【作者】 田园；

【导师】 叶勇；

【作者基本信息】 厦门大学 ， 生态学， 2018， 硕士

【摘要】 本文以福建九龙江口靠近密集虾池的秋茄(Kandelia obovata)红树林为研究对象,共设置两块排污区和两块对照区样地,其中排污区I的排污历史为14年,排污区Ⅱ为8年,探索虾池排污(主要是清塘排污)对红树林地下部分(底质和根系)有机碳主要过程的影响。主要结果如下:底质平均有机碳含量范围为1.78%-2.05%,排污区Ⅰ的底质TOC含量与对照区I之间无明显差别,而排污区Ⅱ的底质TOC含量显著低于对照区Ⅱ。不同地点的TN和TP含量从高到低排列为D1>D2>C2>C1,TN和TP含量范围分别为0.12%-0.16%、0.04%-0.08%,两排污区的底质TN含量均显著高于相邻对照区,且排污区Ⅰ的TN含量增幅较排污区Ⅱ大,排污区Ⅰ底质TP含量显著高于对照区Ⅰ,而排污区Ⅱ的底质TP含量与对照区Ⅱ无显著差别。有机碳储量平均每10cm可达17.56-22.55 t hm-2,两排污区的底质TOC储量显著高于两对照区。C/N值在不同排污样地以及底质深度之间均无显著差异。EOC含量平均值为0.21%-0.34%,排污区Ⅰ与对照区Ⅰ的EOC含量差异不显著,而排污区Ⅱ的底质EOC含量显著高于对照区Ⅱ。随着红树林底质深度的增加,TOC含量、TN含量、TP含量和有机碳储量总体上逐渐减少,且减少幅度在两个排污区更大。以上结果表明,长时期的虾池排污(14年)较短期(8年)对邻近秋茄林的底质碳和养分含量积累效应更为显著,且随底质深度的增加这种作用逐渐减弱。稳定碳同位素(δ13C)分析结果表明:表层0-10 cm处的底质δ13C值在不同排污样地之间无显著差异;40-50cm深度,排污区Ⅰ的底质δ13C平均值-25.53%。显著低于对照区Ⅰ,而排污区Ⅱ和对照区Ⅱ的底质δ13C值无显著差异,这说明虾池排污可能增加了秋茄林底质的不稳定性,且排污区Ⅰ较排污区Ⅱ影响大。高位虾池排污的贡献率最高(21.70%-57.00%)、毗邻海水悬浮物次之(31.00%-50.80%)、红树植物的贡献率最低(8.00%-47.30%),结果反映了高位虾池排污与潮水作用的综合效应。三种根系生物量从高到低排列为:粗根>活细根>死细根。活细根生物量最高值出现在排污区Ⅱ的10-20 cm处,不同排污样地活细根生物量差别不大。死细根和粗根生物量均在排污区Ⅰ显著低于对照区Ⅰ。不同样地三种根系的TOC含量总体上变化不大;总根系TN含量总体表现为:排污区Ⅰ>对照区Ⅰ,排污区Ⅱ>对照区Ⅱ;在0-50cm范围内,排污区Ⅰ总根系的TP含量均显著高于对照区Ⅰ;而各深度排污区Ⅱ与对照区Ⅱ这三种根系的TOC含量、TN和TP含量总体上无明显变化;各层深度及总深度(50cm)的地下部分(底质+根系)有机碳储量、TN和TP储量表现为排污区Ⅰ>对照区Ⅰ且排污区Ⅱ>对照区Ⅱ。经过半年的分解实验,10 cm处的分解细根在两排污区的分解失重率大于两对照区,30 cm处变化不明显。随分解时间增加,各样地TOC含量和C/N值有增有减。埋于10 cm处细根TN含量随分解时间的延长有增加的趋势,且两排污区强于两对照区;30 cm处,排污区Ⅰ分解细根的TN含量显著低于对照区Ⅰ,而排污区Ⅱ与对照区Ⅱ之间无显著差异。在10 cm和30 cm处,排污区I的分解细根TP含量均显著高于对照区Ⅰ,而排污区Ⅱ与对照区Ⅱ之间无明显变化。本研究进一步揭示了高位虾池排污对邻近秋茄林的累积效应:虾池排污对地下TOC含量和储量的影响不明显;致使地下TN、TP的含量和储量增加,且对TP含量和储量影响更大;排污历史越长,高位养虾对周边红树林地下养分含量和储量的影响越大。总之,在高位虾池排污背景下邻近秋茄林的地下有机碳含量和储量变化不明显,但一定程度上显著增加了地下部分TN、TP含量和储量,且排污历史越长增加效应越明显。更多还原

【Abstract】 This study concentrated Kandelia obovata forests which are beside the densely distributed shrimp ponds,alone Jiulongjiang Estruary,Fujian Province.A total of two discharge areas(D1 and D2)and two control areas(C1 and C2)were set up.It has been 14 years since it began to receive effluents from shrimp ponds in discharge area Ⅰ and 8 years in discharge area Ⅱ.Aims of this study were to explore the effects of discharge from shrimp ponds(mainly cleaning-effluents from high-level shrimp ponds)on the main processes of organic carbon in underground parts of mangrove forests.In terms of organic carbon content in sediment,mean values were 1.78%-2.05%;no significant difference was found between discharge area I and control area Ⅰ;while organic carbon content in discharge area Ⅱ was significantly lower than control area Ⅱ.TN and TP contents in sediment showed that discharge area Ⅰ>discharge area Ⅱ>control area Ⅱ>control area Ⅰ.TN content and TP content in sediment was 0.12%-0.16%and 0.04%-0.08%.Sediment TN contents in two discharge areas were significantly higher than the two adjacent control areas.Sediment TP content in discharge area I was significantly higher than control area I and there was no significant difference between discharge area Ⅱ and control area Ⅱ.Average organic carbon storage was 17.56-22.55 t hm-2 at every 10 cm depth,and two discharge areas significantly higher than two control areas.There was no significant difference on C/N values in both areas and depths.Mean value of EOC content was 0.21%-0.34%.There was no significant difference in EOC content between discharge area I and the control area I,while the content of EOC in discharge area Ⅱ was significantly higher than that in control area Ⅱ.With depth increasing,organic carbon content,TN and TP content as well as organic carbon storage in sediment gradually reduced.The above results indicated that the effects of long period direct discharge of effluent from high-level shrimp ponds were more significant than that of the short period and the effects gradually decreased with increasing depths.The results of stable carbon isotope(δ13C)analysis showed that there were no significant differences among the four areas at 0-10 cm depth.At 40-50 cm depth,averageδ13C in sediment in discharge area I was significantly lower than that in control area Ⅰ,while there was no obvious difference between discharge area Ⅱ and control area Ⅱ.This indicated that discharges from shrimp ponds might increase the instability of sediments and discharge area I responded more.In this study,contribution of suspended solids in effluent from shrimp ponds ranged 21.70%-57.00%;contribution of suspended solids in adjacent seawater ranged 31.00%-50.80%;contribution of K.obovata was 8.00%-47.30%.The results reflected the comprehensive effects of tidal action and discharges from shrimp ponds.The order of three kinds of roots biomass ranged from high to low was coarse roots>live fine roots>dead fine roots.The maximum biomass of live fine roots was in the depth of 10-20 cm in discharge area Ⅱ.Both dead fine roots and coarse roots biomass in discharge area Ⅰ were significantly lower than control area I.Organic carbon contents of three kinds of roots did not change obviously in general.TN content in total roots showed that discharge area Ⅰ>control area Ⅰ and discharge area Ⅱ>control area Ⅱ.TP content of total roots in discharge area Ⅰ was significantly higher than that in control area Ⅰ at 50 cm depth.Organic carbon contents,TN and TP contents in three kinds of roots between discharge area Ⅱ and control area Ⅱ did not have significant changes at all depths.The underground part of organic carbon storages,TN and TP storages follow the rule of discharge area Ⅰ>control area Ⅰ and discharge area Ⅱ>control area Ⅱ at all averages depths and total depths(50 cm).After six-month decomposition experiment,the decomposition rates of fine roots were greater at 10 cm depth in two discharge areas than the rates in two control areas,while changes in 30 cm depth were not obvious.As decomposition time increasing,changes of organic carbon content and C/N values of fine roots in all areas were not obvious.TN content of fine roots at 10 cm depth generally had increasing tendency with the extension of decomposition time.At 30 cm depth,TN content of fine roots in discharge area Ⅰsignificantly lower than that in control area Ⅰ while there were no significant differences in discharge area Ⅱ and control area In.At both 10 cm and 30 cm depth,TP content of fine roots in discharge area Ⅰ significantly higher than that in control area Ⅰ while no significant differences were found in discharge area Ⅱ and control area Ⅱ.This study further revealed the cumulative effects of high-level shrimp ponds discharges on the adjacent K.obovata forests.Changes of organic carbon contents and storages were not obvious in underground parts.TN,TP contents and storages generally increased.The longer discharge history the areas have,the greater influence of high-level shrimp ponds on nutrient contents and storages in underground parts of surrounding mangrove forests.In a word,under the background of widely spread high-level shrimp ponds,the underground parts of organic carbon contents and storages had not obvious changes,TN and TP contents and storages generally increased.The longer discharge history the areas have,the more obvious effect the underground parts responded.更多还原