Rapid Detection For Acute Toxicity Of Drilling Fluid And Study For Evaluation Methods For Marine Pollution

In view of the fact that the pollutant type of off-shore oil drilling discharges increases day by day, and the influence on marine environment intensifies unceasingly, the rapid assessment method of marine pollutant's toxicity becomes more important. The marine microalgae which plays the part of the primary productive forces in the ocean is quite sensitive to the toxicity of the pollutant.So it is suitable for the biological acute toxicity inspection. Because of the sensitivity and convenience of the fluorescence technology, it can be used as the main examination method to detect the toxicity of the pollutant rapidly. In this paper, the marine microalage Skeletonema costatum which is sensitive to the toxicity of drilling fluid is selected. The experimental biology artemia which is recommended by the national standards is used as the antithesis. An rapid assessment method for drilling fluids toxicity inspection has been established based on the micro algae fluorescence technology. The toxicity of seven kinds of drilling fluids and its components are determined. The non-determined effect model and the CHARM model are utilized to classify the drilling fluids based on the toxicity data. The prime task achievement includes:1. A rapid assessment method for marine drilling fluids biology toxicity evaluation using the marine microalage Skeletonema costatum as the experimental biology, and based on the fluorescence examination technology has been established. First, the most sensitive biology Skeletonema costatum is screened from five kinds of marine microalgae for the drilling fluids toxicity assessment; Second, the fluorescence microalgae biomass examination technology can avoid the influence of the drilling fluids, and also has other advantages, such as fast, accurate, suitablity for local application; Third, the synthetisch analysis indicates that the 8hEC50 value is well related to the 96hEC50 value of the drilling fluids, so it can be used as indicator of the acute toxicity evaluation; Fourth, the results of this method has good relevance to the method put forward in the GB laws, and the technology also has the advantages of celerity, accuracy and higher accuracy merit; Fifth, the result of drilling fluids toxicity assessment indicates that all the six kinds of drilling fluids are toxic, besides WBF1.2. The poisonous effect relations of the drilling fluid WBF2 is determined initially using Skeletonema costatum as toxicity assessment biology. In the seven single components of drilling fluid WBF2, one kind is the poisonous component, one kind for the low toxicity component, and the other five kinds are all the non-toxic components; In drilling fluid WBF2, when the poisonous component and low toxicity component are mixed, it puts up certain synergy effect in short time, but this effect becomes unconspicuous along with the time; The comprehensive toxicity of drilling fluid WBF2 is mainly decided by the poisonous component, and the non-toxic components possibly cause the enhancement function to the wholly toxicity of the drilling fluid.3. A method for the sea area pollution assessment has been established initially based on the marine microalgae. The sea area pollution evaluation indicator--the non-determined effect model which is based on the marine microalgae has been established. The resaults of the sea area pollution evaluation indacates that the drilling fluid WBF1 is non-toxic and can be discharged to the sea area directly; the other six kinds of drilling fluids are all poisonous, and couldn't be discharged to the sea area directly. The CHARM model is inducted preliminarily, and the result is the same with the result above which shows that WBF1 can be used directly, but others all should be considered conscientious when they are used.In sum, this article utilizes the fluorescence technology to detect the toxicity of drilling fluids and its components, and carry on the classification according to its serviceability. This research provides the technical support for the preparation of non-toxic or low poisonous drilling fluids. This method has the prospective application values.