Identifying urban built-up area boundaries is critical to urban data statistics, size measurement, and spatial control. However, previous methods of extracting urban built-up area boundaries based on low-resolution remote-sensing data are frequently constrained by data accuracy. In this paper, a new method for extracting urban built-up area boundaries using high-resolution remote sensing images based on scale effects is proposed. Firstly, we generate a number of different levels of edge-multiplied hexagonal vector grids. Secondly, the impervious surface densities are calculated based on the hexagonal vector grids with the longest edge. Then, the hexagonal grids with higher impervious surface densities are extracted as the built-up area of the first level. Thirdly, we gradually reduce the spatial scale of the hexagonal vector grid and repeat the extraction process based on the extracted built-up area in the previous step. Eventually, we obtain the urban built-up area boundary at the smallest scale. Plausibility checks indicate that the suggested method not only guarantees the spatial continuity of the resultant urban built-up area boundary, but also highlights the prevailing orientation of urban expansion. The extracted Beijing built-up area boundary can serve as a reference in decision-making for space planning and land-use control.

The increasing rate of sandy desertification lands in Zoige County has been regarded as an imminent threat recently. There is an urgent need to monitor the status, trend of desertification. This study used a land cover classification process of integrating Support Vector Machine classifier (SVM) with threshold method to extract the sandy lands based on Landsat data collected from 1990 to 2017. Furthermore, we quantitatively analyzed the evolution trend of the grassland desertification and verified the effect of desertification control using the unmanned aerial vehicle (UAV) image acquired in 2019. Three conclusions are drawn from the study. First, the sandy land is mainly distributed along the directions of prevailing wind at the edges of mountains in the southwest. Second, the area of sandy lands increased from 29.75 km2 in 1990 to 46.87 km2 in 2005 and then decreased to 22.58 km2 in 2013. While during 2014-2017, the area increased to 33.61 km2. Third, the increasing of sandy lands is closely related to the terrain and water resources distribution. Ecological restoration policies, especially the ecological recovery projects implemented are the main driving factor of desertification reversion. The results of this study can provide effective data and decision support for combating desertification.

Water resources are a key factor for regional sustainable development. However, the published water resource data in China is based on a large geographical scale, such as watershed units, and the data cannot reflect subtle differences in water resource distribution. The paper aimed to distribute water resources of the third-order basin of China into grid-cells of 1 km × 1 km. First, we used Moran’s I index to analyze the spatial pattern of water resources of the third-order basin. Second, we constructed a spatial autocorrelation model between water resources of third-order basins and the associated factors. Third, we applied the model to simulate the gridded water resource distribution and evaluated the simulation accuracy. The results indicated that significant spatial autocorrelation existed among the water resources of third-order basins. Northern China was the low-value clustering area of water resources and Southeast China was the high-value clustering area of water resources. Slope and precipitation were the main factors that influenced the amount of water resources. The simulating accuracy of water resource distribution was very high, apart from some extremely arid regions (Gurbantunggut Desert, Kumtag Desert, and Hexi Desert). On the whole, the gridded water resource distribution map was valid and was helpful for regional water resource management.

Tetracycline (TC) contamination has become hot research topic, but little attention has been paid to its ecotoxicological monitoring. The primary objective of this study is to investigate the impact of TC on human normal liver cells (HL-7702) and find indicators for monitoring their ecotoxicity. The cytotoxicity of TC, at concentrations ranging from 0 to 1000 μg L⁻¹, was assessed on HL-7702 cells. The results showed that TC significantly inhibited the cell viability at a high concentration (1000 μg L⁻¹). The TC at exposure levels ≥ 50–100 μg L⁻¹ significantly increased the levels of extracellular catalase (CAT), malondialdehyde (MDA), alanine transaminase (ALT), and aspartate transaminase (AST), and a significantly positive correlation between the TC concentrations and the values of the above parameters was observed. Swelling of the mitochondrial cristae (MC) and rough endoplasmic reticulum (RER) and the loss of ribosomes in HL-7702 cells, were observed at high TC levels. There was a positive correlation between soil TC concentration and ALT activities. The above results suggest that TC is cytotoxic to HL-7702 cells and that extracellular ALT activities can be used as a sensitive bioindicator for monitoring soil TC contamination. We, therefore, propose that the HL-7702 cell line can be a novel tool for early antibiotics toxicity monitoring.

The excessive exploitation of mineral resources adversely affects the regional ecological environment. Therefore, the timely assessment of changes in ecological environmental quality is crucial for the sustainable development and planning of coal resource-based cities. This study aims to explore an evaluation method for monitoring ecological environmental quality in coal resource-based cities. Specifically, we first built a comprehensive remote sensing ecological index (RSEI) based on four ecological indicators extracted from Landsat images in Zoucheng City. Subsequently, we combined the land use/land cover (LULC) data yielded from Landsat satellite images using the random forest algorithm with the time series RSEI data to analyze the spatiotemporal change characteristics of the ecological environment in Zoucheng City. The findings are summarized as follows: The mean values of the RSEI for the four periods (2006, 2011, 2016, and 2022) in Zoucheng City were 0.4501, 0.4562, 0.6417, and 0.5822, respectively. The mean RSEI increased by 40.66% from 2011 to 2016, demonstrating a significant improvement in the ecological environment. However, the mean RSEI decreased by 9.27% from 2016 to 2022 in Zoucheng City, indicating a decline in ecological environmental quality. This study can serve as a reference for understanding the ecological environment of other coal resourcebased cities.

Participatory systems have been widely adopted in citizen science, environmental monitoring, urban governance, and public collaborative decision-making. Traditional usability theory focuses on individual task performance and user satisfaction, which cannot adequately explain or support voluntary collective participation, participant recruitment, and long-term engagement. To address this gap, this study introduces the new concept participatability and develops a dedicated assessment framework for participatory systems. Based on a systematic review of usability criteria and the unique socio-technical features of participatory systems, this study defines five core evaluation dimensions: salience, adaptability, congruence, privacy safeguarding, and interactive engagement. Two complementary case studies, including a mature citizen science platform and a newly developed campus participatory planning system, are conducted to validate the framework. Empirical results show that participatability is significantly associated with user acceptance, participation willingness, data contribution quality, and long-term system sustainability. Users in collective participation scenarios prioritize participatability over conventional usability. This study provides a theoretically sound and practically applicable framework for understanding, evaluating, and designing participatory systems. The proposed concept and criteria address critical limitations of existing theories and offer practical guidance for system developers and practitioners to improve participation effectiveness.