The aim of this study is to analyze the toxicity of the sediments accumulated in the vicinity of hydropower plants (HPs) on the Ślęza and Bystrzyca rivers in Poland and the possibility of using these sediments for soil enrichment purposes. Thus far, there has been little comprehensive research related to the analysis of the impact of HPs on the properties of sediments. The analysis of the granulometric composition, physicochemical properties, heavy metals (HMs) content in sediments, and the growth of three plant species was carried out, including toxicity (HMs) and germination indices (plants). Most parameters were significant between the points upstream and downstream of the analyzed HPs. It has been shown that the most dangerous toxic factor is the high concentrations of Cu, Ni, and Zn in the sediments upstream of the HP on the Ślęza. In most cases, the HMs content was observed to decrease downstream of the HPs (e.g., Cu in Ślęza River: average of 13.44‐times), a result of changes in the particle size composition and accumulation of sediments at the site of the dam wall. Typically, the sediments tested stimulated growth in the plant species studied in comparison with the control groups (e.g., germination index for Sorghum saccharatum, Bystrzyca: 273.5% downstream of HPs). The C:N ratio increased downstream of the HPs by an average of 37.11% for the Ślęza River and 10.88% for the Bystrzyca River. The requirements for composting material were not met; however, the sediment could be used to enrich soils with an excessively wide C:N ratio.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/ldr.4210

Toxicity studies on sediments near hydropower plants on the Ślęza and Bystrzyca rivers, Poland, to establish their potential for use for soil enrichment

Ecological toxicity of Cd, Pb, Zn, Hg and regulation mechanism in Solanum nigrum L.

To assess heavy metal pollution and human health risks, 481 samples from 59 soil sampling points were collected from different soil layers at an underground depth of 10 m in a tin ore area in Yunnan, China. The soil around the mining area was polluted by heavy metals to varying degrees, and high concentrations of Cd, Pb, As, and Cu posed serious ecological risks. Owing to leaching and infiltration of heavy metals, the lower soil samples were also severely polluted as much as the surface soil. The heavy metals mainly accumulated in the soil layers at depths of 0 − 6 m. Meanwhile, the concentration decreased with an increase in soil depth, after which it stabilised. Residents of the area are currently at danger of being diagnosed with non-carcinogenic disorders, while exhibiting a significantly elevated risk of carcinogenicity; children are at a higher risk than adults. In addition, As was the primary threatening factor to the health of residents. 

Vertical distribution and health risk assessment of heavy metals in soils around tin ore areas in Yunnan, China

This study aimed to assess the impact of a hydropower plant (HP) on the Bystrzyca River (left tributary of the Odra River, Poland) on selected parameters of the bottom sediment within this hydrotechnical structure. The following parameters were examined as part of the analyses: particle size distribution, pH, electrical conductivity (EC), and concentrations of Cd, Cu, Cr, Ni, Pb and Zn. Field studies were carried out upstream and downstream of the HP and at reference points. In addition, the risk of heavy metals in aquatic organisms was assessed using an ecotoxicological method. Based on the Wilcoxon signed-rank test, it was found that the HP influenced all of the parameters tested, except pH. Comparing the points closest to and downstream of the HP, an increase in the average grain diameter of D50 (on average by 750%), and a decrease in the concentrations of most heavy metals: Ni (271%), Zn (216%), Cu (163%), Cr (83.0%), and Cd (74.2%), was observed. The ecotoxicological classification of heavy metal concentrations in sediments indicates, in most cases, little or no impact on aquatic organisms; the values of Ni and Zn in some samples upstream of the HP are exceptions, where remediation using synthetic zeolites, metal accumulation plants, or by electrokinetic methods, is necessary. Fine-grained fractions dominate the clays and sandy clays upstream of the hydropower plants, while sands, sandy clay loams, or sandy clays are dominated downstream. Frequent occurrence of skeletal fractions (>2.0 mm) was observed downstream, i.e., an average of 23.30% in each sample compared to 1.82% upstream of the HP, which is mainly due to greater anthropogenic pressure, especially tourism. The dominance of fine-grained fractions upstream of the HPs favors the accumulation of metals due to the high sorption capacity of these fractions. When comparing the analyzed groups of points, the average pH values are arranged in the following sequence: upstream HP (U) > downstream HP (D) > reference points (R), while EC has opposite values (i.e., U < D < R). This study may support sustainable sediment management and may allow for the development of recommendations related to the rational management of HPs.

https://www.frontiersin.org/articles/10.3389/fenvs.2022.795922/pdf

Assessing the Impact of a Hydropower Plant on Changes in the Properties of the Sediment of the Bystrzyca River in Poland

The restoration of forest ecosystems on metal-contaminated sites can be achieved whilst producing valuable plant biomass. Here, we investigated the metal accumulation and biomass production of young afforestations on contaminated plots by simulating brownfield site conditions. On 16 3-m2 plots, the 15 cm topsoil was experimentally contaminated with Zn/Cu/Pb/Cd = 2854/588/103/9.2 mg kg−1 using smelter filter dust, while 16 uncontaminated plots (Zn/Cu/Pb/Cd = 97/28/37/< 1) were used as controls. Both the calcareous (pH 7.4) and acidic (pH 4.2) subsoils remained uncontaminated. The afforestations consisted of groups of conifers, deciduous trees, and understorey plants. During the four years of cultivation, 2254/86/0.35/10 mg m−2 Zn/Cu/Pb/Cd were extracted from the contaminated soils and transferred to the aboveground parts of the plants (1279/72/0.06/5.5 mg m−2 in the controls). These extractions represented 3/2/3% of the soluble soil Zn/Cu/Cd fractions. The conifers showed 4–8 times lower root-to-shoot translocation of Cu and Zn than the deciduous trees. The contamination did not affect the biomass of the understorey plants and reduced that of the trees by 23% at most. Hence, we conclude that the afforestation of brown field sites with local tree species is an interesting option for their reclamation from an ecological as well as economic perspective.

/pdf/metal-accumulation-and-biomass-production-in-young-258zctey.pdf

Metal Accumulation and Biomass Production in Young Afforestations Established on Soil Contaminated by Heavy Metals

The vertical mobility of heavy metals in the soil profile may affect their bioavailability. In the present study, a field experiment was conducted for 11 years to investigate the vertical mobility ...

https://www.tandfonline.com/doi/pdf/10.1080/26395940.2020.1813053

Rui Zhao

Papers

A field study of vertical mobility and relative bioavailability of Cu and Ni in calcareous soil