การศึกษาคุณภาพน้ำและตะกอนดินอ่าวปากพนังและบริเวณนอกปากทะเลสาบสงขลา

Abstract

The qualities of water and sediment in Pak Panang Bay (PPB) and Off Songkhla Lake mouth (OSKL) were assessed. The information obtained will be used for coastal water quality management in the areas. Two investigations were preformed in February (early dry season) and late May–early June (early wet season) 2007, composed of 15 stations in PPB and 16 stations in OSKL. In PPB, the results showed water temperature in early wet and dry seasons were 32.1±0.93 oC and 28.7±1.6 oC, respectively. In OSKL area, the results showed water temperature in early wet and dry seasons were 31.5±0.4 oC and 30.1±0.8 oC, respectively. The variation of salinity and pH in PPB water was higher than those in OSKL as a result of freshwater discharged from Pak Panang river. Nutrients (N, P and Si) concentration in PPB were higher than OSKL, in particular, reactive phosphate and total phosphorus were much higher. Average chlorophyll a concentration in PPB in early wet and dry seasons were 2.51 ± 2.08 and 1.90 ± 1.27 mg/m3, respectively, and were 0.48 ± 0.15 and 0.58 ± 0.33 mg/m3, respectively, in OSKL. In general, the texture of bottom sediment in PPB was finer than those of OSKL except nearby Laem Ta-Lum-Pok. In OSKL area, organic matter and nutrient contents in sediment were related to percentage of both clay-size (< 2 μm) and silt-size (2 – 63 μm) particles, while PPB were related only to the percentage of clay-size particles. Moreover, the results indicated that some amount of nutrients were entrapped in the Songkhla Lake which less of them were exported to the Gulf of Thailand.