An integrated approach to prioritizing ecological restoration of abandoned mine lands based on cost-benefit analysis.

How to increase the usable land area by adhering to environmentally friendly ecological restoration of mines with limited funds is a challenge that many cities are currently facing. Cost-benefit analysis (CBA) can provide efficient and effective restoration decisions for abandoned mine land (AML) ecological restoration with limited financial resources. Thus, this study proposes an integrated approach for coupling ecological benefits and restoration costs, including hotspots/coldspots analysis based on five ecosystem services (ESs), landscape connectivity analysis based on graph theory model, hidden costs, and project implementation costs to prioritize AML restoration. The study was conducted on 54 abandoned mine lands (AMLs) in Chaoyang city, the ecological security barrier of China's northern sand prevention belt (NSPB). The comprehensive analysis prioritized the restoration of AMLs into four levels, of which 9 mines were in priority I, where restoration was recommended as a priority, and 22 mines were in priority II, where restoration could be carried out within the affordability of funds. In addition, our model indicates areas with high ecological benefits, in which the ecological source area (7423.66 km2) and the ecosystem service hotspots area (2028.44 km2) are mostly distributed in the southwestern part of Chaoyang city, the two mountain ranges of Songling mountain and Nuruerhu mountain. This study provides scientific spatial guidance to ensure that the AMLs realizes effective restoration and management.

Effects of constructing farmland with large amounts of iron tailings as soil reconstruction materials on soil properties and crop growth.

With continuous population growth and farmland decrease, the food security is seriously threatened. Farmland reclamation has been used as a means of raising the agricultural productivity and improving the ecological environment. However, the lack of reclaimed soil represents a serious problem. To verify the feasibility and effect of using large amounts of iron tailings to construct farmland, ten treatments (T1-T10) were designed to represent different soil profiles of regional normal farmland and constructed profiles using iron tailings. All treatments involving an iron tailings layer below topsoil exhibited higher soil water contents. The field capacity under T3 (20-cm iron tailings layer below cinnamon soil (b)) was 19.20% higher than that under T7 (20-cm red clay layer below cinnamon soil (b)), and the field capacity under T5 (20-cm iron tailings layer below cinnamon soil (a)) was 2.26% higher than that under T9 (20-cm red clay layer below cinnamon soil (a)). The soil water contents under T3 and T5 were almost the same as those under T7 and T9, respectively. The water-holding capacity of the 30-cm iron tailings layer (T6) was better than that of the 20-cm iron tailings layer (T2). Additionally, none of the treatments caused salt injury to maize. The maize height and stem thickness under the treatments employing iron tailings layers below topsoil were significantly greater than those in normal farmland; the maize height and stem thickness under T3 were 136.82% and 32.02% greater, respectively, than those under T7, and the values under T5 were 9.13% and 9.56% greater, respectively, than those under T9. The maize yields matched or even surpassed those in normal farmland, namely, the maize yield under T5 was equal to that under T9, and the maize yield under T3 was 12.69% higher than that under T7. In general, the application of an iron tailings layer below topsoil to construct farmland is a feasible and environmentally friendly way to realize sustainable farmland utilization and is beneficial to soil quality and crop yield improvement. Collectively, these results provide insight into the efficient utilization of iron tailings and environmental protection.

Are Iron Tailings Suitable for Constructing the Soil Profile Configuration of Reclaimed Farmland? A Soil Quality Evaluation Based on Chronosequences.

Iron tailings used as soil substitute materials to construct reclaimed farmland soil can effectively realize the large-scale resource utilization of iron tailings and reduce environmental risks. It is vital to understand the mechanisms affecting reclaimed soil quality and determine the appropriate pattern for reclamation with iron tailings. Thus, a soil quality index (SQI) was developed to evaluate the soil quality of reclaimed farmland with iron tailings in a semi-arid region. Soil samples were collected from two reclamation measures (20 cm subsoil + 20 cm iron tailings + 30 cm topsoil and 20 cm subsoil + 20 cm iron tailings + 50 cm topsoil) with reclamation years of 3 (R3), 5 (R5), and 10 (R10) at three soil depths (0-10, 10-20, and 20-30 cm) to measure 13 soil physicochemical properties in western Liaoning, China. Adjacent normal farmland (NF) acted as a reference. Results indicated that iron tailings were suitable for constructing the soil profile configuration of reclaimed farmland. SQI of reclaimed soil increased with the reclamation year, but it has not reached the NF level after 3 years, while it was better than NF after 5 years. The nutrient content of reclaimed soil increased with the reclamation year, but it still did not reach the NF level after 10 years. SQI of R10 (with 50 cm topsoil) was also better than NF but slightly lower than R5 (with 30 cm topsoil). For the semi-arid region with sticky soil texture, the topsoil thickness of reclamation was not the thicker the better, and 30 cm topsoil covered on iron tailings in western Liaoning could achieve a better reclamation effect than 50 cm.

Trace removal of benzene vapour using double-walled metal-dipyrazolate frameworks.

In principle, porous physisorbents are attractive candidates for the removal of volatile organic compounds such as benzene by virtue of their low energy for the capture and release of this pollutant. Unfortunately, many physisorbents exhibit weak sorbate-sorbent interactions, resulting in poor selectivity and low uptake when volatile organic compounds are present at trace concentrations. Herein, we report that a family of double-walled metal-dipyrazolate frameworks, BUT-53 to BUT-58, exhibit benzene uptakes at 298 K of 2.47-3.28 mmol g-1 at <10 Pa. Breakthrough experiments revealed that BUT-55, a supramolecular isomer of the metal-organic framework Co(BDP) (H2BDP = 1,4-di(1H-pyrazol-4-yl)benzene), captures trace levels of benzene, producing an air stream with benzene content below acceptable limits. Furthermore, BUT-55 can be regenerated with mild heating. Insight into the performance of BUT-55 comes from the crystal structure of the benzene-loaded phase (C6H6@BUT-55) and density functional theory calculations, which reveal that C-H···X interactions drive the tight binding of benzene. Our results demonstrate that BUT-55 is a recyclable physisorbent that exhibits high affinity and adsorption capacity towards benzene, making it a candidate for environmental remediation of benzene-contaminated gas mixtures.

An improved similarity-based approach to predicting and mapping soil organic carbon and soil total nitrogen in a coastal region of northeastern China.

Soil organic carbon (SOC) and soil total nitrogen (STN) are major soil indicators for soil quality and fertility. Accurate mapping SOC and STN in soils would help both managed and natural soils and ecosystem management. This study developed an improved similarity-based approach (ISA) to predicting and mapping topsoil (0-20 cm soil depth) SOC and STN in a coastal region of northeastern China. Six environmental variables including elevation, slope gradient, topographic wetness index, the mean annual temperature, the mean annual temperature, and normalized difference vegetation index were used as predictors. Soil survey data in 2012 was designed based on the clustering of the study area into six climatic vegetation landscape units. In each landscape unit, 20-25 sampling points were determined at different landform positions considering local climate, soil type, elevation and other environmental factors, and finally 126 sampling points were obtained. Soil sampling from the depth of 0-20 cm were used for model prediction and validation. The ISA model performance was compared with the geographically weighted regression (GWR), regression kriging (RK), boosted regression trees (BRT) considering mean absolute prediction error (MAE), root mean square error (RMSE), coefficient of determination (R 2), and maximum relative difference (RD) indices. We found that the ISA method performed best with the highest R2 and lowest MAE, RMSE compared to GWR, RK, and BRT methods. The ISA method could explain 76% and 83% of the total SOC and STN variability, respectively, 12-40% higher than other models in the study area. Elevation had the largest influence on SOC and STN distribution. We conclude that the developed ISA model is robust and effective in mapping SOC and STN, particularly in the areas with complex vegetation-landscape when limited samples are available. The method needs to be tested for other regions in our future research.

Effects of urban sprawl on arthropod communities in peri-urban farmed landscape in Shenbei New District, Shenyang, Liaoning Province, China.

Peri-urban farmland provides a diversity of ecological services. However, it is experiencing increasing pressures from urban sprawl. While the effects of land use associated with farming on arthropod assemblages has received increasing attention, most of this research has been conducted by comparing conventional and organic cropping systems. The present study identifies the effects of urban sprawl and the role of non-cropped habitat in defining arthropod diversity in peri-urban farmed landscapes. Multi-scale arthropod data from 30 sampling plots were used with linear-mixed models to elucidate the effects of distance from urban areas (0-13 km; 13-25 km and >25 km, zones I, II, and III, respectively) on arthropods. Results showed that urban sprawl, disturbed farm landscapes, and disturbance in non-cropped habitats had negative effects on arthropods, the latter requiring arthropods to re-establish annually from surrounding landscapes via dispersal. While arthropod species richness showed no obvious changes, arthropod abundance was lowest in zone II. Generally, patch density (PD), Shannon diversity index (SHDI), and aggregate index (AI) of non-cropped habitat were major drivers of changes in arthropod populations. This study contributes to identifying the effects of urban sprawl on arthropod diversity and documenting the multiple functions of farm landscapes in peri-urban regions.

[Cooperative relations between non-cropped habitats and soil animals in suburban farmland Landscape: A case in Shenbei New District in Shenyang, China].

Non-cropped habitat in farm landscape plays a significant role in biodiversity, the functions of arable land and crop yields. This study focused on Shenbei New District in Shenyang City of Liaoning Province in Northeast China, which was a typical area with contradiction between biodiversity conservation and the high demand of agricultural production in the process of urbanization. Information entropy model, hand-picking and Baermann method were used for survey and identification of arthropods and nematodes in soils in urban suburban (US), urban fringe area (UFA) and rural area ( RA). The cooperative relations between the number of soil animals and types, structure as well as the total amount of non-cropped habitat were investigated in these three types of areas using linear regression. Our results showed that the area of single patch in non-cropped habitat was smaller than one hectare in Shenbei New District, and the types and the proportion of non-cropped habitat patches were increasing along with the increase of their distance to the urban center. But the proportion of non-cropped habitats areas appeared under an inverted U-type change. The proportion of non-cropped habitat patches was from 8.6% to 27.8%. The individual number of soil animals showed the U-type trend, while their species number changed irregularly. The individual number of soil animals increased with the increase of the proportion of non-cropped habitat patches in RA and US. There was no obvious correlation between the individual number of soil animal and the proportion of non-cropped habitat patches in UFA. The individual number of soil animals decreased with the increase of the proportion of non-cropped habitats areas. There was no cooperative relation in the proportion of non-cropped habitats and the number of soil animal species.