近年來，重金屬污染所造成之抗生素抗藥性基因（Antibiotic Resistance Genes， ARGs）傳播問題受到廣泛關注。由於重金屬可透過共同選擇作用促進抗藥性基 因於環境中的維持與擴散，因此探討重金屬生物有效性與抗藥性基因之關聯具有 重要意義。然而，傳統以總濃度評估重金屬風險之方法，難以反映生物實際可利 用之部分，因此本研究採用擴散梯度薄膜技術評估土壤中重金屬之生物有效性， 並探討其與抗生素抗藥性基因及銅抗性基因之相關性。本研究以污染土壤、乾淨 土壤以及椰殼活性碳作為建置土壤縮模系統的材料，分別篩分為10 mesh 及 20 mesh 兩種粒徑，以四個不同組別進行，固定每個組別的金屬總量，但改變各組 的生物有效性，探討生物有效性的改變是否會影響土壤中的抗生素抗性基因。本 研究於第7天及第14天採集縮模系統土壤，分析土壤孔隙水重金屬濃度（Cw） 以及Diffusive gradient in thin film 的有效濃度（Ce），同時利用即時定量聚合酶連 鎖反應測定抗生素抗性基因與銅金屬抗性基因之豐度變化。結果顯示，活性碳的 添加可有效降低土壤孔隙水重金屬濃度及DGT測得之銅、鋅與鎘有效濃度，其 中以第14天之下降趨勢最為明顯，顯示活性碳具有降低重金屬生物有效性之能 力。而相較於10 mesh土壤，20 mesh土壤具有較高之孔隙水濃度及DGT有效濃 度，且多數抗生素抗藥性基因之相對豐度亦較高，顯示較小粒徑土壤可能提供較 高之重金屬可移動性與微生物活性。本研究進一步以Spearman相關性分析與冗 餘分析，檢視部分ARGs與CRGs (Copper Resistance Genes)間呈顯著正相關，顯 示重金屬可能透過共同選擇機制促進抗生素抗性基因之維持，同時也顯示 DGT 有效濃度相較土壤孔隙水重金屬濃度對ARGs分布具有較高解釋能力，也再次證 實共選擇效應引起的抗生素抗藥性與金屬的生物有效性比金屬的總濃度更具相 關性。;In recent years， the dissemination of Antibiotic Resistance Genes (ARGs) driven by heavy metal contamination has attracted increasing attention. Heavy metals can promote the persistence and spread of ARGs in the environment through co-selection mechanisms; therefore， investigating the relationship between heavy metal bioavailability and ARGs is of great importance. However， conventional risk assessments based on total metal concentrations often fail to reflect the fraction that is actually bioavailable to organisms. Therefore， this study employed the Diffusive Gradients in Thin Films (DGT) technique to evaluate the bioavailability of heavy metals in soil and to investigate their relationships with ARGs and copper resistance genes (CRGs). A soil microcosm system was established using contaminated soil，uncontaminated soil， and coconut shell–derived activated carbon. The soils were sieved into two particle-size fractions， 10 mesh and 20 mesh， and arranged into four experimental groups. While maintaining a constant total metal content across all groups， metal bioavailability was manipulated to examine whether changes in bioavailability would affect the abundance of antibiotic resistance genes in soil. Soil samples were collected on Days 7 and 14 to determine heavy metal concentrations in soil pore water (Cw) and DGT-measured effective concentrations (Ce). In addition， the abundances of ARGs and copper resistance genes were quantified using quantitative polymerase chain reaction (qPCR). The results showed that the addition of activated carbon effectively reduced both heavy metal concentrations in soil pore water and the DGT-measured effective concentrations of copper， zinc， and cadmium. The reduction was most pronounced on Day 14， indicating that activated carbon has a strong capacity to decrease the bioavailability of heavy metals.Compared with the 10-mesh soil， the 20-mesh soil exhibited higher pore-water concentrations and DGT effective concentrations， as well as higher relative abundances of most ARGs. These findings suggest that finer soil particles may enhance heavy metal mobility and microbial activity. Furthermore， Spearman correlation analysis and redundancy analysis (RDA) revealed significant positive correlations between certain ARGs and CRGs， indicating that heavy metals may facilitate the maintenance of antibiotic resistance genes through co-selection mechanisms. The results also demonstrated that DGT effective concentrations provided greater explanatory power for the distribution of ARGs than pore-water metal concentrations. This finding further confirms that， under co-selection effects， antibiotic resistance is more closely associated with the bioavailability of heavy metals than with their total concentrations.
