NAXOS2018 2018-06-13 Project partner Guoxue Li Tao Jiang Jiali - PowerPoint PPT Presentation

6th International Conference on Sustainable Solid Waste Management Different composting modes shape specific AOB and nirK-type denitrifiers correlated with N 2 O emissions TAO JIANG LESHAN NORMAL UNIVERSITY NAXOS2018 2018-06-13

Project partner Guoxue Li Tao Jiang Jiali Chang China Leshan Leshan Agricultural Normal Normal University University University

Background N 2 O in the air • N 2 O is an important greenhouse gas. • N 2 O content in the air increased 20% in the last 50 years • N 2 O is considered to be an important factor in ozone depletion. GWP data was changed in IPCC Climate Change 2014-Synthesis Report GWP GTP Lifetime(yr) Cumulative Cumulative Temperature Temperature forcing over forcing over change after change after 20 yr 100 yr 20 yr 100 yr CO 2 1 1 1 1 CH 4 12.4 84 28 67 4 N 2 O 121 264 265 277 234 CF 4 50,000 4880 6630 5270 8040 (IPCC, 2014; Ravishankara et al., 2009; Mosier et al.,1998; Houghton et al., 2001)

Background N 2 O emission in agriculture • More than 80% N 2 O emitted from agriculture, including manure management, synthetic fertilizer and manure application / deposition. • Composting is one of the significant sources of N 2 O production, which accounts for approximately 30-50% of the annual global N 2 O emissions from agriculture • When the compost was normally operated, N 2 O emission account for 0.2-3.0% of total nitrogen that was about 26-61 kg CO 2 eq/t manure. (IPCC, 2014; USEPA ， 2011 ； FAOSTAT ， 2013 )

Background N 2 O production by microorganisms Ammonia oxidizer Nitrite oxidizer (bacteria or archaea) nxr amoA hao hao + - NH 4 NH 4 OH [NOH] NO 2 - NO 3 narG napA euk-nr nirK N 2 O 2 H 2 nosZ / ( nirK + nirS ) nirS Denitrifiers N 2 N 2 O NO nosZ norB (Canfield, 2010; Madae et al., 2011; Angnes et al., 2013; Li et al., 2017; Bian et al., 2017)

Scientific problem What about the microbial community structure relationship with N 2 O emissions during composting.

Materials and methods Raw materials • Cornstalk air dried and chopped to ~ 5 -10 cm; • Pig faeces from Ganqingfen system of a local pig farm. Samples TOC TN Ammonium Moisture C/N (g·kg -1 ) (g·kg -1 ) (g·kg -1 ) content (%) Pig faeces 343.7 26.5 7.4 71.8 13.0 Cornstalk 419.0 9.9 — 9.3 42.3 Mixture 367.4 21.2 5.7 63.6 17.3

Materials and methods Composting methods • Materials were composted in 1.2 m 3 bins for 10 week. • Total 3 treatments: 1 5 Static, Turn, Forced aeration. 2 • Turning frequency is 1/week. 4 • Aeration rate is 0.25 L·kgDM -1 ·min -1 . 3 1. Wooden boards with sampling holes; 2. Concrete side wall; 3. Concrete floor and aeration and leachate cavum; 4. Bottom board with aeration holes; 5. Compost materials. + , NO 3 - T, pH, O 2 , ORP, N 2 O, NH 4

Materials and methods Sampling for microbial analysis amoA gene Ammonia oxidizer (bacteria or archaea) nirK gene Denitrifiers  Terminal restriction fragment length polymorphism (T-RFLP)  Clone and sequencing

Results_T/pH/O 2 /ORP Aeration Turn Static Air Aeration Turn Static 80 8.8 A B Temperrature (°C) 60 pH value 8.3 40 7.8 20 7.3 0 0 14 28 42 56 70 0 14 28 42 56 70 Composting time （ d ） Composting time (d) 25 A-T A-M A-B T-T T-M T-B S-T S-M S-B 0 20 ORP Value (mv) O 2 content (%) 15 -200 10 -400 5 A-T A-M A-B F T-T T-M T-B E S-T S-M S-B 0 -600 0 14 28 42 56 70 0 14 28 42 56 70 Composting time (d) Composting time (d)

+ /NO 3 - Results_N 2 O/NH 4 C A-T A-M A-B A 12 8 NH 4+ -N content (g/kg DM) T-T T-M T-B N 2 O emission rate （ g/d/t ） S-T S-M S-B 9 6 6 Aeration 4 Turn 3 Static 2 0 0 14 28 42 56 70 600 Composting time (d) 0 A-T D NO 3- -N content (mg/kg DM) 0 14 28 42 56 70 A-M A-B Composting time （ d ） 400 T-T T-M T-B S-T 200 S-M S-B 0 0 14 28 42 56 70 Composting time (d)

Results_ AOB Combined analysis of T-RFLP and clone sequencing based on bacterial amoA gene Nitrosomonas eutropha Nitrosomonas stercoris

Results_ nirK denitrifier Combined analysis of T-RFLP and clone sequencing based on nirK gene

Results RDA pattern of functional microbial community structure and environmental factors

Conclusion  Variations of physicochemical factors under different composting modes influenced the community structures of AOB and nirK -type denitrifiers, which in turn caused the differential N2O emission patterns.  Co-existence of nitrifier with 45 bp T-RF of amoA gene and denitrifier with 189 bp T-RF of nirK gene could account for the substantial emissions of N2O in forced aeration composting.

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