Ha Long Bay is an attractive landscape and a center of dynamic economic activity; however, it is subject to negative impacts from tourism, activity in its harbor, mining, industry, and urbanization, which is evidenced by the presence of pollutants, including heavy metals, in surface sediment at the bay. To ascertain the extent of the anthropogenic impact, 48 surface sediment samples were collected and analyzed for grain size and the presence of heavy metals (Cu, Pb, Zn, As, Cd). Thirteen sediment types were identified in Ha Long Bay: sand, muddy sand, silty sand, sandy mud, mud, silt, sandy gravel, muddy sandy gravel, gravelly mud, gravelly muddy sand, slightly gravelly sandy mud, slightly gravelly sand, and sandy silt; of these, sandy silt and silty sand are the most common, while the others are less so. Regarding the concentration of heavy metals in the sediment, Cu concentration ranges from 3.80 to 41.72 mg/kg, with an average of 14.53 mg/kg; Pb ranges from 10.17 to 69.90 mg/kg, with an average of 30.39 mg/kg; Zn ranges from 6.34 to 119.21 mg/kg, with an average of 50.87 mg/kg; Cd ranges from 0.03 to 0.20 mg/kg, with an average of 0.08 mg/kg; As ranges from 1.78 to 13.71 mg/kg, with an average of 6.06 mg/kg. The concentrations of Cu, Pb, and As are higher than the Interim Sediment Quality Guideline (ISQG) levels at stations near the shoreline, and lower than the ISQG levels distributed throughout offshore stations.

下龙湾风景秀丽，是活跃的经济活动中心；但是，它受到旅游业，其港口的活动，采矿，工业和城市化的负面影响，这可以通过海湾表层沉积物中包括重金属在内的污染物来证明。为了确定人为影响的程度，收集了48个表面沉积物样品并分析了晶粒大小和重金属（Cu，Pb，Zn，As，Cd）的存在。下龙湾确定了13种沉积物类型：沙，泥沙，粉质沙，沙质泥，泥沙，粉砂，沙砾，泥沙质沙砾，砾石泥，沙质泥沙，砂砾微泥，砂砾微沙和沙质淤泥; 其中，最常见的是沙质粉砂和粉质砂，而其他的则较少。关于沉积物中重金属的浓度，铜的浓度范围为3.80至41.72 mg / kg，平均为14.53 mg / kg。铅的范围为10.17至69.90 mg / kg，平均为30.39 mg / kg；锌的含量范围为6.34至119.21 mg / kg，平均为50.87 mg / kg；镉的含量范围为0.03至0.20 mg / kg，平均为0.08 mg / kg；含量范围为1.78至13.71 mg / kg，平均为6.06 mg / kg。Cu，Pb和As的浓度高于海岸线附近站点的《沉积物质量指南》（ISQG）的水平，但低于整个海上站点分布的ISQG的水平。87 mg / kg；镉的含量范围为0.03至0.20 mg / kg，平均为0.08 mg / kg；含量范围为1.78至13.71 mg / kg，平均为6.06 mg / kg。Cu，Pb和As的浓度高于海岸线附近站点的《沉积物质量指南》（ISQG）的水平，但低于整个海上站点分布的ISQG的水平。87 mg / kg；镉的含量范围为0.03至0.20 mg / kg，平均为0.08 mg / kg；含量范围为1.78至13.71 mg / kg，平均为6.06 mg / kg。Cu，Pb和As的浓度高于海岸线附近站点的《沉积物质量指南》（ISQG）的水平，但低于整个海上站点分布的ISQG的水平。