Levels, source apportionment, and risk assessment of polycyclic aromatic hydrocarbons in vegetable bases of northwest China.

Dietary consumption of contaminated vegetables is the main route of human exposure to polycyclic aromatic hydrocarbons (PAHs). However, there is a lack of research on PAHs in vegetables from northwest China. In this study, the concentrations, sources, and risk assessment of PAHs in the soil and vegetables of Urumqi, an urbanized city in Xinjiang, China, were investigated. The total concentrations of 16 PAHs in soil and vegetable samples ranged 10.58-77.20 and 93.7-1071.8 ng/g, with average values of 2.86 and 242.76 ng/g, respectively. Among vegetable samples, the concentrations were in the order: leafy vegetables (299.08 ng/g) > fruits (192.65 ng/g) > vegetable roots (152.05 ng/g). The source apportionment of PAHs was identified using positive matrix factorization. The primary sources of PAHs in soil samples are oil spills, traffic emissions, coal combustion, and coke combustion. The main sources of PAHs in vegetable samples are oil spills and burning of grass, wood, coal, and coke. In soil samples, the ecological risk caused by PAHs is at a safe level, and the incremental lifetime cancer risks (ILCRs) of ingestion exposure exceed 1.0 × 10-6, which will pose potential risks to human body. The ILCRs of vegetable samples revealed that all groups had potential risks from onion and cabbage consumption (ILCRs > 1.0 × 10-6). In particular, adult women had a higher risk of cancer (ILCRs > 1.0 × 10-4). These results emphasize the importance of combating PAHs pollution in vegetable bases.

Coordination analysis and evaluation of population, water resources, economy, and ecosystem coupling in the Tuha region of China.

The non-coordination between the socio-economic systems and ecosystems of a region is a crucial obstacle to sustainable development. To reveal the relationships between complex urban systems and achieve the goal of sustainable and coordinated urban development, we constructed a coupling coordination degree model (CCDM) and coupling angle model (CAM) and analyzed the degree of coupling coordination and evolution process among the population, water resources, economy, and ecology (PWEE) system of the Tuha region for 2005-2020. The results indicated that: (1) During 2005-2020, the comprehensive development index (CDI) of the population, water resources and economy subsystems was 0.21-0.65, with the three subsystems portraying an overall increase; the average values of the RSEI at five-year intervals were 0.29, 0.28, 0.28, and 0.26, indicating a downward trend in the environmental quality. (2) The coupling coordination effect of the PWEE system portrayed a low level; the coupling coordination degree (CCD) values were 0.28-0.58, portraying a fluctuating upward trend. The level of CCD increased from low disorder to marginal coordination. (3) The PWEE system's scissor difference reflects large evolutionary characteristics. The ecological support capacity was not observed until the late stage. We conclude that the PWEE composite system of the region is in a stage of disordered development. These findings significantly bolster the theoretical underpinnings of sustainable development studies, offering essential scientific theories and methodological frameworks for crafting sustainable development policies tailored to urban systems in the Tuha region.