Rice is a staple food and major source of nutrients, but it also bioaccumulates toxic elements. In this study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to determine tissue-level trace metal spatial distribution in rice (Oryza sativa) seeds from the active Xikuangshan Sb mine area in China. Whole grain quantified elemental bioimages showed the highest concentration of Zn (1755 mg/kg) in the embryo andmicro zones of elevated Sb, As, Pb, Cd as high as 280, 57, 31 and 830 mg/kg, respectively on the husk/bran/endosperm tissues. Bioimages suggest that both Sb and Cd may be competing with Zn for binding sites. Both Sb(III) and Sb(V) species were detected in seeds from upstream and downstream fields indicating the presence of toxic Sb(III). Brown rice is a good source of Zn, but white rice is a safer option if rice is grown in a polluted area.

In the framework of an ecological risk assessment of seaport sediments for terrestrial ecosystems when deposited in quarries, we simulated the “ageing” of sediments exposed to rain. This experiment highlighted an inflection point at the solid/liquid ratio 1/25, after which the extraction of pollutants increases moderately. The raw sediments studied inhibited the germination of Lolium perenne and Armeria maritima (a halophytic species) seeds. Furthermore, they affected the early development of L.perenne. The same sediments, leached at a ratio of 1/25, presented a reduction of acute (germination) and chronic (growth) phytotoxicity. The bioconcentration factors of the metals studied decreased with the leached sediment, except for Cu which was still clearly identified in root parts. Thus rotary leaching tests and phytotoxicity bioassays can be used to provide an initial assessment of the ability of plants, particularly halophytes, to colonize deposits of dredged seaport sediments.

The present study was conducted on clover (Trifolium alexandrinum L. cv Wardan), to investigate the effect of ambient and elevated (ambient +10 ppb O3) ozone (O3) on plants grown in open top chambers (OTCs) germinated from gamma (γ) irradiated seeds. Dry seeds were subjected to irradiation with 0, 5, 10 and 20 krad doses of γ rays from 60Co source. Dose dependent differential responses were observed on growth and biomass, photosynthetic pigments, metabolites, antioxidative defense system of plant. Growth parameters and biomass of plants were severely affected under elevated O3 with increasing radiation doses, except, 5 krad which showed a reverse trend of response. Photosynthetic pigments and total soluble proteins were also reduced with higher dose of γ radiation and elevated O3. Reactive oxygen species formation and membrane damage increased significantly to different extents. Plants grown from seeds irradiated with low dose (5 krad) of γ irradiation depicted more induction of antioxidants (enzymatic and non–enzymatic) than higher doses suggesting their high ameliorative capability against elevated O3. Principal component analysis has also confirmed that plants grown from 5 krad γ irradiated seeds performed better against O3 depicting reduction in negative effect against elevated O3. The experimental findings evidently showed that 5 krad γ radiations altered the O3 induced stress and thus minimized the loss in biomass of the test plant.

Ametryne is an herbicide applied to sugar cane cultures to prevent the emergence of weeds. It is a persistent compound that percolates ground and surface water thus impacting aquatic communities. In this study, we evaluated microbial activity in soil with increased concentrations of ametryne solution and commercial Microgeo biofertilizer. The soil subject to analysis was obtained from a sugar cane cultivation area. The concentration used in the experiment was ametryne 12 μg/L and 1 % of biofertilizer. It was used with the Bartha and Pramer respirometric method to quantify CO₂production and determine microbial activity. Complimentary phytotoxicity tests with Lactuca sativa seeds after respirometry experiments were conducted in the soluble fraction of the soil. According to the results, the addition of biofertilizer promoted microbial activity in the presence of ametryne and reduced ametryne phytotoxicity for Lactuca sativa seeds. Thus, Microgeo biofertilizer can potentially improve biodegradation of ametryne through both bioaugmentation and bioestimulation.

Seed priming effects on Trifolium repens were analysed both in Petri dishes and in two soils (one unpolluted soil and a soil polluted with Cd and Zn). Priming treatments were performed with gibberellic acid 0.1 mM at 22 °C during 12 h or with polyethylene glycol (−6.7 MPa) at 10 °C during 72 h. Both priming treatments increased the germination speed and the final germination percentages in the presence of 100 μM CdCl₂or 1 mM ZnSO₄. Flow cytometry analysis demonstrated that the positive effect of priming was not related with any advancement of the cell cycle in embryos. Seed imbibition occurred faster for primed seeds than for control seeds. X-ray and electronic microscopy analysis suggested that circular depressions on the seed coat, in addition to tissue detachments inside the seed, could be linked to the higher rate of imbibition. Priming treatments had no significant impact on the behaviour of seedlings cultivated on non-polluted soil while they improved seedling emergence and growth on polluted soil. The two priming treatments reduced Zn accumulation. Priming with gibberellic acid increased Cd accumulation by young seedlings while priming with polyethylene glycol reduced it. Priming improved the light phase of photosynthesis and strengthened the antioxidant system of stressed seedlings. Optimal priming treatment may thus be recommended as efficient tools to facilitate revegetation of former mining area.

The study aimed to investigate the biodegradation of contaminated soil with biodiesel, diesel, and petroleum by autochthonous soil microorganisms and also enriched with Bacillus subtilis by means of colorimetric method. The phytotoxicity was evaluated in recently contaminated soil and after 240 days to ensure the decrease of toxicity. The biodegradation assessment was carried out with redox 2,6-dichlorophenol indophenol (DCPIP) indicator and by the extraction of the contaminant in the soil with hexane. The amount of contaminant extracted from recently contaminated soil was compared to the amount found on the buried samples for 240 days. The phytotoxicity rates were evaluated by the use of Lactuca sativa seeds. Values of root and hypocotyl elongation were subjected to analysis of variance using the Kruskal-Wallis test. The results revealed that the autochthonous microorganisms were active on recently contaminated soil with biodiesel, because all biodiesel was biodegraded. Hence, only 0.001 g of biodiesel was extracted, and the phytotoxicity decreased after 240 days. On the other hand, the contaminated soil with diesel and petroleum was little active in 2,6-DCPIP test, and consequently, there was a large contaminant amount in soil after 240 days. Furthermore, petroleum and diesel were phytotoxic after biodegradation. The complex composition of the petroleum and diesel requires interactions of the microbial community able to biodegrade hydrocarbons and also metabolites from biodegradation. The naturally present microorganisms in the soil were capable of degrading the pollutant as much as the samples enriched with B. subtilis. The 2,6-DCPIP test is a simple and inexpensive methodology to analyze the potential biodegradation of all microorganisms of the soil and if the inoculation of the biodegrading microorganisms it will be necessary. Therefore, it would be helpful in bioremediation strategies.

Normal seed germination of native herbaceous species can be reduced by high concentrations of deicer products and their constituent salts. Chloride salts are commonly used during the winter months in temperate climates to remove ice and snow. Although these products greatly improve driving conditions, they can have detrimental effects on the vegetation growing along highways. The purpose of this laboratory study was to determine the impact of a magnesium-based deicer product and a sodium-based deicer product and the major salts they contain on the germination and viability of several species of grasses and forbs native to Colorado and planted in revegetation seedings there. Seeds were placed on blotter paper saturated with either a water control, one of three concentrations of each of the deicing solutions, or one of three concentrations of a pure NaCl or MgCl₂ solution. Increasing concentrations of salt ions generally resulted in delayed and reduced normal seed germination, especially the sodium- and magnesium-based deicer solutions. Germination for most species was lower when seeds were grown in deicer solution compared with germination percent of seeds grown in the pure salt solutions. Some species were more tolerant of one of the salts and deicers. Species with C4 photosynthetic pathway were more tolerant than C3 species of high concentrations of both deicer products. Those species which attained the highest germination percent under moderate or high solution concentrations included blue grama, buffalograss, little bluestem, mountain brome, and slender wheatgrass.

Abiological granular sludge (ABGS) formation is a potential and facile strategy for improving sludge settling performance during zinc removal from wastewater using chemical precipitation. In this study, the effect of pH, seed dosage, and flocculant dosage on ABGS formation and treated water quality was investigated. Results show that settling velocity of ABGS can reach up to 4.00 cm/s under optimal conditions, e.g., pH of 9.0, zinc oxide (ZnO) seeds dosage of 1.5 g/l, and polyacrylamide (PAM) dosage of 10 mg/l. More importantly, ABGS formation mechanism was investigated in NaOH precipitation process and compared with that in bio-polymer ferric sulfate (BPFS)–NaOH precipitation process regarding their sludge structure and composition. In the NaOH precipitation process, ABGS formation depends on some attractions between particles, such as van der Waals attraction and bridging attraction. However, during the BPFS–NaOH sludge formation process, steric repulsion becomes dominant due to the adsorption of BPFS on ZnO seeds. This repulsion further causes extremely loose structure and poor settling performance of BPFS–NaOH sludge.

2,4-Dichlorophenol (2,4-DCP) is widely distributed in wastewaters discharged from several industries, and it is considered as a priority pollutant due to its high toxicity. In this study, the use of different peroxidase extracts for 2,4-DCP removal from aqueous solutions was investigated. Tobacco hairy roots (HRs), wild-type (WT), and double-transgenic (DT) for tomato basic peroxidases (TPX1 and TPX2) were used to obtain different peroxidase extracts: total peroxidases (TPx), soluble peroxidases (SPx), and peroxidases ionically bound to the cell wall (IBPx). All extracts derived from DT HRs exhibited higher peroxidase activity than those obtained from WT HRs. TPx and IBPx DT extracts showed the highest catalytic efficiency values. The optimal conditions for 2,4-DCP oxidation were pH 6.5, H₂O₂0.5 mM, and 200 U mL⁻¹of enzyme, for all extracts analyzed. Although both TPx extracts were able to oxidize different 2,4-DCP concentrations, the removal efficiency was higher for TPx DT. Polyethylene glycol addition slightly improved 2,4-DCP removal efficiency, and it showed some protective effect on TPx WT after 2,4-DCP oxidation. In addition, using Lactuca sativa test, a reduction of the toxicity of post removal solutions was observed, for both TPx extracts. The results demonstrate that TPx extracts from both tobacco HRs appear to be promising candidate for future applications in removing 2,4-DCP from wastewaters. This is particularly true considering that these peroxidase sources are associated with low costs and are readily available. However, TPx DT has increased peroxidase activity, catalytic efficiency, and higher removal efficiency than TPx WT, probably due to the expression of TPX1 and TPX2 isoenzymes.

Municipal solid wastes (MSW) are unavoidable sources of environmental pollution. Improper disposal of municipal waste results in the leaching of toxic metals and organic chemicals, which can contaminate the surface and ground water leading to serious health hazard. In this study, the toxic effects of the leachate prepared from municipal solid waste samples were examined in root meristem cells of barley (Hordeum vulgare L.) at various stages of cell cycle, i.e., G₁, S, and G₂. Seeds of barley were exposed to 2.5, 5, and 10 % of leachates in soil and aqueous media in 48 h at different cell cycle stages. The physicochemical data of the present study revealed that municipal solid waste leachate contains high amount of heavy metals, which significantly affected growth and physiological activities of barley. Significant inhibition in hypocotyl length, germination, and mitotic index were observed at all concentration of leachate treatment. Induction of chromosomal aberrations (CA’s) and micronuclei (MN) formation were also observed with different concentrations of leachate treatment at 7, 17, and 27 h of presoaking durations, which falls in G₁, S, and G₂phase of the cell cycle, respectively. Also, exposure of leachate at S phase of the cell cycle had significant effects in barley through chromosomal aberration and micronuclei formation.