The EU directive has addressed ambitious targets concerning the quality of water bodies. Predicting water quality as affected by land use and management requires using dynamic agro-hydrogeological models. In this study, an agronomic model (STICS) and a hydrogeological model (MODCOU) have been associated in order to simulate nitrogen fluxes in the Seine-Normandie Basin, which is affected by nitrate pollution of groundwater due to intensive farming systems. This modeling platform was used to predict and understand the spatial and temporal evolution of water quality over the 1971–2013 period. A quality assurance protocol (Refsgaard et al. Environ Model Softw 20: 1201–1215, 2005) was used to qualify the reliability of STICS outputs. Four iterative runs of the model were carried out with improved parameterization of soils and crop management without any change in the model. Improving model inputs changed much more the spatial distribution of simulated N losses than their mean values. STICS slightly underestimated the crop yields compared to the observed values at the administrative district scale. The platform also slightly underestimated the nitrate concentration at the outlet level with a mean difference ranging from −1.4 to −9.2 mg NO₃ L⁻¹ according to the aquifer during the last decade. This outcome should help the stakeholders in decision-making to prevent nitrate pollution and provide new specifications for STICS development.

Salinity is one of the major factors contributing in land degradation, disturbance of soil biology, a structure that leads to unproductive land with low crop yield potential especially in arid and semiarid regions of the world. Appropriate crops with sufficient stress tolerance capacity and non-conventional water resources should have to be managed in a sustainable way to bring these marginal lands under cultivation for future food security. The goal of the present study was to evaluate salinity tolerant potential (0, 7, and 14 dS m⁻¹) of six safflower genotypes that can be adapted to the hyper arid climate of UAE and its marginal soil. Several agro-morphological and physiological traits such as plant dry biomass (PDM), number of branches (BN), number of capitula (CN), seed yield (SY), stable isotope composition of nitrogen (δ¹⁵N) and carbon (δ¹³C), intercellular CO₂ concentration from inside to ambient air (Ci/Ca), intrinsic water use efficiency (iWUE), carbon (C%) and nitrogen (N %), and harvest index (HI) were evaluated as indicative of the functional performance of safflower genotypes under salt stress. Results indicated that salinity significantly affected the seed yield at all levels and varied significantly among genotypes. The BN, PDM, CN, and δ¹³C attributes showed clear differentiation between tolerant and susceptible genotypes. The δ¹³C results indicate that the tolerant genotypes suffer less from stress, may be due to better rooting. Tolerant genotypes showed lower iWUE values but possess higher yield. Safflower genotypes (PI248836 and PI167390) proved to be salt tolerant, stable, and higher seed and biomass yielder. There was no G × E interaction but the genotypes that produce higher yield under control were still best even under salt stress conditions. Although salinity reduced crop yield, some tolerant genotypes demonstrate adaptation and good yield potential under saline marginal environment.

Natural clay combing with iron oxide and iron particle was developed to be iron-mixed mesoporous pellet that was packed in a fixed-bed column for removing arsenic from water. The performance of the column in terms of breakthrough curve analysis was investigated with the variations of influent flow rate, adsorbent bed height, initial solution pH, and initial adsorbate concentration. The results indicated that increasing in the flow rate decreased the removal capacities of the adsorbent. A relatively low bed height provided a better and beneficial performance. Higher adsorption capacity was observed with an increase of initial adsorbate concentration. At higher initial solution pH, the repulsive process occurred between adsorbate species and the surface charge of the adsorbent, resulting in a poor performance of the column. The Thomas model fitted very well to the experimental data for all cases. Estimated from the model, the highest adsorption capacity for arsenite and arsenate was found to be about 509 and 430 μg/g, respectively. The Adam-Bohart model provided only a relatively satisfactory fit to the initial part of the experimental data. From a practical view, the new developed pellet could be used as the effective and efficient adsorbent to treat elevated arsenic contaminated groundwater.

Artificial errors in the experimental process may lead to some outliers, which reduce data quality and cause erroneous judgment in soil pollution assessment. Based on this, a method for detecting outliers of soil heavy metal data was proposed in this study. The As, Cd, and Pb concentrations of the soil in Beijing, China, were taken as samples to verify the validity of the method. Results showed that there were 8, 34, and 38 outliers for the As, Cd, and Pb concentrations in the Beijing soil, respectively. The result of re-analyzed revealed that 75.0, 76.5, and 92.1% of the As, Cd, and Pb outliers, respectively, were caused by artificial errors. After correcting, the interpolation accuracy for data was improved significantly. The mean relative error (MRE) of the As, Cd, and Pb outliers decreased by 48.0, 44.6, and 54.7%, while the mean square error of these outliers decreased by 34.2, 33.3, and 46.4%, respectively. The MRE values of the nearest neighboring points which were influenced by the outliers decreased by 5.2, 20.6, and 27.6%, while the mean square error of these points decreased by 5.3, 17.3, and 33.2%, respectively. To our knowledge, this is the first study on detecting outliers of soil heavy metal data. The method considers both spatial and numerical outliers, which avoids the limitation of single method, and can effectively improve the data quality of soil heavy metal concentrations with a finite sample size and analysis time.

Heavy metal-polluted water has become a problem for sustainable environment, agriculture, and human health. Phyto-accumulation is an eco-friendly technique for decontamination of metal-polluted water and soil. The efficiency of phyto-accumulation and rhizo-filtration can be enhanced by the application of certain nutrients to accumulator plants. In this study, we focused on the role of iron (Fe) in rhizo-filtration and phyto-accumulation of cadmium (Cd) from polluted water/media, using Ricinus communis plant. Medium was contaminated with 10 ppm Cd while Fe (2.50, 5.00, and 7.50 ppm) was applied both as foliar spray and medium addition separately. Accumulation of Cd and concentrations of soluble proline, phenolic compounds, and chlorophylls were measured in plant tissues. Addition of Fe into media significantly increased biomass in the plants but decreased Cd absorption by roots and its accumulation in other tissues of the plants. Foliar application of Fe, especially 7.5 ppm, significantly increased biomass as well as accumulation of Cd in tissues of the plants. Contents of soluble proline (41.88 ± 3.56 ppm) and phenolics (171.00 ± 4.98 ppm) in leaves were highly increased by foliar spray of 7.5 ppm Fe on the plants. On the other hand, highest concentrations of free proline (67.00 ± 2.00 ppm) and total phenolics (82.67 ± 2.52 ppm) in plant roots were observed in 7.5 ppm Fe added to media and as foliar spray, respectively. Strong correlations were observed between phenolics content in roots and leaves with Cd accumulation after foliar application of 7.5 ppm Fe.

When copper-based algaecides are used in aquatic systems to decrease cyanobacteria densities, endotoxin fate is a concern, due to the potential for human health and ecological risks. Pulse exposures of algaecides can result in episodic low dissolved oxygen (DO) concentrations (< 2 mg L⁻¹), due to oxygen consumed via microbial oxidation of algal detritus. Research objectives of this study were to determine the influence of declining DO levels on microcystin-LR (MC-LR) degradation and changes in resident bacterial assemblages. It was hypothesized that cyanobacteria cell densities would be positively correlated with rates and extents of DO decline based on the oxygen required for bacteria to degrade cyanobacteria detritus following exposure to copper-based algaecides. In addition, it was hypothesized that total MC-LR concentrations would increase proportionally with increasing cyanobacteria cell densities. Mesocosm experiments were conducted in a pond in Anderson, SC, that frequently experiences cyanobacteria blooms. Three densities of a cyanobacteria assemblage were exposed to a copper ethanolamine algaecide. DO and total MC-LR concentrations were measured with time following algaecide exposures to determine rates and extents of declines. As anticipated, DO concentrations had the highest rate of decline in the highest cell density treatment, followed by medium and low cell densities. MC-LR degradation occurred at similar rates (half-lives 1 to 1.9 days) among cell densities. Acinetobacter and Aeromonas were dominant in treatments following copper exposures. The relationship between cyanobacteria densities and MC-LR half-lives demonstrates the benefits of managing cyanobacteria in early growth stages to minimize MC concentrations.

A strain of Desulfovibrio sp. sulfate-reducing bacteria (SRB) was isolated from a sludge sample. Novel immobilized SRB beads with microalgae (Chlorella vulgaris, Scenedesmus obliquus, Selenastrum capricornutum, and Anabaena spiroides) as the carbon source were prepared and then used to treat wastewater containing 60 mg/L Cu(II) and 600 mg/L sulfate in batch experiments. The microalgae were first degraded by co-existing fermentative bacteria into fatty acids, which then served as a carbon source for SRB. The solution chemical oxygen demand was significantly lower with microalgae substrates than with ethanol as a substrate. Different immobilization methods were evaluated with an orthogonal design, which indicated that the compositional parameters for preparing immobilized beads with an optimal sulfate reduction rate were polyvinyl alcohol (2%), sodium alginate (1%), calcium chloride (6%), silica sand (1%), and a 50-mL volume of SRB suspension. SRB activity in the immobilized beads was distinctly enhanced compared with that of suspended SRB. At an initial pH of 5.5, 72.4–74.4% of sulfate and over 91.7% of Cu(II) were removed, indicating that immobilized SRB beads with plentiful low-cost microalgae as a nutrient source may be an efficient method for acid mine drainage treatment.

The objective of this study was to evaluate lead phytotoxicity on Talinum patens and the morpho-physiological tolerance mechanisms. The following parameters were considered: germination percentage, germination speed index, root and shoot length, fresh and dry matter, lead content in tissues, enzymatic antioxidant system, proline content, lipid peroxidation, root anatomy, cytogenetic analysis, and chlorophyll fluorescence. The experimental design was completely randomized, with five concentrations: 0, 50, 100, 250, and 500 μM Pb(NO₃)₂ and five replicates. Exposure to Pb(NO₃)₂ solutions did not influence germination, shoot length, or fresh and dry matter. However, a Pb(NO₃)₂-dependent concentration effect was observed, which reduced cell division in the root meristematic zone (mitotic index), reducing their length. Superoxide dismutase, catalase, and ascorbate peroxidase showed increased activity when exposed to lead, and the same effect was detected for proline content and lipid peroxidation. There was an increase in the dissipation of excess energy in photosystems, as well as an increase in epidermal thickness. Therefore, Talinum patens plants had morpho-physiological characteristics that favor their germination, development, and metal tolerance.