The use of Cu-based fungicide can pose a risk to nearby surface water bodies due to the run-off of accumulated Cu from agricultural soils. In 2008, we conducted a reconnaissance survey of the presence and concentration of copper in sediments at 18 sites within the Yarra River Catchment, an important horticultural production system in south-eastern Australia. Observed Cu concentrations in sediment samples from the study sites (mean (95 % confidence interval) 12.0 (10.6-13.6) mg/kg dry weight) were similar to the concentrations present in the samples from the reference sites (mean (95 % confidence interval) 12.0 (6.7-16.8) mg/kg dry weight). The data on Cu and other metals in the sediments suggest that that there is unlikely to have been wide spread, diffuse, off-site transport of Cu from the soils of horticultural properties to nearby surface waterways in the Yarra River Catchment and that that observed sediment metal concentrations are unlikely to pose an ecological risk to sediment-dwelling organisms at the study sites. © 2013 Springer Science+Business Media Dordrecht.

The effects of six phosphate (P) fertilizers in mobilizing and immobilizing water-soluble lead (Pb) were determined in a contaminated soil (Alfisol from Shaoxing) from China and four Australian soils (an Oxisol from Twonsville Queensland and three South Australian soils from Cooke Plains (Typic Palexeralf)), Inman Valley (Vertisol), and Two Wells (Natric Palexeralf). The fertilizers tested were single superphosphate (SSP), triple superphosphate (TSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), monocalcium phosphate (MCP), and dicalcium phosphate (DCP) to produce an initial P concentration of 1,000 mg/L. The Chinese soil contained 16,397 mg/kg total Pb, but the Australian soils were uncontaminated. The four Australian soils were each spiked with 1,000 mg Pb/kg soil (as Pb(NO3)2) and incubated for a month. Single superphosphate treatments decreased total soluble Pb in soil solution to 2-14 % of those of the nil-P (0P) treatment in the four Pb-spiked soils and to 48 % in the Chinese Pb-contaminated soil. The DAP treatment followed by the MAP treatment greatly increased the total soluble Pb in soil solution up to 135-500 % of the 0P treatment, except in the Two Wells soil. MCP could decrease the total soluble Pb in Cooke Plains, Inman Valley, Shaoxing, and Two Wells soils while increase it in the Queensland soil; DCP decreased the total soluble Pb in Cooke Plains and Queensland soils while increased it in the Shaoxing and Inman Valley soils. There were close relationships between the total soluble Pb, total soluble Al, and total soluble Fe in the water extracts of each. Soluble Al and Fe ions in soil solution increased soluble Pb concentrations. We conclude that not all phosphate fertilizers immobilize Pb in soils equally well. SSP and TSP are excellent Pb-immobilizing fertilizers, while MAP and DAP are strong Pb-mobilizing fertilizers. MCP and DCP are either Pb-immobilizing fertilizers or Pb-mobilizing fertilizers depending on their reactions with individual soils. © 2013 Springer Science+Business Media Dordrecht.

Pathogens are the leading cause of water quality impairments as defined by the US Environmental Protection Agency and their transport within water bodies is poorly understood. Because of this, watershed-scale, water quality models often have poor bacterial prediction capabilities. To improve the understanding of in-stream bacterial transport, a cow pie was deposited in a recirculating flume with flows ranging from 0.0102 to 0.0176 m³ s⁻¹. Water samples were collected and analyzed for Escherichia coli concentration, E. coli attached fraction, and turbidity. E. coli concentrations ranged from 4.72 × 10³ to 1.70 × 10⁵ CFU 100 mL⁻¹ and turbidity ranged from 1.93 to 369 NTU over both locations and all times. The percentage of E. coli attached to particles ranged from an average of 2.9 to 31 % downstream of the fecal deposition point. Spearman correlation analysis demonstrated that bacteria concentrations were significantly related with water depth (ρ = 0.128, p = 0.018), and the concentration of attached bacteria was significantly correlated with both the total concentration of E. coli (ρ = 0.4081, p = 0.009) and turbidity (ρ = 0.3627, p = 0.0214). This analysis is useful to indicate parameters that should be considered when monitoring or predicting bacteria transport in streams.

A special sequential extraction (SE) procedure for mercury (Hg) was conducted to determine biogeochemical fractions of Hg and their controlling factors in four contaminated soil profiles located in two distinct floodplain ecosystems which differ in their industrial histories and thus in their Hg loads. The first study area is located at the Wupper River (Western Germany) and the soil profiles reveal sum of Hg (Hgₛᵤₘ) concentrations up to 48 ppm. The second study area is located at the Saale River (Eastern Germany) and the soil profiles have Hgₛᵤₘ concentrations up to 4.3 ppm. The majority of Hg was found in fraction IV (FIV, Hg⁰) for both study areas, indicating its anthropogenic origin. Moreover, we have detected Hg in fraction V (FV) and in fraction III (FIII). As Hg in FV is mostly associated with Hg sulfides being formed under reducing conditions, it indicates reduction processes which usually occurred during flooding. Mercury in FIII (organo-chelated Hg) exhibits a moderate mobility and a high methylation potential. Between Hg in FIII and hot-water-extractable carbon (CHWE) as a measure of easy degradable, labile soil organic matter, we found a significant correlation. Sum of Hg seem to have a high affinity to organic carbon (Cₒᵣg). The concentrations of Hg in the mobile and exchangeable fractions FI and FII were low. Moreover, the significant positive correlation between iron (Fe) and Hg in FIV indicate an interaction between Hg and Fe. The majority of the Hg in our soils is considered to be relatively immobile. However, since the formation of more mobile Hg species via oxidation or methylation might occur in floodplain soils, the low Hg concentrations in mobile fractions should not be underestimated due to their high mobility and potential plant availability.

Many airborne and soil-borne nanoparticles (NPs) can enter plants, which are the primary producers in the food chain; recently, studies on the genotoxic effects of NPs on plants are emerging. In the present study, the phytotoxic and genotoxic effects of ZnO and CuO NPs on buckwheat (Fagopyrum esculentum) seedlings were estimated. The inhibition of root growth and biomass at the tested concentrations of NP suspensions and dissolved free ion suspensions were compared. Changes in root morphological features and localization of NPs inside the root epidermis cells were observed. Growth of root treated with ZnO NPs (84.9 and 89.6 %) and CuO NPs (75.4 and 80.1 %) at 2,000 and 4,000 mg L -1, respectively, was decreased significantly than control. The root morphological features and NP incorporation into the root epidermal cells at a high dose of NP showed completely different patterns compared to those for the controls. Through random amplified polymorphic DNA assays for comparison of the effect of ZnO and CuO NPs on DNA stability, it was shown as different DNA polymorphisms at 2,000 and 4,000 mg L-1 of ZnO and CuO NPs, compared to those for controls. Our results provide the first clue to the genotoxic effects of ZnO and CuO NPs on early growth of edible plants such as buckwheat. © 2013 Springer Science+Business Media Dordrecht.

Being predominant inorganic arsenicals, methylarsenicals also occur in anaerobic paddy soils. Therefore, this study investigated the influence of Fe concentrations and arsenic speciation [arsenate (As(V)) and dimethylarsinate (DMA)] in paddy soils on arsenic uptake in rice plant. Rice seedlings were grown in soil irrigated with a Murashige and Skoog (MS) growth solution containing As(V) or DMA with or without 1.8 mM Fe in excess to the background concentration of total iron (0.03 mM) in the soil. Arsenic concentration in rice roots increased initially and then decreased gradually when the seedlings were grown with excess Fe and As(V). In contrast, arsenic concentration in the roots increased steadily ( P < 0.01) when the seedlings were grown without excess Fe and As(V). When the form of the arsenic was DMA, total arsenic (tAs) concentration in rice roots increased gradually ( P < 0.01) and was not affected by the addition of excess Fe in the soil. When rice seedlings were grown with As(V), tAs concentration in rice roots and shoots increased steadily ( P < 0.01) for gradual increase of Fe concentrations in soil. However, tAs concentration in roots and shoots was independent of Fe concentrations in soil when the form of arsenic was DMA. The tAs concentrations in rice shoots also increased significantly ( P < 0.01) with increasing exposure time for both As(V) and DMA. Thus, Fe concentrations in soil affect arsenic uptake in rice plant depending on the speciation of arsenic.

Copper(II) biosorption in the presence of complexing agents (CA) onto orange peel (OP) and chemically modified OP (OPᴴ⁺, OPᴺᵃ⁺, and OP⁽ᴺᵃ⁺⁾⁽ᴴ⁺⁾) was studied. The study of the effect of pH showed that OPᴴ⁺ presented a copper(II) uptake similar to OP in the pH range 1.5–6.0, whereas OPᴺᵃ⁺ and OP⁽ᴺᵃ⁺⁾⁽ᴴ⁺⁾ showed the highest copper(II) uptake in the pH range 4–6. Copper(II) sorption isotherms were obtained with Cu(II)/CA mass ratios of 1:0 and 1:2 at pH 5. The Sips model fitted best the isotherms without CA, whereas the Freundlich and Brunauer-Emmett-Teller (BET) models fitted best the isotherms in the presence of ethylenediaminetetraacetic acid (EDTA) and citrate, respectively. The CA reduced the copper(II) uptake due to the presence of copper(II)-chelated species, though the interference of citrate was less important than that of EDTA. OPᴺᵃ⁺ and OP⁽ᴺᵃ⁺⁾⁽ᴴ⁺⁾ showed a higher copper(II) uptake capacity than OP, also in the presence of CA in solution. Copper(II) sorption mechanisms were studied using energy-dispersive X-ray and Fourier transform infrared spectroscopy and revealed ion exchange as one of the mechanisms. Biosorption reversibility and biosorbent reuse were evaluated in sorption/desorption cycles. Reversibility of copper(II) sorption was obtained (90 % metal recovery), though an important reduction of the metal uptake was observed in the second cycle.

Bioclogging extensively exists in porous media, such as permeable reactive barrier (PRB), constructed wetland, reverse osmosis, and biofilter systems and affects efficiency of sewage treatment. In this paper, variation in biochemical and hydraulic parameters under discontinuous flow condition during the clogging process was obtained. Hydraulic conductivity (K) first decreased sharply to 34.22 % of the original value during the initial 12th day and, finally, decreased to 13.70 %. Hydrodynamic dispersion (D) went through slow increase, fast increase, fast decrease, slow increase, and ultimately decreased to 44.25 %. Porosity (n) decreased obviously, especially during the initial 12 days, and total bacterial counts in the inlet of the column had more than one order of magnitude increase. The bioclogging process can be divided into four stages: (1) severe bioclogging occurred and aerobic microorganisms reproduced rapidly in the inlet, (2) bioclogging existed in the entire sand column and the hydrodynamic dispersion increased drastically as anaerobic microorganisms generated some gas, (3) aerobic and anaerobic microorganisms reproduced and hydrodynamic dispersion decreased rapidly, and (4) microorganisms multiplied continuously and the hydraulic parameters (hydrodynamic dispersion, hydraulic conductivity, and porosity) decreased steadily. Bioclogging then transformed into steady stage. Based on analysis of experimental data, hydraulic conductivity (K) follows the rule of negative exponent relationship, porosity (n) accords with power exponent relationship, and hydrodynamic dispersion (D) is polynomial equation under bioclogging process.

The aim of this study was to statistically compare sampling sites identified along the Berg River system to identify the major point sources of metal pollution from June 2004 to May 2005. Three sites were selected [site A—agricultural farming area, site B—Plot 8000 (close to the informal settlement), and site C—the Newton pumping station] representing different sectors which the river services. Aluminium (Al), iron (Fe), manganese (Mn), and lead (Pb) concentrations were determined using Inductively Coupled Plasma Atomic Emission Spectrometry and were statistically compared and analysed with one-way ANOVAs. For all the metals analysed, site C (industrial area) proved to be the site where the highest average metal concentrations were recorded. Generally, the concentrations recorded at site A (site furthest from the industrial area) were significantly (p < 0.05) lower than the concentrations recorded at both sites B and C. While the Al and Fe concentrations were consistently higher than any of the other metals analysed for, site C was identified as the primary source of metal contamination in the Berg River, resulting from the runoff from industrial activities at this particular site.

The feasibility of a sequentially enhanced process for the remediation of soils contaminated by mixed contaminants, specifically multiple polycyclic aromatic hydrocarbons (PAHs) and heavy metals, was investigated. This process consists of sequential flushing using two chemical agents: a surfactant and a chelate. A series of laboratory column experiments was conducted with three different sequential schemes, designated as SEQ1, SEQ2, and SEQ3, in two distinct flushing stages, to remove PAHs and heavy metals from a field-contaminated soil. The SEQ1 scheme involved flushing 0.2 M ethylenediaminetetraacetic acid (EDTA) followed by flushing 5 % Igepal. The SEQ2 scheme involved flushing 5 % Igepal followed by flushing 0.2 M EDTA. SEQ1 was investigated under a constant hydraulic gradient of 1.2, while the SEQ2 scheme was investigated under hydraulic gradients that increased from 1.2 to 4.0. The SEQ3 scheme consisted of sequential flushing of 5 % Igepal (first stage) and 0.2 M EDTA (second stage) under a constant low hydraulic gradient of 0.2. The selected sequential schemes allowed an assessment of the efficacy of sequencing the surfactant and chelating flushing for the removal of multiple heavy metals and PAHs under various hydraulic gradients. The hydraulic conductivity (or flow) was found to vary depending on the flushing agent and the sequence scheme. Under the high hydraulic gradient, the hydraulic conductivity was lower during chelant flushing stage as compared with surfactant flushing stage in both SEQ1 and SEQ2. However, under a low gradient condition (SEQ3), the hydraulic conductivity was approximately the same during both chelant and surfactant flushing stages. The contaminant removal was also significantly affected by the flushing agent and sequence and the applied hydraulic gradient. Heavy metals were removed during chelant flushing, while PAHs were removed during surfactant flushing. The total removal efficiencies of Pb, Zn, and Cu were 76 %, 63 %, and 11 % in SEQ1 and 42 %, 40 %, and 7 % in SEQ2, respectively, while the total removal efficiencies of phenanthrene, anthracene, benz(a)anthracene, and pyrene were 51 %, 35 %, 58 %, and 39 % in SEQ1 and 69 %, 50 %, 65 %, and 69 % in SEQ2, respectively. Overall, the total mass removal of heavy metals and PAHs was higher in SEQ1 as compared with SEQ2, demonstrating that SEQ1 is the effective sequence scheme. Comparison of the results of high and low gradient conditions (SEQ2 and SEQ3) reveals that the removal of contaminants, especially heavy metals, is rate-limited. Overall, this study showed that the removal of co-existing heavy metals and PAHs from soils is possible through the careful selection of the sequence under which the flushing of chelant and surfactant occurs and depends on the site-specific soil and contaminant conditions. Additional research is needed to establish the most optimal flushing scheme (sequence duration and flow velocity) to remove the mixed contaminants effectively and efficiently. © 2013 Springer Science+Business Media Dordrecht.