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The factors affecting the bound acrylonitrile content of NBR product during the polyme-rization process were investigated, including monomer reactivity ratio, monomer conversion, monomer concentration, and polymerization temperature and pressure, the structural composition of the product was analyzed, and the polymerization reaction kinetics and repeatability experiment were carried out. The results showed that under the polymerization temperature of 5.0 ℃ and polymerization pressure of 0.15-0.20 MPa, NBR products with uniform distribution of acrylonitrile structure units and mass fraction of bound acrylonitrile of 17%-19% could be obtained by using multi-stage addition of acrylonitrile and controlling the monomer conversion of 70%-75%. The polymerization formula and process had good repeatability.

In-situ measurement of nitrous oxide (N 2 O) and methane (CH 4 ) emissions in a typical paddy-cowpea rotation system in Southern Hainan was conducted to determine the characteristics of greenhouse gas emissions under different optimum fertilization treatments. The experiment consisted of 5 treatments:conventional farming fertilization (CON), optimized fertilization (OPT), organic-inorganic fertilization (ORG), slow-controlled optimization fertilization (SCOPT), and no nitrogen as the control (CK). The N 2 O and CH 4 emissions were measured using static chamber-gas chromatography during the all the paddy-cowpea rotation seasons. Global warming potential (GWP) and greenhouse gas intensity (GHGI) were also estimated in this study. The cumulative N 2 O emission during the rice growth season was 0.19-1.37 kg·hm -2 . Compared with the CON treatment, other treatments reduced N 2 O emission by 50% to 86%. The cumulative N 2 O emission during the cowpea growth season was 1.29-3.55 kg·hm -2 . In addition, N 2 O emission increased by 14% as a result of the ORG treatment, whereas that of the remaining treatments decreased by 16% to 59%. The cumulative CH 4 emissions during the paddy growth season were 4.67-14.23 kg·hm -2 . The CH 4 emissions following the CK, OPT, and ORG treatments were higher by 116%, 22%, and 102%, respectively, whereas that of SCOPT was lower by 29%, than that following the CON treatment. Moreover, the cumulative CH 4 emission during the cowpea growth season was 0.03-0.26 kg·hm -2 , and CH 4 absorption occurred during the same period. With regard to the contribution rate of different periods to GWP, the cowpea growth season still had a proportion of 44.7%-54.5%, despite extremely low CH 4 emission. Regarding the two greenhouse gases, N 2 O contributed 66.7%-77.2%. During the entire rotation system, both GWP and GHGI processed by SCOPT were significantly lower than those of the CON treatments. To sum up, the SCOPT treatment was determined to be the optimal fertilization scheme in this study and had the most significant effects on increasing production and reducing greenhouse gas emissions.

Greenhouse gas emissions studies commonly focus on temperate and subtropical regions. As a result, greenhouse gas emissions from agricultural soils in tropical areas are often neglected. Therefore, greenhouse gas fluxes in a Hainan paddy field under different fertilization regimes were studied. This research provides an accurate assessment of CH 4 and N 2 O emissions from paddy fields in China and sound mitigation measures. Through static chamber/gas chromatography techniques, CH 4 and N 2 O emissions, global warming potential (GWP), and greenhouse gas emissions intensity (GHGI) in late rice season under five fertilizer treatments were measured. The treatments included:control (CK), conventional treatment (CON), optimized fertilization treatment (YH), optimized fertilization combined with controlled slow-release fertilizer treatment (ZHY1), optimized fertilization combined with controlled slow-release fertilizer and organic fertilizer treatment (ZHY2). The results showed that the cumulative CH 4 emissions in the CK, CON, YH1, ZYH1, and ZYH2 treatments were 175.70, 60.30, 63.00, 62.80, and 56.60kg·hm -2 , and the cumulative N 2 O emissions were 0.78, 3.40, 1.03, 1.44, and 0.44kg·hm -2 , respectively. Correlation analysis showed that soil temperature and Eh were the main factors driving CH 4 emission. Compared with CK, CON, YH, and ZYH1, the yield of rice in ZYH2 treatment increased by 29.69%, 11.81%, 6.74%, and 10.36%, respectively. While GWP of ZYH2 decreased by 64.80%, 43.23%, 12.93%, and 15.15%, and GHGI decreased by 76.49%, 52.52%, 20.54%, and 23.87%, respectively. Therefore, in terms of yield and greenhouse gas emissions, optimal fertilization combined with sheep manure and slow release fertilizer treatment (ZYH2) is feasible in this region.