The level of mercury (Hg) concentration in soils can be estimated using certain predictors such as the content of organic carbon (Cₒᵣg) or the fine fractions (FFs) such as silt and clay. This study was focused on the potential use of Cₒᵣgand FF contents as the predictors of Hg concentration at the spatial meso-scale in forest soils derived from Triassic sandstones and claystones, Quaternary sands derived from weathering sandstones and Quaternary sands of fluvioglacial origin. To understand the importance of Cₒᵣgand FF contents for Hg retention in mineral soil, the allocation of Hg in physically separated fractions of soil samples was also tested. The experiment was designed over a regular 200 × 200-m grid, where 275 plots were established. The results implied that the concentration of total Hg in mineral soil may vary by several orders of magnitude because of the natural variation in Cₒᵣgcontent. The model where the Cₒᵣgcontent was the only variable explained 44 % of Hg concentration variability in soil, and other significantly correlated variables were the FF content and the C/N ratio. Detailed analysis revealed that the particulate organic matter fraction accumulated more Hg per unit of Cₒᵣgthan in the organic matter associated with FF. The content of Cₒᵣg, FF and C/N ratio allowed, for the local soils, a satisfactory prediction of the spatial distribution and the magnitude of total Hg concentration in soils.

The scope of this study was to investigate the uptake of chromium and nickel by onions (Allium cepa) and potatoes (Solanum tuberosum) and their impact on plant enzymes catalase (CAT, E.C. 1.11.1.6) and peroxidase (POX, E.C. 1.11.1.7). A greenhouse experiment was conducted, simulating the irrigating conditions existing in the two biggest tuber-producing regions of Greece (Asopos and Messapia). Plants were cultivated for 4 months in six irrigation lines, each one supplied by an aqueous solution, containing levels of Cr(VI) and Ni(II) ranging from 0 μg/L (control) to 1,000 μg/L. Significant statistical correlations were observed between (i) the levels of heavy metals in plants, (ii) the levels of heavy metals in plants and in irrigation water, and (iii) the levels of heavy metals and the enzymatic activities in plants. The existing EU legislation has no legal limits for Ni and Cr in food, and the nutritional implications of this study are discussed.

The extent of endosulfan sulfate removal from soils by different planting pattern with sweet corn (Zea mays), cowpea (Vigna sinensis), and cucumber (Cucumis sativus) either cultivated alone or together was investigated in pot experiments. Endosulfan sulfate was removed to the greatest extent in the treatment in which sweet corn was grown alone; only 11.3 and 27.2 % of the initial endosulfan sulfate remained in rhizospheric and bulk soil, respectively, of sweet corn grown alone at day 60. Endosulfan sulfate was also removed from soil to a great extent in treatments where cucumber or cowpea was grown alone; only 30.3 and 38.8 % of endosulfan sulfate remained in their respective rhizospheric soil after 45 days. However, cucumber did not tolerate the toxicity of endosulfan sulfate well and died around 50–55 days when it was cultivated either alone or together with another plant. Cultivation of sweet corn and cowpea together was less effective in removing endosulfan sulfate from soil; about 41.7 and 52.3 % of endosulfan sulfate remained in their respective rhizospheric soils after 60 days. The results showed that single cultivation of the plants was the most efficient way to remediate endosulfan sulfate-contaminated soil in this study. Endosulfan sulfate was detected in both the root and shoot of plants but given the low levels found, bioaccumulation was judged to be a relatively minor factor in endosulfan sulfate removal from soil.

In the present research work, different types of biodiesel were produced by a homogeneous alkali transesterification reaction using soybean oil, pork lard, and castor bean oil as raw materials, to evaluate how their different compositions may affect the biodegradability, namely, in the presence of benzene. Biodiesel was characterized according to the European standard EN 14214. The anaerobic biodegradation of the different types of biodiesel was examined as well as its influence on the biodegradation of benzene. Analyses were performed to determine the volume of methane (directly related to the anaerobic biodegradation of biodiesel), the concentration of benzene over time, and the production of organic acids. The results showed methane production resulting from the anaerobic degradation of all biodiesel types. The differences between the degradation behavior of each fuel were negligible, contrary to what was expected; however, the amount of methane produced was low due to nutrient limitations. This fact was confirmed by the organic acid analysis as well as by the addition of new media. Anaerobic benzene biodegradation was found to be negatively impacted by the presence of all biodiesel types on average; therefore, the results of this study may impact management of sites that contain biodiesel and fuel hydrocarbon contamination.

A laboratory-scale study was conducted to test whether biochar from cow dung as a soil amendment can reduce nutrient leaching from soil irrigated with biogas slurry. Polyvinyl chloride (PVC) columns were packed with soils containing 0, 20, and 40 g kg⁻¹of biochar. The biogas slurry was applied at 0, 200, and 400 ml per column, equivalent to 0, 130, and 260 kg N ha⁻¹. The biogas slurry was diluted to 1,500 ml with water and then applied five times every 6 days at 300 ml each time. All leached solutions were collected separately. Results showed that soil available phosphorus (P) and potassium (K) increased significantly with increased biogas slurry rates and biochar rates. The concentrations of total N, P, and K in leached solutions increased significantly as biogas slurry rates increased. Biochar significantly increased the concentrations of total and available P, total K, and electric conductance in leached solution. Contributions of biochar and biogas slurry treatments to the net amount of N, P, and K in leached solution increased with increased biochar and biogas slurry rates except at 4 % biochar rate where total N was decreased. Nutrient removal rate of biochar was over 10.6 % for total N and negative for total K at 2 % biochar rate. Nutrient removal rate of biochar was over 7.19 % for total P and negative for total N and total K at 4 % biochar rate. It is suggested that both biogas slurry and biochar have the potential to pollute water when leaching happens although biochar has the ability to adsorb N and P from biogas slurry.

In view of the fatal illnesses caused by methylene blue (MB) which is contained in the dye wastewater, the present study focused on the use of natural sunlight in heterogeneous photocatalysis to decolorize and degrade MB. The present study also investigated the effects of enhancers (hydrogen peroxide and persulfate ion) and inhibitors (chloride and carbonate ions) on photodecolorization of MB. Pseudo-first-order rate constants for each studied effect were determined through Langmuir-Hinshelwood model. The recommended conditions to photodecolorize 60 ppm of MB under natural sunlight were 1.0 g/L of titanium dioxide nanopowder at initial pH 10.5 in order to achieve 85.3 % decolorization (rate constant of 10.8 × 10⁻³ min⁻¹). The addition of 4,080 ppm of hydrogen peroxide and persulfate ion significantly enhanced the decolorization efficiency up to 96.6 and 99.3 %, respectively (rate constants of 66.2 and 91.0 × 10⁻³ min⁻¹, respectively). However, the addition of 2,000 ppm of chloride and carbonate ions reduced the decolorization efficiency of MB to 74.7 and 70.2 %, respectively (rate constants of 7.8 and 7.3 × 10⁻³ min⁻¹, respectively). The present study implied that it was possible to use natural sunlight as a light source for photocatalytic treatment of dye in tropical countries like Malaysia.

A pot experiment was conducted to investigate the effect of nitrogen fertilizer on CH₄ emission from a paddy soil under greenhouse conditions. The experiment was designed with two fertilizer types, i.e., controlled-release nitrogen fertilizer (CRNF) and urea (U), and two rice cultivars, i.e., herbicide-resistant transgenic rice (japonica line B2) and its parent conventional rice (japonica cv Xiushui 63). Compared with control (urea), one-time basal application of CRNF increased tiller number, plant height, biomass, and yield in rice and significantly decreased total CH₄ emission from the paddy soil. The total CH₄ emission was significantly lower from the transgenic cultivar than that from the conventional cultivar. It is suggested that CRNF and herbicide-resistant transgenic rice are helpful in mitigating CH₄ emission from the paddy soil.

This study was undertaken to synthesise a novel biomass-based chemically activated carbon from Australian pine cone and to investigate its effectiveness in the removal of anionic dye Congo red from aqueous solution. The effect of activation parameters such as the concentration of phosphoric acid and temperature were identified as the most efficient parameters for activation in the Congo red removal. The synthesised activated carbon was characterised by Fourier transform infrared and different physical properties, such as bulk density, CHNS analysis, carbon yield, particle size, zeta potential and Brunauer–Emmett–Teller surface area were also determined. Batch adsorption study showed that the amount of adsorption depends on various physico-chemical process parameters, such as solution pH, dye concentration, temperature and adsorbent dose. It was observed that Langmuir maximum adsorption capacity was 500 mg/g at a pH of 3.5. Furthermore, pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models were fitted to examine the adsorption kinetic and mechanism of adsorption. Equilibrium data were fitted with Langmuir, Freundlich and Tempkin adsorption isotherm models. Thermodynamic parameters such as ΔG⁰, ΔH⁰, and ΔS⁰were also calculated. Finally, a single-stage batch adsorber design for the Congo red adsorption onto activated carbon particles was presented based on the Freundlich isotherm model equation. These results indicated pine cone biomass is a good and cheap precursor for the production of an effective activated carbon adsorbent and alternative to commercial-activated carbon.

An inexact left-hand-side chance-constrained programming (ILCCP) was proposed and applied to a nonpoint-source water quality management problem within an agricultural system. The ILCCP model can reflect uncertainties presented as interval parameters (manure mass balance, crop nutrient balances, energy and digestible protein requirements, pollutant losses, water quantity constraints, technical constraints, and so on) and left-hand-side random variables (nitrogen requirement of crop i) at the same time. A non-equivalent linearization form of ILCCP was deduced and proved intuitively, which can help handle the left-hand-side random parameters in the constraints. The decision schemes through ILCCP were analyzed under scenarios at different individual probabilities (p ᵢ , denotes the admissible probability of violating the constraint i). The performance of ILCCP was also compared with the corresponding interval linear programming model. A representative nonpoint-source water quality management case was employed to facilitate the analysis and the comparison. The optimization results indicated that the net system benefit in the water quality management case would decrease with increasing probability levels on the whole. This was because that the higher constraint satisfaction of probability would lead to stricter decision space. The optimal scheme shows an obvious downtrend in the application amount of manure as the violation probability levels decreasing from scenarios 1 to 3 (p ᵢ = 0.1, 0.05 and 0.01). This demonstrates that the application amount of manure would be reduced effectively by adjusting strictness of the constraints. This study is the first application of the ILCCP model to water quality management, which indicates that the ILCCP is applicable to other environmental problems under uncertainties.

Quantifying plant biomass and related processes such as element allocation is a major challenge at the scale of entire riparian zones. We applied sub-decimetre-resolution (5 cm) remote sensing using an unmanned aircraft system (UAS) in combination with field sampling to quantify riparian vegetation biomass at three locations (320-m river stretches) along a mining-impacted boreal river and estimated the amounts of Cd, Cu, and Zn stored in the dominant species. A species-level vegetation map was derived from visual interpretation of aerial images acquired using the UAS and field sampling to determine species composition and cover. Herbaceous and shrub biomass and metal contents were assessed by combining the vegetation maps with field sampling results. Riparian zone productivity decreased from 9.5 to 5.4 t ha⁻¹with increasing distance from the source of contamination, and the total amount of vegetation-bound Cd and Zn decreased from 24 to 0.4 and 3,488 to 211 g, respectively. Most Cu was stored at the central location. Biomass and metal contents indicated large variation between species. Salix spp. comprised only 17 % of the total dominant-species biomass but contained 95 % of all Cd and 65 % of all Zn. In contrast, Carex rostrata/vesicaria comprised 64 % of the total dominant-species biomass and contained 63 % of all Cu and 25 % of all Zn. Our study demonstrates the applicability of UAS for monitoring entire riparian zones. The method offers great potential for accurately assessing nutrient and trace element cycling in the riparian zone and for planning potential phytoremediation measures in polluted areas.