The spatial variation, potential sources, and ecological risk of heavy metals (Cd, Co, Cr, Cu, Mn, Hg, Ni, Pb, and Zn) in surface sediments from the typical inflow rivers in Taihu Basin were investigated in June 2010. The results showed that the heavy metal concentrations varied greatly and spatially, and higher metal contamination mainly occurred in the northern and northwestern regions in Taihu Basin. Multivariate statistical analysis demonstrated that Mn might originate from natural sources, whereas Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn were primarily delivered from anthropogenic activities. The geoaccumulation index and enrichment factor values indicated that Cd, Cu, Cr, and Zn were moderately severe enriched, Ni and Pb were moderate enriched, while Co and Hg were at a minor enrichment level, which indicated that their contamination was not a major concern in the inflow rivers of the basin. Compared with the "Consensus-Based Sediment Quality Guidelines," Cr, Cu, Ni, and Zn were most likely to result in ecological toxicity for aquatic organisms. Although Cd was at moderately severe enrichment level, the probable effect concentration quotients of Cd < 1 implied it had no or low adverse effects on organisms. The results also suggest that Cr, Cu, Ni and Zn contamination in the north and northwest of the basin should be addressed as the first priority.

This paper analyzes the daily data of China’s air quality index (AQI) from 2015 to 2020 using kriging, spatial autocorrelation, and gravity center method. The results confirm that China’s air pollution is gradually controlled. From 2015 to 2020, the AQI, the proportion of air pollution days and the city air quality exceedance rate decreased by about 29%, 44%, and 49% respectively. The spatial distribution of air pollution changes with seasons. The heavily polluted area (AQI &gt; 200) is largest in spring, which accounts for 0.48% of the total area, while the polluted area (AQI &gt; 100) is largest in winter due to large area pollution in the North China Plain. The air pollution has strong spatial autocorrelation with a global Moran’s Index larger than 0.7. The Beijing-Tianjin-Hebei region and southern Xinjiang are high-pollution clustering areas. The former is dominated by PM2.5 pollution caused by anthropogenic activities, while the latter is dominated by PM10 pollution from natural sources. Using gravity center method, it works out the air pollution gravity center (APGC), economic gravity center (EGC), the secondary industry gravity center (SIGC), the tertiary industry gravity center (TIGC) and the population gravity center (PGC) in the Beijing-Tianjin-Hebei region and its surrounding areas. Results show that the spatial overlapping indicator of the APGC with the PGC is the highest, and the APGC and the SIGC has the highest shifting consistency indicator. When combining the two indicators, it is obtained that air pollution has the highest degree of spatial coupling with the secondary industry, but low coupling with economic volume. It is indicated that the driving factors of air pollution is the secondary industry. Therefore, it is suggested that the regulation of air pollution should start from optimizing the industrial structure in China.

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Water conservation, soil conservation, biodiversity importance, and sandstorm prevention are important ecosystem services (ES) and the core challenges to sustainable economic and societal development in the Beijing–Tianjin–Hebei (BTH) region. Using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and observation data, we identified high-value ES areas in the BTH region. The high-value ES areas were mainly found in the northern and southwestern parts of the region, like the Yanshan Mountain Range and the Taihang Mountain Range. The ecosystem in the northern mountains is dominated by forest and grassland, and generally provides more valuable ES than does the eastern agricultural plain. Greater species richness was mainly found in the northern mountains with low human activity intensity. Due to its proximity, the Yanshan Mountain Range is critical to the health of the local ecosystem of Beijing. High biodiversity was present in the vicinity of the national nature reserves. Compared with other regions of China, changes in the BTH region are highly intense. Reinforcement of biodiversity conservation and ecosystem restoration in areas with a high degree of ES in the BTH region are capable of effectively improving habitat quality and regional ES.

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