Assessment of Green House Gases (GHGS) Emission from Some Aquaculture Ponds of Andhra Pradesh and West Bengal, India

The Green House Gas Emission (GHGs) from the carp culture ponds (n = 12) of West Godavari, Krishna, and Guntur districts of Andhra Pradesh and from the ponds (n = 4) of Moyna, East Medinipur district of West Bengal, India was assessed through carbon storage and carbon footprint analysis. The average inputs as Carbon Equivalent (CE) were 14407 ± 2651, and 9231 ± 1007 kg/ha in Andhra Pradesh, and West Bengal, respectively. The average carbon storage were 6216 ± 2291, and 5360 ± 1439 kg/ha, in Andhra Pradesh, and Moyna, West Bengal respectively. The emissions of CO2-e and CH4-e were 1.91 ± 0.42 kg CO2-e/kg fi sh and 0.122 ± 0.027 kg CH4-e/kg fi sh, respectively in Andhra Pradesh. The emissions of CO2-e and CH4-e were 0.006 to 2.07 (average 0.72) kg CO2-e /kg fi sh, and 0.0004 to 0.132 (average 0.046) kg CH4-e /kg fi sh production, respectively in Moyna, West Bengal. ABSTRACT *Corresponding author


INTRODUCTION
Global warming is one of the important climate change element. Increase in Greenhouse Gases (GHGs) concentration in the atmosphere is the main reason for climate change as accumulated GHGs in the atmosphere intercepts outgoing infrared radiation which traps heat and raises the temperature in the atmosphere.
During the last three decades world food fi sh production of aquaculture has expanded by almost 12 times, with an average annual rate of 8.8 per cent. Presently 600 aquatic species are raised in captivity in about 190 countries for production in farming systems of varying input intensities and technological sophistication [1]. Thus, there is chance of emitting diff erent GHGs from the diff erent aquaculture systems.
From the aquaculture systems, GHGs can be released to the atmosphere in two ways: diff usive emission (emanation) and emission as bubbles. In diff usive emission, gases dissolved in water molecularly diff use from water to the air. Bubbles form naturally in the bottom and go up periodically. In anaerobic conditions, the gas forms methane, whereas in oxygenated bottoms, carbon dioxide dominates. As methane is not consumed by aquatic organisms, it dissipates in the water column [2].
Gas fl ow between water and the atmosphere changes by the time of day and can be quite variable, and to quantify emission rates, a diff usion chamber can be used. The samples could be analyzed through specifi c gas-chromatographic analysis. However, the methodology is somewhat complex and the analysis is also expensive.
Indirectly the emission of gases can be predicted through carbon footprint analysis of any culture system or Life Cycle Analysis (LCA) of a crop production system. Literatures of some LCA studies of aquaculture practices are available [3][4][5]. In the present study, the GHGs emission from the carp culture ponds of Andhra Pradesh and West Bengal, India has been assessed through carbon storage and carbon footprint analysis. Feed (25-30 % protein), cow dung (organic fertilizer), inorganic fertilizers (urea, single super phosphate, diammonium phosphate), and lime are mainly used as inputs to produce the fi sh.

MATERIALS AND METHODS
For carbon footprint analysis, all the inputs added to an aquaculture system are converted into Carbon Equivalence (CE). Amortization of pond construction was done as per [6]. The Pond inputs and their respective CE emissions are presented in (Table 1).
Soil carbon storage was measured by CORE Method. In this method, sediment samples from the pond was collected by a soil sampler (Corer) in such a way that only the sediment core was collected, no bottom soil below the sediment was collected. The sediment dry bulk density was measured and the sediment organic carbon was determined by CHN Analyzer. The carbon storage (Mg C/ha, mega gram C/ha) was calculated as per [7] as follows = [C (%)*dry bulk density (Mg/m 3 ) *depth (m)* *10 4 m 2 ]/100.
The average C content in the fi sh fl esh on dry weight basis was 42 %.
The chance of C emission = Total input -Carbon storage-Carbon removal through produce About 80-90 % of the carbon could be converted into CO 2 as the dissolved oxygen concentration in the pond environment is 5.0 mg/l (aerobic condition) while about 10-20 % chance of the carbon to be converted into CH 4 as an emission (under anaerobic condition). In the present study, it was considered that 85 % of the C could be converted into CO 2 and 15 % of the carbon could be converted into CH 4 as an emission as the dissolved oxygen concentration was 4.5 to 5.5 mg/l in these aquaculture ponds.
The data were presented with the Standard Deviation (SD) except few cases because of wider variations.

RESULT AND DISCUSSION
The Carbon Equivalent (CE) of all the inputs used in diff erent aquaculture ponds of Andhra Pradesh are presented in table 2. The amortization for pond construction was 27 kg CE/ha. The CE for lime used in these ponds was 5 to 40 kg CE/ ha. The CE for organic (cow dung) and inorganic fertilizers varied from 550 to 4500 kg CE/ha, and from 12 to 4500 kg CE/ ha, respectively. The CE for feed used in these ponds ranged from 7326 to 18559 kg CE/ha during the culture period.
The carbon storage of the fi sh ponds of Andhra Pradesh are given in table 3. The sediment level of the ponds varied from 5.1 to 6.3 cm with an average of 5.78 ± 0.38 cm during the culture period. The dry bulk density of the sediment varied from 0.37 to 1.29 Mg/m 3 with an average of 0.77 ± 0.24 Mg/m 3 .The organic carbon content varied from 0.64 to 2.84 % with an average of 1.55 ± 0.76 %. The carbon storage ranged from 4039 to11466 kg/ha/culture with an average of 6216 ± 2291 kg/ha/culture. The fi sh production levels of these ponds varied from 5000 to10000 kg/ha/culture with an average of 7875 ± 1646 kg/ha/culture. The Carbon Equivalent (CE) of all the inputs used in diff erent aquaculture ponds of Moyna, West Bengal are presented in table 4. The amortization for pond construction was 50 to 115 kg CE/ha. The CE for lime used in these ponds was 160 kg CE/ha. The CE for inorganic fertilizers varied from 214 to 2620 kg CE/ha. The CE for feed used in these ponds ranged from 6400 to 8750 kg CE/ha during the culture period.
The carbon storage of the fi sh ponds of Moyna, West Bengal is given in table 5. The sediment level of the ponds varied from 4.75 to 5.80 cm with an average of 5.16 ± 0.47 cm during the culture period. The dry bulk density of the sediment varied from 0.68 to 0.93 Mg/m 3 with an average of 0.80 ± 0.11 Mg/m 3 .The organic carbon content varied from     The carbon footprint and the emission of CO 2 -e and CH 4 -e from the fi sh ponds of West Godavari, Krishna and Guntur districts of Andhra Pradesh are presented in table 6. The average inputs as Carbon Equivalent (CE) in these ponds varied from 10959 to 21122 kg/ha with an average of 14407 ± 2651 kg/ha. Among the diff erent inputs, feed contributed the maximum carbon of 80 percent to aquaculture ponds followed by organic manure (cow dung) as 15 per cent, inorganic fertilizers as 4 per cent and lime as 1.0 per cent. The carbon storage of diff erent ponds ranged from 4039 to 11466 kg/ha during the culture period with an average of 6216 ± 2291 kg/ha. The CE as output/harvest varied from 2100 to 4200 kg/ha with an average of 3307 ± 691 kg/ha. The chance of Carbon (C) emission varied from 2368 to 6506 kg CE/ha/culture period with an average of 4883 ± 1488 kg CE/ ha/culture period. The culture period in the present study was 210 to 285 days with an average of 231 days.
The chance of emission as CO 2 -equivalent (CO 2 -e) varied from 7363 to 20240 kg/ha with an average of 12212 ± 4631 kg/ha. The chance of C emission as CH 4 -equivalent (CH 4 -e) ranged from 473 to 1298 kg/ha with an average of 975 ± 296 kg/ha/culture period. The emission of kg CO 2 -e per kg of fi sh production was 1.26 to 2.69 with an average of 1.91 ± 0.42 kg CO 2 -e/kg fi sh production while the emission of kg CH 4 -e per kg of fi sh production was 0.075 to 0.158 kg CH 4 -e/kg fi sh with an average of 0.122 ± 0.027 kg CH 4 -e/kg fi sh in Andhra Pradesh.
The carbon footprint and the emission of CO 2 -e and CH 4 -e from the fi sh ponds of Moyna, East Medinipur district of West Bengal are presented in table 7. The average inputs as CE in these ponds were 9231 ± 1007 kg CE/ha/culture period. Among the diff erent inputs, feed contributed 86 per cent CE to aquaculture ponds, followed by inorganic fertilizers of 12 per cent and lime around 1.0 per cent. No organic manure was used in these ponds. The carbon storage was 5360 kg/ha excluding one pond whose carbon balances (input-carbon storage-output/harvest) was negative. The CE as output/ harvest ranged from 1890 to 4305 kg/ha with an average of 2765 ± 1306 kg/ha. The chance of carbon emission varied from 10 to 3000 kg CE/ha/culture period. The average culture period was 300 days.
The chance of CO 2 -e emission varied from 31.0 to 9333 kg/ ha/culture period with an average of 3441 ± 1647 kg/ha while the chance of CH 4 -e emission ranged from 1.99 to 598 kg/ha with an average of 220 kg/ha/culture period. The emission of CO 2 -e ranged from 0.006 to 2.07 kg/kg fi sh production with an average of 0.72 kg/kg fi sh, while the emission of CH 4 -e varied from 0.0004 to 0.132 kg/kg fi sh with an average of 0.046 kg/ kg fi sh production in Moyna, West Bengal.
It has been reported from life cycle impact assessment results that Indian shrimp, Viet Nam pangasius and Phillipines milkfi sh had global warming potential of 3.67 kg CO 2 -e/kg shrimp, 1.32 kg CO 2 -e/kg fi sh and 0.006 kg CO 2 -e/kg fi sh, respectively [3,8] reported from a life cycle assessment that the grow-out phase of marine shrimp had a higher carbon footprint of 47.9967 kg CO 2 -e/kg shrimp in super-intensive culture than the semi-intensive culture which had a value of 1.0042 kg CO 2 -e/kg shrimp [5] reported from life cycle analysis that the production of greenhouse gases by other forms of aquaculture for food production ranged from 3.0 to 15.0 kg CO 2 -e/kg fi sh while [9] reported that tuna fi shing emitted 0.0038 kg CO 2 -e/kg of tuna landed. It has been reported [10] from a life cycle model that Indian major carps in India, Nile tilapia in Bangladesh and stripped catfi sh in Viet Nam had the average Emissions Intensities (EI) from cradle to farm-gate, including emissions from

ACKNOWLEDGEMENT
The funding of NICRA (National Innovation on Climate Resilient Agriculture) for conducting of the present investigation is gratefully acknowledged. We are also highly grateful to all the farmers for their immense help during our investigation.