Organic contaminations and heavy metals in soils cause large harm to human and environment, which could be remedied by planting specific plants. The biochars produced by crop straws could provide substantial benefits as a soil amendment. In the present study, biochars based on wheat, corn, soybean, cotton and eggplant straws were produced. The eggplant straws based biochar (ESBC) represented higher Cd and pyrene adsorption capacity than others, which was probably owing to the higher specific surface area and total pore volume, more functional groups and excellent crystallization. And then, ESBC amendment hybrid Ryegrass (Lolium perenne L.) cultivation were investigated to remediate the Cd and pyrene co−contaminated soil. With the leaching amount of 100% (v/w, mL water/g soil) and Cd content of 16.8 mg/kg soil, dosing 3% ESBC (wt%, biochar/soil) could keep 96.2% of the Cd in the 10 cm depth soil layer where the ryegrass root could reach, and it positively help root adsorb contaminations. Compared with the single planting ryegrass, the Cd and pyrene removal efficiencies significantly increased to 22.8% and 76.9% by dosing 3% ESBC, which was mainly related with the increased plant germination of 80% and biomass of 1.29 g after 70 days culture. When the ESBC dosage increased to 5%, more free radicals were injected and the ryegrass germination and biomass decreased to 65% and 0.986 g. Furthermore, when the ESBC was added into the ryegrass culture soil, the proportion of Cd and pyrene degrading bacteria Pseudomonas and Enterobacter significantly increased to 4.46% and 3.85%, which promoted the co−contaminations removal. It is suggested that biochar amendment hybrid ryegrass cultivation would be an effective method to remediate the Cd and pyrene co−contaminated soil.

Natural organic matter (NOM) affects the environmental behaviors of AgNPs, which may change their phytotoxicity to plants. However, more evidence can be provided to illustrate how NOM influences AgNPs-induced phytotoxicity. In this study, using rice (Oryza sativa) as a model, the effects of NOM, Suwannee River humic acid (SRHA) and fulvic acid (FA), on the dissolution and phytotoxicity of AgNPs were investigated. Silver ions decreased in both AgNPs and AgNO₃ solution in the presence of NOM, and the effect of SRHA was stronger than FA. Image-XRF (iXRF) results showed that Ag mainly remained in the root rather than the shoot of rice seedling exposed to AgNPs. NOM mitigated the negative effects of AgNPs and AgNO₃ on rice with lower germination inhibition rate, less chlorophyll reduction, more relative biomass and less O₂•⁻ content. Moreover, NOM improved root cell viability according to FDA fluorescent dye as well as maintained the normal root morphology. Interestingly, the neutral sugars content from pectin, hemicellulose 1, hemicellulose 2 and cellulose of root cell wall in AgNPs and AgNO₃ treatments differed from the control, while it was close to the regular content in AgNPs/AgNO₃+SRHA/FA groups, which implied that NOM regulated the changes. Besides, SRHA led to less germination and less relative biomass than FA due to different chemical characters. Thus, NOM needs to be considered when studying the phytotoxicity of AgNPs.

Cadmium (Cd), which is a toxic non-essential heavy metal capable of entering plants and thus the food chain, constitutes a major environmental and health concern worldwide. An understanding of the tools used by plants to overcome Cd stress could lead to the production of food crops with lower Cd uptake capacity and of plants with greater Cd uptake potential for phytoremediation purposes in order to restore soil efficiency in self-sustaining ecosystems. The signalling molecule nitric oxide (NO), whose function remains unclear, has recently been involved in responses to Cd stress. Using different mutants, such as nia1nia2, nox1, argh1-1 and Atnoa1, which were altered in NO metabolism, we analysed various parameters related to reactive oxygen and nitrogen species (ROS/RNS) metabolism and seedling fitness following germination and growth under Cd treatment conditions for seven days. Seedling roots were the most affected, with an increase in ROS and RNS observed in wild type (WT) seedling roots, leading to increased oxidative damage and fitness loss. Mutants that showed lower NO levels in seedling roots under Cd stress were more resistant than WT seedlings due to the maintenance of antioxidant systems which protect against oxidative damage.

The present study was aimed at investigating the effects of different acids and pH neutralizers applied to dredged marine sediment for the treatment of heavy metals, and the resulting influence on the sediment quality as a plant growth medium. The inspection of barley germination in the dredged marine sediment revealed that residual salts are critical plant stressors whose adverse effects exceed those exhibited by high-level heavy metals and petroleum hydrocarbons present in the sediment. Acid washing and pH neutralization reduced not only the heavy metal contents but also the sediment salinity (by factors of 6.1–9.5), resulting in 100% germination of barley. For acid-washed and calcium-oxide-neutralized sediment, the barley growth was comparable to that observed in untreated and water washed sediment despite factors of 5.2–8.0 greater sediment salinity in the former. This result represents the protective effect of residual calcium against sodium and chloride toxicity. Water washing of acid-washed and pH-neutralized sediments further enhanced barley growth owing to the reduction in osmotic pressure. This study showed the effect of different sediment-washing reagents on the product quality. It also indicated the significance of balancing the enhancement of product quality and economic cost of further treatment requirements.

There has been a growing concern with the environmental influences of nanomaterials due to recent developments in nanotechnology. This study investigates the impact and fate of hematite nanoparticles (α-Fe₂O₃ NPs) (∼14 nm in size) on a crop species, barley (Hordeum vulgare L.). For this purpose, hematite NPs (50, 100, 200, and 400 mg/L) were hydroponically applied to barley at germination and seedling stages (three weeks). Inductively coupled plasma mass spectrophotometry (ICP-MS) along with vibrating sample magnetometer (VSM) techniques were used to track the NPs in plant tissues. The effects of NPs on the root cells were observed by scanning electron microscopy (SEM) and confocal microscopy. Results revealed that α-Fe₂O₃ NPs significantly reduced the germination rate (from 80% in control to 30% in 400 mg/L), as well as chlorophyll (36–39%) and carotenoid (37%) contents. Moreover, the treatment led to a significant decline in the quantum yield of photosystem II (Fv/Fm). Leaf VSM analysis indicated a change in magnetic signal for NPs-treated samples compared with untreated ones, which is mostly attributed to the iron (Fe) ions incorporated within the leaf tissue. Besides, Fe content in the roots and leaf had gradually increased by the increasing doses of NPs, which was confirming NPs’ translocation to the aerial parts. Microscopic observations revealed that α-Fe₂O₃ NPs altered root cell morphology and led to the injury of cell membranes. This study, in the light of our findings, shows that α-Fe₂O₃ NPs (∼14 nm in size) are taken up by the roots of the barley plants, and migrate to the plant leaves. Besides, NPs are phytotoxic for barley as they inhibit germination and pigment biosynthesis. This inhibition is probably due to the injury of the cell membranes in the roots. Therefore, the use of hematite NPs in agriculture and thereby their environmental diffusion must be addressed carefully.

The collapse of the Fundão dam in Mariana, MG, in 2015 resulted in the overflow of more than 50 million m³ of mud containing mine tailings, leaving a path of destruction and immeasurable social and environmental consequences. Tailings’ chemical and physical assessments revealed the presence of some elements at levels higher than those allowed by Brazilian guidelines. The tailings also showed high density, which restricts vegetation recovery. Therefore, this study aimed to analyze the effects of mud containing mine tailings from the Fundão dam on the germination and initial growth and development of three plant species: millet, maize, and sorghum. These species were cultivated on substrates with five tailings proportions: 0 T (100% sand), 25 T (25% tailings + 75% sand); 50 T (50% tailings + 50% sand); 75 T (75% tailings + 25% sand); and 100 T (100% tailings). In experiment I, the germination and initial growth of seedlings (plants with 1 or none fully expanded leaf) in these substrates were evaluated. In experiment II, growth parameters, photosynthetic efficiency (gas exchange and chlorophyll a fluorescence), metal accumulation, and plant root morphology of the same species were evaluated at the three fully expanded leaves vegetative stage (V3). Overall, the germination of seedlings and the initial growth of the three species analyzed were not affected by the presence of tailings. However, in plants at the V3 stage, morphophysiology variations differed among species, given that their growth, biomass accumulation, and root dynamics were altered. Proportions of tailings in the substrate did not influence the absorption of iron or manganese by the studied plants. At the V3 stage, maize was the most tolerant, with a more robust root system, and showed fewer morphological changes and greater water use efficiency than the other studied species.

The aim of this study was to evaluate the effect of pretreatment on the phytotoxicity and leaching of nitrogen and phosphorus in biosolids from anaerobic digestion in silty loam soil. Soil columns filled with silty loam soil and biosolids (BS) stabilized by conventional (CAD) and advanced (AAD) anaerobic digestion were installed. AAD consisted of the application of sequential pretreatments: ultrasound followed by a low thermal process. The BS loads were equivalent to 30 ton/ha (CAD30 and AAD30) and 90 ton/ha (CAD90 and AAD90), and the soil columns were watered with 29 mL/day of distilled water. Phytotoxicity was evaluated by germination and root growth inhibition and by the germination index (GI) of Triticum aestivum, Lactuca sativa, and Raphanus sativus seeds. Nitrogen leaching varied from 0 to 9 mg/week, while phosphate leaching did not exceed 0.01 mg/week. The nutrient leaching rate depended on the BS application rate and not on the use of pretreatment (p < 0.05). Regarding phytotoxicity, BS application presented a tendency to attenuate the inhibition caused by the silty loam soil, with GI values ranging from 31 to 50%, 62 to 63%, and 70 to 82% for L. sativa, R. sativus, and T. aestivum, respectively.Graphical abstract

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 describes the role of zinc oxide nanoparticles (ZnO NPs) in alleviating arsenic (As) stress in rice (Oryza sativa) germination and early seedling growth. Seeds of rice were primed with different concentrations (10, 20, 50, 100, and 200 mg L⁻¹) of ZnO NPs and As (0, and 2 mg L⁻¹) for 12 days in petri dishes. Two milligrams per liter of As treatment represented a stress condition, which was evidenced by germination rate, seedling length, seedling dry weight, chlorophyll, superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) content of rice shoot. ZnO NPs amendment (10–100 mg L⁻¹) increased the germination rate (2.3–8.9%), shoot weight (18.2–42.4%), root weight (5.2–23.9%), and chlorophyll content (3.5–40.1%), while elevated the SOD (2.2–22.8%) and CAT (7.2–60.7%) activities and reduced the MDA content (17.5–30.8%). As concentrations were significantly decreased by 8.4–72.3% and 10.2–56.6%, respectively, in rice roots and shoots with ZnO NPs amendment (10–200 mg L⁻¹) by the As adsorption of ZnO NPs and promoted biomass of rice. All the amendments improved the Zn concentrations in rice shoots and roots. Overall, ZnO NPs provide effective resistance to arsenic toxicity by increasing germination, biomass, and nutrients of Zn and decreasing As uptake in rice.

In this study, the toxic effects of 1,4-dioxane, a common contaminant, and the protective property of Ceratonia siliqua L. pod extract (Cspe) against this toxicity are aimed to be demonstrated with a versatile model. For this purpose, Allium toxicity test was used and six different experimental groups were formed. While the control group was germinated in tap water, the application groups were germinated in mediums containing 750 mg/L Cspe, 1500 mg/L Cspe, 100 mg/L 1,4-dioxane, 750 mg/L Cspe+100 mg/L 1,4-dioxane, and 1500 mg/L Cspe+100 mg/L 1,4-dioxane. Each group was germinated in related solution for 72 h and alterations in physiological, biochemical, genetic, and anatomical parameters were investigated. Germination percentage, relative injury rate, root length, and weight gain parameters were examined as physiological parameters, and no significant difference was observed in the control group and only-Cspe-treated groups. In groups treated with 100 mg/L 1,4-dioxane, germination percentage, root length, and weight gain were significantly decreased, and the relative injury rate reached the highest value as 0.48. It was determined that all physiological parameters improved in the groups where Cspe and 1,4-dioxane treated together, and the relative injury rate decreased to 0.22 in the group treated with 1500 mg/L Cspe+1,4-dioxane. Genotoxic effects were tested by the micronucleus and chromosomal abnormality frequency, and statistically insignificant micronucleus formation was found in control group and Cspe-treated groups. Micronucleus frequency were found to be 58.00 ± 12.12 and 31.00 ± 07.38 in 1,4-dioxane and 1500 mg/L Cspe+1,4-dioxane-treated groups, respectively. This result showed that the application of 1500 mg/L Cspe had a 46.5% reduction in the frequency of 1,4-dioxane-induced micronucleus and had a protective effect on genomic integrity. It has been found that 1,4-dioxane application induces lipid peroxidation and increases malondialdehyde level 4.5 times compared with control group. Oxidative stress, which was proved by increased malondialdehyde levels in 1,4-dioxane-treated group caused induction of superoxide dismutase and catalase enzymes, and it was determined that enzyme activities increased by 1.99 and 4.9 times, respectively, compared with the control group. Cspe treatment with 1,4-dioxane caused a significant decrease in malondialdehyde level, superoxide dismutase, and catalase enzyme activities, indicating that oxidative stress formation in the cells was repressed. Abnormalities such as cell deformation, cell wall thickening, and flattened cell nuclei were seen in 1,4-dioxane-treated group in the cross sections of root tips, and the frequency of these abnormalities decreased with Cspe application. As a result, it was determined that 1,4-dioxane caused a versatile toxicity in the test material Allium cepa, whereas Cspe application had a dose-dependent protective feature against toxicity in all tested parameters.