Nanshan, an unique natural meadow, has cool climate. In Nanshan, annu- al average temperature was 11.2 ℃; average temperature in the hottest month July was 18.4 ℃, and extremely maximum temperature was 26.8 0℃; ave...Nanshan, an unique natural meadow, has cool climate. In Nanshan, annu- al average temperature was 11.2 ℃; average temperature in the hottest month July was 18.4 ℃, and extremely maximum temperature was 26.8 0℃; average tempera- ture in the coldest month January was 2.2 ℃, and extremely minimum temperature in February was -16.0 ℃. Holstein is resistant to low temperature but not resistant to high temperature. The suitable temperature for Holstein ranges from 11 to 16 ℃, so the climatic environment in Nanshan is suitable for the breeding of Holstein. An- nual average milk yield of each Holstein was up to 6 900 kg, reaching the ad- vanced level of annual average milk yield of each Holstein in China. The milk yield of cows was the highest in June and the lowest in October.展开更多
Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. S...Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. Supported by multi-proxy records including litho-units, organic carbon isotopes, ration of total organic carbon and total nitrogen, organic matter content, bulk dry density, the accumulation rate of organic matter, median grain size, magnetic susceptibility, and Rb/Sr and Ca/Mg ratios obtained from a sedimentary sequence in a small lake （i.e., Dahu Swamp） in the eastern Nanling Mountains in South China, we deduce that variation in the δ15N values results primarily from the sources of organic matter, which are significantly influenced by climatic conditions over the past -16 000 years. A low （or high） lake level resulting from dry （or wet） conditions would lead to more （or fewer） vascular plant remains in the sediments and stronger （or weaker） denitrification associated with hypolimnetic anoxia, resulting in lower （or higher） 615N values. In addition, dry （or wet） conditions would favor weakened （or strengthened） biogeochemical activity in the catchment, which could result in less （or more） external input of δ15N-enriched OM, thus leading to decreased （or increased） δ15N values. Our results indicate that the lake sediment δ15N record in the Nanling Mountains has the potential to provide valuable insight into past East Asian monsoon climate- driven environmental changes.展开更多
基金Supported by the "Duanpingkuai" Project of Hunan Meteorological Bureau in 2014~~
文摘Nanshan, an unique natural meadow, has cool climate. In Nanshan, annu- al average temperature was 11.2 ℃; average temperature in the hottest month July was 18.4 ℃, and extremely maximum temperature was 26.8 0℃; average tempera- ture in the coldest month January was 2.2 ℃, and extremely minimum temperature in February was -16.0 ℃. Holstein is resistant to low temperature but not resistant to high temperature. The suitable temperature for Holstein ranges from 11 to 16 ℃, so the climatic environment in Nanshan is suitable for the breeding of Holstein. An- nual average milk yield of each Holstein was up to 6 900 kg, reaching the ad- vanced level of annual average milk yield of each Holstein in China. The milk yield of cows was the highest in June and the lowest in October.
基金Supported by the National Natural Science Foundation of China(Nos.41071137,40671189)the Research Program of Higher Education Institution in Guangdong Province for High-level Talents,and the Natural Science Foundation of Guangdong Province(Nos.S2011010003413,8151063101000044)
文摘Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. Supported by multi-proxy records including litho-units, organic carbon isotopes, ration of total organic carbon and total nitrogen, organic matter content, bulk dry density, the accumulation rate of organic matter, median grain size, magnetic susceptibility, and Rb/Sr and Ca/Mg ratios obtained from a sedimentary sequence in a small lake （i.e., Dahu Swamp） in the eastern Nanling Mountains in South China, we deduce that variation in the δ15N values results primarily from the sources of organic matter, which are significantly influenced by climatic conditions over the past -16 000 years. A low （or high） lake level resulting from dry （or wet） conditions would lead to more （or fewer） vascular plant remains in the sediments and stronger （or weaker） denitrification associated with hypolimnetic anoxia, resulting in lower （or higher） 615N values. In addition, dry （or wet） conditions would favor weakened （or strengthened） biogeochemical activity in the catchment, which could result in less （or more） external input of δ15N-enriched OM, thus leading to decreased （or increased） δ15N values. Our results indicate that the lake sediment δ15N record in the Nanling Mountains has the potential to provide valuable insight into past East Asian monsoon climate- driven environmental changes.
