Nutrient loads and their impacts on chlorophyll a in the Mae Klong River and estuarine ecosystem: an approach for nutrient criteria development

Abstract

Investigations on the water quality of the Mae Klong River and Estuary were conducted from April 2005 to February 2006 during periods of early-, mid-, and late-loading. Nutrient loads and transfer patterns were studied together with clarification of contaminated sites. The results indicated that NH4+, NO2- + NO3-, Si(OH)4 and PO4(3-) concentrations varied by season and were comparatively high in the mid-loading period. Analysis of DIN:P and Si:P molar ratios indicated that P04(3-) could possibly be a limiting nutrient. Highly contaminated sites were in the middle (Ratchaburi province) and lower (Samut Songkhram province) river zones in which anthropogenic wastewater discharges were significantly (p < 0.05) loaded. Analysis of the DIN and P transfer patterns showed that self-remediation efficiencies were rarely found. The highest DIN and P loads of 23.87 and 4.03 t/day, respectively, were found in Samut Songkhram province. Nutrients were found to contribute to the hypertrophic condition of the lower river and the estuary. The baseline level of chlorophyll a in the upper river was approximately 3.3 microg/L, while levels exceeded 10 microg/L in the estuarine zone. Such chlorophyll a levels were highly significant (p < 0.01) related to DIN and P (with correlation coefficients of 0.44 and 0.37, respectively). In order to maintain river conservation to an acceptable degree, levels of about 20 micromol/L DIN and 1 micromol/L P were suggested as the upper limits. To achieve such levels will require serious consideration with regard to the development of nutrient criteria for water resource conservation management and sustainable utilization purposes.

Production potential of tidal flats for blood clam (Anadara granosa) culture in Bang-tabun bay, Phetchaburi province

“…Salinity increased in May (17.3-29.6‰), which is the late dry season (March-May). Freshwater inflow and precipitationinduced drainage were factors affecting the salinity of water 9 . Chlorophyll a and TSS fluctuated widely among stations and sampled months.…”

Assessment of Nutrient Loads and Self-Remediation: A Case Study of the South Rangsit Canal in Thailand’s Pathum Thani Province

“…According to [11], [13], nutrients in the water could be diluted or enhanced in response to the areas that the water flows through and the nutrient concentrations in turn influence the self-remediation of the waterway. Specifically, the pollutants loads during the rainy season are linked to the point and nonpoint sources [16].…”

“…Moreover, the EFR of the area (along with the south Rangsit canal) were predominantly negative, indicating inadequate self-remediation and the nutrient input-output imbalance [11], a phenomenon that could be attributed to diverse anthropogenic activities that subsequently altered the land-sea fluxes [19] and the balance in the aquatic ecosystem [20].…”

Spatio-Temporal Variations in Water Quality of the Chao Phraya River, Thailand, between 1991 and 2008

“…cluster A) but also the other rivers in the region, i.e. Bangpakong [13], Mae Klong [20] and Tha Chin [21], in which all selected parameters, except temperature, were below the national standard of surface water quality of Thailand at the lowest level, i.e. fairly clean used [22].…”

“…chemical agents and heavy metal) also caused a reduction in DO and are increase in BOD in the lower Chao Phrya River [23,24]. Meanwhile, high NH3-N and derivatives are commonly loaded from surrounding agricultural land uses [20,21].…”