Kualitas Perairan Kali Lamong Kabupaten Gresik Berdasarkan Keanekaragaman Fitoplankton dan Faktor Fisika Kimia

Water Quality of Lamong River in Gresik Regency Based on Phytoplankton Diversity and Chemical Physics Factors

Kali Lamong termasuk dalam wilayah Sungai Bengawan Solo. Bagian hulunya berada di Kabupaten Lamongan dan Mojokerto, sedangkan bagian hilirnya berada di Kabupaten Gresik. Sepanjang aliran sungai Kali Lamong terjadi banyak aktivitas manusia, seperti irigasi, industri, pertanian, dan lainnya, yang dapat menyebabkan pencemaran perairan. Fitoplankton merupakan organisme akuatik yang dapat dijadikan indikator kualitas air pada suatu perairan. Penelitian ini bertujuan untuk menganalisis kualitas air Kali Lamong ditinjau dari keanekaragaman fitoplankton dan faktor fisika kimia. Pengambilan sampel dilakukan di Kali Lamong pada  3 stasiun dengan 3 titik dan 3 pengulangan berupa sampel fitoplankton dan sampel air. Data keanekaragaman fitoplankton dihitung dengan indeks keanekaragaman Shannon-Wiener. Data fisika kimia dianalisis dengan teknik uji kualitas air fisika kimia. Data dihubungkan korelasi antara indeks keanekaragaman fitoplankton dan kualitas air fisika kimia menggunakan SPSS ver.22.00. Hasil penelitian menunjukkan bahwa di perairan Kali Lamong ditemukan fitoplankton terdiri atas 5 divisi, 12 famili, dan 13 marga. Hasil indeks keanekaragaman fitoplankton sebesar 2,40 termasuk kategori sedang. Kualitas perairan Kali Lamong termasuk kriteria baik, dikarenakan secara keseluruhan faktor fisika kimia memenuhi standar baku mutu perairan. Indeks keanekaragaman menunjukkan korelasi negatif dengan pH, dan berkorelasi positif dengan DO, BOD, suhu, dan kekeruhan. Parameter DO memiliki korelasi positif tertinggi menunjukkan korelasi yang kuat dengan indeks keanekaragaman fitoplankton yaitu sebesar +0,687. Berdasarkan indikator fisika kimia dapat disimpulkan bahwa perairan Kali Lamong tercemar dengan kategori ringan.

Lamong River is included in the Bengawan Solo River area. Its upstream part is in Lamongan and Mojokerto regencies, while its downstream part is in Gresik regency. Along the Kali Lamong river there are many human activities, such as irrigation, industry, agriculture, and others, which can cause water pollution. Phytoplankton is an aquatic organism that can be used as an indicator of water quality in a body of water. This study aims to analyze the water quality of Lamong River in terms of phytoplankton diversity and chemical physical factors. Sampling was conducted in Lamong River at 3 stations with 3 points and 3 repetitions in the form of phytoplankton samples and water samples. Phytoplankton diversity data was calculated with Shannon-Wiener diversity index. Chemical physics data were analyzed with chemical physics water quality test techniques. Data were correlated between phytoplankton diversity index and chemical physics water quality using SPSS ver.22.00. The results showed that in the waters of Lamong River, phytoplankton were found consisting of 5 divisions, 12 families, and 13 genera. The phytoplankton diversity index of 2.40 was categorized as medium. The water quality of Kali Lamong is included in the good criteria, because overall the physico-chemical factors meet the water quality standards. The diversity index shows a negative correlation with pH, and a positive correlation with DO, BOD, temperature, and turbidity. The DO parameter has the highest positive correlation showing a strong correlation with the phytoplankton diversity index of +0.687. Based on the physico-chemical indicators, it can be concluded that the waters of Kali Lamong are polluted with a mild category.