Effects of perchlorate stress on the growth and physiological characteristics of rice (Oryza sativa L.) were studied in controlled water culture experiments. Perchlorate stress resulted in varied patterns of biomass allocation to O. sativa organs (roots, stems, and leaves). When stressed with higher perchlorate concentrations, the proportion of root biomass was higher, stem biomass was invariant, while leaf biomass was lower. Coefficients of variation in biomass of different organs followed the order leaf > stem > root, indicating that leaf growth has a higher sensitivity to perchlorate. Compared to the control, the chlorophyll and protein content of leaves and root vigor were lower, whereas malondialdehyde (MDA) content and catalase (CAT) activity were higher and related to perchlorate concentration and duration of stress. Superoxide dismutase (SOD) activity was initially high and then decreased markedly during the experiment, while peroxidase (POX) activity in perchlorate-treated rice was always higher than the POX activity of the control. POX was the most sensitive antioxidant enzyme to perchlorate stress. Correlation analysis showed a positive correlation between SOD activity and the fresh weight of the whole plant, and negative correlation with MDA content. The results suggest that perchlorate could induce oxidative stress and oxidative damage may be the main cause of physiological damage and growth inhibition in rice plants under perchlorate stress.

Defoliation is one of the most important parameters monitored in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). Defoliation is an indicator for forest health and vitality. Conventional statistical analysis shows weak or not significant correlations between tree crown defoliation and climatic conditions or air pollution parameters, because of its high variability. The study aims to evaluate the most important factors among climatic, pollutants (Nₒₓ and NHy) and stand parameters affecting crown defoliation of the main European tree species (Fagus sylvatica, Picea abies, Quercus ilex, Pinus sylvestris and Quercus petraea) through application of a new and powerful statistical classifier, the random forests analysis (RFA). RFA highlighted that tree crown defoliation was mainly related to age in P. abies, to geographic location in F. sylvatica and to air pollution predictors in Q. ilex, while it was similarly linked to meteorological and air pollution predictors in P. sylvestris and Q. petraea. In this study, RFA has proven to be, for the first time, a useful tool to discern the most important predictors affecting tree crown defoliation, and consequently, it can be used for an appropriate forest management.

Potassium silicate drilling fluid (PSDF) is a relatively new type of drilling waste generated by the oil and gas industry. PSDF effects on soil, vegetation, and ground water must be determined before its land disposal and use in reclamation can be regulated. A laboratory column leachate study was conducted to quantify the response of select soil and leachate properties to PSDF at various depths in soil column profiles. A spent PSDF was applied to two soils (sand and loam textures) at four rates (20, 40, 60, 120 m³ ha⁻¹) with two application methods (incorporated, sprayed). Changes to soil and leachate properties were at values that would not be detrimental to most plant species when PSDF was applied at ≤60 m³ ha⁻¹. Applying PSDF at 120 m³ ha⁻¹had significant effects on soil properties and leachate quality. Hydraulic conductivity and field capacity were significantly reduced, and soil available potassium and sulfate concentrations, pH, and salinity increased with PSDF. Incorporated PSDF in the upper 10 cm of soil accelerated PSDF element transport through soil columns to leachate and increased organic carbon and salinity in leachate. PSDF application rate significantly reduced soil field capacity, available nitrogen, and increased salinity at the highest rates in loam soil, suggesting a threshold beyond which conditions will not be suitable for land spraying PSDF. This research demonstrates that PSDF has potential to improve soil short term water availability, macronutrient potassium and sulfur for disposal on cultivated and uncultivated lands. This potential should be field tested.

Pyrene, a four-ring polycyclic aromatic hydrocarbon that is highly resistant to degradation, persists in the environment and exerts its harmful effects toward humans, flora, and fauna when accumulated to a certain level. The ineffectiveness of conventional physical–chemical treatment methods has urged the emergence of biological treatments to degrade pyrene that persists in the environment. In this study, Pleurotus eryngii F032 was originally isolated from our laboratory due to its ability to degrade pyrene. Optimum conditions for pyrene degradation were determined using five different parameters, including pyrene concentration, incubation temperature, pH, agitation, and rhamnolipid concentration. The culture was incubated for 7, 15, 23, and 30 days, respectively, followed by pyrene extraction for degradation analysis. Results show that lower pyrene concentration requires less time for degradation by P. eryngi F032. Moreover, more time is needed for degradation when higher concentration is used, resulting in slower degradation. Optimum pyrene degradation conditions by P. eryngii F032 have been recorded at 40 °C incubation temperature, pH 3, and 2.5 % of rhamnolipid concentration with an agitation speed of 120 rpm. The capability of P. eryngii F032 to utilize pyrene as carbon and energy source depends on the presence of ligninolytic enzymes. The formation of protocatechuic acid resulting from pyrene degradation was detected via GC-MS analysis, which was further confirmed through spectrophotometric analysis.

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.

Water quality protection has become a key concern in water resources development and management. Uncontrolled nutrient input may challenge the quality of some water bodies. This study uses the relatively steep Kan watershed located in the north-west of Tehran (Iran) as an example case study, where an artificial lake is currently under construction for recreational purposes. Two approaches to predict the total annual phosphorous load were assessed: the soil and water assessment tool (SWAT) and the export coefficient approach. River discharge and sediment transport were simulated prior to modeling of the total phosphorous (TP) load in SWAT to make the model more accurate. In addition, an upstream to downstream calibration method was utilized. Findings reveal that the SWAT-simulated phosphorous load had sound Nash–Sutcliffe efficiency (ENS) values (ENSof 75 % for calibration and ENSof 52 % for validation). The relative error in estimating annual TP load was 7 %. The export coefficient approach assigning coefficients of export for each land use is known as an alternative method that can be used for estimating the TP load. Four sets of export coefficients were selected from the literature to examine their suitability in TP load prediction. The results showed significant errors in TP load prediction, which indicates that export coefficients are likely to be watershed-specific. Likewise, the export coefficients were found to vary through four wet months with errors ranging from 9 % to 33 %. This paper demonstrates that the export coefficient method may estimate the pollution load in the Kan watershed with less data than the advance SWAT model. However, it is associated with a higher level of error.

Episodes of pollution resulting from high concentrations of environmental ozone frequently occur in different parts of the world. The ozone can affect human health, natural vegetation, and agricultural productivity. The monitoring of ozone concentrations is essential to aid investigation of its effects and it is also required to assess progress in public management of this pollutant. A new effective and simple technique is presented for the determination of ambient ozone concentrations using a visual procedure. The method is based on the reaction between the dye indigo and ozone, with the formation of colorless products. The bleaching intensity is proportional to the amount of ozone. An indigo color standard scale was developed with the utilization of digital image-based (DIB) calibration and printed as a wheel-chart test kit. Ozone sampling is performed using a passive sampler containing a filter impregnated with indigo. The amount of reacted ozone can be determined by visual comparison using the wheel-chart test kit. The method enables determination of ozone concentrations from 2 to 97 ppb, with intervals of 3 ppb. It does not require an energy source or any post-sampling chemical treatment or analysis, and the ozone concentration can be known immediately, in situ, at the end of the sampling period. The method offers substantial advantages in large-scale mapping and monitoring of ozone or measurements concerning occupational exposure to ozone.

Microorganisms are abundant in many surface and near-surface geochemical environments. They interact with arsenic through a variety of mechanisms, including sorption, mobilisation, precipitation and redox and methylation transformation; sometimes, this is to their benefit, while other times it is to their detriment, substantially affecting the fate and transport of arsenic in the environment. Here, an attempt was made to review the current state of knowledge concerning microbial influences on arsenic transformation and retention processes at the water–solid interface with the goal to elucidate the ability of microorganisms to react with arsenic, and to quantify the role of microorganisms in the biogeochemical arsenic cycle. Such knowledge is indispensable for comprehensive understanding arsenic behaviour in the environment and support accurate assessment of the threat of arsenic contamination to human and environmental health, as well as for the development of novel technologies for arsenic bioremediation.

Cytostatic drugs are pharmaceutically active compounds used in chemotherapy to prevent or disrupt cell division. Only a few environmental studies have been focused on cytostatic drugs, in spite of their toxicity, their increasing consumption, and their discharge into municipal sewage. This fact can be mainly due to the lack of methods for their simultaneous analysis. This research describes the occurrence of 14 cytostatic drugs in influent and effluent wastewater from four wastewater treatment plants located in Seville (Spain) during 1-year period. A preliminary environmental risk assessment was also carried out. Five cytostatic drugs (cytarabine, etoposide, gemcitabine, iphosphamide, and methotrexate) were detected in influent wastewater at concentration levels up to 464 ng L⁻¹(cytarabine). Six of them (cytarabine, doxorubicin, gemcitabine, iphosphamide, paclitaxel, and vinorelbine) were detected in effluent wastewater at concentration levels up to 190 ng L⁻¹(cytarabine). Most of the detected cytostatic drugs are not significantly removed during wastewater treatment. Nevertheless, neither ecotoxicological nor genotoxical risks are expected to occur at the measured concentrations on the aquatic environment.

This work focuses on the effects of two commercial formulations of dispersants on juvenile turbot after 48 h of contamination and 15 days of recovery. Oxidative stress, gill, and immune functions were assessed in seven conditions: exposition to the water-soluble fraction of an oil, mechanical dispersion, two dispersants alone, two types of chemical dispersion and a control group. In the contaminated groups, nominal concentrations of oil and dispersants were 66 and 3.3 mg L⁻¹, respectively. Dispersants alone had weak effects; the soluble fraction induced leucopenia and gill alteration. Chemical and mechanical dispersion induced similar effects. After contamination, a principal component analysis showed two distinct areas: the first one included the control and dispersants groups, the second one dispersion of the oil. After the 15-day recovery period, it was not possible to differentiate the groups. This study shows that, in the experimental conditions tested, the dispersion, either chemical or mechanical, enhances the consequences of exposure to crude oil without long-lasting consequences.