Macroscopic (germination and root growth) and microscopic (mitotic index, chromosome, and nuclear aberrations) analyses have been used to determine the toxicity of environmental pollutants. To better understand the molecular mechanisms of mutation and their effects, molecular markers offer a key perspective, as they measure the direct effects of DNA mutagenic agents. The aim of this study was to evaluate the toxic potential of the fungicides difenoconazole (DZ) and tebuconazole (TZ) on Allium cepa. A reduction was observed in the germination, root growth, and mitotic index at higher concentrations of DZ and TZ, compared to the negative control. In addition, high incidence of chromosome and nuclear aberrations was detected in treated roots. This demonstrates the genotoxic, cytotoxic, and phytotoxic effects of DZ and TZ on the root tips of A. cepa. Moreover, the molecular results indicate a change in the amplification profiles of the simple sequence repeats (SSR) and intersimple sequence repeats (ISSR) obtained from A. cepa after exposure to the tested compounds. Loss and gain of bands increased dose-dependently. Further, the grouping methods distinguished the higher concentrations from the negative control. The ISSR and SSR analyses proved to be efficient tools for evaluating DNA alterations caused by DZ and TZ. In association with macroscopic and microscopic analyses, they constitute an informative approach for environmental mutagen studies.

Lead contamination remains a persistent global environmental problem, the hazards of which are often difficult to identify without specific and targeted research. This study examines environmental contamination arising from the widespread use of lead solder in the joints of large gravity water supply pipelines. Contamination of adjacent grazing lands and subsequent poisoning of domestic livestock are evaluated. In particular, the study demonstrates that replacement of lead joints along an above ground 70 km water supply pipeline in central New South Wales (NSW), Australia, has caused soil lead contamination of up to 20,600 mg/kg. Contamination either side of the pipeline corridor extends to ∼10 m before surface soil lead values correspond more closely to natural background concentrations of 26 mg/kg. The estimated total volume of contaminated soil requiring remediation is 21,000 m³. Contamination is linked to toxicity and mortality in several farm animals and to elevated contamination of grass fodder (up to 50 mg/kg of lead) close to the pipeline. Other similar large-scale above ground reticulation systems in the Sydney (NSW) Metropolitan region and adjacent to the 560 km long Kalgoorlie (Western Australia) Golden Pipeline are shown to present similar environmental hazards. The use of lead solder joints in other international large scale reticulation networks are also identified, demonstrating that this specific anthropogenic hazard is likely to be a more global problem, which has not has been detailed in the research literature to any significant extent.

Ground-level ozone (O₃) pollution has affected carbon metabolism in tree species, which becomes one of the top environmental issues in China. In this paper, 1-year-old seedlings of Phoebe bournei and Pinus massoniana Lamb. were grown under field conditions at a rural site near the city of Taihe (Jiangxi Province). The plants were exposed in open-top chambers either to charcoal-filtered air or nonfiltered ambient air for 145 days. At the end of the growth season, the plants were harvested and the major nonstructural carbohydrates in leaves and roots were determined. Exposure to nonfiltered ambient air compared with filtered air controls caused an increase of sucrose, glucose, fructose, starch, and total nonstructural carbohydrates (TNCs) in fine roots of Ph. bournei, while there is no change in carbohydrate contents in Pi. massoniana roots. Compared with filtered air, in Ph. Bournei, starch and TNCs in leaves were reduced by 48 and 7 %, respectively, in ambient O₃. While, ambient O₃ just increased TNC content by 8.9 % in Pi. massoniana needles compared to filtered air. In summary, ambient O₃ affected carbohydrate metabolism of these two subtropical tree species in China, and Pi. massoniana was less sensitive than Ph. bournei. O₃ induced much greater changes in the amounts of carbohydrates in roots than in leaves.

This study investigates the use of sericite beads and microalgae for the removal of heavy metals from acid mine drainage (AMD) and the simultaneous enhancement of biomass productivity. The experiment was conducted over a period of 6 days in a hybrid system containing sericite beads and microalgae Chlorella sp. The results show that the biomass production increased to ~8.04 times its initial concentration of 0.367 g/L as measured by an optical panel photobioreactor (OPPBR) and had a light transmittance of 95 % at a 305-mm depth. Simultaneous percent removal of Fe, Cu, Zn, Mn, As, and Cd from the AMD effluent was found to be 97.78 to 99.26 %. Biomass production was significantly enhanced by removal of heavy metal ions. We thus found that our hybrid system of sericite beads and microalgae was highly effective in removing heavy metal and in enhancing biomass production and could be a useful alternative treatment of AMD.

Nitrogen inputs to coastal watersheds have been linked to eutrophication. However, the role that domestic sources of wastewater play in contributing nitrogen to coastal watersheds is not well known in the southeastern USA. In a yearlong study (2011–2012), nitrogen concentrations were compared in watersheds served by septic systems and a centralized sewer system in the Coastal Plain of North Carolina. Surface and groundwater samples from septic systems and sewer watersheds were analyzed for total dissolved nitrogen (TDN), total nitrogen, and nitrogen and oxygen isotopes in nitrate. Groundwater beneath the drainfield and adjacent to streams had median concentrations of TDN at 5.9 and 4.4 mg/L, respectively. Additionally, median groundwater-transported loads of TDN to the stream from septic systems sites (0.6 kg-TDN/year) were significantly greater than sites in sewer watersheds (0.2 kg-TDN/year). Isotopic analyses revealed that effluent from septic systems was the primary source of nitrate in watersheds served by septic systems, while fertilizer and/or soil organic matter were dominant sources of nitrate in sewer watersheds. Nitrogen exported from septic systems contributed to elevated nitrogen concentrations in groundwater and streams throughout the watershed, whereas nitrogen exports from sewers were focused at a single point source and affected surface water concentrations. Based on watershed TDN exports from septic systems minus TDN exports from sewers watersheds, it was estimated that septic systems contributed 1.6 kg TDN/ha/year to watershed exports of TDN. Overall, septic systems and sewers contributed to elevated nitrogen loading and should be considered in nutrient-sensitive watershed management.

The mutagenic and genotoxic activity of vinasses collected from a fuel alcohol plant, located in the municipality of Frontino, Northwestern Colombia, were evaluated. Two samples obtained from an 82-L capacity hybrid reactor (UASB-anaerobic filter (AF)-UASB) were studied under laboratory conditions after being treated with biological oxidation, the first, and the second with Fenton reaction consecutively. Mutagenicity was evaluated in vitro by the Ames test using strains TA98 and TA100 with and without S9 metabolic activation. The genotoxic analysis was conducted using the Allium cepa roots assay where chromosomal aberrations were used as clastogenic or aneugenic response markers, and micronuclei as mutagenic response. The Ames test results showed a strain-dependent positive linear association with the vinasse sample concentration before treatment (dose–response effect). Unlike TA100, strain TA98 showed a mutagenic effect in both the presence and absence of metabolic enzymes. After the biological oxidation treatment, vinasse mutagenicity significantly decreased. Finally, after Fenton treatment, the sample did not induce any mutagenic event. Genotoxic activity was observed in all three samples, but there was a higher frequency in the vinasse sample before treatment. Concerning the frequency of micronuclei, no clear association was observed with either the concentration or the type of sample.

A series of column experiments was conducted to evaluate the effect of organic carbon fraction on long-term atrazine elution tailing for calcareous soil (foc = 0.97 %) and calcareous soil with 10 % by weight terra rossa amendment (foc = 1.20 %). Effluent atrazine concentrations were monitored for approximately 400 pore volume to understand the influence of controlling sorption–desorption kinetics on long-term tailing behavior. Laboratory studies showed that the sorption of atrazine was described by rate-limited, nonlinear reversible processes for both soils. Atrazine transport exhibited extensive elution tailing for all experiments due to the presence of hard carbon components such as black carbon and kerogen in both soils. This nonlinear sorption and extensive atrazine tailing behavior were more pronounced and extensive for soil with terra rossa amendment due to the addition of approximately 20 % organic carbon including 10 % hard carbon components from terra rossa soil. A mathematical model incorporating nonlinear, rate-limited sorption/desorption described by a continuous distribution function was used to successfully simulate atrazine transport early-time breakthrough and long-term concentration tailing for both porous media.

As the use of dangerous substances in consumer products increases, these substances may also be found in society’s end products, among them sewage sludge. Measuring concentrations in sewage sludge can be a way to reflect the consumption of a substance. By using substance flow analysis, the inflow, stock and outflow of the specific substance to, e.g. a city region, may be analysed. Bismuth is a heavy metal that is found in increasing levels in sewage sludge in Swedish wastewater treatment plants (WWTPs) and a similar increase cannot be excluded for WWTPs around the world. This study aims to examine possible sources that could explain the amounts measured in one Swedish WWTP. Household products such as cosmetics (24 %) and plastics (14 %) are found to be major sources of Bi measured in sewage sludge. The remaining unidentified amounts in this study (approximately 50 %) are most likely found in effluent waters from industries or sources outside the household. There is, however, no information on measurements of Bi released by industry available and there is no legislation in place that may encourage industry to conduct such measurements.

Solar Photo-Fenton reaction, using FeSO₄ and H₂O₂, is an effective and energy-efficient advanced oxidation process (AOP) for degradation of pesticides. However, a major environmental concern is whether the net toxicity after the photo-Fenton process is within the tolerance limit of the aquatic plants and animals, since the unreacted pesticide and Fenton’s reagent may impart additional toxicity to the treated water. Here, we report the oxidative removal of dichlorvos pesticide in wastewater by solar photo-Fenton reaction along with the residual toxicity analysis of the treated water on an aquatic alga. It was found that at pH 3, dichlorvos, with an initial concentration of 6.9 × 10⁻⁵ mol L⁻¹, was observed to be fully degraded within a batch time of 120 min, though the corresponding reduction of chemical oxygen demand (COD) was about 53 % signifying incomplete mineralisation. In order to predict the transient concentration profiles of dichlorvos under different initial concentrations, a four-parameter mathematical model was formulated. Additionally, the resultant toxicity was also examined using a model blue-green alga Nostoc sp. Compared to the raw wastewater, the net biomass of chlorophyll-a was found to increase significantly. Respective estimate of the protein concentration also indicated the same trend. Therefore, sunlight-assisted photo-Fenton process may be regarded as an effective and safe technique for the treatment of pesticide-contaminated agricultural wastewater.

Grape stalks, a low-cost agro-industrial by-product, were used for the first time as a biosorbent for the removal of uranium from aquatic systems. Basic operating conditions (effect of pH, biosorbent dose, uranium initial concentration, and kinetics) were investigated, and the sorption mechanism was explored. The proposed biosorbent’s efficiency to sequester uranium from different profile aquatic systems was assessed, as well as the potential uranium recovery. Biosoprtion performance increased progressively from pH 1.5 to 4.5, and uranium uptake was a rapid process, where film diffusion was the determining step. Maximum uptake ranged from 90 to 115 mg U(VI) g⁻¹at 15–33 °C, respectively. None of the commonly used adsorption models (Langmuir, Freundlich, Dubinin-Radushkevich) was able to describe the experimental isotherms, whereas the linear model seems to provide the best fit. Kinetic and thermodynamic data implied that both physical and chemical sorption are involved in the process. Species calculation experiments showed that only positively charged and uncharged uranium species can be retained on the biomass. Quantitative uranium recovery was achieved by mild desorbing agents at concentrations as low as 0.1 M. Therefore, grape stalks seem to be a promising biosorbent due to their high sequestration capacity even under high salinity and acidity conditions, low cost, and easy regeneration.