Land use multifunctionality (LUMF) is a pragmatic means of resolving land use conflicts and realising regional sustainability and has critical importance in land system science. In this study, we constructed LUMF classifications from a sustainable perspective and quantified and analysed the deliveries of land use functions (LUFs) in the coastal area of Jiangsu Province, China. On this basis, the “bundle” concept was innovatively introduced into the LUMF research framework to analyse the spatiotemporal effects of trade-offs and synergies among multiple LUFs. The results showed that high-value LUF geographic units tended to cluster in human-dominated landscapes. During the study period (2000–2018), the average provision of regional multifunction increased slightly, while the subfunctions changed in different trends. Four LUF bundles (agricultural zone, mosaic cropland–rural housing zone, coastal natural and seminatural landscape zone, urban development zone) were identified, each having different dominant LUFs and landscape configurations. In each LUF bundle, the most common trade-offs were observed in the environmental and economic functions. The space incompatibilities caused by land development demand in different subregions created a trade-off and synergy among multiple functions. Moreover, LUF relations were not static over time, owing to the effects of urbanisation, coastal reclamation activities, and agriculture protection policies. Based on the above results, this research proposes land use optimisations for different multifunctional areas.

Coastal tidelands are important ecological habitat resources and valuable resources for agricultural land reclamation. Enrichment of potentially harmful elements (PHEs) in soil caused by anthropogenic activity is an important factor implicated in the ecological deterioration of soil in China. A total of 54 soil sample sites were selected from a 30-year reclaimed tideland and an adjoining coastal wetland. Descriptive and multivariate statistical analyses were performed to describe the enrichment, source, health risk status of eight PHEs (As, Co, Cr, Cu, Mn, Ni, Pb, and Zn) after long-term reclamation. Results indicated that after 30 years of reclamation, most soil PHEs are slightly enriched, whereas no serious threat of environmental pollution was observed. In the reclamation area, the enrichment of PHEs in the aquaculture land, industrial land, and cropland was relatively high compared with other land use types, such as tideland and halophyte land. The source analysis divided the PHEs into five categories: (1) Cu; (2) Co and Mn; (3) Cr; (4) As and Pb; (5) Zn and Ni. Cu was completely derived from natural parent materials and other elements were governed by both weathering of parent rock and human activities, including agricultural activities, industrial production, and transportation emissions. The health risk assessment showed that the soil PHEs potentially had no non-carcinogenic risk to the public, but there was an acceptable probability to have cancer due to Cr and As. Meanwhile, children are more susceptible to harm from the PHEs in soil than adults. According to the economic and social development situation in the coastal region, it is necessary to pay attention to the environmental threats of PHEs enrichment.

In recent years, heavy metal contamination in agricultural soils in Jiangsu Province has attracted more and more attention. However, most studies have been characterized by their small scale, few samples, and short-term monitoring. The overall status and temporal accumulation characteristics of heavy metals have not been fully reflected. Therefore, this paper attempted to provide a comprehensive analysis of the current status of heavy metals and provide accurate information for soil pollution management in Jiangsu Province. This paper collected available data in the literature (1993–2021) on heavy metal-polluted agricultural soils in Jiangsu Province. Based on these available data, the weighted mean values of each heavy metal were obtained by meta-analysis. Then, the ecological risks in soils were evaluated and spatiotemporal variations in the accumulation of heavy metals were explored. In addition, suggestions for pollution prevention and control were made by predicting future heavy metal concentrations. The results showed that Cd and Hg were the major polluting elements in Jiangsu Province. The spatial enrichment of heavy metals followed the pattern of southern > northern > central. Heavy metal concentrations in Nanjing, Suzhou, and Xuzhou should be paid special attention. The ecological risk level of heavy metals in agricultural soils in Jiangsu Province was high, predominantly contributed by Hg and Cd. The accumulation of most heavy metals gradually decreased after 2010, while the opposite happened with Cd. Jiangsu Province should continue to take active pollution control measures in order to maintain the decreasing trend of heavy metal concentrations in farmland soils. This study could provide a scientific and theoretical basis for the development of pollution control and soil remediation measures.

This study addresses the critical issue of heavy metal contamination (Ni, Cu, As, Cd, Pb) in rice cultivation, with particular focus on silicon-deficient paddy soils in the Taihu Lake Plain, where Si_NaAc is 87.97 mg kg^-1. While silicon (Si) supplementation has demonstrated efficacy in mitigating heavy metal stress in plants, its effectiveness in Si-deficient soil-rice systems remains insufficiently characterized, particularly at the field scale. Our investigation of four typical crop rotation systems revealed significant contamination risks from As and Cd, with plant-available silicon (PaSi) predominantly influencing the active fractions of these metals. Key factors governing heavy metal accumulation in brown rice included soil metal content (HMs_Soil), soil PaSi (PaSi_Soil), and plant Si (Si_Plant), exhibiting strong predictive power for As (R²=0.69), Cd (R²=0.51), and Cu (R²=0.59) accumulation. Structural equation modeling identified dual mechanisms of Si-mediated metal regulation: direct modulation in the Husk-Brown Rice transfer pathway and indirect suppression through Root-Straw translocation. These findings elucidate Si's pivotal role in impeding heavy metal transfer from soil to edible grains, highlighting the potential of strategic Si fertilization as an effective agronomic intervention for minimizing dietary heavy metal exposure and enhancing food safety in contaminated rice production systems.

Ecologically fragile hilly areas are key regions for safeguarding national ecological security and advancing ecological civilization construction. Accurate assessment of ecosystem service value (ESV) and future scenario simulations in these regions is crucial for improving regional land use and attaining sustainable development. Based on high-resolution remote sensing data of the Longji Mountain area in Guangxi, China, from 2013 to 2023, this study systematically assesses the spatiotemporal evolution characteristics of ESV using the equivalent factor method with localized corrections. This study adopts spatial autocorrelation analysis, geographic modeling, and scenario simulation. It predicts the spatial patterns of ESV for 2028 and 2033 under three scenarios: ecological protection, natural development, and tourism development. The results reveal that: (1) from 2013 to 2023, the total ESV in the Longji Mountain area showed an overall fluctuating trend. It increased first, then declined and recovered slightly, with an average annual growth rate of −0.15%. Spatially, the ESV presented a heterogeneous pattern, characterized by “high-value agglomeration in forest land, medium-value transition in terraced fields, and low-value interpolation in constructed areas”, with distinct clustering features; (2) regional ecological functions are mainly dominated by regulating and supporting services. Climate regulation contributes the highest value. Water supply is the only service with negative value, indicating a persistent water ecological deficit that remains unaddressed; (3) scenario simulations reveal that the total ESV is highest and spatial connectivity is strongest under the ecological protection scenario. Furthermore, a consistent trend is observed across all three scenarios: high-value ESV areas tend to become dominant, while spatial connectivity shows progressive enhancement. The human–land system coupling framework for the ecologically fragile hilly region suggests that ecologically oriented decision-making is the core pathway to sustainably improve ecosystem services and realize regional sustainable development. This study offers scientific support for regional ecological conservation and sustainable advancement.