Assessment of the characteristic of nutrients, total metals, and fecal coliform in Sibu Laut River, Sarawak, Malaysia

Abstract

The concentrations of nutrients (nitrogen and phosphorus), total metals, and fecal coliform (FC) coupling with chlorophyll-a (chl-a), 5-day biochemical oxygen demand (BOD 5 ) and other general environmental parameters were evaluated at the sub-surface and near-bottom water columns of 13 stations in the Sibu Laut River during low and high slack waters. The results indicated that inorganic nitrogen (mainly nitrate) was the primary form of nitrogen whereas organic phosphorus was the major form of phosphorus. The abundance of total heavy metals in Sibu Laut River and its tributaries was in the order of Pb \ Cu \ Zn \ Cd. Fecal coliform concentration was relatively low along Sibu Laut River. The shrimp farm effluents contributed a substantial amount of chl-a, BOD 5 , nutrients, and FC to the receiving creek except for total metals. Nevertheless, the influence was merely noticeable in the intake creek and amended rapidly along Selang Sibu River and brought minimal effects on the Sibu Laut River. Besides, the domestic sewage effluents from villages nearby also contributed a substantial amount of pollutants.

Assessment of Near-Bottom Water Quality of Southwestern Coast of Sarawak, Borneo, Malaysia: A Multivariate Statistical Approach

“…The negative correlation between salinity and nitrogen and positive correlation between pH and nitrogen indicated the contribution of riverine nitrogen source to the Sarawak coastal water. Reference [7] demonstrated that the Sibu Laut River contained high NO 3 − -N concentration which is in agreement with the NO 3 − -N concentration in the coastal water. In addition, the high DO content in coastal water also accelerates the decomposition and nitrification process where organic content was converted to the end product of NO 3 − -N. The present study demonstrated that Sarawak nearbottom coastal water was rich in total phosphorus where it was categorized from mesotrophic to hypertrophic status.…”

“…Station 7 was located near the Sibu Laut River which forms the western boundary of the Kuching Wetland National Park. Shrimp farms and villages were located along the river which contributed substantial organic matter to the river and subsequently the coastal area [7,34]. Coastal water quality at other stations was relatively good and mostly complied with the MWQS, except for NO 3 − -N where all stations violated the MWQS.…”

“…Although deterioration of the coastal environment due to increasing population and urbanization is noticeable in Sarawak [6], the study conducted on Sarawak coastal water is scarce. Aquaculture and domestic sewage with high nutrients content is being discharged directly into rivers [7] while deforestation for timber production and agricultural development has increased soil erosion and inputs of fertilizers in Sarawak River [8,9], all of which could lead to increased sedimentation and eutrophication in coastal areas.…”

“…Comprehensive study on surface water quality has been conducted worldwide but near-bottom water quality is often being neglected in water quality monitoring. Subsurface and near-bottom water often exhibited distinct different water quality due to inadequate mixing in deep water column [7,10,11]. Water quality is a principal factor that influences the biota community structure and health condition [12][13][14][15][16].…”

“…Among them, cluster analysis (CA) and principal component analysis (PCA) have been applied in the assessment of spatial variation of tidal river and freshwater forest streams water quality in Sarawak [7,9,22]. However, the study on Sarawak coastal water quality is scarce; and the application of CA and PCA for the assessment of the Sarawak coastal water quality has not yet been conducted.…”