KEPENTINGAN/PERANAN CAHAYA :

Mempertahankan suhu Proses fotosintesis Siklus hidrologi

SATUAN CAHAYA : Watt, Joule, Lux, Langley, Kalori Foot candle,

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Siklus hidrologi

Sumber: Max Planck Institut For Meteorology (1999)

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PANJANG GELOMBANG ( λ ) : 100 – 3.000 nm (10-9m)

< 300 nm : Ultra Violet

300 – 700 nm : PAR – Photosynthetic Active Radiation Visible Light

300 – 490 nm Biru 490 – 585 nm Hijau 585 – 700 nm Merah

555 nm Kuning Hijau, Pusat Cahaya

> 700 nm : Infra Red

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The electromagnetic spectrum. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com).

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

The electromagnetic spectrum:

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ALAT PENGUKUR CAHAYA :

LUX METER, PYRHELIOMETER

ALBEDOMETER

PHOTOCELL IMMERGEABLE

SECCHI DISK/DISC

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Penurunan cahaya karena :

1. Refleksi – dipantulkan

2. Absorpsi – diserap Refleksi + Absorpsi + Transmisi = 1

3. Transmisi – Dibiaskan

datang pantul

bias

α1 α2

α3

α1 = α2

α1 > α3

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CAHAYA DARI MATAHARI (%) YANG SAMPAI KE BUMI

Total ; Asal Hilang ; Asal Sisa ; Asal

Luar Atmosfir 100 ; 100 48 ; 48 52 ; 52

Atmosfir 100 ; 52 60 ; 31 40 ; 21

Permukaan air 100 ; 21 50 ; 10,5 50 ; 10,5

Dari matahari : 1,92 gcal/cm2/menit

Daerah ekuator : 800-900 gcal/cm2/hari

Kutub pada musim panas : 1.100 gcal/cm2/hari

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Rumus LAMBERT-BEER

Iz = Io. e-kz

z = Kedalaman Iz = Intensitas cahaya pada kedalaman z Io = Intensitas cahaya pada kedalaman 0 (permukaan) e = Bilangan eksponensial k = Coeficient of Extinction, ( Koefisien Peredaman, Pemadaman, Peredupan)

Kz = K air + K Partikel Tersuspensi + K Diss.coll.compound

Nilai K berbeda : Setiap Perairan Setiap Waktu Setiap Panjang Gelombang Setiap Kedalaman

RUMUS LAMBERT-BEER

Iz = Io e-kz

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Iz = I0.e-kz dikalikan Ln

Ln Iz = Ln Io.e-kz

= Ln Io + Ln e-kz

= Ln Io – kz Ln e (Ln e = 1)

= Ln Io – kz

Ln Iz + kz = Ln Io

Kz = Ln Io – Ln Iz

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Kz = Ln Io – Ln Iz

Depth (m) Nilai Cahaya (%)

Ln K

0 100 4,61

0,16

2 86 4,45

0,15

4 74 4,30

0,52

6 44 3,78

0,15

8 38 3,63

0,14

10 33 3,49

Jumlah 1,12S2 Produktivitas Perairan

ZONASI VERTIKAL CAHAYA DI DALAM AIR

0 1 50 100Incident Light (%)

Depth Fotosintesis > Respirasi

Fotosintesis = Respirasi

Fotosintesis < Respirasi

Compensation Depth

ZONE PHOTIC

ZONE APHOTIC

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Pukul Cahaya di permukaan

Cahaya di kedalaman 5 m

% Lux % Lux08 100 100 1 110 100 500 1 512 100 1.000 1 1014 100 900 1 9

Misalnya agar fotosintesis = respirasi diperlukan cahaya 5 lux

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KESUBURAN PERAIRAN DILIHAT DARI CAHAYA

1. Subur (Eutrophe) 0 – 3 m2. Moderat/Sedang (Mesotrphe) 3 – 6 m3. Miskin/tidak subur (Oligotrophe) >6 m

Catatan : - Perairan Tawar - Kedalaman perairan > 6 m

RATA-RATA NILAI PRODUKSI PRIMER BERSIH BERBAGAI LINGKUNGAN (Valiela, 1984)

Lingkungan g/m2 /Tahun

Laut Terbuka 125

Upwelling 500

Continental shelf 300

Hamparan alga dan terumbu 2.500

Estuari tanpa rawa (marsh) 1.500

Total Laut (marine) 4.925

Terrestrial (daratan) 737

Rawa (swamp and marsh) 3.000

Danau dan sungai 400

Total kontinental 4.137

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Images from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html S2 Produktivitas Perairan

ChlorophyllsTwo types of chlorophyll are found in plants and the green algae. ·        chlorophyll a, & ·        chlorophyll bThe difference in their structures is shown in the figure (red disks).

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chlorophyll.html

http://www.chemsoc.org/networks/learnnet/cfb/Photosynthesis.htm

Chlorophyll

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the structure of beta-carotene, one of the most abundant carotenoids. Note: the system of alternating single and double bonds that in this molecule runs along the hydrocarbon chain that connects the two benzene rings.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chlorophyll.html

http://www2.mcdaniel.edu/Biology/botf99/photo/p3igments.htm

Xanthophylls are essentially oxidized Carotenoids and contain oxygen. They are usually red and yellow and do not absorb energy as well as cartenoids. They are also fat soluble.

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http://www2.mcdaniel.edu/Biology/botf99/photo/p3igments.htm

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http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/energyflow/energyflow.html S2 Produktivitas Perairan

THE LIGHT REACTIONS OF PHOTOSYNTHESIS

http://employees.csbsju.edu/hjakubowski/classes/ch331/oxphos/olphotsynthesis.html S2 Produktivitas Perairan

Figure 2. Absorption spectrum of isolated chlorophyll and carotenoid species. The color associated with the various wavelengths is indicated above the graph.

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ENAN M ADIWILAGA

Lantai 2 Wing 14 (N) Nomor 2 – Menghadap ke danau

Telp. Facs 8421731

Rumah : Jl Soka No 18 Kampus IPB Darmaga (Perumdos) Bogor 16680

Telp.Facs. 8621325

HP 0811118108

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