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重金属因其在环境中的持久性、高毒性以及生物蓄积性等特性,广泛的分布于全球各环境介质中,成为全球性的环境公害。重金属可由大气沉降、地表径流、污水直排等途径进入海洋环境[1-4]。海水中的重金属易吸附于颗粒物中,通过络合、沉淀等过程转移并富集于沉积物中[5-6]。当水环境改变时,富集于沉积物中的重金属可再次释放至水环境中,形成“二次污染”[7-8],这种“源”与“汇”之间的转化,对海洋生态系统造成严重危害。因此,海洋沉积物环境中重金属可作为海域重金属污染程度的“指示剂”,蕴含着丰富的环境信息和海洋地质过程,对评价环境生态风险具有重要的意义[6, 9]。
北部湾位于南海西北部,该海域生产力高,生物多样性丰富,是沿海地区重要的渔场及渔业产品的主要来源[10-11]。但由于北部湾是一个半封闭海湾,水动力条件弱,污染物不容易扩散而易富集于海湾内。近年来,随着广西沿海工业化、城市化的快速发展,北部湾近海生态也正面临着日益严重的重金属污染压力[3, 12]。例如,北部湾部分近海港口、潮间带、油田等区域也发现了不同程度的重金属污染[11-13]。此外,北部湾入海河流中,部分河流(如大风江和南流江)污染物含量在雨季处于较高水平,该时期大量的污染物排入北部湾近岸[14]。研究显示,北部湾沉积物芯中重金属含量从1985年至2008年呈显著上升趋势[15],这很可能与陆源污染物输入增加有关。但对于广西北部湾整体海域重金属的相关研究仍相对较少,对海域重金属来源及影响因素的认识仍相对较弱。因此,对北部湾重金属研究及生态风险评价具有重要的意义。
本研究以广西北部湾采集的表层沉积物为对象,分析沉积物中6种重金属(As、Cd、Cu、Hg、Pb和Zn)的污染特征、潜在来源以及生态风险评价,揭示人类活动对北部湾海洋生态的影响,对维护北部湾生态环境提供科学依据。
广西北部湾沉积物重金属污染特征及生态风险评价
Evaluation on sediment pollution and potential ecological risks in Guangxi Beibu Gulf
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摘要: 于2018年夏季采集了广西北部湾表层沉积物样品,分析沉积物中6种重金属(Cu、Pb、Zn、Cd、Hg和As)含量的分布特征,利用数理统计方法研究其来源及主控因素,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,北部湾沉积物中Cu、Pb、Zn、Cd、Hg和As浓度的平均值分别为11.16、18.9、27.8、0.06、0.030、3.73 μg·g−1。不同重金属含量的分布呈现区域性的差异,但其来源主要受到近海人类活动的影响。与其他区域相比,北部湾沉积物重金属含量处于较低水平,但明显高于北部湾历史监测值,表现一定程度的富集。北部湾沉积物重金属含量均符合Ⅰ类沉积物标准,单因子污染影响程度依次为Cu>Pb>As>Zn>Hg>Cd,总体处于低程度污染。除了Hg处于中等潜在生态危害程度外,其他重金属潜在生态危害程度低,生态危害影响依次为Hg>Cd>As>Cu>Pb>Zn,Hg对海域环境污染及潜在危害影响程度最高。Abstract: The distribution characteristics of the concentration of Cu, Pb, Zn, Cd, Hg and As were analyzed based on the geochemical analisis of surface sidement samples in Guangxi Beibu Gulf. The sources, main controlling factors and the potential ecological risks for heavy metal distribution were discussed in this study. The results showed that the average concentrations of Cu, Pb, Zn, Cd, Hg and As were 11.16, 18.9, 27.8, 0.06, 0.030, 3.73 μg·g−1, respectively. The distribution of different heavy metals showed regional differences, but their sources were mainly affected by human activities in the coastal area. Compared with other areas, although the heavy metals in the sediments of Guangxi Beibu Gulf were at relatively low level, those level in the gulf were significantly higher than that historical monitoring level. The level of heavy metals in the sediments of Guangxi Beibu Gulf reached China’s national first-class benchmark of marine sediment quality, and the degree of pollution for six metals were arranged in the following order: Cu>Pb>As>Zn>Hg>Cd, and caused low levels of pollution generally. Except for the medium potential ecological risk of Hg, other metals were at a low ecological risk level, and the order for the ecological risk of the six metals was Hg>Cd>As>Cu>Pb>Zn, and Hg was the primary potential ecological risk factor.
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Key words:
- Beibu Gulf /
- sediment /
- heavy metals /
- ecological risk assessment
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表 1 国家海洋沉积物重金属含量标准值
Table 1. National standard values of heavy metals in marine sediments
指标
Index海洋沉积物质量标准值/(μg·g−1)
Standard value of marine sedimentCu Hg Pb Zn Cd As Ⅰ类Class I 35 0.2 60 150 0.5 20 Ⅱ类Class Ⅱ 100 0.5 130 350 1.5 65 表 2 重金属污染程度及潜在生态风险等级
Table 2. Contaminant grades and potential ecological risk levels of heavy metals
$ {P}_{i} $ 重金属总体污染程度
Overall pollution level$ {E}_{r}^{i} $ 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<8 低度污染 <40 低危害 <150 低危害 8—16 中等污染 40—80 中等危害 150—300 中等危害 16—32 重污染 80—160 较重危害 300—600 重危害 ≥32 严重污染 160—320 重危害 ≥600 严重危害 — — >320 严重危害 — — 表 3 北部湾表层沉积物中重金属的监测结果及与其他区域对比(μg·g-1)
Table 3. The results of measured metals values in the surface sediments of Beibu Gulf and comparison with other regins
数据统计
Data statisticsHg As Cu Zn Pb Cd 参考文献
Reference最小值 Minimum value 0.023 0.39 3.59 ND 12.1 0.04 本研究
This study最大值 Maximum value 0.037 9.21 16.90 62.3 26.7 0.09 平均值 Mean value 0.030 3.73 11.16 27.8 18.9 0.06 标准偏差 Standard deviation 0.005 3.40 4.74 25.4 4.6 0.02 Ⅰ类沉积物/个Class I 17 17 17 17 17 17 湛江湾 Zhanjiang Bay 18.7 73.60 43.89 0.15 [10] 厦门湾 Xiamen Bay 44.0 139.0 54.0 0.33 [19] 广东近岸 Coast of Guangdong Province 0.13 20.83 43.83 139.93 44.29 0.38 [20] 珠江口 Pearl River Estuary 348.0 383.4 102.6 1.72 [21] 北部湾 Beibu Gulf(1998年) 0.03 1.74 1.7 19.9 1.26 0.05 [22] 海南岛北部 Northern Hainan Island 0.02 8.40 8.32 35.87 18.77 0.06 [6] 注:ND为未检出. 表 4 北部湾表层沉积物中重金属和TOC 相关性分析
Table 4. Correlation analysis of heavy metals and TOC in surface sediments of Beibu Gulf
TOC Hg As Cu Zn Pb Cd TOC 1 Hg −0.255 1 As 0.159 0.394 1 Cu 0.706** 0.183 0.532* 1 Zn 0.574* 0.086 0.327 0.792** 1 Pb 0.445 −0.018 0.000 0.397 0.573* 1 Cd −0.081 0.104 −0.019 0.222 0.367 0.547* 1 注:*在0.05水平上显著相关;**在0.01水平上显著相关. 表 5 北部湾表层沉积物中重金属和TOC 主成份分析
Table 5. Principal component analysis of heavy metals and TOC in surface sediments of Beibu Gulf
元素
Element因子载荷
Factor load成分1 成分2 成分3 TOC 0.720 −0.272 −0.557 Hg 0.133 0.775 0.417 As 0.458 0.737 −0.140 Zn 0.902 −0.038 0.015 Cu 0.909 0.196 −0.204 Cd 0.421 −0.229 0.798 Pb 0.697 −0.420 0.353 特征值 3.047 1.486 1.306 贡献率/ % 43.54 21.23 18.66 累积贡献率/% 43.54 64.77 83.43 表 6 北部湾沉积物中重金属污染指数和潜在生态风险评价
Table 6. Contaminant index and potential ecological risk assessment of heavy metal in the sediments of Beibu Gulf
元素
Element$ {C}_{f}^{i} $ $ {E}_{r}^{i} $ 最小值Minimum 最大值Maximum 平均值Mean 最小值Minimum 最大值Maximum 平均值Mean Hg 0.100 0.205 0.150 27.59 56.55 41.31 As 0.020 0.721 0.290 0.50 18.47 7.43 Zn 0.000 0.415 0.240 0 0.82 0.47 Cu 0.103 0.837 0.401 1.14 9.27 4.44 Cd 0.080 0.180 0.121 13.33 30.00 20.17 Pb 0.202 0.445 0.305 2.09 4.62 3.17 Cd 2.25 7.13 4.45 RI 54.71 105.12 76.99 -
[1] ISLAM M S, AHMED M K, RAKNUZZAMAN M, et al. Heavy metal pollution in surface water and sediment: A preliminary assessment of an urban river in a developing country [J]. Ecological Indicators, 2015, 48: 282-291. doi: 10.1016/j.ecolind.2014.08.016 [2] CHEN L, ZHOU S L, WU S H, et al. Concentration, fluxes, risks, and sources of heavy metals in atmospheric deposition in the Lihe River watershed, Taihu region, Eastern China [J]. Environmental Pollution, 2019, 255: 113301. doi: 10.1016/j.envpol.2019.113301 [3] LAO Q B, SU Q Z, LIU G Q, et al. Spatial distribution of and historical changes in heavy metals in the surface seawater and sediments of the Beibu Gulf, China [J]. Marine Pollution Bulletin, 2019, 146: 427-434. doi: 10.1016/j.marpolbul.2019.06.080 [4] 王萧, 张文思, 迟光希, 等. 辽东湾及其附近海域重金属污染研究进展 [J]. 环境化学, 2019, 38(10): 2317-2326. doi: 10.7524/j.issn.0254-6108.2018112606 WANG X, ZHANG W S, CHI G X, et al. The heavy metals contamination in Liaodong Bay and its adjacent waters [J]. Environmental Chemistry, 2019, 38(10): 2317-2326(in Chinese). doi: 10.7524/j.issn.0254-6108.2018112606
[5] ARIKIBE J E, PRASAD S. Determination and comparison of selected heavy metal concentrations in seawater and sediment samples in the coastal area of Suva, Fiji [J]. Marine Pollution Bulletin, 2020, 157: 111157. doi: 10.1016/j.marpolbul.2020.111157 [6] 曾维特, 杨永鹏, 张东强, 等. 海南岛北部海湾沉积物重金属来源、分布主控因素及生态风险评价 [J]. 环境科学, 2018, 39(3): 1085-1094. ZENG W T, YANG Y P, ZHANG D Q, et al. Sources, distribution of main controlling factors, and potential ecological risk assessment for heavy metals in the surface sediment of Hainan island north bay, South China [J]. Environmental Science, 2018, 39(3): 1085-1094(in Chinese).
[7] 张伟, 张洪, 单保庆. 北运河源头区沙河水库沉积物重金属污染特征研究 [J]. 环境科学, 2012, 33(12): 4284-4290. ZHANG W, ZHANG H, SHAN B Q. Characteristics of heavy metal pollution in the sediments from Shahe reservoir, the upper reach of the north canal river [J]. Environmental Science, 2012, 33(12): 4284-4290(in Chinese).
[8] LI S Y, ZHANG Q F. Risk assessment and seasonal variations of dissolved trace elements and heavy metals in the Upper Han River, China [J]. Journal of Hazardous Materials, 2010, 181(1/2/3): 1051-1058. [9] 陈思杨, 宋琍琍, 刘希真, 等. 浙江典型海湾潮间带沉积物污染及生态风险评价 [J]. 中国环境科学, 2020, 40(4): 1771-1781. doi: 10.3969/j.issn.1000-6923.2020.04.045 CHEN S Y, SONG L L, LIU X Z, et al. Evaluation on sediment pollution and potential ecological risks in the intertidal zone of typical bays in Zhejiang Province [J]. China Environmental Science, 2020, 40(4): 1771-1781(in Chinese). doi: 10.3969/j.issn.1000-6923.2020.04.045
[10] CHEN F J, LIN J, QIAN B H, et al. Geochemical assessment and spatial analysis of heavy metals in the surface sediments in the eastern beibu gulf: A reflection on the industrial development of the South China Coast [J]. International Journal of Environmental Research and Public Health, 2018, 15(3): 496. doi: 10.3390/ijerph15030496 [11] LIU G Q, LAO Q B, SU Q Z, et al. Spatial and seasonal characteristics of dissolved heavy metals in the aquaculture areas of Beibu Gulf, South China [J]. Human and Ecological Risk Assessment:an International Journal, 2020, 26(7): 1957-1969. doi: 10.1080/10807039.2019.1629273 [12] 付文超, 孟范平, 王志峰, 等. 北部湾潮间带沉积物和双壳类动物中的重金属: 污染特征与生物积累 [J]. 环境科学学报, 2013, 33(5): 1401-1409. FU W C, MENG F P, WANG Z F, et al. Heavy metals in the intertidal sediments and two marine bivalves along the Beibu Bay: Contamination status and bioaccumulation [J]. Acta Scientiae Circumstantiae, 2013, 33(5): 1401-1409(in Chinese).
[13] YANG J C, WANG W G, ZHAO M W, et al. Spatial distribution and historical trends of heavy metals in the sediments of petroleum producing regions of the Beibu Gulf, China [J]. Marine Pollution Bulletin, 2015, 91(1): 87-95. doi: 10.1016/j.marpolbul.2014.12.023 [14] 劳齐斌, 刘国强, 申友利, 等. 北部湾入海河流营养盐的分布特征及入海通量研究 [J]. 海洋学报, 2020, 42(12): 93-100. LAO Q B, LIU G Q, SHEN Y L, et al. Distribution characteristics and fluxes of nutrients in the rivers of the Beibu Gulf [J]. Haiyang Xuebao, 2020, 42(12): 93-100(in Chinese).
[15] GAN H Y, LIN J Q, LIANG K, et al. Selected trace metals (As, Cd and Hg) distribution and contamination in the coastal wetland sediment of the northern Beibu Gulf, South China Sea [J]. Marine Pollution Bulletin, 2013, 66(1/2): 252-258. [16] HAKANSON L. An ecological risk index for aquatic pollution control. a sedimentological approach [J]. Water Research, 1980, 14(8): 975-1001. doi: 10.1016/0043-1354(80)90143-8 [17] 罗松英, 邢雯淋, 梁绮霞, 等. 湛江湾红树林湿地表层沉积物重金属形态特征、生态风险评价及来源分析 [J]. 生态环境学报, 2019, 28(2): 348-358. LUO S Y, XING W L, LIANG Q X, et al. Speciation, ecological risk assessment and source analysis of heavy metals in the surface sediments of mangrove wetland in Zhanjiang bay [J]. Ecology and Environmental Sciences, 2019, 28(2): 348-358(in Chinese).
[18] 蓝先洪, 孟祥君, 梅西, 等. 辽东湾表层沉积物的重金属污染特征与质量评价 [J]. 海洋学报, 2018, 40(6): 60-73. LAN X H, MENG X J, MEI X, et al. Pollution characteristics and quality assessment of heavy metals in surface sediments from the Liaodong Bay [J]. Acta Oceanologica Sinica, 2018, 40(6): 60-73(in Chinese).
[19] ZHANG L P, YE X, FENG H, et al. Heavy metal contamination in western Xiamen Bay sediments and its vicinity, China [J]. Marine Pollution Bulletin, 2007, 54(7): 974-982. doi: 10.1016/j.marpolbul.2007.02.010 [20] ZHAO G M, LU Q Y, YE S Y, et al. Assessment of heavy metal contamination in surface sediments of the west Guangdong coastal region, China [J]. Marine Pollution Bulletin, 2016, 108(1/2): 268-274. [21] NIU H Y, DENG W J, WU Q H, et al. Potential toxic risk of heavy metals from sediment of the Pearl River in South China [J]. Journal of Environmental Sciences, 2009, 21(8): 1053-1058. doi: 10.1016/S1001-0742(08)62381-5 [22] LIAN X, WANG Y, CHEN Q. Assessment on heavy metals in seawater, surface sediments and organisms at Guangxi inshore [J]. Marine Environmental Science, 2001, 20(2): 59-62. [23] 唐得昊, 刘兴健, 邹欣庆. 海湾表层沉积物重金属污染与潜在生态危害评价: 以深圳湾为例 [J]. 环境化学, 2014, 33(8): 1294-1300. doi: 10.7524/j.issn.0254-6108.2014.08.002 TANG D H, LIU X J, ZOU X Q. Heavy metals pollution and their potential ecological risk assessment in the surface sediment from Shenzhen Bay [J]. Environmental Chemistry, 2014, 33(8): 1294-1300(in Chinese). doi: 10.7524/j.issn.0254-6108.2014.08.002
[24] 李庆召, 李国新, 罗专溪, 等. 厦门湾海域表层沉积物重金属和多环芳烃污染特征及生态风险评价 [J]. 环境化学, 2009, 28(6): 869-875. doi: 10.3321/j.issn:0254-6108.2009.06.019 LI Q Z, LI G X, LUO Z X, et al. Pollution characteristics and ecological risk assessment of heavy metals and polycyclic aromatic hydrocarbons(PAHs) in sediment from Xiamen bay [J]. Environmental Chemistry, 2009, 28(6): 869-875(in Chinese). doi: 10.3321/j.issn:0254-6108.2009.06.019