Predicting the transfer of contaminants in soils is often hampered by lacking validation of mathematical models. Here, we applied Hydrus-2D software to three agricultural soils for simulating the 1900–2005 changes of zinc and lead concentration profiles derived from industrial atmospheric deposition, to validate the tested models with plausible assumptions on past metal inputs to reach the 2005 situation. The models were set with data from previous studies on the geochemical background, estimated temporal metal deposition, and the 2005 metal distributions. Different hypotheses of chemical reactions of metals with the soil solution were examined: 100% equilibrium or partial equilibrium, parameterized following kinetic chemical extractions. Finally, a two-site model with kinetic constant values adjusted at 1% of EDTA extraction parameters satisfactory predicted changes in metal concentration profiles for two arable soils. For a grassland soil however, this model showed limited applicability by ignoring the role of earthworm activity in metal incorporation.

The distribution of six priority phthalic acid esters (PAEs) in suburban farmland, vegetable, orchard and wasteland soils of Tianjin were obtained with gas chromatography-mass spectrometer analysis in 2009. Results showed that total PAEs varied from 0.05 to 10.4 μg g⁻¹, with the median value as 0.32 μg g⁻¹. Di-(2-ethylhexyl) phthalate and di-n-butyl phthalate are most abundant species. PAEs concentrations for the four types of soils exhibited decreasing order as vegetable soil > wasteland soil > farmland soil > orchard soil. PAEs exhibited elevated levels in more developed regions when compared with other studies. The agricultural plastic film could elevate the PAEs contents in soils. Principal component analysis indicated the emission from cosmetics and personal care products and plasticizers were important sources for PAEs in suburban soils in Tianjin. The higher PAEs contents in wasteland soils from suburban area should be paid more attention owing to large amounts of solid wastes appeared with the ongoing urbanization.

The residual levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface sediments collected from Candarli Gulf. Total concentrations of OCPs and PCBs in sediments ranged from 10.2 to 57.3 and 2.8 to 205ngg⁻¹dwt, respectively. DDTs in sediments were derived from the aged and weathered agricultural soils in 61% of the sampling stations while 39% of the sites originated from the recent DDT inputs. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the Bakircay River and petrochemical industry approached the sediment quality guidelines for PCBs and DDTs. Based on ERL/ERM guidelines, DDT and PCBs posed ecological risk to the bottom-dwelling consumers.

Polybrominated diphenyl ethers (PBDEs) have been found at high levels, up to 7.6 × 106 pg/g, in biosolids commonly applied to agricultural soils. A field investigation was carried out in this study to measure concentrations of PBDEs in biosolid-amended agricultural soils in which various amounts of biosolids (20 and 80 t/ha) had been applied. Concentrations of PBDEs in surface soils that had received a single application of 80 t/ha biosolids were one to two orders of magnitude greater than that in soil, which had received a single application of 20 t/ha of biosolids. Assessment of PBDEs levels at different depths, between 0.05 and 1.05 m, in soils that received 80 t/ha biosolids, showed that PBDEs were mobilized from the surface soil to lower depths. Total PBDEs concentrations decreased from 10,250 pg/g dry weight basis (dw) in the 0.05 m soil layer to 220 pg/g dw at a depth of 1 m. The distribution of PBDEs with depth and cation exchange capacity of the soil could be described as exponential functions. The coefficients of correlation ranged from 0.47 to 0.57 and 0.47 to 0.67, respectively. Despite the deviation in the experimental measurements induced by variables, such as non-uniform biosolid application, heterogeneity of the soil, and the uneven surface of the field, variations of PBDEs along the soil profile in the biosolid-amended soil were clearly demonstrated.

A batch equilibrium experiment was conducted to determine the adsorption and desorption isotherms of chlorothalonil for a range of agricultural soils in Ireland. The sorption isotherms in tillage soils were described by the Freundlich model in a nonlinear form while in the grassland soil, the adsorption was almost linear. The experimental sorption data fit the Freundlich (R ² > 0.99) and the linear (R ² > 0.99) model very well. Chlorothalonil exhibited fast initial adsorption within the first hour until steady state, after which the sorption potential decreased and varied by about 3 % up to 10 h. Desorption equilibrium took twice the time needed for adsorption. The adsorption of chlorothalonil onto the soils studied was strong and the experimental Freundlich adsorption coefficients (K f) ranged from 17.74 to 78.19 (mg¹ ⁻ ¹/ⁿ kg⁻¹) (L)¹/ⁿ , and these were correlated with cation exchange capacity and organic carbon content. All tillage soils exhibited L-type isotherm, whereas Elton grassland soil showed near C-type (linear) isotherm, probably due to the highest organic carbon content among other soil. Desorption process revealed hysteresis with the Freundlich desorption coefficients being greater than for adsorption, meaning that not all chlorothalonil adsorbed could be easily desorbed. Only 3 to 8 % was desorbed in the single desorption step during the batch equilibrium experiment. Calculated K ₒc values showed that chlorothalonil has slight to low mobility in the soils studied associated with high adsorption, and hence may constitute a greater risk to surface waters by runoff than to ground waters by leaching.

During the intensive flood in May–June 2010, the floodplains in Little Poland Vistula Gap, used mostly for agriculture, were waterlogged for a period of over 1 month. The aim of the study was to assess the effect of the flood on the level of contamination of the soils in this region. The analysis included basic physicochemical soil properties, contents of ten metals, and concentrations of 16 polycyclic aromatic hydrocarbons (PAHs). The studies cover two territories on opposite sites of the river Vistula (Wilkow and Janowiec) differing in their areas (70 and 4.6 km2) and time of water logging (30 and 10 days). Forty soil samples were collected from both areas immediately after the flood event from the upper (0–30 cm) soil layer together with four samples from the 30–60-cm depth layer. This was supplemented by eight samples from the flood-deposited sediment layer (thickness, 2 cm). The concentrations of identified metals (As, Ba, Cr, Sn, Zn, Cd, Co, Cu, Ni, Pb) at all the sampling points were below the Polish legal limits for the upper layer of soils for agriculture use. The same regarded the median contents of nine PAHs compounds specified in the Polish regulations. In both areas, the median contents of Σ16 PAHs (0.21–0.35 mg kg−1), Zn (10.3–10.6 mg kg−1), Pb (9.2–10.7 mg kg−1), and Cd (0.03 mg kg−1) were much below the mean concentrations of those contaminants in arable soils on the national and European levels. The results show that this severe flooding episode in “clean” agricultural area had no immediate negative impact on the soils as regards the basic physicochemical properties (organic matter content, acidity, nitrogen content) and did not result in excessive soil contamination.

Arbuscular mycorrhizal fungi (AMF) hold a crucial role in ecosystems because they are involved in nutrient cycling between soil and plants. This work aimed at evaluating the impacts that atmospheric pollution by polycyclic aromatic hydrocarbons may have on infectivity of indigenous AMF in soils. Two agricultural soils (Maconcourt, La Bouzule) were exposed for 2 weeks to ambient air (control, C) or to atmospheric phenanthrene (PHE) deposition (180 μg m−3 air). After exposure, soils were divided into a top (0–1 cm) and a bottom (1–15 cm) layer fraction. AMF infectivities of soils were determined after 2 weeks of atmospheric exposition using leek (Allium porum) as bioassay plant. Atmospheric PHE was mainly recovered in the top layer of soil (500–1,350 μg kg−1) of both soils and did not readily diffuse into the depth. Atmospheric contamination led to decreases in AMF infectivities of the top layer in both soils and affected the growth of leeks. Our results not only report evidence that infectivity of indigenous AMF is sensitive to PHE in soils but also emphasize that AMF are primary affected by the soil layer regardless to the pollution level.

The validity of the soil quality standard for copper (Cu) established by the Spanish legislation (Spanish Royal Decree 9/2005) is evaluated in representative agricultural Mediterranean soils under an accumulator crop (Lactuca sativa L. var. Romaine cv. Long Green), considering both the effect of the metal on crop growth (biomass production) and its accumulation in the edible part of the plant. For saline soils, such a soil quality standard seems not to be valid taking into account both of the aspects evaluated. For non-saline soils, the soil quality standard also seems not to be valid since, considering the metal accumulation in the edible part of the plant, the soil quality standard should be above such standard; but considering the productivity function of soil (biomass production), the standard should be much below, meaning that this function is being greatly affected by the presence of high concentrations of Cu. The soil quality standard for each soil considered should correspond to a value between its respective EC50 and EC10 values (effective concentrations of added Cu causing 50% and 10% inhibition on the biomass production), depending on the politicians and/or farmers' compromise with yield production and, therefore, with soil productivity. These threshold values were greater for the soil having more organic matter and clay content, showing that Cu toxicity also depends on these properties. Further research in other agricultural areas of the region would improve the basis for proposing adequate soil quality standards as highlighted by the European Thematic Strategy for Soil Protection.

The aim was to study the influence of soil properties on the leaching of nitrate, phosphate and organic matter (OM) following the application of sewage sludge to contrasting soils. Seventy agricultural soils from different parts of Spain were amended with sewage sludge (50 t dry weight ha−1), and a controlled column study was developed. After 2, 4 and 6 months of incubation, distilled water, equivalent to an autumn rainfall event of 25 l m−2 in Mediterranean environments, was applied and leachates collected and analysed: pH, electrical conductivity (EC), chemical oxygen demand (COD), phosphate and nitrate. The mean values of pH in the leachates after 2, 4 and 6 months were similar and close to the neutrality. The highest concentrations for the rest of the parameters analysed were found after 2 months of incubation and diminished for 4 and 6 months, especially COD. Soil pH and texture were the most relevant soil properties controlling the leaching of the analysed parameters. The OM mineralization seemed to be enhanced at high values of soil pH, thus increasing the nitrate and reducing the COD leaching. However, phosphate levels were reduced at high values of soil pH. In addition, leaching was promoted in sandy soils. Other soil properties influenced phosphate leaching being the equivalent calcium carbonate soil content as the most relevant. Soil organic carbon was negatively related to the EC and nitrate concentration in the leachates but resulting in a weak contribution compared with soil pH and texture. Concerns about nitrate pollution have been confirmed.

We performed a 2-year microcosm study to assess the effectiveness of red mud, a by-product of bauxite processing, in stabilizing contaminated mine waste and agricultural soil. Our study used red mud from a long-term disposal area in Almásfüzitő, Hungary with a pH of 9.0. A 5% (by weight) red mud addition decreased the highly mobile, water-extractable amount of Cd and Zn by 57% and 87%, respectively, in the agricultural soil and by 73% and 79%, respectively, in the mine waste. In a laboratory lysimeter study, the addition of red mud reduced the concentration of Cd and Zn in the leachate by about two third of the original. The metal content of the leachate was below the Maximum Effect Based Quality Criteria for surface water as determined by a risk assessment in the metal-contaminated area of the Toka valley near Gyöngyösoroszi, Hungary. The addition of red mud did not increase the toxicity of the treated mine waste and soil and decreased the Cd and Zn uptake of Sinapis alba test plants by 18–29%. These results indicate that red mud applied to agricultural soil has no negative effects on plants and soil microbes and decreases the amounts of mobile metals, thus indicating its value for soil remediation.