Suatu kajian untuk menilai kesan gabungan aktiviti guna tanah dan perubahan musim terhadap kualiti sumber air telah dijalankan di Terusan Utara, Kedah. Kajian ini dijalankan di lima stesen terpilih selama 12 bulan berdasarkan Indeks Kualiti Air (WQI) dan Piawaian Interim Kualiti Air Kebangsaan (INWQS). Kajian mendapati kualiti air di Terusan Utara berada pada Kelas III dan berlaku peningkatan kualiti air dari hulu ke hilir. Hampir semua stesen berpotensi sebagai punca pencemaran berdasarkan aktiviti guna tanah terutamanya di Pelubang, Jitra serta Tunjang. Kajian menunjukkan terdapat perbezaan yang signifikan ketika perubahan musim pada DO, TSS serta BOD, namun tidak pada ammonia, pH dan COD. Secara amnya, kombinasi aktiviti guna tanah dan perubahan musim boleh mempengaruhi atau memberi kesan terhadap kualiti sumber air. Oleh itu, tindakan segera perlu dilakukan untuk mengawal punca pencemaran bagi memastikan kualiti sumber air di Terusan Utara kekal terpelihara.
Oxidation of p-Cresol was investigated by using ozonation process. The aim of this research is to assess the effectiveness
of ozonation on oxidation of micropollutant such as p-Cresol. Ozonation performance was evaluated based on p-Cresol
concentration reduction and chemical oxidation demand (COD) reduction. It was found ozonation at pH11 achieved
the highest p-Cresol degradation, with 95.8% of p-Cresol reduced and 96.0% of COD reduced, for an initial 50 mgL-1
of p-Cresol. The degradation of p-Cresol could be expressed by second-order of kinetic model. The second-order rate
constant k increases as the initial pH increased, but decreases with the increasing of initial p-Cresol concentrations.
Besides, the absorption spectra of p-Cresol over ozonation time were analyzed by spectrophotometry. The evolution of
absorption spectra of p-Cresol degradation suggests that the oxidation of p-Cresol follows three stages mechanisms
with cycloaddition as the first step to produce aromatic intermediates followed by ring-opening reactions, degradation
of the intermediates, and subsequently achieved mineralization.