Field comparison of the effectiveness of agricultural and nonagricultural organic wastes for aided phytostabilization of a Pb-Zn mine tailings pond in Hunan Province, China

Environmental pollution and human health risk due to tailings storage facilities in China

Tailings storage facilities (TSFs) represent an anthropogenic source of pollution, resulting in potential risks to both environmental integrity and human health. To date, the environmental and human health risks from TSFs in China have been under-researched. This study attempts to address this gap by developing, and geo-statistically analyzing two comprehensive databases. The first database (I) focuses on failed TSFs; we supply the statistics of environmental damages from 143 TSF failure incidents. Notably, approximately 75 % of the failure incidents involved tailings flows released into water bodies, resulting in a significant exacerbation of environmental pollution. To better inform ecological and human health risks, we present another database (II) for 147 non-failed TSFs to investigate the soil heavy metal contamination, considering 8 heavy metals. The findings reveal that (i) Cd, Pb, and Hg are the prominent pollutants across the non-failed TSF sites in China; (ii) lead‑zinc and tungsten mine tailings storage sites exhibit the most severe pollution; (iii) Pb, Cd, and Ni present noteworthy non-carcinogenic risks to human health; (iv) >85 % of TSF sites pose carcinogenic risks associated with arsenic; and (v) health risks resulting from dermal absorption surpass ingestion for the majority of heavy metals, with the exception of Pb, where ingestion presents a more pronounced route of exposure. Our study presents a comprehensive evaluation of environmental and human health risks due to TSFs, highlighting the necessity for risk assessment of >14,000 existing TSFs in China.

Comprehensive assessment of the microbial community structure in a typical lead-zinc mine soil

Understanding the microbial community structure in soil contaminated with heavy metals (HMs) is a precondition to conduct bioremediation in mine soil. Samples were collected from a typical lead-zinc (Pb-Zn) mine to assess the microbial community structure of the HMs concentrated in the soil. The goal was to analyze the bacterial and fungal community structures and their interactions using the 16S rRNA genes and internal transcribed spacer high-throughput sequencing. Analyses at different sampling sites showed that contamination with HMs significantly reduced the bacterial richness and diversity but increased that of the fungi. The predominant bacteria genera of Acidobacteriales, Gaiellales, Anaerolineaceae, Sulfurifustis, and Gemmatimonadaceae, and predominant fungal genera of Sordariomycetes, Talaromyces, and Mortierella were assumed as HM resistant genera in Pb-Zn mining area. The pH effect on the bacterial and fungal communities was opposite to those of Cd, Pb, and Zn. This study offers comprehensive outlooks for bacterial and fungal community structures upon multiple HM stresses in the soil around a typical Pb-Zn mine area.

Implications of spatial heterogeneity of tailing material and time scale of vegetation growth processes for the design of phytostabilisation

Phytostabilisation projects for tailing dams depend on processes occurring at spatial scales of 10⁶ m² and at decadal time scales. Most experiments supporting the design and monitoring of such projects have much smaller spatial and time scales. Usually, they are only designed for one single scale. Here, we report the results of three coupled experiments performed at pot, lysimeter and field plot scales using six sampling periodstimes from 3 to 20 months. The work explicitly accounts for the sampling times when evaluating the effects of amendments on the performance of plants grown in tailing substrates. Two treatments with potentially complementary roles were applied: zeolites to decrease availability of Cd, Cu, Pb and Zn and green fertilizer to increase the availability of nutrients. Zeolites have a positive influence on plant development, especially in the early stages. Analyses of the pooled datasets for all sampling times revealed the possibility of predicting plant physiological variables, such as protein concentrations, pigments and oxidative stress enzyme activities, as a function of the factors extracted by principal component analysis from the metal concentrations in plants, phosphorus concentrations in plants, and sampling times. Two potentially general methodological rules were extracted: account for the spatial geochemical variability of tailings, and cover the broadest possible range of time scales by experiments. The proposed experimental methodology can be of general use for the design of tailing dam remediation technologies with improvements involving the set of measured variables and sampling frequency and by carefully relating the costs to the institutional aspects of tailing dam management.