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MSP 513 : PRODUKTIVITAS PERAIRAN - SDP SIGID HARIYADI Produktivitas & Lingkungan Perairan (Proling) Dept. MSP – FPIK - IPB.

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Presentasi berjudul: "MSP 513 : PRODUKTIVITAS PERAIRAN - SDP SIGID HARIYADI Produktivitas & Lingkungan Perairan (Proling) Dept. MSP – FPIK - IPB."— Transcript presentasi:

1 MSP 513 : PRODUKTIVITAS PERAIRAN - SDP SIGID HARIYADI Produktivitas & Lingkungan Perairan (Proling) Dept. MSP – FPIK - IPB

2 I. Faktor Abiotik II. Faktor Biotik 1. Cahaya 2. Temperatur 3. Nutrien 4. Oksigen 5. Kualitas fisika-kimia air lainnya: kekeruhan/TSS, bahan toksik 1. Kompetisi 2. Pemangsaan / grazing FAKTOR-FAKTOR yang mempengaruhi Produksi Primer

3 ESSENTIAL NUTRIENT Tucker, MR Essential Plant Nutrients: their presence in North Carolina soils and role in plant nutrition Salah satu dari 11 element utama dalam produksi bahan organik: C, H, O, N, P, K, S, Na, Ca, Mg dan Cl

4  biomass-limiting nutrients: membatasi produksi biomass  rate-limiting nutrients: membatasi laju produktivitas primer C (carbon) C

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7 *kelarutan pada air murni 10°C, 1 atm N 2 – Nitrogen O 2 – Oksigen Ar – Argon CO 2 – Karbon dioksida

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9 Kelarutan CO 2 dalam air murni pada berbagai temperatur CO 2 berupa gas, di atmosfer : 0,027- 0,044 % (0,033%), tetapi kelarutannya tinggi : 1194 ml/L

10 44 g CO 2  (1,2 x 32) g O 2 1 g CO 2  g O 2 Bila PQ = 1,0 maka 1 mol CO 2 akan menghasilkan 1 mol O 2 Tetapi PQ ≠ 1  PQ = 1.2 maka 1 mol CO 2 akan menghasilkan 1,2 mol O 2

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13 C 6 H 12 O O 2  6 CO H 2 O + energi (674 kcal) Tiap 1 mol glukosa yang dibakar (dioksidasi) menghasilkan energi Tiap 1 mol glukosa yang dibakar (dioksidasi) menghasilkan energi 674 kcal., maka : 674 kcal., maka :

14 – Bila karbohidrat sederhana terdekomposisi : RQ =  O 2 /  CO 2 = 1.0 – Dekomposisi & respirasi yang terjadi tidak hanya pada karbohidrat sederhana, tetapi juga lemak, protein dan berbagai bahan lainnya pada proporsi yang berbeda-beda  CO 2 yang diproduksi lebih kecil dari O 2 terpakai  Sehingga  CO 2 /  O 2 < 1.0 atau RQ = 0.85  Berarti Σ O 2 dikonsumsi X 0.85 = CO 2 dihasilkan oleh proses dekomposisi aerobik & respirasi dalam jangka waktu tertentu (Respiratory Quotient)

15 In water  Cyanobacteria possess carboxysomes, which increase the concentration of CO 2 around RuBisCO to increase the rate of photosynthesis. Cyanobacteriacarboxysomes  An enzyme, carbonic anhydrase, located within the carboxysome releases CO 2 from the dissolved hydrocarbonate ions (HCO 3 – ). Before the CO 2 diffuses out it is quickly sponged up by RuBisCO, which is concentrated within the carboxysomes.carbonic anhydrase  HCO 3 – ions are made from CO 2 outside the cell by another carbonic anhydrase and are actively pumped into the cell by a membrane protein. They cannot cross the membrane as they are charged, and within the cytosol they turn back into CO 2 very slowly without the help of carbonic anhydrase. This causes the HCO 3 – ions to accumulate within the cell from where they diffuse into the carboxysomes.  Pyrenoids in algae and hornworts also act to concentrate CO 2 around rubisco Pyrenoidsalgaehornworts

16 RuBisCO The enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO or just rubisco is used in the Calvin cycle to catalyze the first major step of carbon fixation. RuBisCO is thought to be the most abundant protein in the world since it is present in every plant that undergoes photosynthesis and molecular synthesis through the Calvin cycle.Calvin cycle RuBisCO catalyzes either the carboxylation or oxygenation of ribulose-1,5-bisphosphate (known as RuBP) with carbon dioxide or oxygen. What makes it unique and different to every other enzyme is the fact that it can survive on its own without the need of the plant so even if it is dead it remains and helps decomposition. This is due to it not being affected by temperature or pH.RuBP

17 phosphoglyceric acid glyceraladehyde-3-phosphate

18  Carbon dioxide diffuses into the stroma of chloroplasts and combines with a five-carbon sugar, ribulose1,5- biphosphate (RuBP). The enzyme that catalyzes this reaction is referred to as RuBisCo, a large organic molecule. This catalyzed reaction produces a 6-carbon intermediate which decays almost immediately to form two molecules of the 3-carbon compound, 3- phosphoglyceric acid (3PGA).RuBPRuBisCo3PGA  Carbon dioxide is captured in a cycle of reactions known as the Calvin cycle or the Calvin-Benson cycle. It is also known as just the C 3 cycle.  The fact that this 3-carbon molecule is the first stable product of photosynthesis leads to the practice of calling this cycle the C 3 cycle.

19  As carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases until limited by other factors.light-independent reactions  RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. RuBisCO  When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. However, if the carbon dioxide concentration is low, RuBisCO will bind oxygen instead of carbon dioxide.fix carbon dioxide  This process, called photorespiration, uses energy, but does not produce sugars.photorespiration

20  photorespiration is an entirely negative term because it represents a severe loss to the process of using light energy in photosynthetic organisms to fix carbon for subsequent carbohydrate synthesis.  By leading to the loss of up to half of the carbon that has been fixed at the expense of light energy, photorespiration undoes the work of photosynthesis. But during hot and dry conditions, the stomata close to prevent excessive water loss and the continuing fixation of carbon in the Calvin cycle dramatically reduces the relative concentration of CO 2. When it reaches a critical level of about 50 ppm the rubisco stops fixing CO 2 and begins to fix O 2 instead. Even though the detoured process feeds some PGA back into the cycle, the photorespiration process causes rubisco to operate at only about 25% of its optimal rate.Calvin cycle

21 An increase in the carbon dioxide concentration increases the rate at which carbon is incorporated into carbohydrate in the light-independent reaction, and so the rate of photosynthesis generally increases until limited by another factor. As it is normally present in the atmosphere at very low concentrations (about 0.04%), increasing carbon dioxide concentration causes a rapid rise in the rate of photosynthesis, which eventually plateaus when the maximum rate of fixation is reached.

22 In 1905, when investigating the factors affecting the rate of photosynthesis, Blackmann formulated the Law of limiting factors. This states that the rate of a physiological process will be limited by the factor which is in shortest supply. Any change in the level of a limiting factor will affect the rate of reaction. For example, the amount of light will affect the rate of photosynthesis. If there is no light, there will be no photosynthesis. As light intensity increases, the rate of photosynthesis will increase as long as other factors are in adequate supply. As the rate increases, eventually another factor will come into short supply. The graph below shows the effect of low carbon dioxide concentration. It will eventually be insufficient to support a higher rate of photosynthesis, and increasing light intensity will have no effect, so the rate plateaus.

23 If a higher concentration of carbon dioxide is supplied, light is again a limiting factor and a higher rate can be reached before the rate again plateaus. If carbon dioxide and light levels are high, but temperature is low, increasing temperature will have the greatest effect on reaching a higher rate of photosynthesis.

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25 Temp  rate of photosynthesis [CO 2 ]  rate of photosynthesis

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27 1% CO 2 dalam air berdissosiasi :  Karena mengandung CO 2 (berarti juga asam karbonat), maka air melarutkan kapur menjadi kalsium karbonat : CaCO 3 + H 2 CO 3 Ca(HCO 3 ) 2  Berkaitan dengan reaksi ini, dikenal:  CO 2 pengimbang -- utk mempertahankan jumlah Ca(HCO 3 ) 2  CO 2 agresif = sejumlah CO 2 utk melarutkan kapur lebih lanjut Bila CO 2 pengimbang berkurang, maka: hidrolisa dissosiasi I dissosiasi II asam karbonat bikarbonat karbonat CO 2 + H 2 O H 2 CO 3 H + + HCO 3 - H + + CO 3 = Ca(HCO 3 ) 2 CaCO 3 + H 2 O + CO 2

28 asam karbonat bikarbonat karbonat CO 2 + H 2 O H 2 CO 3 H + + HCO 3 - H + + CO 3 = Selain kesetimbangan di atas, bikarbonat dan karbonat dalam air juga mengalami hidrolisa :  HCO 3 - +H 2 O H 2 CO 3 + OH -  CO 3 = +H 2 O HCO OH - Dissosiasi asam karbonat dapat juga dituliskan: H 2 CO 3 H 2 O + CO 2 Pada perairan basa, kesetimbangan 2 di atas dapat merupakan sistem buffer (penyangga pH) perairan: karbonat ( garam ) --- CaHCO 3 asam karbonat ( asam lemah ) -- H 2 CO 3 { & Pada sistem buffer ini :  Penambahan basa kuat  bereaksi dg. H 2 CO 3  garam + HCO 3 -  Penambahan asam kuat  bereaksi dg. HCO 3 - atau CO 3 =  H 2 CO 3  sistem buffer = campuran SigidHariyadi

29 % 50% HCO 3 - CO 3 = CO pH & H 2 CO 3  Bentuk-bentuk CO 2 di perairan alam: Ca(HCO 3 ) 2 CaCO 3 + CO 2 + H 2 O garam asam garam netral CO 2 bebas & berupa asam : (H 2 CO 3 )  hydrated state SigidHariyadi 29

30 12 C 13 C 14 C radioaktif non radioaktif 98,9 % 14 N + n 14 C + H 14 C + O 2 14 CO 2 hanya dari 12 CO 2 _______ 1,2 x neutron Isotop-isotop C pada CO 2 : SigidHariyadi

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33 CO 2 mg/L = x 10 6 [H + ] x mg/L alkalinitas sebagai HCO 3 CO 2 mg/L = x 10 6 [H + ] x mg/L alkalinitas total sebagai CaCO

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35 Referensi:    

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