Taking the sediments of Shenzhen urban mangrove wetland as the research object, the mineral composition and physical and chemical properties of the sediments are analyzed, and the characteristics of mineral composition and influencing factors are explored. The main results show that the whole rock mineral composition in surface sediment is given priority to clay minerals (16.5%?73.5%) and quartz (22.0%?81.2%), and there are differences in the contents of potash feldspar, pyrite, and rock salt in different samples at different depths. The main types of clay minerals in surface sediments are imonite (44%?76%), kaolinite (0%?40%), chlorite (0%?24%), and illite (2%?21%), and are dominated by imonite. The distribution characteristics of clay minerals at different depths are basically the same as those in surface sediments. There are significant differences in the composition of clay minerals in the sediments of the Pearl River Estuary and Daya Bay without vegetation. Correlation analysis shows that the composition of whole rock minerals is mainly affected by salinity, TS and TOC, while the composition of clay minerals is mainly affected by pH, salinity, TOC, and sediment particle size.

Taking six most common garden plants in Shenzhen were used as research objects, the amount of dust retention per unit leaf area and the particle size composition of dust were studied. The microscopic morphology and the structure of leaf surface as well as the composition and distribution characteristics of the retained particles were investigated. The influence of meteorological factors on the dust retention characteristics of plants was clarified. The results showed that: 1) The dust retention amount per unit leaf area of different plant types was Ficus microcarpa (0.74±0.21 g/m²) > Schefflera arboricola (0.42±0.26 g/m²) > Ficus hispida (0.24±0.26 g/m²) > Ixora chinensis (0.20±0.07 g/m²) > Ophiopogon bodinieri (0.18±0.10 g/m²) > Plumeria rubra (0.15±0.10 g/m²). 2) The six types of garden plants were mainly composed of particles with particle size α>10 μm. The weight of particles with size α>10 μm accounts for 59.21%~88.92% (except for F. microcarpa) of the total weight. S. arboricola had the strongest dust-retaining ability for particles with size α>10 μm (0.34±0.20 g/m²). F. microcarpa had the strongest dust-retaining ability for particles with size 3 μm<α<10 μm (0.51±0.15 g/m²) and 0.15 μm<α<3 μm (0.14±0.07 g/m²). 3) Stoma, fold, groove, flocculent protuberance and villi on the surface were conducive to the retention of dust. The main elements of the retained particles were O, Si and Al. 4) The large particles (α>10 μm) detained by the leaves of the six garden plants were susceptible to wind speed and temperature. The results of this study can be used to guide the arrangement of garden plants in Shenzhen and provide a scientific evidence for the plant dust retention effect to improve air quality.