a b s t r a c tThe proportion of rock fragments in soil affects water availability and therefore the characteristics of plants. The objective of this study was to evaluate the effect of rock-fragment content on plant water consumption, biomass, growth and water-use efficiency (WUE) under different water conditions. Four gravimetric treatments of rock-fragment contents (0, 10, 30 and 50%) and four treatments of water content were tested in sandy loamy soils. The water contents of the rock-free soil were 15-19% (80-100% of field capacity), 11-15% (60-80% of field capacity), 9-11% (47-60% of field capacity) and 6-9% (32-47% of field capacity). Transpiration, plant height, basal stem diameter and biomass of korshinsk peashrubs in the treatments were measured and compared. Plants grown in the soil with rock fragments transpired less, especially under well-watered conditions. The mean daily transpiration of plants in the soils with 30 and 50% rock-fragment contents was 18% (P = 0.021) and 34% (P = 0.001) lower, respectively, in 2014, and 25% (P = 0.008) and 31% (P = 0.002) lower, respectively, in 2015 relative to the soil without rock fragments and was not lower in the soil with 10% rock fragments. Plant height, basal stem diameter and biomass did not differ significantly between rock-fragment contents of 0 and 30% but were lower at 50%. WUE, the ratio between total transpiration and biomass, was highest at 30% and then decreased at 50%. Increasing plant water stress could thus improve WUE. The rock fragments in the soil had significant effects on plant water consumption, biomass, growth and WUE. Optimizing the rock-fragment content is necessary when the relationships between plants and water in stony ecosystems are evaluated.

Roadside soils are regarded as a reservoir for heavy metal pollution, which potentially leads to ecosystem deterioration as well as serious hazard to human health. A comprehensive investigation was conducted for the levels, relationship with soil properties, and potential sources of heavy metals (Hg, Cu, Zn, Pb, Cd, and Cr) in roadside soils in six cities (Changzhi, Jincheng, Yuncheng, Linfen, Xinzhou, Datong) of Shanxi Province; and the corresponding ecological risk and human health risk associated with the concentrations of heavy metals were addressed. Heavy metal concentrations of 112 roadside soil samples in the surveyed cities were, in decreasing order, Zn, Cu, Cr, Pb, Cd, and Hg, which were higher than corresponding background values. The highest concentrations were in Changzhi. The results of Pearson correlation analysis demonstrated that positive correlations in varying degrees existed between soil properties such as electrical conductivity, total nitrogen, total phosphorus, and total organic carbon with specific heavy metals and that negative correlations were observed for clay and electrical conductivity. Anthropogenic sources related to traffic emissions and industrialization were the main sources of heavy metals in roadside soils according to principal component analysis. The ecological risk assessments were achieved by pollution index and potential risk index, indicating that contamination with Hg was the most serious, which posed the highest risk to the ecosystems in the surveyed cities; and the ecological risk in Changzhi ranked at the top compared with other cities. For the human health risk assessment, the results demonstrated that the noncarcinogenic and carcinogenic risks were in the acceptable range in the surveyed cities. However, there was a higher health risk from heavy metal exposure for children than adults, and the main exposure pathway was soil ingestion. In addition, Changzhi was the city with the highest noncarcinogenic and carcinogenic risks, and the main human health risks were posed by Cr contamination in roadside soil, which was different from the results of ecological risks. Both results of ecological and health risk assessment demonstrated that the higher risk exhibited in southern and southeastern cities than northern cities in Shanxi Province.

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This study was aim to reveal the characteristics of nutrients and heavy metals associated with ecological risks in the sediments of Fenhe River, Taiyuan Section. The concentrations of nutrients (TN, TP, TOM) and heavy metals (As, Cu, Zn, Pb, Cr, Ni, Hg, Cd) were investigated. Spatial distribution, correlation analysis and source identification were facilitated to indicate nutrients and heavy metal pollution's characteristics. Evaluations of heavy metals’ contamination degree were achieved by comprehensive ecological risk indexes including Igeo, Iin, Cf, PLI and RI. The results showed that nutrients were accumulated in the middle part and were mainly from embryophyte, zooplankton and phytoplankton or algae based on C/N values. Large spatial variabilities existed in heavy metals distribution patterns and source identification of heavy metals were natural sources and anthropogenic activities based on PCA model. Results of different ecological risk indexes showed that pollution associated with Hg was rated as moderate ecological risk which was the significant contamination, higher ecological risks mainly existed in the middle part.