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重金属具有蓄积性、持久性以及高毒性等特点,且拥有广泛的来源,主要有河流径流、城镇污水、工业废水以及近海养殖等[1 − 4],现已成为海洋环境中备受关注的重要污染物之一[5]. 作为各种污染物主要的汇[6 − 8],沉积物富集了大量的重金属,并且受海水环境变化的影响,重金属会从沉积物中释放至海水中,不仅影响海水水质,而且易于在水生生物体内富集,通过食物链转移至捕食者或者人体,对人体健康和海洋生态系统造成长期的影响[9 − 10]. 海湾是链接陆地和海洋的重要界面,受到人类活动影响剧烈,是研究重金属污染物发生沉降、输运、转化和埋藏等生物地球化学过程的重要环境. 因此,对海湾沉积物重金属开展研究,分析海洋重金属的污染程度,对海湾环境生态风险评价具有重要的意义[11].
位于惠州市南部的大亚湾,由于海产资源丰富,已成为是中国南方重要的海湾之一[12]. 位于广东省南部的红海湾,凭借丰富的海洋渔业资源,使得海水养殖业发展迅速,已被列为汕尾市经济开发区,同时也是南海半封闭型海湾规模化养殖试验区[13]. 然而,近几十年来,随着这两大海湾区域经济的发展,海洋生态环境状况已遭受人类活动所带来的不同程度的危害[14 − 15],城镇生活污水排放、工业企业污染排放、近海养殖等带来的重金属污染成为该区域面临的主要环境问题[16 − 18]. 例如,杨文超等[18 − 19]对2010—2018年期间大亚湾内表层沉积物中的5类重金属进行研究,发现重金属高值区均集中在石化区一带,推测重金属的主要来源可能是沿岸水产养殖和工业企业排放. 唐得昊等[17]对大亚湾2015年采集的23个表层沉积物种5类重金属分析结果显示,重金属总体污染程度达到了中等污染水平,汞(Hg)是潜在风险最高的. 孙钦帮等[15]2015年对红海湾近岸表层沉积物中7类重金属的分析,发现海域沉积物重金属 Cu、Pb、Zn、Cr和As的主要来源为工业废水与城市污水. 尽管前人对该区域重金属开展了不少研究,但是一方面随着经济发展和人口增加会加剧海洋沉积物污染程度,另外一方面,随着国民海洋环保理念不断增强和国家层面海洋环保政策不断完善,使得已有的报道不能充分反映大亚湾和红海湾沉积物中重金属的生态风险状况.
本研究以大亚湾和红海湾为研究靶区域,采集表层沉积物并分析其中7种重金属含量,分别为砷(As)、锌(Zn)、镉(Cd)、铜(Cu)、铬(Cr)、汞(Hg)和铅(Pb),研究了重金属的空间分布,并推断其潜在来源. 此外,结合潜在生态风险评价法,对沉积物中重金属的污染程度进行评价,以期为改善大亚湾和红海湾海洋环境质量、建立美丽海湾建设提供科学理论依据.
广东省大亚湾和红海湾表层沉积物重金属分布特征及风险评价
Distribution and ecological risk assessment of heavy metal sediments in Daya Bay and Honghai Bay of Guangdong Province
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摘要: 2021年夏季采集了大亚湾和红海湾表层沉积物样品,分析了沉积物中铜(Cu)、砷(As)、铬(Cr)、镉(Cd)、汞(Hg)、铅(Pb)和锌(Zn)含量,探讨了重金属分布及污染特征,重金属之间及与总有机碳(TOC)的相关关系,并评价了重金属的总体污染状况和潜在生态风险. 结果显示,大亚湾Hg、As、Cr、Cu、Zn、Cd 和 Pb含量平均值分别为0.03、8.71、59.8、14.2、99.4、0.05、33.4 mg·kg−1,红海湾Hg、As、Cr、Cu、Zn、Cd 和 Pb含量平均值分别为0.05、9.03、46.3、15.4、77.7、0.07、34.1 mg·kg−1. 大亚湾Hg、As含量近岸低于远岸,Cr、Cu和Zn含量近岸高于远岸,Cd和Pb近岸和远岸相差不大. 除重金属Cr之外,红海湾其他重金属含量近岸明显高于远岸. 除Hg和Cr与TOC无显著相关性,沉积物中As、Cu、Zn、Cd和Pb与TOC呈显著正相关性. 大亚湾和红海湾沉积物重金属,单因子污染影响程度依次为Cr>Zn>Pb>As>Cu>Pb>Cd,总体污染程度很低. 基于总金属综合潜在风险评价,大亚湾和红海湾沉积物的风险较低,生态危害影响依次为,Hg>Cd>As>Pb>Cu>Zn>Cr.Abstract: In the summer of 2021, surface sediment samples were collected from Daya Bay and Honghai Bay. The concentrations of Cu, As, Cr, Cd, Hg, Pb and Zn in the sediments were analyzed to investigate the distribution and pollution characteristics of heavy metals. The relationships between the heavy metals and total organic carbon (TOC) were also examined, and an assessment of the overall pollution status and potential ecological hazards of the heavy metals was conducted. The results showed that the average concentrations of Hg, As, Cr, Cu, Zn, Cd, and Pb in Daya Bay sediments were 0.03, 8.71, 59.78, 14.2, 99.4, 0.05, and 33.4 mg·kg−1, respectively. In Honghai Bay sediments, the average concentrations of Hg, As, Cr, Cu, Zn, Cd, and Pb were 0.05, 9.03, 46.29, 15.4, 77.7, 0.07, and 34.1 mg·kg−1, respectively. The concentrations of Hg and As were lower near the coast than offshore in Daya Bay, while the concentrations of Cr, Cu, and Zn were higher near the coast than offshore. The difference in Cd and Pb concentrations between nearshore and offshore areas was not significant. In Honghai Bay, except for Cr, the concentrations of other heavy metals were significantly higher near the coast than offshore. Except for Hg and Cr, there was a significantly positive correlation between the concentrations of As, Cu, Zn, Cd, Pb, and TOC in the sediments. The single factor pollution degree of heavy metals in Daya Bay and Honghai Bay sediment was ranked as Cr>Zn>Pb>As>Cu>Pb>Cd, indicating a low pollution status. Based on the comprehensive potential risk assessment of total metals, the risks associated with the sediments in Daya Bay and Honghai Bay were low, with the ecological hazards ranked as Hg>Cd>As>Pb>Cu>Zn>Cr.
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Key words:
- the Daya Bay and Honghai Bay /
- sediment /
- heavy metals /
- ecological risk assessment.
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表 1 我国海洋沉积物中重金属含量的标准值
Table 1. The standard values of heavy metals in marine sediments of China
指标
Index海洋沉积物质量标准值/( mg·kg−1)
Standard value of marine sedimentAs Cd Cr Cu Hg Pb Zn 第Ⅰ类 Class Ⅰ 20 0.5 80 35 0.2 60 150 第Ⅱ类 Class Ⅱ 65 1.5 150 100 0.5 130 350 第Ⅲ类 Class Ⅲ 93 5 270 200 1 250 600 表 2 沉积物中重金属污染程度及潜在生态危害程度分类
Table 2. Contaminant grades and potential ecological hazard levels of heavy metals in sediment
Eir 单个重金属潜在生态危害程度
Potential ecological hazard of single metalRI 重金属总体潜在生态危害程度
Overall potential ecological hazard of metals≤50 低等 ≤150 低等 40—80 中等 150—300 中等 80—160 较重 300—600 较重 160—320 重度 600—1200 重度 >320 极严重 >1200 极严重 表 3 大亚湾和红海湾沉积物中重金属含量及其他区域对比(mg·kg−1)
Table 3. Comparison of heavy metals in surface sediments of Daya Bay, Honghai Bay and other bays(mg·kg−1)
区域
Zone数据统计
Data statistics汞(Hg) 砷(As) 铬(Cr) 铜(Cu) 锌(Zn) 镉(Cd) 铅(Pb) 采样时间
Sampling time参考文献
Reference大亚湾
Daya Bay最小值 0.01 6.59 45.9 10.9 78.1 0.03 30.2 2021.09 本研究 最大值 0.04 10.9 67.4 16.6 109 0.08 36.6 平均值 0.03 8.71 59.78 14.2 99.4 0.05 33.4 标准偏差 0.01 1.38 7.91 2.0 11.1 0.02 2.10 I 类沉积物数量 5 5 5 5 5 5 5 红海湾
Honghai Bay最小值 0.005 2.63 14.4 3.4 21.7 0.00 14.5 最大值 0.104 19.2 65.2 36.1 133 0.23 57.0 平均值 0.049 9.03 46.3 15.4 77.7 0.07 34.1 标准偏差 0.025 5.19 16.2 10.3 33.8 0.07 13.1 1类沉积物数量 9 9 9 8 9 9 9 大亚湾 Daya Bay 平均值 0.04 7.35 — 18.9 83.1 — 33.2 2018.12 [18 − 19] 大亚湾 Daya Bay 平均值 0.12 6.78 — 22.8 81.9 — 31.7 2015.01 [18 − 19] 大亚湾 Daya Bay 平均值 0.10 43.1 23.6 88.6 — 33.2 2015.10 [17] 红海湾 Honghai Bay 平均值 0.07 7.97 15.32 6.29 57.9 0.03 25.4 2015.05 [15] 深圳湾 Shenzhen Bay 平均值 — 23.2 — 79.3 307 2.26 74.5 2012.11 [23] 大鹏湾 Dapeng Bay 平均值 0.05 — 63.6 15.7 87.1 — 35.9 1998—2006 [24] 珠江口 Pearl River Estuary 平均值 — — — 348 383 1.72 103 2007.07 [25] 广东省近岸
Coast of Guangdong Province平均值 0.13 20.8 — 43.8 140 0.38 44.3 2008.01 [26] 北部湾Beibu Gulf 平均值 0.03 3.73 — 11.2 27.8 0.06 18.9 2018.08 [3] “—”:没有数据. “—”: No data. 表 4 大亚湾和红海湾沉积物重金属之间及与TOC之间的相关分析
Table 4. Correlation between heavy metals and TOC in sediments of Daya Bay and Honghai Bay
TOC 汞 砷 铬 铜 锌 镉 铅 TOC 1 汞 0.31 1 砷 0.588* 0.71** 1 铬 0.41 0.09 0.37 1 铜 0.68* 0.74** 0.82** 0.54* 1 锌 0.66* 0.44 0.71** 0.87** 0.85** 1 镉 0.60* 0.80** 0.81** 0.38 0.94** 0.71** 1 铅 0.65* 0.72** 0.75** 0.66* 0.94** 0.88** 0.86** 1 *在0.05水平上显著相关;**在0.01水平上显著相关.
*Significantly correlated at the 0.05 level; **Significantly correlated at the 0.01 level.表 5 大亚湾和红海湾表层沉积物重金属单因子污染指数、综合污染指数、潜在单个重金属生态风险系数和总体生态风险指数
Table 5. Single factor pollution index (Cim), comprehensive pollution index (Cf), potential ecological hazard coefficients (Eir), and risk indices (RI) of heavy metals in surface sediments of Daya Bay and Honghai Bay
站位
StationCim Cf Eir RI As Cd Cr Cu Hg Pb Zn As Cd Cr Cu Hg Pb Zn DYW01 0.33 0.12 0.82 0.39 0.07 0.54 0.67 2.93 5.07 12.9 1.24 4.35 9.18 5.38 1.58 39.7 DYW02 0.42 0.10 0.79 0.47 0.17 0.57 0.71 3.23 6.42 10.7 1.20 5.35 21.6 5.70 1.67 52.7 DYW03 0.44 0.16 0.84 0.45 0.12 0.56 0.73 3.29 6.7 17.1 1.27 5.03 15.1 5.60 1.72 52.6 DYW04 0.45 0.06 0.57 0.31 0.21 0.50 0.52 2.63 6.95 6.43 0.87 3.52 27.5 5.03 1.23 51.6 DYW05 0.55 0.10 0.70 0.41 0.21 0.61 0.69 3.28 8.38 10.7 1.06 4.68 27.5 6.10 1.64 60.1 HHW01 0.81 0.46 0.63 1.03 0.52 0.95 0.82 5.22 12.5 49.3 0.95 11.6 68.2 9.5 1.94 154 HHW02 0.32 0.06 0.31 0.17 0.28 0.29 0.27 1.69 4.92 6.43 0.46 1.87 36.1 2.92 0.63 53.3 HHW03 0.96 0.28 0.82 0.87 0.32 0.84 0.89 4.97 14.8 30.0 1.23 9.81 42 8.35 2.1 108.2 HHW04 0.13 0.00 0.18 0.10 0.03 0.24 0.14 0.82 2.02 0.00 0.27 1.1 3.3 2.42 0.34 9.4 HHW05 0.41 0.10 0.56 0.29 0.24 0.56 0.45 2.61 6.36 10.7 0.84 3.23 31.5 5.63 1.07 59.3 HHW06 0.41 0.08 0.57 0.29 0.21 0.54 0.44 2.53 6.36 8.57 0.86 3.23 26.9 5.38 1.03 52.3 HHW07 0.45 0.16 0.75 0.41 0.23 0.60 0.58 3.18 6.88 17.1 1.14 4.61 30.2 6.00 1.36 67.3 HHW08 0.14 0.08 0.79 0.47 0.21 0.66 0.61 2.97 2.17 8.57 1.2 5.35 26.9 6.63 1.45 52.3 HHW09 0.43 0.10 0.60 0.35 0.17 0.44 0.47 2.56 6.58 10.7 0.91 3.94 22.3 4.38 1.12 49.9 均值 average 0.45 0.13 0.64 0.43 0.21 0.56 0.57 — 6.86 14.23 0.96 4.83 27.73 5.64 1.35 — “—”:没有数据. “—”: No data. -
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