Macroalgae culture-induced carbon sink in a large cultivation area of China.

Macroalgae culture-induced carbon sink in sediments has been little investigated. Here, total organic carbon (TOC), total nitrogen (TN), and δ13C were examined in sediments in a cultivation field of macroalgae (kelp and Gracilariopsis lemaneiformis) in Sansha Bay, Southeast China. Both proxies of C/N (TOC to TN ratio) and δ13C indicated a multisource of TOC. Based on a three-endmember model, macroalgae-derived TOC (TOCma) accounted for < 35% of the total TOC, averaging 16 ± 9% (mean ± SD). On average, terrestrial and phytoplankton-derived TOC showed much higher percentages of 24 ± 17% and 60 ± 20%, respectively (t-test, p < 0.02). A preliminary estimate suggested that TOCma represents a carbon sink of 8.2 × 103 tons per year, corresponding to about 22% of the sink associated with phytoplankton and macroalgae and 8 ± 6% of the macroalgae carbon production in Sansha Bay. Considering its production magnitude, the macroalgae-induced carbon sink seems to be insignificant, on a national or global scale, to phytoplankton, though it should be taken into account given the small cultivation area.

CO2 emission characteristics and reduction responsibility of industrial subsectors in China.

Industrial subsectors have an important role in reducing China's carbon dioxide (CO2) emissions. The present study analyzes the CO2 emission characteristics of selected subsectors. Results show that the electric and heat power sector is the major industrial CO2 emitter, and CO2 emissions of most sectors present huge inter-provincial and inter-regional differences. Then, the CO2 emission reduction responsibility of provincial-level industrial subsectors is confirmed by the decoupling model. Results show that the development of a low-carbon economy in the nonmetal sector is ideal, and the economic growth in Shanxi and Guizhou is moving toward a low-carbon and energy-saving mode. Moreover, the subsectors that each province should focus on are identified. Finally, constructive suggestions for policymakers to promote low-carbon economy and sustainable development are provided.