Can human activities enhance the trade-off intensity of ecosystem services in arid inland river basins? Taking the Taolai River asin as an example

Combining chemical analysis and toxicological methods to access the ecological risk of complex contamination in Daye Lake

As one of the nine primary non-ferrous metal smelting bases in China, Daye Lake basin was polluted due to diverse human activities. But so far the pollution status and related ecological risks of this region have not been detailly investigated. In current study, pollutants including heavy metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in eight sediment samples from Daye Lake were quantified. 18S rRNA gene sequencing was employed to profile the nematode community structure within these sediments. Model organism Caenorhabditis elegans (C. elegans) were further applied for a comprehensive ecological risk assessment of Daye Lake. Notably, Cadmium (Cd) was identified as a key driver of ecological risk, reaching an index of 1287.35. At sample point S4, OCPs particularly p,p'-DDT, displayed an extreme ecological risk with a value of 23.19. Cephalobidae and Mononchida showed strong sensitivity to pollutant levels, reinforcing their suitability as robust bioindicators. The composite pollutants in sampled sediments caused oxidative stress in C. elegans, with gene Vit-2 and Mtl-1 as sensitive biomarkers. By employing the multiple analysis methods, our data can offer valuable contributions to environmental monitoring and health risk assessment for composite polluted areas.

Threshold effect of ecosystem services in response to human activity in China's urban agglomeration: a perspective on quantifying ecological resilience

Ecological resilience reflects the role of human activity intensity (HMI) on regional ecosystem services (ESs), and resilience improvement is crucial for the high-quality development of urban agglomeration areas. However, a theoretical framework for ecological resilience needs to be developed based on ES thresholds under human activities. Based on the threshold index, we used threshold regression model to determine of the nonlinear dominant factors affecting ESs and to identify the priority areas for ecological restoration. The results suggest that (1) CS, HQ, and TES declined, while FP increased. The spatial distribution of each ES showed higher values in the central region and lower values in the surrounding areas. HMI showed a significant upward trend, with expanding high-HMI areas. There is a threshold effect in the relationship between HMI and ESs, leading to variations in their positive, non-monotonic, or non-linear interactions. (2) HMI positively and significantly affects ESs, especially at low threshold levels. The effect of HMI on ESs is negative in counties with higher threshold levels rather than in lower-level grids. (3) The critical area of artificial potential ecological restoration was 712 km2, primarily concentrated around urban; the critical area of natural restoration was 490 km2. Therefore, the threshold in the relationship between HMI and ESs should be given more attention. This study serves as a guide for picking out key regions for territorial ecological restoration.

Identifying and warning against spatial conflicts of land use from an ecological environment perspective: A case study of the Ili River Valley, China

Spatial conflicts of land use (SCLU) arise during land-use change, which causes an imbalance of land-use spatial patterns and negatively affects society, the economy, and ecology. Previous research has focused on identifying and measuring SCLU, with less attention on the negative effects. The incorporation of risk assessment methods to evaluate potential conflict risks has been limited. The current study presents methods for measuring SCLU and assessing potential conflict risks from the ecological environment perspective. The spatial comprehensive conflicts index and potential conflict risk index were used to identify and measure the SCLU and to assess and warn against potential conflict risks, respectively, based on a case study in the Ili River Valley in China. The impacts of terrain restriction and land-use change on the SCLU were explored. Results indicate that (1) the SCLU area in the Ili River Valley decreased by 2,608 km2 from 2010 to 2020, compared to the previous decade, the degree of conflict weakened, and the main body of the SCLU gradually shifted northwest. (2) The potential risk areas cover 20,268 km2 in 2020-2030 and are mainly distributed in the "Khorgas City-Huocheng County-Yining City-Yining County" group of towns, as well as along the Ili-Kunes rivers and in the ecological protection zone in the south of the Ili River Valley, which shows the clustering along the city and distribution along the river in the spatial pattern. (3) Topography had a significant impact on the SCLU, and the main types of land-use change in the severe-conflict zone were the reduction of grassland and the expansion of arable and built-up land. For future conflict mitigation in the Ili River Valley, cautioning against urban sprawl and safeguarding land ecological security is critical. This study systematically investigates and analyzes SCLU across three dimensions: theory, methodology, and application to produce a theoretical and practical framework to identify SCLU and assess potential conflict risks.