Wen-Yan He

Urban shallow lakes are sentinel ecosystems whose stability is increasingly threatened by acute, sediment-laden storm floods. While chronic nutrient loading has been extensively studied, rapid risk assessment tools for short-pulse disturbances are still missing. Our aim was to develop a resilience-based, process-linked framework that couples depth-averaged hydrodynamics, advection-diffusion sediment transport and light-driven macrophyte habitat suitability to quantify hour-scale ecological risk and week-scale recovery. The ecological risk model integrates a depth-averaged hydrodynamic module, an advection–diffusion sediment transport routine, and species-specific light-suitability functions. We tested the model against field observations from Xinglong Lake (Chengdu, China) under 5-year and 50-year design storms. Ecological risk exhibited a clear west-to-east gradient. Under the 5-year storm, high-risk cells (complete inhibition) formed a narrow band at the eastern inlet and overlapped 82% with the SSC > 0.1 kg m⁻³ plume at 6 h; several western macrophyte beds returned to “suitable” status by 72 h. In contrast, the 50-year event pushed R > 0.9 over all macrophyte beds, with slow recovery after 192 h. Lake-scale risk peaked above 80% within 24 h for both return periods, but residual risk remained elevated in the 50-year scenario owing to the larger spatial footprint. The study provides a transferable early-warning tool for lake managers to decide when to trigger low-cost interventions and species-specific resilience rankings to guide targeted vegetation protection in shallow urban lakes worldwide.

Vanadium (V) pollution in soil has been widely noted, while knowledge about the effect of soil colloid on migration of V is scarce. Batch adsorption-desorption and transportation of the colloid-adsorbed V in columns packed with quartz sand under various environment conditions were carried out to explore the retention and transportation of V by colloidal kaolinite. Batch adsorption-desorption studies show that the adsorption of V by the colloidal kaolinite was mainly specific adsorption and redox played a limited role in the adsorption process. The maximum adsorption capacity of the colloidal kaolinite was 712.4 mg g⁻¹, and about 5.9–8.7% of the adsorbed V could be desorbed. Both the adsorption-desorption and migration of V with colloidal kaolinite were highly ambient condition dependent. The column studies show that V was highly mobile in the saturated porous media. An easier transfer of V with an increase in pH, IS, and velocity of flow was noted. However, the increase of IS lead to the blockage of the colloidal kaolinite transportation. The recovery rate of the colloidal kaolinite at pH 7 and 9 was 2.0 and 2.1 times that at pH 5, respectively. The migration of colloidal-adsorbed V in sand column preceded that of V ion, but more colloidal-bound V than V ion remained in the column. Lack of consideration of the combination and co-transportation of V and colloidal kaolinite will lead to an overestimation of the risk of V to deeper soil profiles and groundwater. Graphical abstract

Vanadium (V) is a toxic metal, which dominantly exists as V⁵⁺ in an aquatic environment. Rice straw, which is an abundant agricultural by-product throughout China was used to treat V⁵⁺ containing wastewater as an adsorbent after phosphoric acid treatment. The effects of initial V⁵⁺ concentration, solution temperature, pH and reaction time on V removal by phosphoric acid modified rice straw (AcM) were systematically assessed. A pH range of 2.0–3.0 was favorable for V removal and the adsorption capacity of V by AcM increased with elevated solution temperature. The maximum adsorption capacity for water containing 500 mg V⁵⁺ L⁻¹ was 24.70 mg V g⁻¹dry matter under the optimum operation (3.33 g L⁻¹ AcM, pH = 2.0, 50 °C, and 200 rpm for 4 h). Adsorption experiment data fitted well to pseudo-second-order kinetic and Langmuir adsorption isotherm models. In the presence of coexisting ions, Na⁺, Cu²⁺, NO₃⁻ and Cl⁻ had no significant (P > 0.05) effect on V removal. These results indicated that AcM derived from agricultural waste was effective to remove V⁵⁺ from aqueous solution.

High concentration of fluorine (F) in agricultural soils has got significant attention considering its impacts on human health, but little information was available about F distribution in farmland soil profiles around phosphorous chemical industry factories. In present study, farmland soil profiles and relevant medium samples were collected from farmlands around a main phosphorous chemical base in southwest China. At 0–100-cm profiles, concentrations of soil total F (Ft, 400.9–1612.0 mg kg⁻¹) and water soluble F (Fw, 3.4–26.0 mg kg⁻¹) decreased with profile depth in industrial areas. Industrial activities enhanced F concentration in soil mainly at 0–40-cm profiles. No disparity for both Ft and Fw distributions in paddy-dry land rotation field and dry land indicates short-term land utilization could not affect the F distribution in soil profiles. Correlation analysis showed soil organic matter and wind direction were important factors influencing the distribution of F in soil profiles. The shutdown of factory and government control of industrial emissions effectively decreased the ambient air F (Fa) concentrations in industrial areas. In where Fa and dustfall F concentrations were high, high soil Ft, Fw, and crop edible part F concentrations were found.

Two typical red soils were sequentially cultivated with celery (Apium graveolens L.) and Chinese cabbage (Brassica chinensis L.) in a greenhouse to determine the effect of lead (Pb) on plant availability of phosphorus (P) and potassium (K) in the soils. The concentrations of available P as estimated by the 0.05 mol L⁻¹ HCl-0.025 mol L⁻¹ (1/2 H₂SO₄) extraction and available K estimated by the NH₄OAc extraction method in the crop-free soils were not affected by Pb treatment. Plant P concentrations in the above-ground part of celery and Chinese cabbage exposed to Pb were either lower or showed no significant difference to the control.

Vanadium (V) is widely used industrially, and plays an important role in the biosphere. Sensitive and reliable analytical methods to determine V in various kinds of samples are of extensive interest. Mainly two spectrophotometric methods developed in the last decade are discussed, namely complex formation methods and catalytic methods. The former is based on either oxidation or reduction of V leading to coloured complexes with proper reagents; they are applicable to determination of V at the mg L⁻¹ level. Catalytic methods are based on the ability of V to catalyse the oxidation of various organic dyes and are applicable to determination at the μg L⁻¹ level. Both methods are used for determination of V in environmental and biological samples.