基于IPCC Tier 1层级的中国反刍家畜胃肠道甲烷排放格局变化分析

依据政府间气候变化委员会(IPCC)2006年公布的反刍家畜胃肠道CH4排放系数(奶牛61 kg CH4头-1a-1,肉役牛47 kg CH4头-1a-1,绵羊和山羊均为5 kg CH4头-1a-1)和IPCC Tier 1计算方法,结合《中国统计年鉴》和《中国畜牧业统计年鉴》,估算了中国以及各个省份1990—2010年CH4的排放总量,绘制出中国反刍家畜胃肠道CH4排放格局及历史变化图。研究结果表明:11990—2010年期间,中国反刍家畜胃肠道CH4排放量(5.90—7.65 Tg)总体呈现先上升(1995年最高)后下降的趋势,其中肉役牛(主要是黄牛和水牛)胃肠道CH4排放量(4.33 Tg)及其所占比例(65%)最大。奶牛胃肠道CH4排放量及其比例呈现逐年增加的趋势,2006年(0.83 Tg,12.7%)超过山羊和绵羊胃肠道CH4排放量及其比例,成为中国反刍家畜胃肠道CH4排放第二大源。但是,奶牛单位产奶量所排放的CH4量逐年降低,表明中国奶牛饲养技术与生产性能不断提高。2中国反刍家畜胃肠道CH4排放格局呈现区域集中特点,主要集中在中西部和北部的各个省份,其中四川、内蒙古、新疆、河南、西藏、山东、河北、黑龙江、云南和甘肃等10个省份的排放量占中国排放总量的50%以上。总之,1990—2010年间,中国反刍家畜胃肠道CH4排放总量为(6.77±0.46)Tg(肉役牛为主要排放源),随时间推移呈现先上升后下降的趋势;中国反刍家畜胃肠道CH4排放的格局呈区域集中分布,中西部和北部的各个省份占60%以上。

Using intergovernmental panel on climate change Tier 1 to analyze the trends and distribution patterns of enteric methane emissions from ruminants in China during 1990-2010

The present study aimed to reveal historical trends and distribution patterns of enteric methane (CH₄) emissions from ruminants in China between 1990 and 2010. Enteric CH₄ emissions were calculated using the Tier 1 equation provided by the Intergovernmental Panel on Climate Change (IPCC). The enteric CH₄ emission factors of different ruminant subcategories were the corresponding default values provided by the IPCC (2006), such as 61 kg CH₄ head^-1 a^-1 for dairy cows, 47 kg CH₄ head^-1 a^-1 for both beef and draught cattle, and 5 kg CH₄ head^-1 a^-1 for both sheep and goats. In addition, information about the population size of cattle, dairy cows, goats, and sheep was obtained from the Statistical Yearbook of China and Statistical Yearbook of China''s animal husbandry. The enteric CH₄ emissions in each province were also estimated to obtain the distribution pattern of national enteric CH₄ emissions from 1990 to 2010. The results showed that the total enteric CH₄ emissions of ruminants ranged from 5.90 to 7.65 Tg, with the maximum value being obtained in 1995. The enteric CH₄ emissions from beef and draught cattle (mainly cattle and buffalo) exceeded 4.33 Tg, accounting for more than 65% of total enteric CH₄ emissions. The enteric CH₄ emissions from dairy cows showed a continuous rising trend with advancing years. In 2006, the amount and proportion of enteric CH₄ emissions from dairy cows (0.83 Tg, 12.7%) exceeded that detected from goats and sheep, and represented the second largest source of enteric CH₄ emissions in the ruminant production system. However, enteric CH₄ emissions per kg of milk production decreased, indicating that the efficiency of dairy farming had greatly improved from 1990 to 2010. The distribution pattern of the enteric CH₄ emissions showed regional variation, and was mainly distributed in the northern, western, and central regions of China. For example, 10 provinces (including Sichuan, Inner Mongolia, Xinjiang, Henan, Tibet, Shandong, Hebei, Heilongjiang, Yunnan, and Gansu) accounted for more than 50% of total enteric CH₄ emissions. The distribution pattern of the enteric CH₄ emissions of ruminant subcategories also exhibited regional variation. The enteric CH₄ emissions of beef and draught cattle were mainly distributed in the southwest and central regions of China, with 10 provinces (including Sichuan, Yunnan, Guangxi, Guizhou, Henan, Shandong, Hunan, Hebei, Tibet, and Anhui) in China accounting for more than 55% of total enteric CH₄ emissions by these ruminants. The enteric CH₄ emissions of dairy cows were mainly distributed in the northern regions of China, with six provinces (including Xinjiang, Inner Mongolia, Heilongjiang, Henan, Hebei, and Shandong) in China accounting for more than 55% of total enteric CH₄ emissions by this group. The enteric CH₄ emissions of goats were mainly distributed in the northern and central regions of China, with five provinces (including Inner Mongolia, Shandong, Sichuan, Henan, and Jiangsu) in China accounting for more than 50% of total enteric CH₄ emissions by this group. The enteric CH₄ emissions of sheep were mainly distributed in the northwest regions of China, with five provinces (including Xinjiang, Inner Mongolia, Tibet, Qinghai, and Gansu) in China accounting for more than 60% of total enteric CH₄ emissions by this group. In summary, ruminants represented (6.77 ± 0.46) Tg (of which more than 65% was from beef and draught cattle) of national enteric CH₄ emissions from 1990 to 2010, which initially increased and then decreased with advancing years. The distribution pattern of national enteric CH₄ emissions exhibited regional variation, with 60% of total enteric CH₄ emissions originating from the northern, western, and central regions of China.