Thallium (Tl) is a highly toxic rare element. Severe Tl poisoning can cause neurological brain damage or even death. The present study was designed to investigate contents of Tl and other associated heavy metals in arable soils and twelve common vegetables cultivated around a steel plant in South China, a newly-found initiator of Tl pollution. Potential health risks of these metals to exposed population via consumption of vegetables were examined by calculating hazard quotients (HQ). The soils showed a significant contamination with Tl at a mean concentration of 1.34 mg/kg. The Tl levels in most vegetables (such as leaf lettuce, chard and pak choy) surpassed the maximum permissible level (0.5 mg/kg) according to the environmental quality standards for food in Germany. Vegetables like leaf lettuce, chard, pak choy, romaine lettuce and Indian beans all exhibited bioconcentration factors (BCF) and transfer factors (TF) for Tl higher than 1, indicating a hyperaccumulation of Tl in these plants. Although the elevated Tl levels in the vegetables at present will not immediately pose significant non-carcinogenic health risks to residents, it highlights the necessity of a permanent monitoring of Tl contamination in the steel-making areas.

Given that the biological treatment of antibiotic wastewater can easily induce resistant bacteria, the photocatalytic degradation of antibiotics is considered as a better method for treating antibiotic wastewater. Therefore, the ability to remove Tylosin (TYL) and Tetracycline (TC) in aqueous solution using rare earth element Tb-doped g-C₃N₄ under simulated natural solar radiation was investigated. A series of rare earth Tb³⁺ doped mesoporous g-C₃N₄ were successfully prepared by nitric acid treatment and Tb(NO₃)₃·5H₂O samples showed significantly higher degradation efficiency for TYL and TC than pure g-C₃N₄. Leaching toxicity experiments were carried out on the catalyst using chard seeds and demonstrated negligible toxicity of the leachate from the catalyst. The structure, elemental state, optical properties, morphology, and photogenerated carrier separation of the prepared xTCN catalysts were characterized by XRD, XPS, UV–Vis DRS, TEM, and PL. The results show that Tb doping enhanced the photocatalytic activity of the g-C₃N₄ catalyst by narrowing the band gap while improving the light-trapping ability; The separation and transport rate of photogenerated carriers were significantly increased after Tb doping. Finally, a simple, efficient, and non-polluting Tb-doped carbon nitride photocatalyst is successfully developed in this paper.

Crops, particularly in the Northeast region of Mexico, have to cope with increasing soil salinization due to irrigation. Chloride (Cl⁻) concentration has been strongly related to enhance cadmium (Cd) uptake by plants due to increased solubility in the soil solution. The effect of irrigation with slightly saline water from a local well was evaluated in this work on the accumulation and translocation of Cd in Swiss chard (Beta vulgaris L.) grown in soil historically amended with stabilized sewage sludge under a regime of phosphorus and zinc fertilization. A factorial pot experiment was conducted with two phosphate fertilizer levels (PF, 0 and 80 kg ha⁻¹dry soil, respectively), two Zn levels (0 and 7 kg ha⁻¹dry soil), and two sources of water for irrigation deionized water (DW) and slightly saline well water (WW) from an agricultural site. Additionally, a human risk assessment for Cd ingestion from plants was assessed. Results showed that Cl⁻salinity in the WW effectively mobilized soil Cd and increased its phytoavailability. A higher level of Cd was found in roots (46.41 mg kg⁻¹) compared to shoots (10.75 mg kg⁻¹). Although the total content of Cd in the edible parts of the Swiss chard irrigated with WW exceeded permissible recommended consumption limit, bioavailable cadmium in the aboveground parts of the plant in relation to the total cadmium content was in the range from 8 to 32 %. Therefore, human health risks might be overestimated when the total concentration is taken into account.

Previous researches have confirmed that modified nanoscale carbon black (MCB) can decrease the bioavailability of heavy metals in soil and accumulation in plant tissues, resulting in the increase of biomass of plant. However, as a nanoparticle, the effects of MCB on plant cell morphology and microbial communities in Cd-contaminated soil are poorly understood. This study, through greenhouse experiments, investigated the effects of MCB as an amendment for 5 mg·kg⁻¹ Cd-contaminated soil on plant growth, plant cellular morphogenesis, and microbial communities. Two types of plants, metal-tolerant plant ryegrass (Lolium multiflorum), and hyperaccumulator plant chard (Beta vulgaris L. var. cicla) were selected. The results indicated that adding MCB to Cd-contaminated soil, the dry biomass of shoot ryegrass and chard increased by 1.07 and 1.05 times, respectively, comparing with control group (the treatment without MCB). Meanwhile, the physiological characteristics of plant root denoted that adding MCB reduced the damage caused by Cd to plants. The acid phosphatase activity of soils treated with MBC was higher and the dehydrogenase activity was lower than control group during whole 50 days of incubation, while the urease and catalase activity of soils treated with MBC were higher than control group after 25 days of incubation. When compared with the treatment without MCB, the abundances of nitrogen-functional bacteria (Rhodospirillum and Nitrospira) and phosphorus-functional bacteria (Bradyrhizobium and Flavobacterium) increased but that of nitrogen-functional bacteria, Nitrososphaera, declined. The presence of MCB resulted in increased microbial community abundance by reducing the bioavailability of heavy metals in soil, while increasing the abundance of plants by increasing the amount of available nitrogen in soil. The result of this study suggests that MCB could be applied to the in-situ immobilization of heavy metal in contaminated soils because of its beneficial effects on plants growth, root cellular morphogenesis, and microbial community.