Nutrient load into the ocean can be retained during the process of plant uptake and sedimentation in marshes along the bay zone. Seasonal variations of biomass and nutrient concentration in three dominated plant assemblages and associated sediments were monitored in this study area to determine effects of salt marsh on nutrient retention. Results showed that plant aboveground biomass displayed a unimodal curve with nutrient concentration generally decreased from spring to winter. Belowground biomass was relatively low during the rapid growth period with nutrient concentration tending to decrease and then increase during this period. Plant total nitrogen (TN) pools are higher than total phosphorus (TP) pools, and both pools showed significant seasonal variations. Water purification coefficients (WPC) of nutrients by plant assimilation were 34.4/17.3, 19.3/24.0, and 5.14/6.04 t/(m(2) year) (TN/TP) for Phragmites australis, Spartina alterniflora, and Scirpus mariqueter, respectively. Overall, these results suggest that higher annual plant biomass and nutrient assimilation contribute to greater nutrient retention capacity and accumulation in sediments, thereby enabling reduced eutrophication in transitional waters.

The aims of this paper were to survey the total Hg levels and distribution character in intertidal sediment in continental coast of Shanghai, and identify the environment factors that might influence the sediment Hg concentrations, and to assess the pollution degree and potential ecological risk of Hg in sediment. Eighty-eight surface sediment samples and 18 sediment cores were collected for Hg contamination analysis. Physicochemical properties including Eh, particle size, content of total organic carbon (TOC), and acid volatile sulfide (AVS) were also measured. Index of geo-accumulation (I geo) and potential ecological risk index were used respectively to assess the pollution levels and the ecological risk of sediment Hg. The average of total Hg concentrations in surface sediments was 107.4 ± 90.9 ng/g with the range from 0 to 465.9 ng/g. Higher Hg concentrations were generally found in surface sediments near sewage outfalls and the mouth of rivers. Total Hg concentrations were significantly correlated with TOC (p < 0.05) both in surface (r = 0.24) and core (r = 0.29) sediments, but not with the other environment factors (Eh, AVS, and particle size). Geo-accumulation index indicated that Hg contamination in intertidal sediments was generally at none to moderate degree, while potential ecological risk index demonstrated that the risk caused by Hg were at moderate to considerable level. Intertidal sediment in continental coast of Shanghai has generally been contaminated by Hg, and it might pose moderate to considerable risk to the local ecosystem. The Hg contamination is related more to the coastal pollution sources and complicated hydrodynamic and sedimentary conditions than the other environment factors studied.

The wintertime concentrations and diel cycles of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) associated to atmospheric particulate matter with aerodynamic diameter lesser than 10 μm were determined at the biggest student residence in Algeria located in Bab-Ezzouar, 15 km southeast from Algiers city area. Samplings were carried out from December 2009 to March 2010, and organic compounds were characterized using gas chromatography coupled with mass spectrometric detection. Volatile PAHs were also monitored inside some student residence rooms in order to evaluate the impact of indoor air pollution to student health. For the sake of comparison, aerial concentrations of n-alkanes and PAHs were determined in parallel in the Oued Smar industrial zone and two suburban areas, all located in Algiers. Total concentrations recorded in CUB1 student residence ranged from 101 to 204 ng m(-3) for n-alkanes and from 8 to 87 ng m(-3) for PAHs. Diel cycles have shown that, while concentrations of n-alkanes peaked at morning and afternoon-evening and dropped at night, those of PAHs exhibited higher levels at morning and night and lower levels at afternoon-evening, likely due to the reactivity of some PAHs. As expected, the indoor levels of PAHs were larger than in the outdoor of the student residence and were of serious health concern. Overall, the concentrations of n-alkanes and PAHs were as high as those observed in the industrial zone and higher than the two suburban sites.

Upon completion of exploration and extraction of mineral resources, many mining sites have been abandoned without previously putting environmental protection measures in place. As a consequence, mine waters originating from such sites are discharged freely into surface water. Regional scale analyses were conducted to determine the hydrochemical characteristics of mine waters from abandoned sites featuring metal (Cu, Pb–Zn, Au, Fe, Sb, Mo, Bi, Hg) deposits, non-metallic minerals (coal, Mg, F, B) and uranium. The study included 80 mine water samples from 59 abandoned mining sites. Their cation composition was dominated by Ca²⁺, while the most common anions were found to be SO₄ ²⁻ and HCO₃ ⁻. Strong correlations were established between the pH level and metal (Fe, Mn, Zn, Cu) concentrations in the mine waters. Hierarchical cluster analysis was applied to parameters generally indicative of pollution, such as pH, TDS, SO₄ ²⁻, Fe total, and As total. Following this approach, mine water samples were grouped into three main clusters and six subclusters, depending on their potential environmental impact. Principal component analysis was used to group together variables that share the same variance. The extracted principal components indicated that sulfide oxidation and weathering of silicate and carbonate rocks were the primary processes, while pH buffering, adsorption and ion exchange were secondary drivers of the chemical composition of the analyzed mine waters. Surface waters, which received the mine waters, were examined. Analysis showed increases of sulfate and metal concentrations and general degradation of surface water quality.

Following the technical closure of the brown lignite Meirama mine (NW Spain) in April 2008, the reclamation of the mined area is being accomplished with the controlled flooding of its large pit. During the first 7 months of flooding, the sequential arrest of the ground water dewatering system led to the growth of an acidic water body of about 2 hm(3). Since October 2008, the surface waters from some local streams have been diverted towards the pit so that these have become the major water input in the flooding process. Surface water has promoted a major change in the chemical composition of the lake water so that, at present, its surface has a circum neutral pH, net alkalinity, and low conductivity. At present, the lake has slightly more than one half of its final volume, and it is expected the overflow in 3 to 3.5 years. The lake is meromictic, with a sharp chemocline separating the acidic monimolimnion (pH ≈ 3.2, acidity ≈ 150 mg CaCO3/L, κ 25 ≈ 2.4 mS/cm) from the main water body (pH ≈ 6.5, alkalinity ≈ 15 mg CaCO3/L, κ 25 ≈ 0.3 mS/cm). Oxygen is being depleted at the bottom of the lake so that the monimolimnion became anoxic in January 2011. Above the chemocline, the composition of the lake is similar, but not identical, to that of the flooding stream waters. Close to the surface, some constituents (pH, metals) show strong seasonal variations in coincidence with the phytoplankton growing periods. Those parameters whose limits are legally prescribed comply with the corresponding water quality standards, and they are also consistent with the forecasting results obtained in early modeling. At present, a project considering the construction of an uptake tunnel to exploit the lake is being developed for the emergency water supply of the metropolitan area of A Coruña.

This work aims to analyze the relationship between root growth, mitogen-activated protein kinase (MAPK), auxin signaling, and cell cycle-related gene expression in cadmium (Cd)-stressed rice. The role of MAPKs in auxin signal modification and cell cycle-related gene expression during root growth was investigated by disrupting MAPK signaling using the MAPKK inhibitor PD98059 (PD). Treatment with Cd caused a significant accumulation of Cd in the roots. A Cd-specific probe showed that Cd is mainly localized in the meristematic zone and vascular tissues. Perturbation of MAPK signaling using PD significantly suppressed root system growth under Cd stress. The transcription of six MAPK genes was inhibited by Cd compared to the control. Detection using DR5-GUS transgenic rice showed that the intensity and distribution pattern of GUS staining was similar in roots treated with PD or Cd, whereas in Cd plus PD-treated roots, the GUS staining pattern was similar to that of the control, which indicates a close association of MAPK signaling with auxin homeostasis under control and Cd stress conditions. The expression of most key genes of auxin signaling, including OsYUCCA, OsPIN, OsARF, and OsIAA, and of most cell cycle-related genes, was negatively regulated by MAPKs under Cd stress. These results suggest that the MAPK pathway plays specific roles in auxin signal transduction and in the control of the cell cycle in response to Cd stress. Altogether, MAPKs take part in the regulation of root growth via auxin signal variation and the modified expression of cell cycle-related genes in Cd-stressed rice. A working model for the function of MAPKs in rice root systems grown under Cd stress is proposed.

Chlorinated ethenes (CE) are among the most frequent contaminants of soil and groundwater in the Czech Republic. Because conventional methods of subsurface contamination investigation are costly and technically complicated, attention is directed on alternative and innovative field sampling methods. One promising method is sampling of tree cores (plugs of woody tissue extracted from a host tree). Volatile organic compounds can enter into the trunks and other tissues of trees through their root systems. An analysis of the tree core can thus serve as an indicator of the subsurface contamination. Four areas of interest were chosen at the experimental site with CE groundwater contamination and observed fluctuations in groundwater concentrations. CE concentrations in groundwater and tree cores were observed for a 1-year period. The aim was to determine how the CE concentrations in obtained tree core samples correlate with the level of contamination of groundwater. Other factors which can affect the transfer of contaminants from groundwater to wood were also monitored and evaluated (e.g., tree species and age, level of groundwater table, river flow in the nearby Ploučnice River, seasonal effects, and the effect of the remediation technology operation). Factors that may affect the concentration of CE in wood were identified. The groundwater table level, tree species, and the intensity of transpiration appeared to be the main factors within the framework of the experiment. Obtained values documented that the results of tree core analyses can be used to indicate the presence of CE in the subsurface. The results may also be helpful to identify the best sampling period for tree coring and to learn about the time it takes until tree core concentrations react to changes in groundwater conditions. Interval sampling of tree cores revealed possible preservation of the contaminant in the wood of trees.

Three multiple input and multiple output-type fuzzy-logic-based models were developed as an artificial intelligence-based approach to model a novel integrated process (UF–IER–EDBM–FO) consisted of ultrafiltration (UF), ion exchange resins (IER), electrodialysis with bipolar membrane (EDBM), and Fenton’s oxidation (FO) units treating young, middle-aged, and stabilized landfill leachates. The FO unit was considered as the key process for implementation of the proposed modeling scheme. Four input components such as H₂O₂/chemical oxygen demand ratio, H₂O₂/Fe²⁺ ratio, reaction pH, and reaction time were fuzzified in a Mamdani-type fuzzy inference system to predict the removal efficiencies of chemical oxygen demand, total organic carbon, color, and ammonia nitrogen. A total of 200 rules in the IF–THEN format were established within the framework of a graphical user interface for each fuzzy-logic model. The product (prod) and the center of gravity (centroid) methods were performed as the inference operator and defuzzification methods, respectively, for the proposed prognostic models. Fuzzy-logic predicted results were compared to the outputs of multiple regression models by means of various descriptive statistical indicators, and the proposed methodology was tested against the experimental data. The testing results clearly revealed that the proposed prognostic models showed a superior predictive performance with very high determination coefficients (R ²) between 0.930 and 0.991. This study indicated a simple means of modeling and potential of a knowledge-based approach for capturing complicated inter-relationships in a highly non-linear problem. Clearly, it was shown that the proposed prognostic models provided a well-suited and cost-effective method to predict removal efficiencies of wastewater parameters prior to discharge to receiving streams.

The combination of zero-valent iron (ZVI) with anaerobic sludge for enhancing reductive transformation and dechlorination of p-chloronitrobenzene (p-ClNB) was investigated in this study. p-ClNB was quickly reduced into p-chloroaniline (p-ClAn) and subsequently dechlorinated into aniline in the complex system, and the strengthening factor for pseudo-first-order transformation rate constant of p-ClNB (Q, k ZVI ₊ ₛₗᵤdgₑ/(k ₛₗᵤdgₑ + k ZVI)) was above 3. The Q values for the different ZVI types with anaerobic sludge were as following: Reduced ZVI (RZVI) > Industrial ZVI > Nanoscale ZVI (NZVI). Thereinto, the aggregation of NZVI occurred, and its reaction activity declined. Furthermore, the increase of ZVI dosage promoted the p-ClNB transformation, but the p-ClAn dechlorination rate and Q value were not improved. With the anaerobic biomass increasing, the dechlorination rate of p-ClAn was significantly enhanced, and the Q value had positive relation with the mass ratio of anaerobic sludge to RZVI.

The levels of organochlorine pesticides (OCPs) in the water, suspended solids, and sediments from Lake Chaohu during the high water level period were measured by a solid-phase extraction gas chromatograph–electron capture detector. The spatial distributions of the three phases and the water/suspended solids and sediment/water partition coefficients were analyzed. The results showed the following: (1) The mean contents of OCPs in the water, suspended solids, and sediments were 132.4 ± 432.1 ng/L, 188.1 ± 286.7 ng/g dry weight (dw), and 13.7 ± 9.8 ng/g dw, respectively. The dominant OCP components were isodrin (85.1 %) for the water, DDTs (64.4 %) for the suspended solids, and both isodrin (48.5 %) and DDTs (31.8 %) for the sediments. (2) β-HCH was the primary isomer of HCHs in the water and sediments, and the proportions were 61.7 and 41.3 %; γ-HCH was the primary isomer in the suspended solids, accounting for 49.3 %; p,p′-DDT was the dominant content of DDTs in the water and suspended solids, whereas p,p′-DDD was the main metabolite of DDTs in the sediments. (3) The concentrations of contaminants in the water from the western lake were greater than those from the eastern lake, but the concentrations in the suspended solids from the western lake were less than those from the eastern lake. (4) There was no significant correlation between the water–suspended solids partition coefficient K d and the n-octanol–water partition coefficient K ₒw, and between the sediment–water organic-C weighted sorption coefficients K ₒc and K ₒw.