花蓮萬榮地區蛇紋岩水田土壤之理化特性與重金屬含量

Physichemical properties and heavy metals of paddy soils from serpentinites at Wan-Rong, Hualien

范心彤(Hsin-Tung Fan)

指導教授 ： 許正一

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2011年)

https://doi.org/10.6346/NPUST.2011.00067

摘要

蛇紋岩多發生於板塊撞擊交界帶上，其風化生成之土壤中鎂含量極高，故Ca/Mg比值偏低，且錳、鉻、鎳及鈷等重金屬含量較高，黏土礦物組成特殊，不管在土壤肥力或重金屬污染潛勢上都有值得探討的議題。本論文針對花蓮萬榮地區之三個蛇紋岩水田土壤，探討其土壤理化特性和重金屬含量，並且單一試劑萃取法(single extraction)與序列萃取法(sequential extraction)測定不同型態的鐵、錳、鉻、鎳、鈷，再以X-ray繞射探討原生礦物組成與次生礦物之轉變。研究結果顯示，三個土壤樣體主要為坋質壤土、砂質壤土，故陽離子交換容量低。全量鈣/鎂比值雖遠低於1.0，但交換性鈣/鎂次比值範圍則在4.24-29.1之間。鉻和鎳全量範圍分別為242-762 mg/kg及211-2010 mg/kg，遠高於土壤污染管制標準。鐵、錳、鉻、鎳、鈷的結合型態，主要是以被固定在礦物晶格內的殘餘態為主，各元素間移動性順序為錳＞鈷＞鎳＞鐵＞鉻。以台灣有機農業土壤之重金屬容許量0.1 N HCl萃取法評估，鎳在WR-1及WR-3的表土層皆超過此一容許量。雖然鉻、鎳及鈷含量高於一般土壤，但真正能被植物所吸收的量卻不高。此外，X-ray繞射顯示主要礦物為綠泥石、蛇紋石、海泡石、雲母等，其中樣體WR-2、WR-3全部及WR-1 C層中，含有蒙特石。

關鍵字

蛇紋岩土壤 ； 鉻 ； 鎳 ； 單一試劑抽出法 ； 序列萃取

並列摘要

Serpentinites are generally found in the margins between tectonic plates, which are derived into soils characterized by high Mg content, low Ca/Mg ratio, extremely high contents of heavy metals (eg. Mn, Cr, Ni, Co), and unique clay mineral compositions. There are many suspended issues to be explored in the soil fertility and contamination potential of the metals. This study performed three paddy soil profiles from Wan-Rong, Hualien with physichemical properties and heavy metal contents. Single and sequential extraction were also applied to fractionate the metal phases. The mineral transformation was performed by XRD. The experimental results indicated that major soil textures are silty loam and sandy loam and the CEC is very low. Total Ca/Mg ratio is much lower than 1.0, while exchangeable Ca/Mg ranges from 4.24 to 29.1. Total Cr and Ni ranged from 242 to 762 mg/kg and from 211 to 2010 mg/kg, are much higher than the soil pollution control standards. The dominant phase of all metals by sequential extraction is the residual form which consists of silicate framework. According the fractionation, the order of mobility is Mn ＞ Co ＞ Ni ＞ Fe ＞ Co. Regrading 0.1N HCl extraction evaluated for organic farming standardization, the Ni contents in the surfaces soils from pedons WR-1 and WR-3 exceeded this standard. The amount of Cr, Ni, and Co in plant uptake is not high, even if their levels is higher than those in the other soils. In soil mineralogy, the dominant minerals are chlorite, serpentine, sepiolite, and mica, with less extent in smectite.

並列關鍵字

serpentinitic soils ； chromium ； nickel ； single extraction ； sequential extraction

參考文獻

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