过量氮和磷引起的富营养化对海水无机碳源汇强度的影响

IOCAS-IR > 海洋环流与波动重点实验室

	过量氮和磷引起的富营养化对海水无机碳源汇强度的影响
其他题名	Influence of external source nitrogen and phosphate on inorganic carbon source/sink
	张乃星
学位类型	博士
	2008-06-01
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	氮磷富营养化模拟实验无机碳体系碳源汇
摘要	过量氮和磷引起的海水富营养化引起了一系列的生态环境效应，探讨二者的耦合关系对阐明全球海洋生态环境变化机制意义重大。本论文首次探讨了过量氮和磷引起的富营养化对海水无机碳体系的影响，通过室内系统模拟实验，构筑了过量氮和磷与无机碳体系变化的定量耦合关系，在此基础上获得了中国近海典型海域特别是南黄海近十年氮和磷演变引起的无机碳源汇格局变化，获得了以下一系列新的结果和认识： 1、不同营养盐（NO3-、NH4+、NO2-和PO43-）对水体溶解无机碳体系均有重要影响，且影响程度有较大的差异。在模拟实验中，当NO3-<188 μmol/L，NH4+<126 μmol/L，NO2-<39.5 μmol/L时均可明显提高水体的固碳能力，相应水体中的DIC、HCO3-和 pCO2均较空白对照组时有一定程度的下降。当N浓度达到一定值后，其固碳能力减弱，DIC、HCO3-和pCO2出现相反变化。当NH4+>126 μmol/L和NO2->39.5 μmol/L时pCO2增加，向大气释放CO2。在PO43-添加组中，当浓度小于19.5μmol/L时DIC、pCO2较空白对照组下降，水体表现为大气CO2的汇，其固碳能力高于N组。在孔石莼添加组中，各营养盐组水体的固碳能力均高于空白对照组，相应水体中DIC、HCO3-和pCO2的下降明显。其中，同一营养盐浓度水平下，NH4+组中各无机碳组分的变化幅度明显高于NO3-和NO2-组，PO43-组的无机碳体系变化幅度低于N组。其中，当NO3-、NH4+和NO2-浓度分别在71 μmol/L，49.7 μmol/L和11.7 μmol/L时，pCO2下降明显，水体表现为大气CO2的强汇。对无机碳各参数的变化量与营养盐进行多元回归分析，得到以下统计关系： ⊿DIC=-0.937(⊿PO43-)-0.34(⊿NO3-)-0.46(⊿NH4+)+0.11(⊿NO2-)（R2=0.69, n=30，Sig.<0.05） ⊿HCO3-=-1.357(⊿PO43-)-0.35(⊿NO3-)-0.57(⊿NH4+)-0.013(⊿NO2-)（R2=0.76, n=32, Sig.<0.05） ⊿CO32-=0.344(⊿PO43-)+0.16(⊿NO3-)+0.18(⊿NH4+)+0.076(⊿NO2-)（R2=0.69, n=32, Sig.<0.05） ⊿pCO2=-1.321(⊿PO43-)-0.12(⊿NO3-)-0.31(⊿NH4+)-0.032(⊿NO2-)（R2=0.84, n=35, Sig.<0.01） 2．氮、磷对海水无机碳体系的源汇格局影响主要受控于水体浮游藻类对营养盐的利用。模拟实验各种情况下Chl-a的浓度均有不同程度的变化。在N组中，当NH4+<126 μmol/L，随着NH4+浓度的增加，Chl-a浓度增加，而高浓度（NH4+>126 μmol/L）的实验组中，Chl-a则随浓度的增加而下降。当NO2-和PO43-的浓度分别大于39.5 μmol/L和19.5 μmol/L时，水体中Chl-a随营养盐浓度的增加而出现下降趋势，不同的是NO3-添加组在实验浓度范围内藻类均出现了不同程度的增长，这可能与浮游藻类对过量营养盐的耐受性不同有关。在低浓度时，PO43-组pCO2的下降最为明显，这与 PO43-组Chl-a的含量较高相一致，其次为NH4+，NO3-高于NO2-，可见在实验水体中PO43-对于藻类新陈代谢作用影响明显，从而作用到无机碳上的影响也就最为明显。对各实验水体⊿Chl-a与无机碳各组分作相关性分析发现，⊿Chl-a与⊿pCO2的相关性最为明显（R2=0.75，p<0.0001），这可能是因为浮游藻类光合作用和分解作用消耗或生成的首先是海水中的游离CO2（即pCO2）。在孔石莼组中，由于大藻对过量营养盐的耐受性较强，因此各组中藻类干重均有一定程度的增长。藻类干重的增加以NH4+最为明显，其次为NO3-和NO2-，这可能与其对N盐的优先吸收顺序NH4+>NO3->NO2-有关。加PO43-组中藻类的干重增加量低于NH4+和NO3-组，这与大藻的生理特性有关。对藻类干重增加量⊿m与⊿DIC作相关性发现，二者相关性明显（R2=0.64，p<0.01），这是由于孔石莼光合作用同时吸收HCO3-和CO2为碳源有关。 3、近年来，中国近海由于海水过量氮磷引起的富营养化，可使大部分海域海水无机碳汇强度增加应用室内模拟获得的无机碳与氮、磷之间的定量耦合关系，估算了过量氮、磷引起的富营养化条件下，中国近海水体无机碳源汇的变化情况。结果表明，近十年来，由于氮、磷浓度的增加而导致渤海、南黄海、北黄海和东海每年从大气中多吸收0.197×106t C、0.302×106t C、0.039×106t C和2.233×106t C，东中国近海营养要素的含量的变化及组成比例的时间性和地区性差异是造成各海区碳通量差异的重要因素；对2006年南黄海水文、化学、生物与无机碳体系之间的相互关系进行综合分析，可知水体无机碳体系与营养盐水平密切相关。
其他摘要	External source nitrogen and phosphate can cause series of domino effect on entironment. It is very important to clarify the coupling relationship between nutrient and inorganic carbon system for global marine entironment. In this paper, we studied the influence of external source nutrient (nitrate and phosphate) on dissolved inorganic carbon system through simulation experiments in laboratory for the first time. Furthermore, we concluded change of inorganic carbon source and sink at South Yellow Sea and other typical seas. A series of results and viewpoint are presented as followed: 1. Different nutrient form (NO3-, NH4+, NO2- and PO43-) have various impact on dissolved inorganic carbon system. At the simulated experiments, when the NO3-<188μmol/L，NH4+<126μmol/L and NO2-<39.5μmol/L, the concentration of DIC and HCO3- significantly increased while the pCO2 decreased compared with the control groups. The concentration change of DIC、HCO3- and pCO2 inversed when the nitrogen increased to certain concentration. When the NH4+>126μmol/L and NO2->39.5μmol/L, the pCO2 increased and the water present as carbon source. At the PO43- addition groups, the concentration of DIC increased while pCO2 decreased compare with the control groups. And the seawater presents as CO2 sink. At the Ulva pertusa addition groups, the concentration of HCO3- and pCO2 significantly decreased compare with the control groups. At the same nutrient concentration level, the change of dissolved inorganic carbon system in NH4+ addition groups was higher the NO3- and NO2- groups. All the N addition groups were higher than the PO43- addition groups at the amount of dissolved inorganic carbon change. The pCO2 decreased significantly and the seawater present as CO2 sink when the concentration of NO3-, NH4+ and NO2- each was at 71μmol/L, 49.7μmol/L and 11.7μmol/L. The statistical multianalysis formulas between the increased amount of dissolved inorganic carbon system and nutrient was followed: ⊿DIC=-0.937(⊿PO43-)-0.34(⊿NO3-)-0.46(⊿NH4+)+0.11(⊿NO2-)（R2=0.69, n=30，Sig.<0.05） ⊿HCO3-=-1.357(⊿PO43-)-0.35(⊿NO3-)-0.57(⊿NH4+)-0.013(⊿NO2-)（R2=0.76, n=32, Sig.<0.05） ⊿CO32-=0.344(⊿PO43-)+0.16(⊿NO3-)+0.18(⊿NH4+)+0.076(⊿NO2-)（R2=0.69, n=32, Sig.<0.05） ⊿pCO2=-1.321(⊿PO43-)-0.12(⊿NO3-)-0.31(⊿NH4+)-0.032(⊿NO2-)（R2=0.84, n=35, Sig.<0.01） 2. The impact on dissolved inorganic carbon system by nitrogen and phosphate is mainly controlled by nutrient using of phytoplankton. The concentration change of Chl-a was various with the kinds and concentrations of nutrient. When NH4+<126μmol/L, the concentration of Chl-a increased from 2.43μg/L to 2.55μg/L with the concentration of NH4+ increased. The concentration of Chl-a decreased when NH4+>126μmol/L. When NO2->39.5μmol/L or PO43- >19.5μmol/L, the concentration of Chl-a decreased. While at the NO3- addition groups, the concentration of Chl-a was all increased. That’s because the phytoplankton has different tolerance with excessive nutrient. The pCO2 decreased significantly which was consistent with the Chl-a concentration at the PO43- addition groups. The decrease extent of pCO2 was NH4+>NO3->NO2-. PO43- has the high relationship with phytoplankton’ photosynthesis, so the impact on inorganic carbon was most obvious. The Chl-a concentration of nutrient addition groups compared with control (⊿Chl-a) shows a significant negative correlation with ⊿pCO2 (R2 =0.75, p<0.0001). The dry weight of Ulva pertusa was increased at all groups that’s because Ulva pertusa has higher tolerance with excessive nutrient. The dry weight of Ulva pertusa at NH4+ groups was higher than NO3- and NO2- groups which was consistent with nitrogen absorbing order NH4+>NO3->NO2-. The dry weight increase of Ulva pertusa at PO43- addition groups was lower than NH4+ and NO3- addition groups. The dry weight of Ulva pertusa at nutrient addition groups compared with control shows a significant correlation with ⊿DIC. That’s because Ulva pertusa absorb HCO3- and CO2 in photosynthesis. 3. The intensity of inorganic carbon sink at most seas was enhanced by the nitrogen and phosphate enrichment in recent years. We calculated the amount change of inorganic carbon source/sink caused by excessive N and P under the relationship between inorganic carbon and nutrient. In recent years, Bohai Sea, South Yellow Sea, North Yellow Sea and East China Sea each has absorbed 0.197×106tCa-1, 0.302×106tCa-1, 0.039×106tCa-1 and 2.233×106tCa-1 for the increase concentration of N and P. The change of nutrient concentration and component was the main reason for diverse carbon flux in seas. The inorganic carbon system was significantly correlated with nutrient concentration and the amount of phytoplankton through analyzing the data of South Yellow Sea in 2006a.
页数	107
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1327
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	张乃星. 过量氮和磷引起的富营养化对海水无机碳源汇强度的影响[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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