The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released b...The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released by the decomposition of jellyfish on the ecosystem in the field. The release of nitrogen and phosphorus from the decomposition of Nernopilerna nomurai was examined in a series of experiments under different incubation conditions such as different pH values, salinity values, temperatures and nitrogen and phosphorus concentrations. The results showed that the complete decomposition of Nemopilema nomurai generally took about 4-8 d. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai could be divided into two stages： the early stage and the later stage, although the efflux rate of nitrogen was one order more than phosphorus. In the early stage of the decomposition of Nemopilema nomurai, the concentrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in seawater increased rapidly, and the concentration of nitrogen could reach the highest level in the whole degradation process. In the later stage of the decomposition, the concentrations of dissolved nitrogen and total nitrogen declined slowly, while the concentration of phosphorus in water could reach a maximum in the degradation process. High pH, low salinity, high temperature and N/P will promote the release of nitrogen; low pH is unfavorable to the release of nitrogen but favorable to the release of phosphorus. In addition, we found the concentrations of ammonium and phosphate in the bottom water were higher than those in the surface water during the period of jellyfish bloom in the ]iaozhou Bay, proving that nutrients released by the decomposition of jellyfish have significant influence on nitrogen and phosphorus in the field. For the whole Yellow Sea, nutrients released by jellyfish carcasses may reach up to （2.63±2.98）x10^7 mol/d of dissolved nitrogen （DN） and （0.74±0.84）x10^8 mol/d of dissolved phosphorus （DP） during the period of jellyfish bloom. The values are comparable to riverine inputs in a day, but much higher than sediment-water exchange flux in the Yellow Sea. The great amounts of nutrients must have significant influence on the nutrients balance of the Yellow Sea during the period of jellyfish dead and decomposition. Both the experimental data and field observations proved that the decomposition of jellyfish may release a great amount of nutrient to the surrounding environment during the period of jellyfish decomposition.展开更多
目的】探讨长期定位施磷条件下小麦产量、土壤有效磷水平及籽粒养分含量变化,为旱地小麦合理施用磷肥,提高产量、改善品质提供理论依据。【方法】基于2004年在黄土高原开始的长期定位试验,于2014—2015、2015—2016和2016—2017连续3年...目的】探讨长期定位施磷条件下小麦产量、土壤有效磷水平及籽粒养分含量变化,为旱地小麦合理施用磷肥,提高产量、改善品质提供理论依据。【方法】基于2004年在黄土高原开始的长期定位试验,于2014—2015、2015—2016和2016—2017连续3年取样,研究不同施磷量对小麦产量,生物量,产量构成,籽粒氮、磷、钾含量,土壤有效磷含量及磷吸收利用的影响。【结果】与不施磷相比,长期施磷使小麦产量平均提高67%,生物量提高58%,穗数和穗粒数分别增加64%和8%,而千粒重降低7%。施磷量与小麦产量、生物量呈抛物线关系,获得最高产量6 465 kg·hm^(-2)的施磷量为144 kg P_2O_5·hm^(-2)。籽粒氮含量随施磷量增加而降低,磷和钾含量随施磷量增加而提高。土壤有效磷含量与施磷量呈显著正相关,小麦获得最高产量时播前和成熟期有效磷含量分别为16.9和20.4 mg·kg^(-1)。磷吸收利用效率随施磷量增加而降低,施磷量提高50 kg P_2O_5·hm^(-2),需磷量增加0.4 g·kg^(-1),磷收获指数降低1.3%,生理效率降低45.1 kg·kg^(-1)。【结论】综合考虑小麦的籽粒产量和关键养分含量,研究区域旱地小麦应以95%的最高产量为实际生产目标,施磷量为94 kg P_2O_5·hm^(-2),播前土壤有效磷为12.0 mg·kg^(-1),成熟期为13.8 mg·kg^(-1)。展开更多
基金The National Natural Science Foundation of China under contract No.41376092the National Key Project for Basic Research of China under contract No.2011CB403602the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11030202
文摘The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released by the decomposition of jellyfish on the ecosystem in the field. The release of nitrogen and phosphorus from the decomposition of Nernopilerna nomurai was examined in a series of experiments under different incubation conditions such as different pH values, salinity values, temperatures and nitrogen and phosphorus concentrations. The results showed that the complete decomposition of Nemopilema nomurai generally took about 4-8 d. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai could be divided into two stages： the early stage and the later stage, although the efflux rate of nitrogen was one order more than phosphorus. In the early stage of the decomposition of Nemopilema nomurai, the concentrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in seawater increased rapidly, and the concentration of nitrogen could reach the highest level in the whole degradation process. In the later stage of the decomposition, the concentrations of dissolved nitrogen and total nitrogen declined slowly, while the concentration of phosphorus in water could reach a maximum in the degradation process. High pH, low salinity, high temperature and N/P will promote the release of nitrogen; low pH is unfavorable to the release of nitrogen but favorable to the release of phosphorus. In addition, we found the concentrations of ammonium and phosphate in the bottom water were higher than those in the surface water during the period of jellyfish bloom in the ]iaozhou Bay, proving that nutrients released by the decomposition of jellyfish have significant influence on nitrogen and phosphorus in the field. For the whole Yellow Sea, nutrients released by jellyfish carcasses may reach up to （2.63±2.98）x10^7 mol/d of dissolved nitrogen （DN） and （0.74±0.84）x10^8 mol/d of dissolved phosphorus （DP） during the period of jellyfish bloom. The values are comparable to riverine inputs in a day, but much higher than sediment-water exchange flux in the Yellow Sea. The great amounts of nutrients must have significant influence on the nutrients balance of the Yellow Sea during the period of jellyfish dead and decomposition. Both the experimental data and field observations proved that the decomposition of jellyfish may release a great amount of nutrient to the surrounding environment during the period of jellyfish decomposition.
文摘目的】探讨长期定位施磷条件下小麦产量、土壤有效磷水平及籽粒养分含量变化,为旱地小麦合理施用磷肥,提高产量、改善品质提供理论依据。【方法】基于2004年在黄土高原开始的长期定位试验,于2014—2015、2015—2016和2016—2017连续3年取样,研究不同施磷量对小麦产量,生物量,产量构成,籽粒氮、磷、钾含量,土壤有效磷含量及磷吸收利用的影响。【结果】与不施磷相比,长期施磷使小麦产量平均提高67%,生物量提高58%,穗数和穗粒数分别增加64%和8%,而千粒重降低7%。施磷量与小麦产量、生物量呈抛物线关系,获得最高产量6 465 kg·hm^(-2)的施磷量为144 kg P_2O_5·hm^(-2)。籽粒氮含量随施磷量增加而降低,磷和钾含量随施磷量增加而提高。土壤有效磷含量与施磷量呈显著正相关,小麦获得最高产量时播前和成熟期有效磷含量分别为16.9和20.4 mg·kg^(-1)。磷吸收利用效率随施磷量增加而降低,施磷量提高50 kg P_2O_5·hm^(-2),需磷量增加0.4 g·kg^(-1),磷收获指数降低1.3%,生理效率降低45.1 kg·kg^(-1)。【结论】综合考虑小麦的籽粒产量和关键养分含量,研究区域旱地小麦应以95%的最高产量为实际生产目标,施磷量为94 kg P_2O_5·hm^(-2),播前土壤有效磷为12.0 mg·kg^(-1),成熟期为13.8 mg·kg^(-1)。
