Abstract：
Seagrass beds are susceptible to deterioration and heavy metals represent a crucial impact factor. The accumulation of heavy metal in two tropical seagrass species were studied in South China in this study and multiple methods were used to identify the heavy metal sources. E. acoroides (Enhalus acoroides) and T. hemperichii (Thalassia hemperichii) belong to the genus of Enhalus and Thalassia in the Hydrocharitaceae family, respectively. Heavy metal concentrations in the two seagrasses followed the order of Cr > Zn > Cu > Ni > As > Pb > Co > Cd based on the whole plant, and their bioconcentration factors were 31.8 ± 29.3 (Cr), 5.7 ± 1.3 (Zn), 7.0 ± 3.8 (Cu), 3.0 ± 1.9 (Ni), 1.2 ± 0.3 (As), 1.7 ± 0.9 (Pb), 9.1 ± 11.1 (Co) and 2.8 ± 0.6 (Cd), indicating the intense enrichment in Co and Cr within the two seagrasses. The two seagrasses were prone to accumulate all the listed heavy metals (except for As in E. acoroides), especially Co (BCFs of 1124) and Cr (BCFs of 2689) in the aboveground parts, and the belowground parts of both seagrasses also accumulated most metals (BCFs of 27) excluding Co and Pb. The Pb isotopic ratios (mean 208Pb/204Pb, 207Pb/204Pb and 206Pb/204Pb values of 38.2054, 15.5000 and 18.3240, respectively) and Cd isotopic compositions (δ114/110Cd values ranging from -0.09‰ to 0.58‰) within seagrasses indicated the anthropogenic sources of Pb and Cd including coal combustion, traffic emissions and agricultural activities. This study described the absorption characteristics of E. acoroides and T. hemperichii to some heavy metals, and further demonstrated the successful utilization of Pb and Cd isotopes as discerning markers to trace anthropogenic origins of heavy metals (mainly Pb and Cd) in seagrasses. Pb and Cd isotopes can mutually verify and be helpful to understand more information in pollution sources and improve the reliability of conclusion deduced from concentrations or a single isotope.
摘要：
海草床容易变质，重金属是至关重要的影响因素。本研究研究了中国南方两种热带海草中重金属的积累，并采用多种方法鉴定了重金属来源。E.acoroides（Enhalusacoroides）和T.hemperichii（Thalassiahemperichii）属于Hydrocharitaceae科中的Enhalus和Thalassia属，分别。两种海草中重金属浓度按全厂顺序依次为Cr>Zn>Cu>Ni>As>Pb>Co>Cd,它们的生物富集因子为31.8±29.3(Cr)，5.7±1.3（锌），7.0±3.8(Cu),3.0±1.9(Ni),1.2±0.3（As），1.7±0.9(Pb),9.1±11.1(Co)和2.8±0.6(Cd)，表明两种海草中Co和Cr的强烈富集。这两种海草容易积累所有列出的重金属（除acoroides中的As），特别是地上部分的Co（BCFs为1124）和Cr（BCFs为2689），两种海草的地下部分也积累了除Co和Pb以外的大多数金属（BCFs为27）。Pb同位素比(平均208Pb/204Pb，207Pb/204Pb和206Pb/204Pb值分别为38.2054、15.5000和18.3240）和海草中的Cd同位素组成（δ114/110Cd值范围为-0.09‰至0.58‰）表明Pb和Cd的人为来源包括煤燃烧，交通排放和农业活动。本研究描述了acoroides和hemperichii对某些重金属的吸收特性，并进一步证明了成功利用Pb和Cd同位素作为识别标记来追踪海草中重金属（主要是Pb和Cd）的人为来源。Pb和Cd同位素可以相互验证，有助于了解污染源中的更多信息，并提高从浓度或单一同位素推导结论的可靠性。
