Spatio-Temporal variations of dissolved organic matter and several trace metals at lower Kinabatangan River Catchment, Sabah
Tropical catchment serve as an important source of dissolved organic matter to aquatic ecosystems. Dissolved organic matter play an significant role in aquatic biochemical processes by providing nutrients for aquatic biota, act as a key component within the carbon cycle as well as controlling the sp...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/25772/1/Spatio-Temporal%20variations%20of%20dissolved%20organic%20matter%20and%20several%20trace%20metals.pdf |
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| Summary: | Tropical catchment serve as an important source of dissolved organic matter to aquatic ecosystems. Dissolved organic matter play an significant role in aquatic biochemical processes by providing nutrients for aquatic biota, act as a key component within the carbon cycle as well as controlling the speciation and mobility of metal compounds. Extensive land conversion has been particularly observed in Lower Kinabatangan River Catchment; however, the environmental implications of this expanding agro-forestry industry specifically on dissolved organic matter quality and quantity as well as trace metal distribution has yet to be quantified. Therefore, the objectives of this study were to determine the spatial and temporal variations of dissolved organic matter and trace metal. Besides that, the relationship between trace metal concentrations, spectroscopic properties of dissolved organic matter and water parameters with each other were also investigated in this study. A total of 180 water samples draining from an oil palm plantation, secondary forest and semi-natural vegetation at Lower Kinabatangan were collected between October 2015 to May 2016. Results of the linear discriminant analysis indicated that freshness index and cadmium metal were dominant for water samples from oil palm plantation. Whereas, temporally varied nickel and chromium metal concentration were observed in waters during dry and wet periods respectively, while Peak M intensity were significant during both periods. The predominance of freshness index could indicate fresher autochthonous organic materials of recent microbial contributions to the aquatic DOM pools within oil palm plantation. In addition, sunlight abundance and rainfall events enhanced microbial and/or photodegradation processes that led to high values of DOM with low molecular weight, as characterized by fluorescence peak M. In general, although cadmium, nickel and chromium concentrations are significant at oil palm plantation as well as during dry and wet periods respectively, all the measured concentrations of trace metal in water were found either in trace or below detection level. These reflects that the metal compounds are from natural origin, with little to no input from anthropogenic sources. The distribution of trace metals at Lower Kinabatangan River Catchment was significantly influenced by fluctuation of pH level. The water pH is generally control by inputs of organic materials, which in turn affects the interaction between DOM and metal. |
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