Relative contributions of natural and anthropogenic factors to the distribution patterns of nature reserves in mainland China.

Nature reserves (NRs) are designated as a result of the ecosystem, species, economy, population, and land use coordination. However, the extent to which these factors influence the geographical pattern of NRs is unclear. Here, 11 indices (seven natural and four anthropogenic) were examined to identify these relationships in over 2600 terrestrial NRs in mainland China at the provincial level. Correlation analysis between natural and anthropogenic factors and NRs showed that desert and grassland had a positive correlation with NR coverage and area, and a negative correlation with NR density. This result was reversed in the correlation analysis between forest wetland coverage, endangered species, wildlife and NR coverage, area, and density. Similar results were found in the correlation analysis of all anthropogenic factors (population density, agricultural land, roads, and per capita GDP) with the coverage, area, and density of NRs. Canonical correspondence analysis (CCA) showed that three significant natural indicators (desert ecosystems, grasslands ecosystems, and forested and wetlands ecosystems) could explain 64.2 % of the pattern of NRs. The largest contributor was desert coverage, explaining 48.3 % (P = 0.002) of all indicators, followed by grassland coverage, explaining 8.6 % (P = 0.012), and forest and wetland coverage, explaining 7.3 % (P = 0.008). Human activities were significantly positively correlated with forest and wetland coverage, flora, and fauna, and negatively correlated with desert and grassland coverage. Compared with sand and grassland in the western region, the forest wetlands and wildlife in the eastern and central provinces were under greater pressure from anthropogenic activities. Therefore, natural factors determine the general layout of NRs, while the influence of anthropogenic activities makes the distribution of NRs patchy. When establishing national parks, governments must design strategies to coordinate areas with high biodiversity and high levels of human activity.

Identification of ozone sensitivity for NO2 and secondary HCHO based on MAX-DOAS measurements in northeast China.

In this study, tropospheric formaldehyde (HCHO) vertical column densities (VCDs) were measured using multi-axis differential optical absorption spectroscopy (MAX-DOAS) from January to November 2019 in Shenyang, Northeast China. The maximum HCHO VCD value appeared in the summer (1.74 × 1016 molec/cm2), due to increased photo-oxidation of volatile organic compounds (VOCs). HCHO concentrations increased from 08:00 and peaked near 13:00, which was mainly attributed to the increased release of isoprene from plants and enhanced photolysis at noon. The HCHO VCDs observed by MAX-DOAS and OMI have a good correlation coefficient (R) of 0.78, and the contributions from primary and secondary HCHO sources were distinguished by the multi-linear regression model. The anthropogenic emissions showed unobvious seasonal variations, and the primary HCHO was relatively stable in Shenyang. Secondary HCHO contributed 82.62%, 83.90%, 78.90%, and 41.53% to the total measured ambient HCHO during the winter, spring, summer, and autumn, respectively. We also found a good correlation (R = 0.78) between enhanced vegetation index (EVI) and HCHO VCDs, indicating that the oxidation of biogenic volatile organic compounds (BVOCs) was the main source of HCHO. The ratio of secondary HCHO to nitrogen dioxide (NO2) was used as the tracer to analyze O3-NOx-VOC sensitivities. We found that the VOC-limited, VOC-NOx-limited, and NOx-limited regimes made up 93.67%, 6.23%, 0.11% of the overall measurements, respectively. In addition, summertime ozone (O3) sensitivity changed from VOC-limited in the morning to VOC-NOx-limited in the afternoon. Therefore, this study offers information on HCHO sources and corresponding O3 production sensitivities to support strategic management decisions.

Pyrene-Based Fluorescent Porous Organic Polymers for Recognition and Detection of Pesticides.

Eating vegetables with pesticide residues over a long period of time causes serious adverse effects on the human body, such as acute poisoning, chronic poisoning, and endocrine system interference. To achieve the goal of a healthy society, it is an urgent issue to find a simple and effective method to detect organic pesticides. In this work, two fluorescent porous organic polymers, LNU-45 and LNU-47 (abbreviation for Liaoning University), were prepared using π-conjugated dibromopyrene monomer and boronic acid compounds as building units through a Suzuki coupling reaction. Due to the large π-electron delocalization effect, the resulting polymers revealed enhanced fluorescence performance. Significantly, in sharp contrast with the planar π-conjugated polymer framework (LNU-47), the distorted conjugated structure (LNU-45) shows a higher specific surface area and provides a broad interface for analyte interaction, which is helpful to achieve rapid response and detection sensitivity. LNU-45 exhibits strong fluorescence emission at 469 nm after excitation at 365 nm in THF solution, providing strong evidence for its suitability as a luminescent chemosensor for organic pesticides. The fluorescence quenching coefficients of LNU-45 for trifluralin and dicloran were 5710 and 12,000 (LNU-47 sample by ca. 1.98 and 3.38 times), respectively. Therefore, LNU-45 serves as an effective "real-time" sensor for the detection of trifluralin and dicloran with high sensitivity and selectivity.