广西廉州湾海水环境质量综合监测

随着广西最大的河口三角洲廉州湾海洋环境压力的不断加大,地质环境综合监测评价工作难以满足经济发展和环境保护需求。结合前人研究成果和岸段排污特征,在廉州湾布设了20个监测站位,于夏、冬两季通过取样分析、现场测量等手段相结合进行数据采集,并分析了需氧量、营养盐、重金属等要素的时空分布以及变化特征。结果表明: 受径流输入和沿岸排污共同影响要素而变化较大,要素等值线呈现带状或者小尺度半闭合状分布,在南流江出海口等值线较为密集; 氮营养盐以硝酸盐(NO₃-N)为主,平均含量0.066~4.35 mg/L,含量较高的重金属有Pb、Zn、Cd、As; 与历史数据对比显示营养盐增加明显,且化学需氧量(chemical oxygen demand,COD)较高的状况并未有改善; 以滩涂养殖区污染最为严重,夏、冬两季几乎均为富营养化和重污染级,重污染等级比例两季平均值超过50.00%。总体上来看,该湾成为河流污染输入和周边陆源污染物的承纳海盆,并受到地质环境条件的限制而导致海水交换能力较差,现有污染状况同时还与人类对海岸利用开发加大有关。监测成果为进一步实施广西重点规划区海岸带立体化地质监测提供基本资料,并为当地海岸带防灾减灾等提供依据。

Comprehensive monitoring of seawater environmental quality in Lianzhou Bay of Guangxi

With the increasing of the marine environmental pressure of Lianzhou Bay, the largest estuarine delta in Guangxi, the comprehensive monitoring and evaluation of geological environment is difficult to meet the need of economic development and environmental protection. Combined with previous research results and pollutant discharge characteristics of coastal segments, the authors set up twenty monitoring stations in Lianzhou Bay, and these monitoring stations collected data by the sampling and analysis and in-site measurement in summer and winter respectively. And then the authors analyzed the spatio-temporal distribution and variation characteristics of the factors, such as oxygen demand, nutrients and heavy metals. The results showed that the factors are primarily influenced by runoff inflow and coastwise pollutant discharge. The distribution of the factors contours is banded or small-scale semi-closed, and the contours are dense in the estuary of Nanliu River. The nitrogen nutrients are mainly nitrates (NO₃-N), whose average content is 0.066~4.35 mg/L, and the heavy metals with relatively high content include Pb, Zn, Cd, and As. The comparison with historical survey data shows that there is an obvious increasement in nutrients and the situation of high chemical oxygen demand (COD) is unimproved. The pollution grade in aquaculture area is the highest, with eutrophication and heavy pollution both in summer and winter, and the average ratio of heavy pollution grade is more than 50.00%. So, Lianzhou Bay has become the loading basin of river pollution inflow and surrounding land-based pollutants, and its seawater exchange capacity is poor because of the limit of geological settings. Meanwhile, the current pollution situation also has a relationship with human discharge and coastal utilization. The monitoring results can provide basic data for the further three-dimensional geological monitoring along the coastal zone of the key planning area in Guangxi, and give reference to disaster prevention and mitigation of the local coastal zone.