雷州湾东海岛滨岸地下水化学要素变化特征和水质现状

Feature of variation of groundwater chemical elements and status of water quality along Donghaidao shore in Leizhou Bay

对位于雷州湾东海岛滨岸测井地下水进行了小、大潮周日取样及其化学测试。对Ca2+、K+、Na+、Cl-、SO42-、TDS和总硬度变化与相互关系的分析显示,离子平均值范围为35.65~3 610.41 mg/L,K最低,Cl-、Na+依次最高,TDS为4 970.89~6 441.48 mg/L,总硬度为1 054.75~1 409.65 mg/L,统计特征随潮期有所不同;离子比例较为稳定性,Cl-含量占88~98%,为Cl-·SO42--Na+·Ca2+型水,潮周期内要素变化较剧烈,但同步性较好,绝对振幅以Cl-、Na+最高,相对振幅以SO42-、Na+最高,Na+、Cl-占离子强度I的比例较高,离子重新配对,盐效应明显,具有侵入特征;γNa+/γCl-为0.75~0.83,γHCO-3/γCl-为0~0.015,测次SAR平均值分别为16.60、20.17,活性系数r最高为0.77;线性拟合表明:阳离子对Cl-趋向性以K+最高,其次是Na+;离子平均含量序列很好地满足指数规律;上述要素线性相关显著,又以Na+、Cl-与各要素相关系数最高,再次表明两者具有主导性;γCl-/γHCO-3表明咸化程度较高,潮周期内离子拟合趋势线斜率k>0,表明调查期间呈现缓慢咸化趋势;水质除了总硬度为IV^V类,其它均为V类,总体结果为较差。

Based on the test data of groundwater samples during two tidal cycles from monitoring well located at Donghaidao ahore,Leizhou Bay,the paper analyzed the variations of Ca2+,K+,Na+,Cl-,SO42-,TDS and total hardness.The results show that chemical elements' variation is apparent,ions is 35.65-3610.41mg/L with lowest K+and highest Cl-and Na+respectively.TDS is 4970.89 6441.48 mg/L and total hardness is 1054.75-1409.65 mg/L,the statistical features of ions vary with tidal periods.The percentage of ions in chemical element is relatively stable and the groundwater type is Cl-·SO42- -Na+·Ca2+featuring seawater intrusion,and the averaged concentration alignment of ions meet exponential allocation well in tidal cycles;Cl and Na have highest absolute amplitudes and SO42- and Na+have highest relative amplitudes,both Na+ and Cl- take high proportion of ion strength I,ions re-pairing and salt effects are significant;γNa+/γCl- is 0.75-0.83,γHCO3-/γCl- is 0-0.015 and SAR is 16.60,20.17 in two tidal cycles in separation;linear correlations reveal that Cl-and Na+have very good relationship with other elements,the averaged γCl-/γHCO3- shows high saline level and there are gentle increase of ions in tidal cycles with fitness slope k > 0;groundwater quality is V type except hardness ranging is IV-V and the general assessment result is poor.