Pengaruh Padatan Tersuspensi terhadap Konsentrasi Klorofil-a dan Fosfat Inorganik Terlarut di Muara Banjir Kanal Barat, Semarang

Abstract

The large number of activities along the West Banjir Kanal river has triggered a change in the condition of its sea waters. The condition most affected is turbidity which caused high concentration of Total Suspended Solid (TSS) in estuary waters and interfere with the entry of sunlight into the waters. The purpose of the study is to determine the effect of the of concentration TSS on the concentration chlorophyll a and dissolved inorganic phosphate (DIP) in the waters of West Banjir Kanal estuary. Water sampling was conducted on October 3, 2019. Water quality parameters such as brightness, pH, temperature, DO and salinity were measured in situ. Meanwhile, chlorophyll a, TSS and DIP measurements were analyzed in the laboratory. The results showed that the highest concentration of TSS, chlorophyll a and DIP were in the estuary area and decreased with further distance from the river mouth with concentration were 70.17-151.50 mg/L, 0.03–2.67 µg/L and 0.71–0.98 µM respectively. Based on the results of the Principal Component Analysis (PCA) showed that TSS affected chlorophyll a by 8.7% (r=0.392; p<0.05) and DIP by 54.46% (r=0.931; p<0.01). The low regression between TSS and chlorophyll a was due to the presence of large amounts of inorganic particles in the West Banjir Kanal river, which makes the river waters become turbid. So, the turbidity of the waters caused the release of phosphate in the sediment to water column which was used by phytoplankton for photosynthesis, so the TSS not only contain sediment particles, but also phytoplankton.

Banyaknya aktivitas di sepanjang sungai Banjir Kanal Barat Semarang, memicu kondisi perairan lautnya menjadi berubah.  Kondisi yang paling terpengaruh adalah kekeruhan yang menyebabkan tingginya konsentrasi Material Padatan Tersuspensi (MPT) di perairan muara dan mengganggu masuknya cahaya matahari ke perairan. Penelitian ini bertujuan untuk mengetahui pengaruh MPT terhadap konsentrasi klorofil-a dan fosfat inorganik terlarut (DIP=Dissolved Inorganic Phosphate) di perairan Muara Banjir Kanal Barat Semarang. Pengambilan sampel air dilakukan pada tanggal 3 Oktober 2019. Parameter kualitas perairan seperti kecerahan, pH, suhu, DO dan salinitas diukur secara in situ. Sedangkan pengukuran klorofil-a, MPT dan DIP dianalisis di laboratorium. Hasil penelitian menunjukkan bahwa konsentrasi MPT, klorofil-a dan DIP tertinggi di daerah muara sungai dan menurun dengan makin jauhnya muara sungai dengan konsentrasi secara berturut-turut sebesar 70,17-151,50 mg/L, 0,03-2,67 µg/L dan 0,71-0,98 µM. Berdasarkan hasil Analisis Komponen Utama (AKU) menunjukkan bahwa MPT mempengaruhi klorofil-a sebesar 8,7% (r = 0,392; P < 0,05) dan fosfat inorganik terlarut sebesar 54,46% (r = 0,931; P < 0,01). Rendahnya hubungan antara MPT dengan klorofil-a ini disebabkan oleh adanya masukan partikel anorganik dalam jumlah besar di badan Sungai Banjir Kanal Barat yang membuat perairan sungai menjadi keruh. Jadi kekeruhan perairan menyebabkan terlepasnya fosfat di sedimen yang dimanfaatkan oleh fitoplankton untuk proses fotosintesa, sehingga yang terkandung dalam MPT selain partikel sedimen juga fitoplankton.