臺灣博碩士論文加值系統

本研究是「南海生地化整合研究」(SIBEX；South China Sea Integrated Biogeochemical Experiments)首次南海沉積物收集器錨錠的結果。兩串列沉積物收集器分別在台灣西南海域(M1)，及南海海盆北部(M2)進行錨錠，並在M2 的南方採集岩心。其主要目的在探討不同深度之沉降顆粒通量及Pb-210 活性的時空變化，並且量測岩心之沉積速率，以瞭解顆粒物
質在南海生地化作用所扮演的角色及分佈特徵。
M1 及M2 在不同深度之顆粒通量大部份由淺至深逐漸增加。在時序相對變化上，M1 顆粒通量的變化幅度比M2 大，其水深948 m 的顆粒通量時序變化最大，最大值可達2025mg/m2/d。除少數例外，深層(948 m)收集器之通量皆高於淺層(248 m)者，這可能是顆粒側向傳輸的影響。M2 站水深240 m 的顆粒通量較其下方各深度高且變化也較大。較深的三組收集器(1240(1240m、2240 m 及3240 m)在錨錠期內所得之顆粒通量時序變化幅度甚小，且有同步性。M1 及M2 之各深度平均顆粒通量範圍為199~554mg/m2/d，均比前人在南海所觀測者(平均為76~104 mg/m2/d)高，但卻與陸源輸入南海之平均顆粒通量(280 mg/m2/d)相當，表示在約10年間顆粒通量有極大的改變，故仍需繼續作較長期的錨錠研究。
M1及M2兩錨錠站沉降顆粒Pb-210 之活性，在時序變化上大致各有同步性的趨勢，且隨深度增加，此快速往深處增加的現象反映沉降顆粒之清除效率在低濃度狀況下相當高。兩站之燒失量(L.O.I.)皆與Pb-210 之活性稍成反比，顯示Pb-210 可能被生物顆粒或有機質所排斥。而M1 及M2 在水深約240 m 之顆粒通量皆與L.O.I.呈正比關係，表示淺層的高顆粒通量可
能是生物顆粒或有機質所造成。
本研究區域之沉積速率藉由岩心超量Pb-210 分佈推算，其值介於9.01~23.13 cm/100yr，如此快速之沉積速率是受混合作用與外來物質側向堆積的影響。由超量Pb-210 所穿透的岩心深度推測，表層沉積物均已受擾動與混合。由沉積物超量Pb-210 存量所推測之Pb-210 通量遠大於由收集器所觀測者，顯示有Pb-210 由他處之表層沉積物經側向輸入而堆積。由收集器之平均顆粒通量粗估其對應之沉積速率約為10 cm/ka，比由超量Pb-210 所估者低一級數。上層沉積物因受強烈擾動且與側向輸入之沉積物混合堆積而使由超量Pb-210 法所得之沉積速率高估約10 至20 倍。

This study reports the first sediment trap mooring results obtained
under the SIBEX program (South China Sea Integrated Biogeochemical
Experiments). Two strings of sediment traps were deployed respectively
at M1 located to the southwest of Taiwan, and M2 in the northern basin
of the South China Sea (SCS). Box cores were also taken at several
sites to the south of M2. The main purposes are to measure settling
particulate fluxes at various depths for the studies of temporal and spatial
variations of the particulate flux and 210Pb activity. The box cores were
used to determine the sedimentation rates. These are to enhance our
understanding of the characteristics of the particulate distribution and the
roles the particulate matter plays in the biogeochemical processes in the
SCS.
Particulate fluxes measured from different depths at M1 and M2
generally increase with depth. In temporal variation, M1 has higher
amplitudes than M2, with highest amplitudes at 948 m where highest flux
(2025 mg/m2/d) was observed. The particulate flux at 948 m has higher
values than at 248 m, probably due to lateral transport. At M2, the
particulate flux at 240 m has higher values with greater amplitudes than at
greater depths, i.e. 1240 m, 2240 m and 3240 m, where their particulate
fluxes show a synchronous trend with small amplitudes in temporal
variation. The time-averaged particulate flux for each trap ranges from
199 to 554 mg/m2/d, consistently higher than previous observations
(76~104 mg/m2/d). However, our values are comparable to the mean
particulate flux (280 mg/m2/d) estimated from terrigenous inputs. The
apparent changes in particulate flux in the SCS over the past ten years
warrants further investigations.
The temporal variations of Pb-210 show a synchronous trend and a
rapid increase with depth as observed at M1 and M2. This rapid
increase of Pb-210 with depth reflects effective scavenging by sinking
particulates although particulate concentrations are low. The loss on
ignition (L.O.I.) at M1 and M2 was inversely correlated with Pb-210,
indicating that Pb-210 was expelled from biogenic particulates or organic
matter. The particulate fluxes around 240 m at M1 and M2 were
generally positively correlated with the L.O.I., suggesting that the high
particulate fluxes are probably contributed by biogenic particulates or
organic matter.
The sedimentation rates as determined from excess Pb-210 profiles
range from 9.01~23.13 cm/100yr. These rapid sedimentation rates
reflect the effect of mixing and additional sediments accumulated through
lateral transport. The surface layers of these cores were subject to
perturbation and mixing, based on the penetration depths of the excess
Pb-210. The Pb-210 flux estimated from the inventory of excess Pb-210
in the sediments is much greater than that observed from the traps,
suggesting that additional Pb-210 has been accumulated via lateral
transport and slumping of nearby surface sediments. Based on the mean
particulate flux observed, one may roughly estimate the corresponding
sedimentation rate of about 10 cm/ka, which is an order of magnitude
lower than those determined by the excess Pb-210 method. Because the
upper layers of the sediments have been strongly disturbed and mixed
with the additional sediments accumulated through lateral transport, the
sedimentation rates as determined by the excess Pb-210 method are
probably over-estimated by a factor of 10 to 20.

摘要…………………………………………………………… I
Abstract ………………………………………………………… III
目錄…………………………………………………………… V
圖目錄………………………………………………………… VII
表目錄………………………………………………………… VIII
一、緒論……………………………………………………… 1
二、材料及方法……………………………………………… 4
2-1 採樣區域………………………………………… 4
2-2 沉降顆粒的處理………………………………….. 4
2-3 岩心的處理……………………………………….. 6
2-4 燒失量(L.O.I.) …………………………………… 6
2-5 Pb-210 活性分析方法…………………………….. 6
2-6 Po-210 活性分析方法……….…………………… 10
2-7 Po-210 活性修正方法……………………………... 11
2-8 顆粒粒徑分析…………………………………..... 12
三、結果與討論……………………………………………….. 14
3-1 顆粒通量……..……………………………………… 14
3-1.1 M1 各深度顆粒通量時序變化……………… 14
3-1.2 M2 各深度顆粒通量時序變化……………… 14
3-1.3 M1 及M2 各深度平均顆粒通量比較………. 21
3-1.4 陸源輸入之顆粒通量……………………….. 23
3-2 濕篩觀察描逑與燒失量(L.O.I.)……………………… 23
3-2.1 濕篩觀察描逑...…………………………..…. 23
3-2.2 燒失量(L.O.I.)………………………………. 24
3-3 沉降顆粒Pb-210 之活性變化………………………. 26
3-3.1 M1 各深度Pb-210 活性之時序變化………. 26
3-3.2 M2 各深度Pb-210 活性之時序變化………. 26
3-3.3 M1 及M2 各深度的平均Pb-210 活性比較.. 29
3-4 Pb-210 之活性與顆粒通量及L.O.I.的相關性……… 29
3-5 岩心之Pb-210 活性分佈……………………………... 32
3-5.1 有機質及含水率的變化……….………….... 32
3-5.2 粒徑分佈………………………….…………. 37
3-5.3 岩心Pb-210 與Po-210 之活性分佈………… 37
3-5.4 與懸浮顆粒及沉降顆粒之比較……………… 44
3-6 沉積速率與混合速率之分佈………………………… 48
3-6.1 沉積速率之分佈……………………………. 48
3-6.2 混合速率之分佈…………………………….. 53
3-7 沉積物超量Pb-210 之通量………………………….. 54
3-7.1 起始超量Pb-210 之活性…………………… 54
3-7.2 Pb-210 之存量(inventory)和通量(flux)….… 54
四、結論.…………………….……………………………….. 57
參考文獻………………………………………………………... 59
附錄1 粒徑組成分析之比較實驗……………………………... 65
圖目錄
頁碼
圖1 研究區域與參考文獻之採樣位置圖………………………. 2
圖2 Pb-210 等活性射源因硫酸鉛的自我吸收效應而下降之效
率校正曲線…………………..……………………………. 9
圖3 M1 顆粒通量之時序變化…………………………………… 19
圖4 M2 顆粒通量之時序變化…………………………………… 20
圖5 M1 及M2 各深度之平均顆粒通量圖……………………… 22
圖6 M1 及M2 沉降顆粒於各深度之L.O.I.分佈圖…………….. 25
圖7 M1 沉降顆粒Pb-210 活性之時序變化……………………… 27
圖8 M2 沉降顆粒Pb-210 活性之時序變化……………………… 28
圖9 M1 及M2 沉降顆粒之Pb-210 與顆粒通量關係圖……….. 30
圖10 M1 及M2 沉降顆粒之Pb-210 與L.O.I.關係圖…………. 31
圖11 各岩心之含水率及L.O.I.之垂向分佈圖…………………. 36
圖12 BX-C 及BX-D 各粒徑組組成之垂向分佈圖……………. 41
圖13 BX-E 各粒徑組組成之垂向分佈圖………………………. 42
圖14 BX-C 總Pb-210 與Po-210 的剖面及超量Pb-210 的自然
對數分佈…………………………………………………... 43
圖15 BX-D 總Pb-210 剖面及超量Pb-210 的自然對數分佈… 45
圖16 BX-E 總Pb-210 剖面及超量Pb-210 的自然對數分佈..… 46
表目錄
頁碼
表1.1 沉積物時序收集器於M1 及M2 兩錨錠站之施放與回收
相關資料…………………………………………………. 5
表1.2 箱型岩心BX-C、BX-D 及BX-E 採樣位置及相關資料5
表2.1 M1 錨碇串列不同深度之顆粒通量、L.O.I.和Pb-210 活性15
表2.2 M2 錨碇串列不同深度之顆粒通量、L.O.I.和Pb-210 活性17
表3 M1、M2 與Wiesner et. al.(1996)之平均顆粒通量比較…… 22
表4.1 BX-C 之含水率、L.O.I.、Pb-210 及Po-210 分析結果…… 33
表4.2 BX-D 之含水率、L.O.I.和Pb-210 分析結果………..…… 34
表4.3 BX-E 之含水率、L.O.I.和Pb-210 分析結果….…..……… 35
表5.1 BX-C 之粒徑組成垂向分佈………………………………. 38
表5.2 BX-D 之粒徑組成垂向分佈……………………………… 39
表5.3 BX-E 之粒徑組成垂向分佈………………………………. 40
表6.1 表層沉積物之Pb-210 及Po-210 活性…………………… 47
表6.2 M1 及M2 各深度之沉降顆粒Pb-210 平均活性…………. 47
表6.3 懸浮顆粒在不同深度之Pb-210 與Po-210 比活性……… 47
表7.1 由簡單模式計算所得之沉積速率、起始超量Pb-210、超
量Pb-210 存量及通量值…………………………………. 51
表7.2 M1 及M2 之Pb-210 平均沉降通量……………………… 51
表8 南海北部深水沉積物的沉積速率值……………………….. 52

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