Understanding the response of plant diversity to urbanization is essential for conserving urban biodiversity. In this paper, a meta‐analysis of 34 articles and 163 observations regarding the impact of urbanization on plant diversity was conducted. The results revealed that urbanization had marked negative effects on plants. Urbanization had positive effects on introduced species and negative effects on native species. In the subgroup analysis, we found that trees responded better to the effect of urbanization than herbs and shrubs. There was no evidence that urban size, population density, nighttime light, and GDP per capita had moderating effects on plant richness. Based on meta‐regression analyses, native species in urban areas were less affected by urbanization at lower latitudes. Overall, urbanization had a marginally negative effect on plant abundance. The effects of urbanization on plant diversity during different stages of urban development were inconsistent. Our research shows that the suburbs play a crucial role in the urbanization gradient; there, plants survive with high species richness.

This study investigates the presence, origin, and associated ecological and human health risks of polycyclic aromatic hydrocarbons (PAHs) in soils from uncultivated lands and beach sediments within the Yellow River Delta (YRD), China. The measured concentrations of 16 priority PAHs in soils spanned 24.97–326.42 ng/g (mean: 130.88 ng/g), while concentrations in sediments ranged from 46.17 to 794.32 ng/g, averaging 227.22 ng/g. In terms of composition, low-molecular-weight PAHs predominated in soil samples, whereas high-molecular-weight compounds were more prevalent in sediments. The positive matrix factorization (PMF) model results suggested that petroleum pollution and fuel combustion were the main sources of PAHs in soils, whereas the contribution in sediments was derived from petroleum and traffic pollution. The ecological risk assessment results indicated that there existed no obvious ecological risk of soil PAHs, but sediment PAHs could negatively impact the surrounding ecological environment, especially in the northern coastal beach area. In addition, soil PAHs posed no potential carcinogenic risk to humans. Further pollution prevention and management measures are required in this region to ensure the safety of the environment.

Wetland plants are essential for ecosystem functions. However, wetland plants in peri-urban areas have been affected by increased human interference. Hence, analyzing the drivers of plant diversity could be extremely useful for biodiversity conservation. The main objective was to investigate the response of plant diversity in wetlands (e.g., plant richness, plant abundance, and taxonomic distinctness) to the environment in peri-urban areas. The results show that the wetland area is the most important factor influencing plant diversity in peri-urban areas. Plant richness and abundance decreased significantly with a decreasing wetland area. The cultivated land decreased the abundance of native plants and indirectly promoted native plant growth and spread by increasing the total organic carbon content of the water. Forest encroachment on wetlands significantly reduced native plant abundance. The effects of soil pH, water body pH, soil organic matter, and slope on introduced species showed opposite trends to those on native plants. Introduced plants were significantly more adapted to the land use around the wetland than native plants. The green land and forest areas promoted the spread of introduced plants. Introduced plants were significantly less adapted to the physicochemical properties of the soil and water than native species. Humans, through agricultural cultivation, have caused introduced plants in cultivated lands to escape to wetlands, resulting in an increase in introduced species. The riparian zone length showed opposite effects for aquatic and terrestrial plants. Pollution from urbanization and agriculture both positively and negatively affects aquatic plants. The response of aquatic plants to nutrients in the water was better than their response to soil nutrients and the response of terrestrial plants to soil nutrients. Terrestrial plants can better withstand pollution from urbanization and agricultural activities, as well as the erosion of wetlands from forested and cultivated lands.

The Yellow River Delta (YRD) is the most complete wetland ecosystem in the warm temperate zone of China and is rich in oil resources. However, with petroleum extraction and the development of the economy, pollution of the YRD has been paid increasing attention, in particular, pollution via polycyclic aromatic hydrocarbons (PAHs), as they have caused great harm to human health and the ecosystem balance. Based on the investigations of a research group in 2009, this study re-collected samples according to the same sampling points and analyzed the concentration, composition, source, ecological risk and health risk of PAHs in 2021. The concentration of ΣPAH₁₆ in the surface soil of YRD in 2009 ranged from 2.6 to 8275.46 ng/g, with an average of 1744.41 ng/g. The concentration of ΣPAH₁₆ in 2021 ranged from 56.25 to 582.56 ng/g, with an average of 149.63 ng/g. Therefore, the pollution situation in the YRD in 2021 was significantly improved compared with 2009. The composition of PAHs in soil in 2009 and 2021 was similar, which was dominated by low-ring PAHs. The evaluation results of the toxicity equivalent factor method showed that there was no potential ecological risk in the soil in 2009 and 2021. The evaluation results of the lifetime cancer risk increment model showed that the incremental lifetime cancer risk models (ILCRs) of soil PAHs in 2009 and 2021 were lower than the safety threshold of 10⁻⁶; therefore, there was no carcinogenic risk. The existing management measures for oil wells need to be further promoted to protect the regional ecological environment in the YRD.

The distributions and sources of polycyclic aromatic hydrocarbons (PAHs) and their ecological and health risks were explored in uncultivated land soils and coastal beach sediments in the Yellow River Delta (YRD), China. The results indicated that the total concentrations of 16 priority PAHs in soils ranged from 24.97 to 326.42 ng/g, with an average value of 130.88 ng/g, and in sediments, the total concentrations ranged from 46.17 to 794.32 ng/g, with an average value of 227.22 ng/g. Low-molecular-weight (LMW) PAHs were the dominant component in soils, and high-molecular-weight (HMW) PAHs were the dominant component in sediments. The positive matrix factorization (PMF) model results suggested that petroleum pollution and fuel combustion were the main sources of PAHs in soils, whereas the contribution in sediments was derived from petroleum and traffic pollution. The ecological risk assessment results indicated that there existed no obvious ecological risk of soil PAHs, but sediment PAHs could negatively impact the surrounding ecological environment, especially in the northern coastal beach area. In addition, soil PAHs posed no potential carcinogenic risk to humans. Further pollution prevention and management measures are required in this region to ensure the safety of the environment.