粤港澳大湾区典型潮间带环境多介质中Cd形态空间分布特征及其影响因素

Multiphase Spatial Distribution Characteristics of Cd Morphology in Typical Intertidal Zones in the Guangdong-Hong Kong-Macao Greater Bay Area and Its Influencing Factors

在粤港澳大湾区典型潮间带开展了14个站位同步采样和观测,分析各采样点表水、孔隙水、悬浮物和沉积物中Cd形态的空间分布特征,并结合环境因子采用统计分析方法探讨不同介质中Cd形态分布差异的影响因素.结果表明,各潮间带环境表水、孔隙水、悬浮物和沉积物中Cd含量范围分别为0.41~15.03μg·L^(-1)、0.41~27.54μg·L^(-1)、0.41~4.88 mg·kg^(-1)和0.20~5.30 mg·kg^(-1),东莞沙角湾Cd含量显著高于其他采样点,主要与东莞发达的电子和制造业有关;同一采样点表水中Cd浓度略低于孔隙水,而悬浮物中Cd含量与沉积物相当.形态分析结果显示:表水和孔隙水中Cd均以离子态为主,质量分数分别为67.23%~97.56%和33.33%~97.16%;悬浮物和沉积物中Cd均以残渣态为主,质量分数分别为45.45%~96.36%和45.80%~97.27%.Pearson相关性分析表明溶液相中络合态Cd与氧化还原电位(ORP)和pH呈显著负相关,与总有机碳呈显著正相关;固相沉积物中生物有效态Cd与黏土含量、ORP和固相有机碳呈显著正相关,与pH呈显著负相关.进一步采用单因子线性回归分析得出溶液相中ORP对络合态Cd影响最大,回归系数分别为0.864和0.824;固相不同深度沉积物生物有效态Cd受黏土含量影响显著,回归系数分别为0.968、0.980、0.977和0.877.上述结果综合表明,大湾区典型潮间带环境Cd总含量分布受城市经济发展特色影响,而形态分配则与环境因子密切相关.

Simultaneous sampling and observation were conducted at 14 stations in typical intertidal zones of the Guangdong-Hong Kong-Macao greater bay area.The spatial distribution characteristics of Cd morphology in surface water,pore water,suspended matters,and sediments at each sampling site were analyzed,and the influencing factors of Cd morphology changes in each medium were discussed using statistical analyses based on environmental factors.The results showed that the total contents of Cd in surface water,pore water,suspended matters,and sediments in each intertidal zone ranged from 0.41-15.03μg·L^(-1),0.41-27.54μg·L^(-1),0.41-4.88 mg·kg^(-1),and 0.20-5.30 mg·kg^(-1),respectively.The contents of Cd in Shajiao Bay were significantly higher than those in other sampling sites,which should be related to the developed electronics and manufacturing industries in Dongguan.The concentration of Cd in surface water was slightly lower than that in pore water,whereas the content of Cd in suspended matter was comparable to that in sediment at the same sampling site.The results of morphological analysis showed that the ionic-state Cd was dominant in both surface water and pore water,accounting for 67.23%-97.56%and 33.33%-97.16%,respectively.In suspended matter and sediment,Cd was mainly in the residual state,accounting for 45.45%-96.36%and 45.80%-97.27%,respectively.Pearson correlation analysis showed that the complex-state Cd in the aqueous phase was negatively correlated with oxidation reduction potential(ORP)and pH and positively correlated with total organic carbon.The bioavailable Cd in solid sediment was significantly positively correlated with the proportion of clay,ORP,and solid organic carbon and significantly negatively correlated with pH.The single factor linear regression analysis showed that ORP had the greatest effect on the complex-state Cd in the aqueous phase,with regression coefficients of 0.864 and 0.824,respectively.The bioavailable Cd in solid sediment at different depths was significantly affected by the proportion of clay,and the regression coefficients were 0.968,0.980,0.977,and 0.877,respectively.The above results indicate that the distribution of total Cd content in the typical intertidal environment of the Greater Bay Area was affected by the characteristics of urban economic development,whereas the allocation of Cd morphology was closely related to environmental factors.