廢水處理型人工濕地降低溫室氣體排放之研究－沉積物與碳匯間關係之分析

自18世紀工業革命過後，全球溫室氣體排放大量增加，造成溫室效應加劇。除了最主要受到關注的二氧化碳（CO_2）之外，氧化亞氮（N_2O）及甲烷（CH_4）更因為具有更高的全球暖化潛勢，因此也逐漸受到關注。近年來，水質淨化型人工濕地因具有操作及維修成本較低的優勢，在處理廢污水上不再只是使用傳統活性污泥污水廠，而是多了人工濕地的選項。濕地植物會吸收大氣中之二氧化碳行光合作用，並轉為有機碳儲存在濕地系統內；然而，在處理廢污水時也會有CO_2、CH_4及N_2O等溫室氣體的產生。人工濕地在國內外應用的數目及面積規模逐年增加，因此需要瞭解人工濕地排放溫室氣體之狀況。本研究共設置4座不同控制環境條件之人工濕地模槽，分別為空白對照組（B）、添加含優勢厭氧氨氧化菌株體污泥及種植紅海欖（Rhizophora stylosa）組（PA）、添加生活污水處理廠污泥組（S），以及添加生活污水處理廠污泥及種植紅海欖組（PS）。由不同的進流水濃度下，透過監測溫室氣體濃度，並進行土壤沉積物的性質分析，藉以得知在何種條件下可以得到最好的碳匯能力。由紅樹林枯葉落物量來推算總初級淨生產力，結果顯示PA槽及PS槽分別為1,146及1,536 g C m^(-2) yr^(-1)。又根據土壤碳庫之估算結果發現，土壤碳含量皆呈現表層土壤（0～15cm）大於底層土壤（15～30cm）。B模槽總碳庫量為10,083 g C m^(-2)、PA模槽為8,637 g C m^(-2)、S模槽為9,405 g C m^(-2)、PS模槽為9,164 g C m^(-2)。各模槽碳庫量與土壤碳累積量有關，PA及PS模槽因有植物吸收土壤養分，因此土壤碳庫量皆低於無種植植物之B及S模槽。由人工濕地之碳匯能力結果得知，只有PS模槽在進流碳源水體時具有碳匯能力（1,371g CO_2-eq m^(-2) yr^(-1)），4個模槽在其它條件下皆為碳源。其中，B及PA模槽最高碳匯能力皆在進流亞硝酸鹽水體（-2,422 g CO_2-eq m^(-2) yr^(-1)及-149 g CO_2-eq m^(-2) yr^(-1)），S模槽之最高碳匯能力是在進流碳源水體（-3,528g CO_2-eq m^(-2) yr^(-1)）。結果顯示若要增加碳匯能力，植物的生產力對於固碳能力相當重要。

關鍵字

人工濕地；溫室氣體；碳匯；碳源；碳庫；碳收支

並列摘要

After the Industrial revolution in the 18th century, the emission of greenhouse gas have increased significantly and also made global warming worsen. Besides CO_2 which is the main concern , N_2O and CH_4 are getting more and more attention because of its ability of causing global warming. In recent years, Constructed treatment wetland has become the tendency for wastewater treatment. Because it compares to the traditional wastewater treatment plants. Constructed treatment wetland is easier to operate and has lower maintenance cost. Wetland plants absorb CO_2 in the atmosphere and photosynthesize. It turns CO_2 into organic carbon and saves in the wetland system. But when treating sewage, there are also producing greenhouse gas. The increase of constructed wetland area and application. Related search is needed. This study is located at the wetland which is on the top floor of Department of Marine Environment and Engineering building. There are four different types of constructed wetland: Control (C) , added enriched culture Anammox bacteria sludge and planted Rhizophora stylosa (PA) , added activated sludge (S) , added activated sludge and planted Rhizophora stylosa (PS); By inflowing different water , through monitoring the gas concentration, and analyzed sediments. Use the data to know under which condition can have the best carbon sink ability. This study use mangrove forest litter to calculate net primary production (NPP). The NPP of PA and PS is 1,146, 1,536 g C m^(-2) yr^(-1). Found from the carbon stocks results. The soil organic carbon in four constructed wetland all show that the topsoil (0~15 cm) is bigger than subsoil (15~30 cm). The soil organic carbon of C is 10,083 g C m^(-2), PA is 8,637 g C m^(-2), S is 9,405 g C m^(-2), PS slot is 9,164 g C m^(-2). Carbon stocks are related to soil organic carbon. PA and PS have absorbed nutrient from soil so their carbon stocks are lower than C, S which don't have any plants planted. The results show that C is always carbon source under any conditions. When inflowing water with nitrite have the best carbon sink (-2,422 g CO_2-eq m^(-2) yr^(-1)); PA is always carbon source under any conditions. When inflowing water with nitrite have the best carbon sink (-149 g CO_2-eq m^(-2) yr^(-1)); S is always carbon source under any conditions. When inflowing water with nitrite have the best carbon sink (-3,528g CO_2-eq m^(-2) yr^(-1)); PS only have its carbon sink ability (1,371g CO_2-eq m^(-2) yr^(-1)) when inflowing water with carbon. In other inflow cases are all carbon resources. So to increase carbon sink ability. Plant productivity plays a big part in carbon fixation.

並列關鍵字

carbon sink ； carbon source ； carbon stocks ； carbon accumulation ； constructed wetlands ； greenhouse gases

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廢水處理型人工濕地降低溫室氣體排放之研究－沉積物與碳匯間關係之分析

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