Urban green space plays a significant role in protecting the environment and purifying the air. In a city, green infrastructures are interconnected in a large system, which can play a positive role in the ecological protection of the city; meanwhile, in the main urban areas of large cities with complex land use types, the distribution of green infrastructure is disorderly, and how to effectively determine the actual effect of green space on PM_2.5 at an urban small scale is still a challenge. Smog in southern Chinese cities primarily occurs in spring and winter, so we chose Nanjing, one of the largest megacities in southern China, as a case study, and chose spring and winter as the research time series. We took 11 air monitoring points as the core and delimited a radius of 500 meters as the research area, tracked and monitored the changes in PM_2.5 values at 11 stations for 2 months, and then conducted a correlation analysis between this change and the NDVI (Normalized Difference Vegetation Index) values of the 11 regions. The analysis shows that in the main urban area, green space can have an obvious influence on the ambient air state within 500 m. In addition, when the NDVI value was high, the PM_2.5 concentration in the corresponding area was low, and the correlation reached 0.89 on average (1 is a perfect correlation); the mean regression equation was y = 56.3–0.088x. In addition, the correlation was stronger when the PM_2.5 concentration was higher, indicating that green space in the main urban area can play an obvious ecological efficiency role in the extremely polluted atmospheric environment. These research results reveal for the first time the impact of green space on air particles in small-scale urban space, which is conducive to better optimization of green space layout to better give full play to the ecological function of green space in response to public health events.

Environmental particulate pollution is a major global environmental health risk factor, which is associated with numerous adverse health outcomes, negatively impacting public health in many countries, including China. Despite the implementation of strict air quality management policies in China and a significant reduction in PM_2.5 concentrations in recent years, the health burden caused by PM_2.5 pollution has not decreased as expected. Therefore, a comprehensive analysis of the health burden caused by PM_2.5 is necessary for more effective air quality management. This study makes an innovative contribution by integrating the Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI), and Soil-Adjusted Vegetation Index (SAVI), providing a comprehensive framework to assess the health impacts of green space coverage, promoting healthy urban environments and sustainable development. Using Nanjing, China, as a case study, we constructed a health impact assessment system based on PM_2.5 concentrations and quantitatively analyzed the spatiotemporal evolution of premature deaths caused by PM_2.5 from 2000 to 2020. Using Multiscale Geographically Weighted Regression (MGWR), we explored the impact of greening improvement on premature deaths attributed to PM_2.5 and proposed relevant sustainable governance strategies. The results showed that (1) premature deaths caused by PM_2.5 in Nanjing could be divided into two stages: 2000–2015 and 2015–2020. During the second stage, deaths due to respiratory and cardiovascular diseases decreased by 3105 and 1714, respectively. (2) The spatial variation process was slow, with the overall evolution direction predominantly from the southeast to northwest, and the spatial distribution center gradually shifted southward. On a global scale, the Moran’s I index increased from 0.247251 and 0.240792 in 2000 to 0.472201 and 0.468193 in 2020. The hotspot analysis revealed that high–high correlations slowly gathered toward central Nanjing, while the proportion of cold spots increased. (3) The MGWR results indicated a significant negative correlation between changes in green spaces and PM_2.5-related premature deaths, especially in densely vegetated areas. This study comprehensively considered the spatiotemporal changes in PM_2.5-related premature deaths and examined the health benefits of green space improvement, providing valuable references for promoting healthy and sustainable urban environmental governance and air quality management.

The precious aquatic plant Nymphaea hybrid, is valued for its ornamental and economic importance but is highly sensitive to environmental fluctuations. However, the interactive effects of light and temperature, two critical abiotic factors, on its photosynthetic performance and underlying structural basis remain poorly understood. In this paper, we conducted a two-factorial experiment in which N. hybrid plants were exposed to five light–temperature regimes for 9 days: control (T0, 800 μmol·m⁻²·s⁻¹ + 25/20 °C); low light–low temperature—LLLT (T1, 200 μmol·m⁻²·s⁻¹ + 15/10 °C); low light–high temperature—LLHT (T2, 200 μmol·m⁻²·s⁻¹ + 35/30 °C); high light–low temperature—HLLT (T3, 1400 μmol·m⁻²·s⁻¹ + 15/10 °C); and high light–high temperature—HLHT (T4, 1400 μmol·m⁻²·s⁻¹ + 35/30 °C). We systematically investigated changes in photosynthetic pigments, gas exchange, chlorophyll fluorescence, and leaf ultrastructure by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that: The HLLT treatment (T3) inflicted the most severe damage, triggering a rapid decline in net photosynthetic rate (Pn), maximal photochemical efficiency (F_v/F_m), and chlorophyll content, coupled with a significant increase in intercellular CO₂ concentration (Ci). Ultrastructurally, T3 caused stomatal closure, disintegration of thylakoid membranes, and accumulation of large osmophilic granules, indicating severe photo-oxidative stress. In contrast, the LLHT treatment (T2) demonstrated remarkable resilience, with physiological and structural parameters closely resembling the control. The HLHT treatment (T4) caused intermediate damage, primarily through non-stomatal limitations over time. Our findings demonstrate a significant light–temperature interaction in N. hybrid. The thermophilic nature of N. hybrid was evident: high temperature mitigated the negative effects of low light, whereas low temperature, especially in combination with high light, acted synergistically to cause catastrophic damage to the photosynthetic apparatus. This study provides a mechanistic understanding of N. hybrid’s environmental adaptability, offering critical insights for its cultivation management under changing climate conditions, especially in high altitude and high latitude areas.