Nowadays trace metal contamination of soils represents an important environmental hazard. Nevertheless, the use of some secondary waste products as amendments may restore the common soil functions. This paper focuses on the chemical and biological influence of wood biochar (BC), wood ash (WA) and humic substances (HS), alone and in the mixtures, on a heavily multi-contaminated sandy loam soil. The soil was amended by above-mentioned materials to follow a pH-increasing design (pHCa from 6.0 to 6.5, 7.0 and 7.5); soil samples were analyzed after 3, 30, and 60 days using a set of variables, namely the plant-available trace element concentrations (Cu, Cd, and Zn), microbial biomass carbon (Cmic), and microbial quotient (qCO2), as well as toxicity to Sinapis alba and Daphnia magna. Wood ash and WA + HS were the most efficient treatments to decrease mobile Cd and Zn concentrations in the soil, while HS, BC, and BC + HS combinations were the most effective in reducing the Cu mobility. The effect of BC and WA on the Cmic and qCO2 was mostly negative, whereas adding HS markedly increased Cmic and reduced qCO2 in soil. After amendment applications, the root elongation of mustard was significantly increased in HS and combined treatments (BC + HS, WA + HS). Additionally, BC + HS, WA + HS and WA 8.4% significantly decreased the toxicity of leachates to D. magna to the low-, or non-toxic levels. Our results suggest that the combination of amendments with HS can be a suitable remediation strategy for heavily contaminated soils.

Interpolyelectrolyte complexes (IPECs) formed by the interaction of two oppositely charged polyelectrolytes have been proposed as soil structure stabilizers. However, little is known about the environmental safety of IPECs. The goal of this study was to investigate the toxicity of a positively charged IPEC formed by two commercial polymers, namely the cationic biopolymer poly(diallyldimethylammonium chloride) (PDDA) and the anionic biopolymer lignohumate (LH), a humic-based plant growth promoter. Toxicity was assessed using cultures of the bacteria Escherichia coli, the ciliate Paramecium caudatum, mammalian (Bos taurus) spermatozoa in vitro, and three plant species (Sinapis alba, Raphanus sativus, and Triticum durum). The responses of test organisms were evaluated in contact with (1) polymer and water and (2) polymer and soil. In water, PDDA and IPEC were highly toxic to bacteria and ciliates at all concentrations and less toxic to mammalian cells. Higher plants were less sensitive to the polymers, and the toxicity progressively decreased in the order PDDA > IPEC > LH. In soil matrices; the phytotoxicity of PDDA and IPEC was found to be quite low, and none of the polymers was toxic to plants at concentrations that allowed the formation of polymeric soil crusts against erosion. This is because the toxicity of cationic polymers decreases as they enter the soil matrix and bind to organic matter and minerals.

This study aimed to use bioassays (single and multispecies) with organisms from different trophic levels to assess soil quality in reclaimed coal mining areas. Soil samples were collected from four sites: two sites with recent reclaim processes (one using topsoil and other using clayey soil), an natural attenuation site, and a control soil. The evaluated parameters were divided into (1) ecotoxicological tests (avoidance test with Eisenia andrei (earthworms) and Armadillidium vulgare (isopods); germination test with Sinapis alba seeds (mustard); reproduction tests with Folsomia candida (collembolans); bacterial toxicity test); (2) population and community assessments (a fungal count; microbial community analysis using Biolog EcoPlatesᵀᴹ); (3) microcosms scale evaluation (the MS-3 multispecies system); and (4) chemical analysis (soil parameters, soil metal, and cations and anions in soil leachate). Results pointed to toxicity in the natural attenuation site that compromised of habitat function, probably due to low pH and low nutrient levels. The most recent reclaim process, using topsoil and clay soil, improved soil quality and fertility, with a further increase in habitat quality and heterogeneity. This study shows that some techniques used to reclaim degraded mining areas are effective in rebuilding habitats, sustaining soil biota, and reestablishing ecosystem services.

Nanoparticles (NPs) are commonly used, and concerns about their possible adverse effects are being voiced as well. However, little is known about the fates of NPs released to the environment. The aim of the study was to (i) evaluate the ability of Sinapis alba and Lepidium sativum plants to take up platinum nanoparticles (Pt-NPs) and translocate them to aboveground organs, (ii) compare the accumulation efficiency of different forms of platinum and (iii) identify the forms in which platinum is stored in plant tissues. Plants were cultivated on medium supplemented with different concentrations of Pt-NPs and [Pt(NH₃)₄](NO₃)₂. Platinum content in plants was determined using inductively coupled plasma mass spectrometry. For the identification of the presence of Pt-NPs in plant tissues, gamma spectrometry following iron irradiation was applied. It was found that L. sativum and S. alba are tolerant to applied concentrations of Pt-NPs and have an ability to take up platinum from the medium and translocate it to aboveground organs. The highest concentration of platinum was observed in plant roots (reaching 8.7 g kg⁻¹for S. alba). We tentatively conclude that platinum is accumulated as nanoparticles. The obtained results suggest future application of plants for phytoremediation and recovery of noble metal nanoparticles.

The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical–physical properties. After the amendment of Cu (5 or 10 mg Cu l⁻¹) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg⁻¹DW, more than three times higher than in S. alba (31.56 mg Cu kg⁻¹DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to threefold to fourfold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.

Heavy metal phytoextraction is a soil remediation technique, which makes use of plants in removing contamination from soil. The plants must thus be tolerant to heavy metals, adaptable to soil and climate characteristics, and able to take up large amounts of heavy metals. Most of the high biomass productive plants such as, maize, oat and sunflower are plants, which do not grow in cold climates or need intensive care. In this study three “weed” plants, Borago officinalis; Sinapis alba L. and Phacelia boratus were investigated for their ability to tolerate and accumulate high amounts of Cd and Pb. Pot experiments were performed with soil containing Cd and Pb at concentrations of up to 180 mg kg⁻¹ and 2,400 mg kg⁻¹ respectively. All three plants showed high levels of tolerance. Borago officinalis; and Sinapis alba L. accumulated 109 mg kg⁻¹ and 123 mg kg⁻¹ Cd, respectively at the highest Cd spiked soil concentration. Phacelia boratus reached a Cd concentration of 42 mg kg⁻¹ at a Cd soil concentration of 100 mg kg⁻¹. In the case of Pb, B. officinalis and S. alba L. displayed Pb concentrations of 25 mg kg⁻¹ and 29 mg kg⁻¹, respectively at the highest Pb spiked soil concentration. Although the Pb uptake in P. boratus reached up to 57 mg kg⁻¹ at a Pb spiked soil concentration of 1,200 mg kg⁻¹, it is not suitable for phytoextraction because of its too low biomass.

The present study evaluated the relationship between estrogenic hormone concentrations (17α-ethinylestradiol and 17β-estradiol) in surface waters in the Metropolitan Area of São Paulo (Brazil) and environmental variables. Four sampling stations were monitored ranging from a protected area to streams discharging human effluent in and around Billings Reservoir. Four sampling campaigns were carried out in each seasonal period: dry and wet. Samples for hormone analysis (in ng L⁻¹) were concentrated (1000×) using solid-phase extraction C₁₈ cartridges and analyzed by liquid chromatography coupled to quadrupole mass spectrometry detection, with 100 ng L⁻¹ limit of quantification. Water temperature, pH, electrical conductivity (EC), and total dissolved solids were determined in situ; total phosphorus and Sinapis alba bioassays were performed subsequently. Reservoir active capacity (AC) and precipitation were also obtained. Estrogenic hormone concentrations were always below limit of quantification at pristine site; at the other sampling stations, 17β-estradiol concentrations varied from below limit of quantification to 1720 ng L⁻¹ and 17α-ethinylestradiol from below limit of quantification to 1200 ng L⁻¹, with the highest concentrations found in the streams discharging into the reservoir. These streams showed higher Pearson’s correlation between 17α-ethinylestradiol, total phosphorus, and electrical conductivity when compared with reservoir stations. Germination index and EC presented negative correlation (Pearson’s r = − 0.61), denoting a phytotoxicity increase with EC increment. AC influenced the dilution of pollutants and showed negative correlations with total phosphorus (Pearson’s r = −0.56). These results highlight the relevance of including streams in water-monitoring programs, since they are important pollutants loads into watersheds.

This study evaluated the effects of abattoir wastewater irrigation on plant growth and development. The soils used in this study were collected from Primo Smallgoods Abattoir (Port Wakefield, South Australia) at different sites such as currently irrigated (CI), currently not irrigated (CNI) and soil outside the irrigation area as control (CTRL). A completely randomised block design was employed for the plant growth experiment, where four crops (Pennisetum purpureum, Medicago sativa, Sinapis alba and Helianthus annuus) were grown separately on three different soils (CI, CNI and CTRL) in plastic pots. Two types of water (tap water and wastewater) and two loadings were applied throughout the planting period based on the field capacity (FC 100 and 150 %). The overall dry matter yield was compared between the soils and treatments. Under wastewater irrigation, among the four species grown in the CI soil, P. purpureum (171 g) and H. annuus (151 g) showed high biomass yields, followed by S. alba (115 g) and M. sativa (31 g). The plants grown under tap water showed about 70 % lower yields compared to the abattoir wastewater irrigation (AWW). Similar trends in the biomass yields were observed for CNI and CTRL soils under the two water treatments, with the biomass yields in the following order CI > CNI > CTRL soils. The results confirm the beneficial effects of AWW at the greenhouse level. However, a proper cropping pattern and wastewater irrigation management plan is essential to utilise the nutrients available in the wastewater-irrigated land treatment sites. The increase in fertility is evident from the effects of wastewater on biomass growth and also the abundance of nutrients accumulated in plants. A mass balance calculation on the applied, residual and the plant-accumulated nutrients over a few cropping periods will help us in understanding the nutrient cycling processes involved in the abattoir-irrigated land treatment sites, which will serve as an effective tool for the environmental management.

The recent rapid expansion of nanotechnologies has increased concern over the impact of engineered nanoparticles (ENPs) on the environment and biota. Although the toxicity of ENPs has received considerable attention in the recent years, there are still gaps in our knowledge of the mechanisms responsible for their effects. In this study, we tested the toxicity of various metal oxide ENPs (Al₂O₃, CuO, Fe₃O₄, MnO, TiO₂, and ZnO), including nanowires together with their bulk counter particles and soluble metal salts, on germinating seeds of Sinapis alba L. Fe₃O₄, TiO₂, MnO₂, and Al₂O₃ ENPs did not negatively affected seed germination at any tested concentrations. However, CuO and ZnO ENPs showed a dose-dependent inhibition of germination. Metal ions were more toxic than metal oxide particles at corresponding concentrations. The highest toxicity was exhibited by Cu, followed by Zn, Fe, Al, and Mn ions. A comparison of ENPs with bulk materials did not reveal significantly higher ENP toxicity. Similarly, nanowires showed effects similar to other nanoparticles and bulk materials. Our results indicate that the nanosize or shape of particles did not play a crucial role, whereas metal ions released into cultivation media and accumulated in seedlings contributed significantly to the phytotoxicity of metal oxides.

We performed a 2-year microcosm study to assess the effectiveness of red mud, a by-product of bauxite processing, in stabilizing contaminated mine waste and agricultural soil. Our study used red mud from a long-term disposal area in Almásfüzitő, Hungary with a pH of 9.0. A 5% (by weight) red mud addition decreased the highly mobile, water-extractable amount of Cd and Zn by 57% and 87%, respectively, in the agricultural soil and by 73% and 79%, respectively, in the mine waste. In a laboratory lysimeter study, the addition of red mud reduced the concentration of Cd and Zn in the leachate by about two third of the original. The metal content of the leachate was below the Maximum Effect Based Quality Criteria for surface water as determined by a risk assessment in the metal-contaminated area of the Toka valley near Gyöngyösoroszi, Hungary. The addition of red mud did not increase the toxicity of the treated mine waste and soil and decreased the Cd and Zn uptake of Sinapis alba test plants by 18–29%. These results indicate that red mud applied to agricultural soil has no negative effects on plants and soil microbes and decreases the amounts of mobile metals, thus indicating its value for soil remediation.