The aim of this study was to assess possible genotoxic effects on floriculturists in a region of the state of Rio Grande do Sul, in the south of Brazil, using the micronucleus test (MN) and comet assay. Thirty-seven floriculturists and 37 individuals not exposed to pesticides participated in the study. The micronucleus test was performed with epithelial cells of the oral mucosa. In the microscopic analysis, 2000 cells were evaluated per subject, verifying the frequency of MN and the frequency of other nuclear abnormalities (nuclear buds, binucleated cells, and karyorrhexis). For the comet assay in the peripheral blood lymphocytes, 100 cells were classified in five classes, according to the migration of DNA fragments, thereby generating the frequency of damaged cells and the damage index. There was no difference between the exposed and control groups in the frequencies of MN and other nuclear abnormalities in the epithelial cells of the oral mucosa. However, the comet assay showed that both the frequency of DNA damaged cells and the damage index were significantly greater in the exposed group. The results therefore indicate that floriculturists are exposed to mixtures of pesticides with genotoxic potential.

As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm³. Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm³, respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil in kaolin clay normally had three kinds of effects including oil filling, coating, and bridging. Finally, a resistivity-based ANN model was established based on the database collected from the experiment data. The performance of the model was proved to be reasonably accepted, which puts forward a possible simple, economic, and effective tool to detect the oil content in contaminated clayey soils just with four basic parameters: wet density, dry density, measured moisture content, and electrical resistivity.

The objective of this study was to assess the growth of water hyacinth (Eichhornia crassipes) and its ability to accumulate Cu from polluted water with high Cu concentrations and a mixture of other contaminants under short-term exposure, in order to use this species for the remediation of highly contaminated sites. Two hydroponic experiments were performed under greenhouse conditions for 7 days. One of them consisted of growing water hyacinth in Hoagland solution supplemented with 15 or 25 mg Cu/L and a control. The other one contained water hyacinth growing in polluted river water supplemented with 15 mg Cu/L and a control. Cu was accumulated principally in roots. The maximum Cu concentration was 23,387.2 mg/kg dw in the treatment of 25 mg Cu/L in Hoagland solution. Cu translocation from roots to leaves was low. The mixture of 15 mg Cu/L with polluted water did not appear to have toxic effects on the water hyacinth. This plant showed a remarkable uptake capacity under elevated Cu concentrations in a mixture of pollutants similar to pure industrial effluents in a short time of exposure. This result has not been reported before, to our knowledge. This species is suitable for phytoremediation of waters subject to discharge of mixed industrial effluents containing elevated Cu concentrations (≥15 mg Cu/L), as well as nutrient-rich domestic wastewaters.

Quantitative structure–activity relationships (QSAR) for no observed adverse effect levels (NOAEL, mmol/kg/day, in logarithmic units) are suggested. Simplified molecular input line entry systems (SMILES) were used for molecular structure representation. Monte Carlo method was used for one-variable models building up for three different splits into the “visible” training set and “invisible” validation. The statistical quality of the models for three random splits are the following: split 1 n = 180, r ² = 0.718, q ² = 0.712, s = 0.403, F = 454 (training set); n = 17, r ² = 0.544, s = 0.367 (calibration set); n = 21, r ² = 0.61, s = 0.44, r ₘ ² = 0.61 (validation set); split 2 n = 169, r ² = 0.711, q ² = 0.705, s = 0.409, F = 411 (training set); n = 27, r ² = 0.512, s = 0.461 (calibration set); n = 22, r ² = 0.669, s = 0.360, r ₘ ² = 0.63 (validation set); split 3 n = 172, r ² = 0.679, q ² = 0.672, s = 0.420, F = 360 (training set); n = 19, r ² = 0.617, s = 0.582 (calibration set); n = 21, r ² = 0.627, s = 0.367, r ₘ ² = 0.54 (validation set). All models are built according to OCED principles.

Wastewater management is not limited to the technology used to collect and treat wastewater. It begins with the early planning phase of building a society and includes considerations of how that society will grow. Therefore, history, culture, religion, and socioeconomy are important components to include in any relevant and integrated studies of wastewater management and reuse. Engineering, health, chemistry, biology, food production, cultural heritage, and the needs of people of all ages should be considered together when making management decisions regarding issues so intimately tied with humanity as water and sanitation. Other escalating challenges such as poverty, food, and water scarcity, migration and instability, flooding and catastrophes, diseases and mortality, etc. should also be considered as part of wastewater management and reuse planning. Emerging contaminants could be associated with the urbanization, modernization, and industrialization of several countries. Several arid countries have developed water security strategies where wastewater reuse is a major component. The existing wastewater treatment technologies in these countries are, in most cases, unable to remove such contaminants which may affect irrigation waters, industrial products, groundwater, etc. People would have to accept that the food on their tables could be irrigated with treated wastewater that they generated a few months ago, even if very advanced technologies were used to treat it. The purpose of this review is to highlight multidisciplinary areas of research on wastewater and to propose applicable and affordable mechanisms by which we may consider wastewater as a legitimate resource.

Using a theoretical model, this paper argues that as firm productivity increases, there is a decrease in firm-level pollution intensity. However, as productivity increases, firms tend to increase their aggregate output, which requires the use of additional resources that increase pollution. Hence, an increase in productivity results in two opposing effects where increased productivity may in fact increase pollution created by a firm. We describe the joint effect of these two mechanisms on pollution emissions as the “productivity dilemma” of pollution emission. Based on firm-level data from China, we also empirically test this productivity dilemma hypothesis. Our empirical results suggest that, in general, firm productivity has a positive and statistically significant impact on pollution emission in China. However, the impact of productivity on pollution becomes negative when we control for increases in firm output. The empirical evidence also confirms the positive influence of productivity on output, which suggests that the main determinant of pollution is the firm’s output. The empirical results provide evidence of the existence of, what we describe as, the productivity dilemma of pollution emission.

Adding sorbents to sediments has been suggested as an effective technology for contaminated sediment remediation. In this study, a zirconium-modified zeolite (ZrMZ) was prepared, characterized, and used as a sediment amendment to control phosphorus (P) release from eutrophic lake sediments. The efficiency of ZrMZ in immobilizing P from water and sediments was investigated through a series of experiments. The phosphate adsorption capacity for ZrMZ decreased with increasing water pH. The adsorption of phosphate on ZrMZ followed a pseudo-second-order kinetic model. The equilibrium adsorption data of phosphate on ZrMZ could be well described by the Langmuir isotherm model with a maximum monolayer adsorption capacity of 10.2 mg P/g at pH 7 and 25 °C. Sequential extraction of P from the phosphate-adsorbed ZrMZ suggested that most of P bound by ZrMZ existed as the NaOH extractable P (NaOH-P) and residual P (Res-P) and was unlikely to be released under natural pH and reducing conditions. The addition of ZrMZ into sediments reduced the inorganic P activity in the sediments by transforming bicarbonate–dithionite extractable P (BD-P) to NaOH-P and Res-P. The contents of bioavailable P such as water-soluble P (WS-P), NaHCO₃extractable P (Olsen-P), and algal available P (AAP) in sediments reduced after the sediments were mixed with ZrMZ, making P in the sediments more stable. The addition of ZrMZ into sediments significantly reduced the releasing flux of P from the sediments to the water column under different conditions. Results of this study indicate that the ZrMZ is a promising sediment amendment for controlling the internal P loading of lake sediments.

Aspergillus niger was inoculated to the roots of five plants, and the Syngonium podophyllum-A. niger combinate system (SPANCS) was found to be the most effective in removing uranium from hydroponic liquid with initial uranium concentration of 5 mg L⁻¹. Furthermore, the hydroponic experiments on the removal of uranium from the hydroponic liquids with initial uranium concentrations of 0.5, 1.0, and 3.0 mg L⁻¹ by the SPANCS were conducted, the inhibitory effect of A. niger on the growth of S. podophyllum in the SPANCS was studied, the accumulation characteristics of uranium by S. podophyllum in the SPANCS were analyzed, and the Fourier transform infrared (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectra were measured. The results show that the removal of uranium by the SPANCS from the hydroponic liquids with initial uranium concentrations of 0.5, 1.0, and 3.0 mg L⁻¹ reached 98.20, 97.90, and 98.50 %, respectively, after 37 days of accumulation of uranium; that the uranium concentrations in the hydroponic liquids decreased to 0.009, 0.021, and 0.045 mg L⁻¹, respectively, which are lower than the stipulated concentration for discharge of 0.050 mg L⁻¹ by the People’s Republic of China; that A. niger helped to generate more groups in the root of S. podophyllum which can improve the complexing capability of S. podophyllum for uranium; and that the uranium accumulated in the root of S. podophyllum was in the form of phosphate uranyl and carboxylic uranyl.

Previous research has revealed that agricultural intensification in the Chao Lake Valley since the 1980s has led to significant heavy metal and phosphorus (P) contamination of estuarine sediments in this region. However, the pore water plays a more important role than do sediments in the cycling of nutrients and metals in estuarine ecosystems. Average concentrations of Cd, Cr, Ni, Pb, and P in the pore water of estuarine sediments were 0.634, 3.11, 4.98, 3.98, and 49.9 μg L⁻¹, respectively. Average diffusive fluxes of these elements from the pore water to overlying water were −0.015, 0.058, 0.768, −0.238, and 20.0 μg m⁻² d⁻¹, respectively. Compared with similar studies, the values of heavy metal fluxes were low, indicating minimal diffusion between sediments and overlying waters; however, P diffusion from the sediment pore water to overlying water was high, indicating that the sediments may be a direct source of P to overlying water. Since P is a major cause of algal blooming in agricultural estuaries of Chao Lake, the obtained results could be useful in developing effective management strategies to control pollution in the Chao Lake Valley.