250
R.R. Twilley et a!.
accounts for about 70 o/o of dissolved inorganic nitrogen (DIN; Cardenas
1995). Along the inner boundary of the Gulf in the Jambeli Channel, nitrate concentrations increase from the surface ( 1-6jlM) to a depth of more
than 10m (>20 f.!M; Pesantes and Perez 1982). Similarly, nitrite concentrations are higher (0.6-0.9jlM) at 5 m depth than at surface and tend to
increase during the wet season near the mouth of estuaries, particularly in
the Jubones River (Stevenson 1981). The subestuaries have low nutrient
loading and lack clear seasonal changes of N0 3 -, NH/, and DON concentrations with river discharge. Average N0 3 -, NH/, and DON concentrations in the Guayas, Churute, and Salado subestuary are 12, 3.0, lljlM, 11,
2.4, 12jlM, and 7, 3.3, 7jlM, respectively (Cardenas 1995).
Soluble reactive phosphate (SRP) concentrations in surface waters of the
Gulf range from 0.6 to 1.0 jlM and reach about 2.0 jlM near Puna Island.
Concentrations increase with depth (20m: < 1.0 jlM; 70 m: > 1.9jlM) and
higher bottom concentrations are particularly evident near shoal areas
along the southeast boundary of the Gulf proximate to the Jubones River.
Soluble reactive phosphate (SRP) represents about 55 o/o of the total phosphorus (TP) pool in the Guayas River estuary (Cardenas 1995) and, as DIN,
lacks a clear seasonal pattern (Fig.17.3). The similarity of average SRP concentrations in Guayas (2.4jlM), Churute (2.6jlM), and Salado (2.2jlM) subestuaries may be the result of buffer mechanisms that maintain SRP concentrations within the 1-3jlM range. With a few exceptions, dissolved
organic phosphorus (DOP) concentrations in the Gulf are approximately
2jlM (Cardenas 1995) and mean concentrations in subestuaries vary between 0.7 and 0.9jlM.
Dissolved silicate distributions in surface waters of the Gulf are related
to freshwater discharge. Concentrations in the outer Gulf are 5-10 jlM,
compared to 46jlM in the inner Gulf during the dry and 120 jlM during the
wet season (Stevenson 1981). Similarly, mean Si concentrations are conspicuously higher in the subestuaries (Guayas 124jlM, Churute 146jlM,
Salado 56jlM) during the wet season (Cardenas 1995). Elevated silicate
levels during both the dry (153jlM) and wet seasons (206jlM) in the upper
Guayas subestuary indicate the importance of the Guayas river as a major
source of silicate (Fig. 17.3).
R.R. Twilley et a!.
accounts for about 70 o/o of dissolved inorganic nitrogen (DIN; Cardenas
1995). Along the inner boundary of the Gulf in the Jambeli Channel, nitrate concentrations increase from the surface ( 1-6jlM) to a depth of more
than 10m (>20 f.!M; Pesantes and Perez 1982). Similarly, nitrite concentrations are higher (0.6-0.9jlM) at 5 m depth than at surface and tend to
increase during the wet season near the mouth of estuaries, particularly in
the Jubones River (Stevenson 1981). The subestuaries have low nutrient
loading and lack clear seasonal changes of N0 3 -, NH/, and DON concentrations with river discharge. Average N0 3 -, NH/, and DON concentrations in the Guayas, Churute, and Salado subestuary are 12, 3.0, lljlM, 11,
2.4, 12jlM, and 7, 3.3, 7jlM, respectively (Cardenas 1995).
Soluble reactive phosphate (SRP) concentrations in surface waters of the
Gulf range from 0.6 to 1.0 jlM and reach about 2.0 jlM near Puna Island.
Concentrations increase with depth (20m: < 1.0 jlM; 70 m: > 1.9jlM) and
higher bottom concentrations are particularly evident near shoal areas
along the southeast boundary of the Gulf proximate to the Jubones River.
Soluble reactive phosphate (SRP) represents about 55 o/o of the total phosphorus (TP) pool in the Guayas River estuary (Cardenas 1995) and, as DIN,
lacks a clear seasonal pattern (Fig.17.3). The similarity of average SRP concentrations in Guayas (2.4jlM), Churute (2.6jlM), and Salado (2.2jlM) subestuaries may be the result of buffer mechanisms that maintain SRP concentrations within the 1-3jlM range. With a few exceptions, dissolved
organic phosphorus (DOP) concentrations in the Gulf are approximately
2jlM (Cardenas 1995) and mean concentrations in subestuaries vary between 0.7 and 0.9jlM.
Dissolved silicate distributions in surface waters of the Gulf are related
to freshwater discharge. Concentrations in the outer Gulf are 5-10 jlM,
compared to 46jlM in the inner Gulf during the dry and 120 jlM during the
wet season (Stevenson 1981). Similarly, mean Si concentrations are conspicuously higher in the subestuaries (Guayas 124jlM, Churute 146jlM,
Salado 56jlM) during the wet season (Cardenas 1995). Elevated silicate
levels during both the dry (153jlM) and wet seasons (206jlM) in the upper
Guayas subestuary indicate the importance of the Guayas river as a major
source of silicate (Fig. 17.3).