Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and tot...Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and total nitrogen （TN） in black soil beach （BSB）. We measured SOC and TN in severely degraded and non-degraded grasslands to calculate differences in carbon and nitrogen storage, and field survey results were extrapolated to the entire headwaters area of the Qinghai-Tibetan Plateau （36.3xlos krn~） to determine SOC and TN losses from these grasslands. We also evaluated changes in SOC and TN in severely degraded grasslands that were artificially re-vegetated five, seven and nine years ago. Totally 92.43 Tg C and 7.08 Tg N were lost from the BSB in the headwater area, which was approximately 50% of the original C and N soil pools. Re-vegetation of the degraded grasslands in the headwater area would result in a gain of 32.71 Tg C in the soil after five years, a loss of 5.5a Tg C after seven years and an increase of 44.15 Tg C after nine years. The TN increased by 53.09% and 59.98% after five and nine years, respectively, while it decreased by 4.92% after seven years of re-vegetation. The results indicate that C and N stocks followed a ＂V＂ shaped pattern with re- vegetation time. Understanding plant-soil interactions during succession of artificially planting grassland ecosystems is essential for developing scientifically sound management strategies for the effectively re-vegetated BSB.展开更多
The physical and chemical properties of BRIS （beach ridges interspersed with swales） soil are unsuitable for agricultural purposes. A proper fertilizer and crop management practices are required. The relationship be...The physical and chemical properties of BRIS （beach ridges interspersed with swales） soil are unsuitable for agricultural purposes. A proper fertilizer and crop management practices are required. The relationship between different level of nitrogen fertilizer, growth and pineapple fruit yield vary N36 were studied. The experiment was conducted using randomized complete block design of seven treatments with four replicates, Prior to artificial flower induction, seven different rates of nitrogen fertilizer at 0, 200, 400, 600, 800, 1,000 and 1,200 kg-ha^-1 were applied in four equal split doses. As the level of nitrogen fertilizer was increased, a decrease in acidity of fruits and an increase in crown weight were observed. However an increase in mean length of D leaf, mean fruit length, mean fruit weight, mean fruit to crown ratio were obtained as the rate of nitrogen fertilizer was increased from 0-600 kg.N-ha^-1. Further increase however led to a decrease in the same parameters.展开更多
基金financially supported by the grants from the Ministry of Science and Technology,China (Grant No. 2012BAC01B02)the Ministry of Environmental Protection,China (Grant No. 201209033)
文摘Both overgrazing and climate change contribute to grassland degradation in the alpine regions of China and negatively affect soil carbon and nitrogen pools. We quantified changes in soil organic carbon （SOC） and total nitrogen （TN） in black soil beach （BSB）. We measured SOC and TN in severely degraded and non-degraded grasslands to calculate differences in carbon and nitrogen storage, and field survey results were extrapolated to the entire headwaters area of the Qinghai-Tibetan Plateau （36.3xlos krn~） to determine SOC and TN losses from these grasslands. We also evaluated changes in SOC and TN in severely degraded grasslands that were artificially re-vegetated five, seven and nine years ago. Totally 92.43 Tg C and 7.08 Tg N were lost from the BSB in the headwater area, which was approximately 50% of the original C and N soil pools. Re-vegetation of the degraded grasslands in the headwater area would result in a gain of 32.71 Tg C in the soil after five years, a loss of 5.5a Tg C after seven years and an increase of 44.15 Tg C after nine years. The TN increased by 53.09% and 59.98% after five and nine years, respectively, while it decreased by 4.92% after seven years of re-vegetation. The results indicate that C and N stocks followed a ＂V＂ shaped pattern with re- vegetation time. Understanding plant-soil interactions during succession of artificially planting grassland ecosystems is essential for developing scientifically sound management strategies for the effectively re-vegetated BSB.
文摘The physical and chemical properties of BRIS （beach ridges interspersed with swales） soil are unsuitable for agricultural purposes. A proper fertilizer and crop management practices are required. The relationship between different level of nitrogen fertilizer, growth and pineapple fruit yield vary N36 were studied. The experiment was conducted using randomized complete block design of seven treatments with four replicates, Prior to artificial flower induction, seven different rates of nitrogen fertilizer at 0, 200, 400, 600, 800, 1,000 and 1,200 kg-ha^-1 were applied in four equal split doses. As the level of nitrogen fertilizer was increased, a decrease in acidity of fruits and an increase in crown weight were observed. However an increase in mean length of D leaf, mean fruit length, mean fruit weight, mean fruit to crown ratio were obtained as the rate of nitrogen fertilizer was increased from 0-600 kg.N-ha^-1. Further increase however led to a decrease in the same parameters.
文摘根据海洋监测规范中沉积物中油类的检测方法(GB 17378.5—2007),应用超生萃取滩涂石油污染土壤中的石油烃,研究萃取剂、萃取时间、萃取次数、萃取温度以及液固比的影响。结果表明,超生萃取滩涂石油污染土壤的最佳条件为:萃取剂为二氯甲烷,萃取温度30℃,萃取时间15 min,液固比为6∶1 m L/g,萃取次数为2次。在此条件下,2%,1%,0.5%和0.1%的石油污染滩涂底质的萃取率分别达到90.09%,88.86%,82.65%和85.71%。
