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A pretreatment method was established for separating microplastics from digestive system of bivalve sample. Qualitative and quantitative analysis of microplastics was carried out by micro-Fourier transformed infrared (μ-FT-IR) spectroscope and Stereo microscope. The method was applied to analyze the microplastics in the digestive system in Chlamys farreriand Mytilus galloprovincialis.The results showed that the digestion system of using 10% KOH had high digestion efficiency. With this digestion system, the recoveries of polypropylene (PP), polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) ranged from 96.7% to 98.6%, with relative standard deviation (RSD, n= 3) of ≤ 3.19%. We collected Chlamys farrerifrom local markets (n= 50) and Mytilus galloprovincialisfrom both local markets (n= 50) and wild environments (n= 15) in Qingdao, China. The results showed that microplastics were found in over 80% of the individuals purchased from the market and 40% of the wild collected individuals. The average abundance of microplastics in Chlamys farreripurchased from different markets varied between 5.2 and 19.4 items/individual or between 3.2 and 7.1 items g−1(wet weight of digestive system), while in Mytilus galloprovincialis, the numbers varied between 1.9 and 9.6 items/individual or between 2.0 and 12.8 items g−1. Farmed mussels (Mytilus galloprovincialis) contained more microplastics (average 1.9 items per individual, 3.17 items g−1) than wild mussels (average 0.53 items individual, 2.0 items g−1). Three shapes of microplastics, including fibers, fragments and granules were separated from the samples above. Among which, fibrous microplastics, being the most dominant ones, took up 84.11% of total microplastics. The average size of fibrous microplastics ((0.66 ± 0.70) mm) was larger than that of the other two shapes of microplastics. The number of microplastics decreased with increasing microplastic sizes. Microplastics of less than 500 μm coming from different markets were in the range of 26% to 84%. And it was found that the most common polymer component in the samples was cellophane (CP), followed by polypropylene (PP). The method has some advantages such as simplicity, high efficiency, and low damage to the microplastics in the sample, and can be used to detect and analyze microplastics in seafood.

A method of capillary electrophoresis (CE) coupled with inductively coupled plasma-mass spectrometry (ICP-MS) was established to determine lead ion [Pb(II)], trimethyl lead (TML), and triethyl lead (TEL). An extraction technology for lead with different species in algae was proposed and optimized for qualitative and quantitative analyses. Experimental results showed that these three lead compounds could be effectively separated within 20 min by CE-ICP-MS in a buffer solution of 70 mM H3BO3and 17.5 M Na2B4O7(pH 8.9). This method had good reproducibility for migration time (relative standard deviation (RSD) < 4%) and peak area (RSD < 5%). On the basis of this, the three lead compounds were detected in the linearity range of 10–200 μg L−1with the correlation coefficient over 0.90. The detection limits for Pb(II), TML and TEL (S/N= 3, Pb) were 0.091, 0.023 and 0.030 μg L−1, respectively. The fractional extraction rate of Pb exceeded 80%, and the recoveries of Pb(II), TML, and TEL in algae samples were 103.6%, 95.7% and 90.6%, respectively. The detection results of lead content in laver and kelp samples showed that Pb in algae mainly existed in the form of Pb(II). Given its simplicity, high efficiency, and low sample consumption, the method could provide technical support for the quality control of marine algae and other marine products.

A total of 30 kinds of fish samples, 5 kinds of shellfish samples and 4 kinds of crustacean samples from the Nansha sea area in China were digested using a microwave digestion system with HNO3-H2O2as the digestion reagent. Then, the contents (ICP-MS determination) and ecological chemical characteristics of rare earth elements (REEs) were studied. The results showed that the method of microwave digestion-ICP-MS for the determination of rare earth elements was perfect, and the linear relationship for each element was good with r≥ 0.9997. The detection limit reached ng L−1level with a relative standard deviation (RSD, n= 3) of less than 5.0%. The recovery of REEs was between 91.5% and 106.7%. The total amount of REEs in fishes, shellfishes, and crustaceans were (5.0–34.8) μg kg−1, (30.4–1481) μg kg−1, and (103–863) μg kg−1, individually. The order of the enrichment average contents of the REEs in the three species was crustacean>shellfish>fish. The 14 kinds of REE contents in fish/shellfish/crustacean showed a significantly positive correlation (r> 0.80). The contents of light REEs (from La to Eu) were higher than those of heavy REEs (from Gd to Lu). The light and heavy REEs demonstrated obvious fractionation, and the REE distribution pattern in fish/shellfish/crustacean was consistent with the negative anomaly of Gd. The σEu values had negative anomalies, which were similar to the σEu values in the corresponding area sediment, and σCe values showed positive anomalies, which showed that Ce followed a different oxidation and reduction process in the organism and sediment deposition. At the same time, the enrichment relationship of REEs in sediment and organism was also studied. In this study, the content and distribution of REEs in the tropical marine fish/shellfish/shellfish were analyzed, which could provide basic data for the study of the level, migration, and accumulation of REEs in the environment of South China Sea.

According to the basic idea of similarity theory, the pile model in saturated transverse isotropic clay is determined. It imitates the moment of different positions along the pile and acceleration of each test point on the soil surface, under the same largest exciting force with different frequencies on the top of the pile. The results of experiment show that the variation trends of the moment are the same for different frequencies of excitation, looking like an inverse S. Acceleration value of each test point on the soil surface decreases with decline of the exciting frequency.

To further verify the feasibility of theoretic calculation, according to similarity theory, the principles and methods of pile foundation-soil interaction in saturated soft clay are determined. It studies acceleration interaction of each test point on the soil surface under the same largest shock force with different frequency on the top of the pile. The results of experiment show that the acceleration interaction trend of each point changes with the change of shock frequency, it shapes like a down N with the shock frequency of 5Hz, like an M with the shock frequency of 10Hz, like a down V under the shock frequency of 15Hz～30Hz. With the shock frequency of 40Hz and 50Hz, it likes a plane curve (hyperbolic curve) shape.