Hiện trạng chất lượng môi trường biển tại bãi ngao Hiệp Thạnh tỉnh Trà Vinh năm 2016 – 2017

Abstract

     Based on the results of marine environmental survey at hard clam farming in Hiep Thanh commune, Duyen Hai district, Tra Vinh province during 2016-2017. The article presented distribution characteristics of some ecological factors in the study area. In particular, the temperature has a small variation from 29.4-31.6ºC; the salinity has a quite large variation from 1.00-15.80 ‰; both are within the living limits of clam. The average content of NH₄⁺ is highest at the end of the season and higher 2 times than the limit allowed (>100 μg/l - QCVN 10-MT:2015/BTNMT). The average content of TSS of all three survey periods are over the limit allowed (>50 mg/l - QCVN 10-MT:2015/BTNMT) in turn: at beginning season 61.04±10.65 mg/l, at midseason 150.46±19.21 mg/l and at the end of the season 87.25±45.95 mg/l. NSSH raw highest at the end of the season (average: 169.23±81.80 mgC/m³/ngày) and inside limit NSSH raw of many seas in Vietnam. The content of Chlorophyll_a highest at beginning season (average: 11.69±2.97 μg/l). Evolution of environmental quality shows that: The parameters of temperature, DO, BOD₅, NO₂^- have little fluctuation while the remaining parameters (salinity, TSS, TOM, TN, TP, POC, NH₄⁺, NO₃^-, PO₄^3-, NSSH, Chlorophyll_a) have high fluctuation. There are 7 parameters with highest concentration at the end of the season: TOM, TN, TP, NH₄⁺, NO₃^-, PO₄^3-, NSSH and the lowest average content of DO also appears at this stage. The parameters of DIN, DIP and Chl_a have a positive correlation with each other, with the correlation coefficient Pearson (r) ranged from 0.342 – 0.756 (with p<0.05).

Keywords: Marine environment, hard clam farming, organic matter, nutrient.