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湿地围垦转化为农田直接影响碳循环过程,但之前的众多研究忽略了相关人为活动如农资生产、农用器械使用等所产生的碳排放.为了更全面认识湿地围垦为农田所导致的这种变化,以崇明岛为研究地区,基于通量观测和生命周期评价,本文分别探讨当考虑和不考虑人为活动伴随的碳排放时,生态系统总碳排放的变化.结果表明:如果只考虑生态系统与大气间的碳通量,农田仍表现为碳汇,但与自然湿地相比,其碳排放增加了10.47t(CO_2-eq)·hm~(-2);当将农业生产中人为活动碳排放纳入计算后,崇明岛自然湿地和围垦农田的碳排放总量分别为-15.38和6.54 t(CO_2-eq)·hm~(-2),碳排放增加了21.92 t(CO_2-eq)·hm~(-2),其中,人为活动碳排放为11.45 t(CO_2-eq)·hm~(-2);田间种植和农资生产的碳排放共占农田生命周期碳排放总量的84.6%,化肥的生产施用是农田生命周期碳排放的主要来源之一.围垦使生态系统乃至区域尺度的碳源汇属性发生变化,需重新评估其影响;同时,为了达到低碳农业的目的,需减少化肥施用、提高化肥使用效率.
The conversion of wetland to farmland has a direct impact on the carbon cycle, but many previous studies have neglected the carbon emissions from related anthropogenic activities such as agricultural production and farm equipment use. In order to better understand this change caused by the reclamation of wetlands into farmland, Based on the flux observation and life cycle assessment, this paper explores the changes of total carbon emissions of ecosystems with and without consideration of anthropogenic carbon emissions, respectively. The results show that if we only consider the relationship between ecosystem and Compared with natural wetlands, carbon emissions in the atmosphere increased by 10.47t (CO 2 -eq) · hm -2. When anthropogenic carbon emissions from agricultural production After the calculation, the total carbon emissions of natural wetlands and reclaimed farmlands in Chongming Island were -15.38 and 6.54 t (CO 2 -eq) · hm -2, respectively, and the carbon emission increased by 21.92 t (CO 2 -eq) · hm ~ (-2). Among them, anthropogenic carbon emission was 11.45 t (CO 2 -eq) · hm -2. Carbon emissions from field planting and agricultural production accounted for 84.6% of total farm life cycle carbon emissions. Fertilizer The application of production is one of the main sources of farmland carbon emissions in the life cycle Carbon sink property even regional scale system change, need to re-evaluate its impact; Meanwhile, in order to achieve the purpose of low-carbon agriculture, the need to reduce the chemical fertilizer, fertilizer use efficiency.