This study provides a combined dataset on N loss pathways and fluxes from sloping cropland in the purple soil area, southwestern China. A lysimeter experiment was conducted to quantify nitrate leaching (May 2004–May 2010) and N₂O emission (May 2009–May 2010) losses. Nitrate leaching was the dominant N loss pathway and annual leaching fluxes ranged from 19.2 to 53.4 kg N ha⁻¹, with significant differences between individual observation years (P < 0.05). Direct N₂O emissions due to N fertilizer use were 1.72 ± 0.34 kg N ha⁻¹ yr⁻¹, which corresponds to an emission factor of 0.58 ± 0.12%. However, indirect N₂O emissions caused by nitrate leaching and surface runoff N losses, may contribute another 0.15–0.42 kg N ha⁻¹ yr⁻¹. Our study shows that nitrate leaching lowered direct N₂O emissions, highlighting the importance for a better understanding of the tradeoff between direct and indirect N₂O emissions for the development of meaningful N₂O emission strategies.

Here we evaluate the performance and limitations of two frequently used model-types to predict trace element solubility in soils: regression based “partition-relations” and thermodynamically based “multisurface models”, for a large set of elements. For this purpose partition-relations were derived for As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Se, V, Zn. The multi-surface model included aqueous speciation, mineral equilibria, sorption to organic matter, Fe/Al-(hydr)oxides and clay. Both approaches were evaluated by their application to independent data for a wide variety of conditions. We conclude that Freundlich-based partition-relations are robust predictors for most cations and can be used for independent soils, but within the environmental conditions of the data used for their derivation. The multisurface model is shown to be able to successfully predict solution concentrations over a wide range of conditions. Predicted trends for oxy-anions agree well for both approaches but with larger (random) deviations than for cations.

The inducibility and specificity of different czcRS operons in Pseudomonas putida X4 were studied by lacZ gene fusions. The data of β-glycosidase activity confirmed that the czcR3 promoter responded quantitatively to zinc. A zinc-specific biosensor, P. putida X4 (pczcR3GFP), was constructed by fusing a promoterless enhanced green fluorescent protein (egfp) gene with the czcR3 promoter in the chromosome of P. putida X4. In water extracts of four different soils amended with zinc, the reporter strain detected about 90% of the zinc content of the samples. Both the bioavailability assessment and the sequential extraction analysis demonstrated that the immobilization of zinc was highly dependent on the physico-chemical properties of soils. The results also showed that the lability of zinc decreased over time. It is concluded that the biosensor constitutes an alternative system for the convenient evaluation of zinc toxicity in the environment.

There are limited data on persistent organic pollutants (POPs) in the soils of the Tibetan Plateau. This paper presents data from a survey of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in 40 background surface (0–5 cm) soils of the Tibetan Plateau. Soil concentrations (pg/g, dw) ranged as follows: DDTs, 13-7700; HCHs, 64-847; HCB, 24-564; sum of 15 PCBs, 75-1021; and sum of 9 PBDEs, below detection limit −27. Soil DDT, HCB, PCB and PBDE concentrations were strongly influenced by soil organic carbon content. HCH concentrations were clearly associated with the proximity to source regions in south Asia. The air–soil equilibrium status of POPs suggested the Tibetan soils may be partial “secondary sources” of HCB, low molecular weight PCBs and HCHs and will likely continue to be “sinks” for the less volatile DDE and DDT.

Soil suspensions (slurries) are commonly used to estimate the potential of soil microbial communities to mineralize organic contaminants. The preparation of soil slurries disrupts soil structure, however, potentially affecting both the bacterial populations and their protozoan predators. We studied the importance of this “slurry effect” on mineralization of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA, ¹⁴C-labelled), focussing on the effects of protozoan predation. Mineralization of MCPA was studied in “intact” soil and soil slurries differing in soil:water ratio, both in the presence and absence of the protozoan activity inhibitor cycloheximide. Protozoan predation inhibited mineralization in dense slurry of subsoil (soil:water ratio 1:3), but only in the most dilute slurry of topsoil (soil:water ratio 1:100). Our results demonstrate that protozoan predation in soil slurries may compromise quantification of contaminant mineralization potential, especially when the initial density of degrader bacteria is low and their growth is controlled by predation during the incubation period.

A quantitative knowledge of the fate of deicing chemicals in the subsurface can be provided by joint analysis of lab experiments with numerical simulation models. In the present study, published experimental data of microbial degradation of the deicing chemical propylene glycol (PG) under flow conditions in soil columns were simulated inversely to receive the parameters of degradation. We evaluated different scenarios of an advection-dispersion model including different terms for degradation, such as zero order, first order and inclusion of a growing and decaying biomass for their ability to explain the data. The general break-through behavior of propylene glycol in soil columns can be simulated well using a coupled model of solute transport and degradation with growth and decay of biomass. The susceptibility of the model to non-unique solutions was investigated using systematical forward and inverse simulations. We found that the model tends to equifinal solutions under certain conditions.

This study aimed at relating the abundance and diversity of invertebrate communities of urban soils to chemical and physical soil characteristics and to identify the taxa most sensitive or tolerant to soil stressors. The invertebrate community of five urban soils in Naples, Italy, was sampled. To assess soil quality invertebrate community indices (Shannon, Simpson, Menhinick and Pielou indices), Acarina/Collembola ratios, and the soil biological quality index (QBS) were calculated. The chemical and physical characteristics of the soils strongly differed. Abundance rather than taxa richness of invertebrates were more affected by soil characteristics. The community was more abundant and diverse in the soils with high organic matter and water content and low metal (Cu, Pb, Zn) concentrations. The taxa more resistant to the urban environment included Acarina, Enchytraeids, Collembola and Nematoda. Collembolans appeared particularly sensitive to changing soil properties. Among the investigated indices, QBS seems most appropriate for soil quality assessment.

Orange trees are widely cultivated in regions with high concentrations of tropospheric ozone. Citrus absorb ozone through their stomata and emit volatile organic compounds (VOC), which, together with soil emissions of NO, contribute to non-stomatal ozone removal. In a Valencia orange orchard in Exeter, California, we used fast sensors and eddy covariance to characterize water and ozone fluxes. We also measured meteorological parameters necessary to model other important sinks of ozone deposition. We present changes in magnitude of these ozone deposition sinks over the year in response to environmental parameters. Within the plant canopy, the orchard constitutes a sink for ozone, with non-stomatal ozone deposition larger than stomatal uptake. In particular, soil deposition and reactions between ozone, VOC and NO represented the major sinks of ozone. This research aims to help the development of metrics for ozone-risk assessment and advance our understanding of citrus in biosphere-atmosphere exchange.

The role of indigenous and non-indigenous arbuscular mycorrhizal fungi (AMF) on As uptake by Plantago lanceolata L. growing on substrate originating from mine waste rich in As was assessed in a pot experiment. P. lanceolata inoculated with AMF had higher shoot and root biomass and lower concentrations of As in roots than the non-inoculated plants. There were significant differences in As concentration and uptake between different AMF isolates. Inoculation with the indigenous isolate resulted in increased transfer of As from roots to shoots; AMF from non-polluted area apparently restricted plants from absorbing As to the tissue; and plants inoculated with an AMF isolate from Zn–Pb waste showed strong As retainment within the roots. Staining with dithizone indicated that AMF might be actively involved in As accumulation. The mycorrhizal colonization affected also the concentration of Cd and Zn in roots and Pb concentration, both in shoots and roots.

Lead contamination of urban residential soils is a public health concern. Consequently, there is a need to delineate hotspots in the landscape to identify risk and facilitate remediation. Land use is a good predictor of some environmental pollutants. However, in the case of soil lead, research has shown that land use is not a useful proxy. We hypothesize that soil lead is related to both individual landscape features at the parcel scale and the landscape context in which parcels are embedded. We sampled soil lead on 61 residential parcels in Baltimore, Maryland using field-portable x-ray fluorescence. Thirty percent of parcels had average lead concentrations that exceeded the USEPA limit of 400 ppm and 53% had at least one reading that exceeded 400 ppm. Results indicate that soil lead is strongly associated with housing age, distance to roadways, and on a parcel scale, distance to built structures.