Lime was investigated as a soil amendment to decrease phosphorus (P) loss in runoff from two Delaware sandy loam soils, one high and one low in P. Soils were limed at three rates (control and target pH values of 6 and 6.8, respectively), packed into runoff boxes (2,000 cm²) and received simulated rainfall (80 mm h⁻¹ for 30 min). Lime showed potential to decrease P loss in runoff, but its effectiveness was soil specific and dependant on other management factors also. Lime decreased dissolved reactive P (DRP) and dissolved organic P (DOP) loss by 20–25 and 52–93 %, respectively, for the high-P soil and particulate P (PP) by 13 % for the low-P soil. The majority of P lost in runoff was DOP (3–29 %) or PP (64–96 %). Lime increased PP losses from the finer-textured soil following P application, indicating that increased P sorption can lead to increased losses if P is sorbed to more erodable particles. Initial soil P status was more important than liming in determining P loss. While amendments may decrease P losses in the short term, addressing nutrient imbalances at the field scale is clearly necessary in the long term. Losses increased significantly following inorganic P application. Although P was sorbed rapidly, with less than 2 % of added P removed in runoff, mean concentrations in excess of 700 μg l⁻¹ DRP, 2,500 μg l⁻¹ OP and 6,500 μg l⁻¹ PP were recorded for both soils immediately following P application.

In situ remediation with waste material is an inexpensive method to reduce contaminant availability in polluted soil. The experiments were done to investigate the effects of possible in situ application of two different amendments: inorganic material (marble sludge) and organic material (horticultural waste compost) on chemical and biological properties of abandoned metalliferous mine wastes. The results show that the application of inorganic material raises the pH above neutrality and the combination of inorganic and organic material would produce the highest ratio of biological activity. The reductions of available Zn, Pb and As in lime, organic and lime/organic amendments were favoured by incubation time. However, available Cd content increased after 275 days of incubation, except the treatment with inorganic amendment. This work denoted that the application of lime with organic amendments has a better effect than the lime alone because the addition of both amendments improves both soil chemical and biological properties.

The performance of the magnetic anion exchange resin, MIEX®, in the pretreatment of reclaimed water for managed aquifer recharge (MAR) was investigated. MIEX® can effectively remove aromatic organic substances with molecular weights above 10 kDa and between 1 and 5 kDa, which are always present recalcitrant during soil infiltration. The removal of organic substances is accompanied by the elimination of other undesirable components in MAR, such as nitrogen and phosphorus. The optimal process parameters are at resin doses of 5–10 mL L⁻¹ and contact time of 10–15 min, as determined via jar tests. The efficiency of the MAR pilot system was consistent throughout the long running time, during which the MIEX® treatment significantly contributed (30 to 60 %) to the removal of both organic and inorganic materials (i.e., dissolved organic carbon, ultraviolet absorbance at 254 nm, color, nitrate, ammonia, phosphorus, and sulfate). The quality of the MAR final effluent is lower than the groundwater standard for drinking sources (type III in GB/T 14848-93). Based on this study, MIEX® treatment is a suitable and efficient pretreatment method for the removal of extra dissolved organic matters and nitrates in reclaimed water for MAR.

As global mercury emissions from coal fire power plants increase with the continuing rise of coal consumption, mercury capture methods are being developed to prevent mercury’s escape into the atmosphere. Titanium dioxide (TiO₂) in the presence of ultra violet light (UV-A; λ ₘₐₓ ∼360 nm) and oxygen will capture mercury as the solid product HgO₍ₛ₎. Testing the effects of TiO₂ in the presence of other pollutants has so far been limited. We have performed kinetic and product studies of mercury adsorption in the presence of the gaseous flue co-pollutant NO₂₍g₎. We extensively studied the gas-phase reaction of NO₂(g) with Hg ₍g₎ ⁰ . We compared the gas-phase reaction to the same reaction performed in the presence of thin TiO₂ particle surfaces from 0 to 100 % relative humidity. The second-order rate constant was measured to be k = (3.5 ± 0.5) × 10⁻³⁵ cm⁶ molecules⁻² s⁻¹, independent of the presence of titania or the total surface area available for adsorption. Exposure of NO₂₍g₎ to titania surfaces that were already saturated in captured mercury (HgO₍ₛ₎) increased total mercury uptake onto the surface. We discuss the implications of this study to the capture of mercury emissions prior to release to the atmosphere.

The complete mineralization of the conazole fungicide triadimefon in water at pH 3 using electrochemical advanced oxidation processes, electro-Fenton and photo electro-Fenton, was achieved. The electrochemical system consisted of a one-compartment electrochemical cell of 100 mL provided with a glassy carbon mesh electrode (cathode) and a concentric outer steel mesh as anode. The electrolysis was realized at constant current. The most remarkable features are as follows: (1) photo electro-Fenton process reaches a complete mineralization of triadimefon after 2 h of electrolysis with respect to electro-Fenton method; and (2) 4-chlorophenol, hydroquinone, carboxylic acids, and inorganic ions were detected as intermediates of degradation processes, which end with the complete mineralization of triadimefon to CO₂ + H₂O. (3) A reaction pathway for the oxidation of triadimefon fungicide by hydroxyl radicals that accounts for almost all detected intermediates is proposed.

The use of plant-derived sorbent was investigated as a remediation strategy for low-energy intertidal wetlands contaminated by crude oil spills. Effectiveness of plant-derived sorbent as a wicking agent was evaluated in microcosms simulating intertidal wetlands. Microcosms were designed to impose three different oil penetration depths (0.25, 0.5, and 1.0 cm), two different tidal amplitudes (±5 and ±10 cm above oil-contaminated surface), and two different types of sorbents (raw bagasse and hydrophobic-treated bagasse). We observed that the use of plant-derived sorbent was beneficial not only in removing oil but also in preventing further contamination. Oil penetration depth and tidal amplitude both negatively influenced the effectiveness of the sorbent. Effectiveness of the hydrophobic-treated sorbent was always higher than that of untreated one at any given oil penetration depth and tidal amplitude. Effectiveness of hydrophobic-treated sorbent was relatively low compared to that of raw bagasse. The most plausible explanation is that oil wicking mainly occurred during low tide. From a cost-effectiveness point of view, we suggest the use of raw bagasse immediately after an oil spill for remediation of low-energy intertidal wetlands. The observed results imply that this technique has potential to stimulate biodegradation by wicking oil out of contaminated intertidal wetlands subsurface to the aerobic zone where biodegradation can take place.

The relationships between the Ni concentrations of the mudflat snails Telescopium telescopium and the surface sediments have not been reported yet from tropical intertidal areas. In this study, telescope snails and surface sediments were collected from 18 geographical sampling sites in intertidal areas of Peninsular Malaysia. The concentrations of Ni were measured in seven different soft tissues of the snails namely foot, cephalic tentacles, mantle, muscle, gill, digestive cecum, and remaining soft tissues. It was found that different concentrations of Ni were found in the different soft tissues, indicating different mechanisms of sequestration and regulation of Ni in these different tissues. By comparing the Ni concentrations in the similar tissues, spatial variations of Ni were found in the different sampling sites although there was no consistent pattern of Ni in these sites. The highest Ni variation based on the ratio of maximum to minimum values indicated that cephalic tentacle and foot were the main organs having high Ni variation. The use of correlation analysis and multiple linear stepwise regression analysis revealed that digestive cecum of T. telescopium could be used to reflect the Ni contamination of the sampling site. Also, the digestive cecum and gill were found to be the main bioaccumulation and storage sites for Ni. From the Ni accumulation patterns in all the populations investigated, tissue redistributions of Ni in gill was identified and could be proposed as an indicator of high Ni bioavailability and contamination in the sampling site. To our knowledge, this is the first and most comprehensive study on Ni accumulation in the different soft tissues of T. telescopium from tropical intertidal areas, in relation to the sediment data.

A novel heterotrophic-autotrophic denitrification (HAD) approach supported by mixing granulated spongy iron, methanol, and mixed bacteria was proposed for the remediation of nitrate-nitrogen (NO₃-N) contaminated groundwater in a dissolved oxygen (DO)-rich environment. The HAD process involves biological deoxygenation, chemical reduction (CR) of NO₃-N and DO, heterotrophic denitrification (HD), and autotrophic denitrification (AD). Batch experiments were performed to: (1) investigate deoxygenation capacities of HAD; (2) determine the contributions of AD, HD, and CR to the overall NO₃-N removal in the HAD; and (3) evaluate the effects of environmental parameters on the HAD. There were 174, 205, and 2,437 min needed to completely reduce DO by the HAD, spongy iron-based CR, and by the mixed bacteria, respectively. The HAD depended on abiotic and biotic effects to remove DO. CR played a dominant role in deoxygenation in the HAD. After 5 days, approximately 100, 63.0, 20.1, and 9.7 % of the initial NO₃-N was removed in the HAD, HD, AD + CR, and CR incubations, respectively. CR, HD, and AD all contributed to the overall NO₃-N removal in the HAD. HD was the most important NO₃-N degradation mechanism in the HAD. There existed symbiotic, synergistic, and promotive effects of CR, HD, and AD within the HAD. The decrease in NO₃-N and the production of nitrite-nitrogen (NO₂-N) and ammonium-nitrogen (NH₄-N) in the HAD were closely related to the C to N weight ratio. The C to N ratio of 3.75:1 was optimal for complete denitrification. Denitrification rate at 27.5°C was 1.36 times higher than at 15.0°C.