Abstract：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.
2018, Vol. 5 
