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Soil heavy metal pollution caused by human activities has become one of the most critical environmental issues with a global concern. Phytoremediation is widely used due to its low cost and environmental friendliness. However, the impact of heavy metals on plant growth remains unclear. This study investigated the effects on the growth and photosynthetic activity of Picris divaricata Vant. under different cadmium concentrations using a hydroponics cultivation system. The results showed that the growth and photosynthetic processes of P. divaricata exhibited a phenomenon of promotion in low Cd concentrations and inhibition in high Cd concentrations. Under a low to medium Cd concentration (≤25 μM), there was no Cd toxicity in terms of plant growth, but high concentrations of Cd inhibited plant growth. The Fe content of leaves gradually increased as the Cd concentration increased; it reached 201.8 mg kg−1 in 75 μM Cd. However, there was no significant difference in Mn between the 75 μM Cd treatment and the control (p > 0.05). The contents of carotenoid ranged between 3.06 and 3.26 mg/g across the different Cd treatments, showing no significant differences. The treatment with 5–75 μM Cd did not directly affect the photosynthesis of P. divaricata. Higher Cd concentrations reduced the stomatal density on the of P. divaricata leaves, resulting in stomatal and mesophyll conductance limitations, indirectly affecting P. divaricata photosynthesis. These research results provide a reference for evaluating and selecting heavy metal tolerant plants and provide environmentally friendly approaches to remediate heavy metal pollution.

The unique climate and the landscape of severely cold regions in winter attract many tourists. The outdoor thermal environment affects the space use and the tourist experience, becoming one of the key factors in the design of tourist attractions. The outdoor thermal comfort of tourists from different regions should be considered, but it has been poorly studied in winter in severely cold regions. This paper explores the differences in outdoor thermal comfort in winter between local and non-local tourists through the field measurement of the thermal environment and a questionnaire survey of thermal comfort at tourist attractions in Harbin, China. The results show that the proportion of local tourists who expect the air temperature and solar radiation to rise in winter is higher than that of non-local tourists. The thermal sensation vote of local tourists is generally higher than that of non-local tourists. When the Physiologically Equivalent Temperature (PET) < −6 °C, the thermal satisfaction of non-local tourists is higher than that of local tourists. When the PET value is −10 °C, the thermal comfort of non-local tourists is the highest. The thermal comfort decreases with the rise or fall of the PET value. When −28 °C < PET < −7 °C, the thermal comfort of non-local tourists is generally higher than that of local tourists. This paper provides a reference and evaluation basis for urban tourist attractions’ outdoor thermal environment design in severely cold regions.

The geographical distributions of Cd and several other heavy metals (HMs) (Hg, Cu, Ni, Pb, Zn, Cr, As, Co, and V) were characterized in 90 (p > 0.05) terra rossa samples across the Anhui karst area. Significant enrichment of HM was observed in this soil, mainly associated with the weathering of Cd-enriched carbonate rocks. Then, this enrichment was developed in 31 profiles. Our investigations revealed pedogenic processes as the dominant factors accounting for the enrichment of Hg, Cu, Ni, As, Co, and V. We also observed that all soil samples had a silty clay texture, with a pH scope of 4.08–8.04 and a median value of 6.50. In addition, the soil samples had relatively high saturation, with basic cations over 6.68%. The enrichment of the HMs based on their distinct factors were as follows: Cd (3.92) > As (2.55) > Zn (1.62) > Ni (1.50) > Cu (1.47) > Pb (1.47) > V (1.43) > Cr (1.23) > Co (1.19) > Hg (1.12). Finally, terra rossa samples derived from carbonate rocks were categorized as Cambisols, Luvisols, and Regosols. The soil profiles of Cambisols and Luvisolsis were less developed, so the HM concentrations were relatively low. The Regosols profile contained the highest total Cd concentration and exhibited a higher capacity to immobilize Cd compared with other soil profiles. Regosols are also characterized by high pH values (scope of 7.05 to 8.22, with an average value of 7.56). The contents of HM also exhibited minor changes across the Regosol, Cambisol, and Luvisol profiles, implying that the karst development degrees of weathering in Anhui were relatively low.

Abstract In this paper, we prove the existence and uniqueness of solutions for a singular fractional differential equation boundary value problem with p-Laplacian operator. The main results of this paper are obtained by constructing the monotone iterative sequences of upper and lower solutions and applying the comparison result. Finally, we also provide an illustrative example in support of the existence theorem. Our results generalize some related results in the literature.

Good daylighting performance positively affects students’ physical and mental health, learning efficiency, and the building’s energy-saving capability. Due to the terrace classroom having ample space, large capacity, the ability to avoid obstructing sight, and the ability to meet various use needs, it is the most important place in university buildings. However, research on the daylighting performance of university terrace classrooms is limited, leading to a lack of quantitative guidance in early design stages. This study aims to explore the effects of interior space and window geometry of terrace classrooms in universities in severe cold regions on daylighting performance. This research took Shenyang as an example; spatial daylight autonomy (sDA300,50%) and useful daylight illuminance (UDI100–2000) were selected as daylighting performance evaluation indices. Based on the Grasshopper parametric platform, the simulation was carried out using Ladybug and Honeybee plugins. Correlation and regression analyses revealed the relationship between interior space and window geometry parameters and the evaluation indices. The results showed the following: window-to-floor ratio (WFR), classroom height (Htc), window height (Hw), window-to-wall ratio (WWR), classroom width (Wtc), and window width (Ww) have positive effects on improving the daylight sufficiency of the terrace classrooms facing each orientation, and the degree of the effect decreases in order. To ensure the overall daylighting performance, the Wtc can be maximized. The width of walls between windows for south-facing and west-facing classrooms should be 0.9 m. The WWR and WFR for south-facing classrooms should be 0.3–0.5 and 0.11–0.14, respectively. The WWR and WFR for north-facing classrooms should be 0.6–0.7 and 0.14–0.20, respectively. Prediction models are established for the sDA300,50% and UDI100–2000 of the terrace classrooms facing each orientation.