollution originated at the chlor-alkali plant, hence resulting in lower average THg concentrations in Delta specimens. 

Organic matter deposited onto the suspended sediment has a large influence on the specific surface area. On one hand, it appears that organic matter blocks some sites available for physical adsorption of inert gas (BET adsorption) and, on the other hand, it probably partly causes flocculation and agglomeration of particles in the upper estuary, such floes and agregates being destroyed downstream in the salinity intrusion zone. 

O2 can be used as a tracer to help identify the origin of water masses. The warm, saline intrusion into the Atlantic Ocean from the Mediterranean Sea is relatively O2 deficient. Alternatively, the waters down-welling from Polar Regions have elevated O2 concentrations. 

A wide range of groundwater chemistry has been recorded in crystalline rock environments. Shallow groundwaters (usually <200 m) are dominantly Ca-Na-HCOa formed by the interaction of atmospherically recharged meteoric water with the soil and shallow bedrock. These waters are fresh with dilute dissolved loads and young, as indicated by the presence of tritium. Occasionally, saline intrusions from adjacent seawater bodies or upwelhng of deeper saline fluids can influence the chemistry of shallow groundwaters. 

Todd D. K. (1989) Sources of Saline Intrusion in the 400foot Aquifer, Castroville Area, California. Report for Monterey County Flood Control and Water Conservation District Salinas, CA, 41p. 

Figure 3.5 Schematic illustration of particle fluxes in the Clyde and Humber Estuaries. Arrow size denotes relative magnitude of the flux. The broken line represents the boundary of the saline intrusion and the river. REM and MEM denote river and marine end-members, respectively. All terms are defined in the text.

Thatcher and Harleman (97) have reported on the application of 1-D models in salinity intrusion regions in estuaries. They recognize the role of the longitudinal density variations in the momentum equation and in the dispersion term. They suggest the following relationship for the longitudinal dispersion term in that case ... 

The 1-D case is by far the best handled. Lee and Harleman (55) developed a useful finite-difference model. Later work by the MIT group with real-time, 1-D, unsteady flows has developed a finite element model which is very versatile, dealing with salinity intrusion (57, 91), general water-quality problems 18), temperature (7), and nitrogen dynamics 65), Mathematical models and users manuals are available for these cases. 

Diurnal changes must also be taken into consideration. For example, the dissolved oxygen concentration in freshwaters is dependent on temperature (as well as depth, altitude, saline intrusion) and competing autotrophic (photosynthesis) and heterotrophic (respiration) processes, which leads to significant day/night variations. Thus, sampling at frequent intervals over 24 h periods is recommended when investigating these processes. 

The chloride content of groundwater may be due to the presence of soluble chlorides from rocks, saline intrusion, connate and juvenile waters or contamination by industrial effluent or domestic sewage. In the zone of circulation, the chloride ion concentration normally is relatively small. Chloride is a minor constituent in the Earth s crust sodalite and apatite are... 

Saline intrusion occurring in pumped coastal aquifer. 

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