Suhaimi Suratman

Spatial and seasonal changes of dissolved and particulate organic C in the North Sea

Sampling of the central region of the North Sea was carried out to study the spatial and seasonal changes of dissolved and particulate organic C (DOC and POC, respectively). The surface waters were collected during four cruises over a year (Autumn 2004–Summer 2005). DOC and POC concentrations were measured using high temperature catalytic oxidation methods. The surface water concentrations of DOC and POC were spatially and temporally variable. There were significantly different concentrations of DOC and POC between the inshore and offshore waters in winter and summer only, with no clear trend in autumn and spring. Highest mean concentrations of DOC were measured in spring with lower and similar mean concentrations for other seasons. POC showed a clear seasonal cycle throughout the year with highest surface mean concentrations found in autumn and spring, but lowest in winter and summer. The DOC distributions during autumn and spring were strongly correlated with chlorophyll suggesting extracellular release from phytoplankton was an important DOC source during these two seasons. The lower concentrations of DOC in summer were probably due to the heterotrophic uptake of labile DOC. The seasonal changes in the C:N molar ratios of surface DOM (dissolved organic matter) resulted in higher mean C:N molar ratios in spring and lower ratios in winter. These high ratios may indicate nutrient limitation of heterotrophic uptake immediately after the spring bloom. There is limited data available for DOC cycling in these productive shelf seas and these results show that DOC is a major component of the C cycle with partial decoupling of the DOC and DON cycling in the central North Sea during the spring bloom.

Dissolved organic matter release by an axenic culture of Emiliania huxleyi

Measurements of the release of dissolved organic nitrogen (DON) and carbon (DOC) were carried out on an axenic batch culture of the coccolithophorid Emiliania huxleyi. This unicellular marine alga was cultured using a media with nitrate as the sole N source and the changes of DOM concentrations measured over 14 days. Results showed that there was a significant release of DON, i.e.7.6M N day1 during mid-exponential growth phase (days 57). The highest release of DOC was also recorded in the same growth phase and accounted for 24.0M C day1.

Sandbar-regulated hydrodynamic influences on river hydrochemistry at Mengabang Telipot River, Peninsular Malaysia

Influences of river hydrodynamic behaviours on hydrochemistry (salinity, pH, dissolved oxygen saturations and dissolved phosphorus) were evaluated through high spatial and temporal resolution study of a sandbar-regulated coastal river. River hydrodynamic during sandbar-closed event was characterized by minor dependency on tidal fluctuations, very gradual increase of water level and continual low flow velocity. These hydrodynamic behaviours established a hydrochemistry equilibrium, in which water properties generally were characterized by virtual absence of horizontal gradients while vertical stratifications were significant. In addition, the river was in high trophic status as algae blooms were visible. Conversely, river hydrodynamic in sandbar-opened event was tidal-controlled and showed higher flow velocity. Horizontal gradients of water properties became significant while vertically more homogenised and with lower trophic status. In essence, this study reveals that estuarine sandbar directly regulates river hydrodynamic behaviours which in turn influences river hydrochemistry.

A Baseline Assesment on the Distributions and Sources of Aliphatic and Polycyclic Aromatic Hydrocarbons in Abiotic Environment of Terengganu National Park

A baseline study to assess the distributions of aliphatic and polycyclic aromatic hydrocarbons in abiotic environment consisting of soil, sediment and atmospheric particulate samples was carried in Terengganu National Park. Aliphatic hydrocarbons were found in all three media studied whilst polycyclic aromatic hydrocarbon (PAH) compounds were detected, only in the atmospheric particulate samples, at trace levels. The 24 hr-PM10 and Total Suspended Particulate (TSP) concentrations is still below the recommended Malaysian Air Quality Guidelines for the respective parameter. Analyses of the results suggest that terrestrial plant waxes is the main source of aliphatic hydrocarbons in the study area whereas sources for PAHs in the particulate samples are most likely derived from combustion sources. The detection of PAHs in the aerosol samples also suggest possible anthropogenic input of particulate matter to the study area; however the levels are still well below the values reported for other locations in Malaysia.

A Preliminary Study of the Distribution of Nitrogen Compounds in Tasik Kenyir, Malaysia

A preliminary study of N compound levels in Tasik Kenyir, Terengganu, Malaysia was conducted from August to October 2010. In general, most of the monitoring stations had relatively higher concentrations of N compounds in the bottom water compared to the surface water. In comparison with other selected study areas in Malaysia, the concentration of N compounds in Tasik Kenyir were low, most likely due to less anthropogenic activities around the lake. Based on the National Water Quality Standard (NWQS) classification for Malaysia, the N compound levels for both the surface and bottom waters of Tasik Kenyir can be considered at a natural level (Class 1), indicating that the water is suitable for the conservation of the natural environment, for water supply with practically no treatment necessary, and for fishery activity including that for very sensitive aquatic species.