In this paper, we establish a structure theorem of naturally ordered rpp semigroups with max-idempotents. Results on naturally ordered semigroups with max- idempotents in the literature are extended and amplified. Som...In this paper, we establish a structure theorem of naturally ordered rpp semigroups with max-idempotents. Results on naturally ordered semigroups with max- idempotents in the literature are extended and amplified. Some previous results obtained by Blyth, McFadden, Cuo and Xie on regular and abundant ordered semigroups are ex- tended to ordered roo semigrouos.展开更多
Human activities have increased reactive nitrogen(Nr)input to terrestrial ecosystems compared with the pre-industrial era.However,the fate of such Nr input remains uncertain,leading to missing sink of the global nitro...Human activities have increased reactive nitrogen(Nr)input to terrestrial ecosystems compared with the pre-industrial era.However,the fate of such Nr input remains uncertain,leading to missing sink of the global nitrogen budget.By synthesizing records of Nr burial in sediments from 303 lakes worldwide,here we show that 9.6±1.1 Tg N year^(-1)(Tg=10^(12) g)accumulated in inland water sediments from 2000 to 2010,accounting for 3%-5% of global Nr input to the land from combined natural and anthropogenic pathways.The recent Nr burial flux doubles pre-industrial estimates,and Nr burial rate significantly increases with global increases in human population and air temperature.Sediment ratios of C:N decrease after 1950 while N:P ratios increase over time due to increasingly elevated Nr burial and other related processes in lakes.These findings imply that Nr burial in lakes is overlooked as an important global sink of Nr input to terrestrial ecosystems.展开更多
文摘In this paper, we establish a structure theorem of naturally ordered rpp semigroups with max-idempotents. Results on naturally ordered semigroups with max- idempotents in the literature are extended and amplified. Some previous results obtained by Blyth, McFadden, Cuo and Xie on regular and abundant ordered semigroups are ex- tended to ordered roo semigrouos.
基金supported by the National Natural Science Foundation of China(41773068,42061124001,31901163,32171583,and 41822701)Fund of Guangdong Provincial National Science Foundation(2018A030310518,2019A1515011568)+1 种基金General Project of Guangzhou Scientific Research Program(201904010160)the“Toward International Nitrogen Management System”funded by the United Nations Environment Program(GEF project ID:5400-01142).
文摘Human activities have increased reactive nitrogen(Nr)input to terrestrial ecosystems compared with the pre-industrial era.However,the fate of such Nr input remains uncertain,leading to missing sink of the global nitrogen budget.By synthesizing records of Nr burial in sediments from 303 lakes worldwide,here we show that 9.6±1.1 Tg N year^(-1)(Tg=10^(12) g)accumulated in inland water sediments from 2000 to 2010,accounting for 3%-5% of global Nr input to the land from combined natural and anthropogenic pathways.The recent Nr burial flux doubles pre-industrial estimates,and Nr burial rate significantly increases with global increases in human population and air temperature.Sediment ratios of C:N decrease after 1950 while N:P ratios increase over time due to increasingly elevated Nr burial and other related processes in lakes.These findings imply that Nr burial in lakes is overlooked as an important global sink of Nr input to terrestrial ecosystems.
