Occurrence of synthetic musks in the sediment-seawater system of the Yellow Sea and East China Sea during wet and dry seasons.

Synthetic musks are aroma compounds used worldwide as substitutes for natural musks, which have become ubiquitous pollutants in the environment. The land-based input and partition behavior of synthetic musks in sediments and seawater are important for understanding their fate in the marine environment. In this study, a total of 292 seawater and sediment samples from 146 sites of the Yellow Sea and East China Sea were collected during wet and dry seasons and used to determine four synthetic musks, tonalide, galaxolide, musk xylene and musk ketone. Only tonalide was detectable in 10.6% and 17.8% of seawater samples at a concentration range of 23.7-38.2 ng/L and 19.0-24.8 ng/L in wet season and dry season, respectively. In sediments, both galaxolide and tonalide were detectable, with a sum total synthetic musks concentration ranging from 1.4 to 36.6 ng/g dry weight (dw) in wet season and 1.0 to 14.1 ng/g dw in dry season. The concentration of tonalide in seawater was significantly higher in wet season than in dry season and the concentration of synthetic musks in sediments of some coastal areas also exhibited higher concentrations in wet season than in dry season. Fugacity analysis showed that tonalide in the Yellow Sea exhibited a trend of diffusion from sediment to seawater or a state of equilibrium, while no diffusion trend was observed in the East China Sea. The hazard quotient values for tonalide and galaxolide in sediment and seawater samples were lower than 0.1, indicating that they present a low ecological risk. This research provides novel insights that help understand the pollution status, diffusion behavior and ecological risk of synthetic musks in marine environments.

Occurrence and distribution of organophosphate flame retardants in seawater and sediment from coastal areas of the East China and Yellow Seas.

Organophosphates (OPEs) are manmade organic pollutants that are widely used as flame retardants, plasticizers, and antifoaming and hydraulic agents. In this study, seven OPEs in seawater and sediment from the Yellow Sea and East China Sea were determined to study the distribution and diffusion behavior, and to evaluate the environmental risks. The ΣOPEs in the seawater and sediments ranged from below the method detection limit (1.0, indicating high ecological risks to aquatic organisms.

Fate and ecological risks of current-use pesticides in seawater and sediment of the Yellow Sea and East China Sea.

With the frequent use of chemical pesticides, the current-use pesticides (CUPs) emerge and concentrate in the sea. The partition between the sediment and seawater is essential for understanding the environmental fate of CUPs. However, there is little research on this topic. In the present study, seventeen CUPs were screened in seawater and sediment samples collected from the Yellow Sea and East China Sea. Total concentration of 17 CUPs in surface seawater samples ranged from 9.5 to 267.3 ng/L, with 6 CUPs presenting 100% detection frequency. Carbendazim, tricyclazole, tebuconazole, atrazine and imidacloprid accounted for >80% of all CUPs, which was due to their large application in the local agriculture and fishing activities. Higher concentration sites were located near the shore and Yangtze river estuary, indicating intense human activities and riverine input that elevated the level of CUPs in marginal sea. The pesticides in seawater were mainly found in the surface followed by the bottom layer, which indicated that atmospheric deposition and re-suspension played key roles for their vertical distribution characteristics. The high fugacity fraction ratios (ff > 0.5) indicated the non-equilibrium state of pesticides that might have been transferred from sediment to seawater at most sites. These 17 detectable pesticides in seawater were at low levels, presenting ignorable or low toxic effects to aquatic organisms.

High throughput extraction strategy for simultaneous analysis of 19 tetrabromobisphenol A and halogenated carbazole analogs in seafood.

Tetrabromobisphenol A (TBBPA), halogenated carbazole (HCZ), and their analogs are the emerging pollutants invading the marine environment. So far, a few methods have been reported for the simultaneous analysis of these pollutants due to their large polarity difference. In this study, an effective extraction and cleanup strategy was developed for the simultaneous determination of 19 TBBPA and HCZ congeners in seafood. The 19 analytes could be directly analyzed through high performance liquid chromatography after ultrasonic extraction (methanol, duplicate ethyl acetate-acetone (1:1, v/v)) and gel permeation chromatography cleanup. The acceptable spike-recoveries were within 65.7-118.3%; the precision was intra-/inter-day RSDs: 0.0-6.7%/0.0-8.5%; and the matrix effects were between -14.1% and 12.4%. The detection limits and quantification limits were 0.002-0.014 and 0.020-0.200 µg g-1 dw, respectively. Additionally, this method successfully analyzed the seafood samples and the concentrations of these analytes were in range of nd-5.4 µg g-1 dw.

Modeling and simulation of muscle forces of trans-tibial amputee to study effect of prosthetic alignment.

BACKGROUND: The muscle forces tend to change when any musculoskeletal system is damaged. It is necessary to predict and explain the patterns of muscle forces in the stump of a left trans-tibial amputee during walking, and to study the effects of the prosthetic alignment. METHODS: Musculoskeletal modeling and computer simulation were combined to calculate muscle forces in the trans-tibial lower limb during walking. The prosthesis was aligned to be in optimal position for the subject and then changed into +6 degrees and -6 degrees in the sagittal plane relatively. Kinematic data of the stump wearing a prosthesis and ground reaction forces were simultaneously recorded by a gait analysis system and a force platform, respectively. The data were input into a model of the lower trans-tibial extremity with three-dimensional geometry and the corresponding seven muscle forces were predicted by a static optimization. FINDINGS: Muscles performed much more actively in stance than in swing phase. Most muscles appeared very active around both heel-strike and toe-off. Muscle forces predicted were similar to that in temporal distribution at all three alignment conditions but the major muscles such as gluteus maximus, hamstrings, vasti and rectus femoris generated remarkable greater forces in -6 degrees and +6 degrees alignments than the normal condition. INTERPRETATION: The above results showed the muscle forces increasing at the mal-alignment. Because the incorrect alignment could break the relative position of the socket and foot, and that would generate the extra joint moments. As a result, muscle forces increased, and the long-duration fatigue occurs more easily. The finding suggests that the proper prosthetic alignment is very important for the stump muscles normal activities.