Spatial variations of tidal water level and their impact on the exposure patterns of tidal land on the central Jiangsu coast

The exposed area of intertidal zone varies with tidal water level changes, If intercomparisons of satellite images are adopted as a method to determine geomorphological changes of the intertidal zone in response to accretion or erosion processes, then the effect of water level variations must be evaluated. In this study, two Landsat TM images overpassing the central Jiangsu coastal waters on 2 January and 7 March 2002, respectively, were treated by the changing detection analysis using Image Differencing and Post-classification Comparison. The simultaneous tide level data from four tide gauge stations along the coast were used for displaying the spatial variations of water levels and determining the elevations of waterlines. The results show that the spatial variations of water levels are highly significant in the central Jiangsu coastal waters. The huge differences of tidal land exposure patterns between the two imaging times are related mainly to the spatial variations of tidal water levels, which are controlled by the differences in tidal phases for different imaging times and the spatial variations of water level over the study area at each imaging time. Under complex tidal conditions, e.g., those of the central Jiangsu coastal waters, the tide-surge model should be used to eliminate effectively the effects of water level variations on remote sensing interpretation of geomorphological changes in the intertidal zone.

Exposure Patterns of Multiple Pesticides and Urinary Alterations of Trimethylamine(TMA)and Trimethylamine N‑Oxide(TMAO)among Pregnant Women

Environmental exposure to pesticides is widespread and commonly occurs in mixtures,and pregnant women are particularly concerned.Trimethylamine N-oxide(TMAO),a dietary-derived catabolite linked to cardiometabolic disease,may be influenced by pesticide exposure.However,limited knowledge exists regarding the associations,and studies have primarily been restricted to single pesticides.To address this gap,we examined the associations of pesticide exposure with urinary TMA,TMAO,and TMAO-to-TMA ratio among 1067 pregnant women residing in a rural area.Latent class analysis(LCA)was applied to identify distinct patterns of pesticide exposure based on urinary metabolite concentrations.Multiple linear regression(MLR)models and Bayesian kernel machine regression(BKMR)models were employed to estimate the effects of single pesticides,exposure patterns,and combined exposure.Four distinct pesticide exposure patterns were identified.Higher concentrations of pesticide metabolites were found to be associated with increased urinary TMAO levels(β:0.043 to 0.254,p<0.05).In the MLR models for individual pesticides and exposure patterns,carbofuran phenol(CFP),pentachlorophenol(PCP),and 2-phenylphenol(OPP)exhibited positive associations with urinary TMA concentrations,while pyrethroid pesticide metabolites were correlated with the up-regulation of the TMAO-to-TMA ratio.Significant positive associations of pesticide mixtures with TMA,TMAO,and TMAO-to-TMA ratio were observed in the BKMR model,primarily driven by PCP and trans-DCCA.Our findings provided a perspective to reveal that the mechanisms and contributions to TMAO alterations may vary among different pesticides in mixture exposure.