Suitability evaluation of carrying capacity and utilization patterns on tidal flats of Bohai Rim in China

Tidal flats in the Bohai Rim are facing threats from human activities. Quantifying the carrying capacity and suitability of tidal flats is of great significance to the regional environment and resource management. In this study, the existing social and natural data were collected and the natural conditions of tidal flats, e.g., the distributions and utilization patterns, were investigated through remote sensing image interpretation and field investigation in the Bohai Rim. Then, a multi-index evaluation system was developed with indexes organized under the framework of the analytic hierarchy process (AHP) and the Drivers-State-Impact (DSI) framework, processed by fuzzy evaluation, and weighted by the entropy method. The studies show that the rapid expansion of industry-port-town, salt pans or aquafarms in the Bohai Rim during 1990-2020 squeezed the space of tidal flats. Despite the limitation of the declining resource condition, the carrying capacity of tidal flats in the Bohai Rim increased slightly during 2000-2018 because of the great improvement in economic and ecological conditions. We estimate 59.93% of the land resources are suitable for economic development while others are temporarily unsuitable for reclamation due to their high ecological importance. The land use data and macro-evaluation system of tidal flat utilization patterns herein can provide references for coastal resource management and ecological restoration.

[Fate Simulation of 2,4,4'-Trichlorobiphenyl in the Bohai Rim Using the Multimedia Model]

To study the multimedia transfer and fate of polychlorinated biphenyls (PCBs) in the Bohai Rim, we used the BETR-Urban-Rural model to simulate and calculate the concentration distribution, fate distribution, and transfer processes of 2,4,4'-trichlorobiphenyl (PCB28) in nine environmental compartments under a steady-state assumption. The input parameters and output results of the model underwent sensitivity analysis and uncertainty analysis, respectively. The results showed that the simulated concentrations of PCB28 in fresh water, rural soil, urban soil, and sediment could fit the measured concentrations well, thus verifying the reliability of the model. The concentration of PCB28 in urban soil was the highest, and the average concentration was 5.26×10^-6 mol·m^-3. In contrast, the concentration of PCB28 in rural air was the lowest, and the average concentration was 5.79×10^-14 mol·m^-3. When the environmental system reached equilibrium, the largest sink of PCB28 in the Bohai Rim was soil, accounting for approximately 96.45% of the total amount remaining in the system. The mutual transfer processes between air and other environmental compartments were the dominant pathways for PCB28 inter-media transport in the Bohai Rim. Most PCB28 entering the Bohai Sea was transferred by airflow, and the fluxes from rural air to coastal water accounted for approximately 97.22% of the total fluxes of PCB28 entering the sea. According to the result of sensitivity analysis, the emission rates, grid dimensions, and transport velocity were the key parameters affecting the model output. Uncertainty analysis showed that the distributions of PCB28 concentrations in rural air and urban air fitted well with lognormal distributions, and the coefficients of variances (CVs) were 0.44 and 0.41, respectively.

Impact of agricultural waste burning in the Shandong Peninsula on carbonaceous aerosols in the Bohai Rim, China

A total of 11 5PM2.5 samples were collected for analyzing organic carbon (OC) and elemental carbon (EC) at Tuoji Island (TI), China from November 2011 to December 2012. The results showed that annual arithmetical means of OC and EC concentrations were 3.8 ± 2.7 and 2.2 ± 2.2 μg m(-3), which contributed 8% and 4% of PM2.5 mass concentrations, respectively. High EC concentrations occurred in winter, contributed mainly by EC outflow from the northwest source region, while high OC concentrations were found during spring, attributed largely to biofuel burning in the Shandong Peninsula, and short distance and favorable transport from the peninsula to the TI. Agricultural waste open burning in the peninsula caused the largest variability of OC concentration in summer. Eliminating agricultural field burning in the peninsula can reduce at least one-third of concentration levels and half of northward transport fluxes of OC and EC in Bohai Rim in summer.