To elucidate the origin of the wide-spread contaminations of plant derived commodities with various alkaloids, we employed co-cultures of pyrrolizidine alkaloid (PA) containing Senecio jacobaea plants with various alkaloid free acceptor plants. Our analyses revealed that all plants grown in the vicinity of the Senecio donor plants indeed contain significant amounts of the PAs, which previously had been synthesized in the Senecio plants. These findings illustrate that typical secondary metabolites, such as pyrrolizidine alkaloids, are commonly transferred and exchanged between living plants. In contrast to the broad spectrum of alkaloids in Senecio, in the acceptor plants nearly exclusively jacobine is accumulated. This indicates that this alkaloid is exuded specifically by the Senecio roots. Although the path of alkaloid transfer from living donor plants is not yet fully elucidated, these novel insights will extend and change our understanding of plant-plant interactions and reveal a high relevance with respect to the widespread alkaloidal contaminations of plant-derived commodities. Moreover, they could be the basis for the understanding of various so far not fully understood phenomena in cultivation of various crops, e.g. the beneficial effects of crop rotations or the co-cultivation of certain vegetables.

Dietary arsenic (As) intake from food is of great concern, and developing a reliable model capable of predicting As concentrations in plant edible parts is desirable. In this study, pot experiments were performed with 16 Chinese upland soils spiked with arsenate [As(V)] to develop a predictive model for As concentrations in pepper fruits (Capsicum annum L.). Our results showed that after three months’ aging, concentrations of bioavailable As (extracted by 0.05 M NH₄H₂PO₄) in various soils varied widely, depending on soil total As concentrations and soil properties such as soil pH and amorphous iron (Fe) contents. Furthermore, both the bioconcentration factor (BCF, denoted as the ratio of fruit As to soil As) and total As concentrations in pepper fruits were largely determined by concentrations of bioavailable As, which explained 27% and 69% variations in the BCF and fruit As concentrations, respectively. Apart from bioavailable As, soil pH and Fe contents were another two important factors influencing As accumulation in pepper fruits. Taking the three factors into account, concentrations of fruit As can be well predicted using a stepwise multiple linear regression (SMLR) analysis (R² = 0.80, RMSE = 0.17). Arsenic species in soils and edible parts were also analyzed. Although As(V) predominated in soils (>96%), As in pepper fruits presented as As(V) (46%) and arsenite [As(III)] (39%) with small amount of methylated As (<15%). Aggregated boosted tree (ABT) analysis revealed that inorganic As concentrations in pepper fruits were determined by concentrations of bioavailable As, phosphorus (P) and Fe in soils. In contrast to inorganic As, methylated As concentrations were not correlated with those factors in soils. Taken together, this study established an empirical model for predicting As concentrations in pepper fruits. The predictive model can be used for establishing the As threshold in fruit vegetable farming soils.

The long-term use of animal manure in agriculture has resulted in estrogen pollution, which poses risks to facility vegetable soils. Owing to the complex soil composition, estrogen may exhibit a variety of behaviors at the water/soil interface. This study demonstrated the role of humic acid (HA) on the 17β-estradiol (E2) adsorption by clay minerals (montmorillonite, kaolinite, and hematite). The interfacial behaviors were investigated using adsorption kinetics and isotherms data. Then, the effects of temperature, pH, and bisphenol A (BPA) on the interactions between humic-mineral complexes and E2 were explored. The adsorption of E2 is an exothermic and spontaneous process, and the addition of HA to minerals significantly promoted their E2 adsorption capacities. Higher pH levels (>10) and the presence of BPA decreased the adsorption capacities of minerals and mineral complexes for E2. Moreover, intercalation, hydrophobic partitioning, π-π interactions and hydrogen bonding could dominate the E2 adsorption onto complexes. These results provided insight into the interfacial behaviors of E2 on the surfaces of humic-mineral complexes and promoted the understanding of the migration and transport of estrogens in soils.

This study was initiated after the appearance of chlorotic and necrotic lesions on vegetation in the vicinity of a glassworks. The aim was to establish whether the cause was an uncontrolled release of gaseous fluorides. Five different plant species (Norway spruce, peach, common hornbeam, common bean, common grape vine) were collected in the influenced area, and the fluorine (F) content was determined by a fluoride ion selective electrode after prior total sample decomposition by alkaline carbonate fusion. The measurement results were reported together with their measurement uncertainties (MUs), which were evaluated according to the Guide to the Expression of Uncertainty in Measurement. The F contents at comparable distances from the emitter and in a clean area, free from natural or anthropogenic fluoride emissions, were 87–676 and 10 μg g⁻¹, respectively, thereby confirming the release of gaseous fluorides from the glassworks. The F contents in samples of Norway spruce taken at various radial distances from the emitter suggest that the emitted gaseous fluorides were spread about evenly in all directions from the source following an inverse-power function. Estimated distances at which the F content would decrease to 50 μg g⁻¹ (allowed maximum content of F in feeding stuffs) and 21 μg g⁻¹ (maximum fluoride content in vegetables and fruits in relation to the upper limit of fluoride intake for humans) were 378 m and 571 m, respectively, from the emitter. Evaluation of our results for compliance with specification revealed a lack of regulation on fluoride content in the diet of humans and animals as well as a lack of guidelines on how to take into account MU.

This study analyzed the effect of heavy metal eluents (0.3 mol/L C₆H₈O₇, 5 × 10⁻⁴ mol/L EDTA, and 0.01 mol/L Na₂S₂O₃) on the content of organic matter, hydrolytic nitrogen, available phosphorus and potassium, and species composition of bacteria and fungi in vegetable soils. The obtained results documented that the treatment of the soil, consisting of shaking the sample with a mixture of eluents, significantly increased the content of organic matter, hydrolytic nitrogen, and available phosphorus and potassium. The mixed solutions of eluents increase the maximum available P in the soil by 279.3%, and hydrolytic N by 30.7%. The eluents affected, to a certain extent, the dominant species of microorganisms in the soil, but did not increase species richness and evenness in all soil samples.

This study examined the influences of three subsets of environmental factors (i.e. soil physicochemical properties including pH, organic matters and soil texture, landscape patterns, and parent materials) on the spatial variations and sources of soil trace metal contamination across an urban-rural environmental gradient in Guangzhou City, southern China. We collected 318 surface soil samples from forests, orchards, farmlands, and urban lawns using a random tessellation design for selecting sample sites. The geo-accumulation indices showed that 18%–88% of soil samples were contaminated: moderate to high contamination with Cd and Hg, low to moderate contamination with Cu, Pb, Zn and Ni, and low contamination with As and Cr. However, less than 13% of soil samples were considered to have exceeded the national standards causing environmental and human health concerns. The mean geo-accumulation indices increased in the order of forest, paddy field/orchard, vegetable, road/residential, and park/residential areas for As, Cd, Ni, Pb, Zn, closely following a land disturbance gradient. Spearman Correlation and Cluster Analyses showed that Pb-Cu-Zn had traffic-related origins, Cd-Hg were mainly influenced by fertilization or industrial emissions, and As-Cr-Ni had geogenic origins for agricultural soils. In contrast, the Ni, Hg and Cd contamination sources for urban soils included both anthropogenic and geogenic origins. The Stepwise Regression and Partial Redundancy Analyses showed that three subsets of environmental factors explained 43%–87% of variations of soil contamination for both agricultural and urban soils. We concluded that soil contamination was mainly controlled by soil physiochemical properties followed by landscape patterns. Soil absorption of aerial loads of trace metal pollutants dominated the soil contamination processes. Our findings implied that improving soil physiochemical properties and landscape designs can strengthen environmental buffering and carrying capacity, thus alleviating soil contamination and reducing non-point-source pollution in the study region.

Thallium (Tl) is a trace metal of severe toxicity. Its health concerns via consumption of contaminated vegetables have often been overlooked or underestimated. This study was designed to gain insight into the actual level and distribution characteristics of Tl and metal (loid)s (Pb, Cd, Cr, Sb, Mn, Cu, Zn, Ni, and Co) in agricultural soils and common vegetables cultivated in different zones (upstream, midstream, and downstream) of a densely populated residential area in a typical mine city, which has been open-pit exploiting Tl-bearing pyrite minerals since 1960s. The results show that most of the agricultural soils exhibit contaminated levels of Tl, with Tl contents (upstream: 1.35–4.31 mg/kg, midstream: 2.43–5.19 mg/kg, and downstream: 0.65–2.33 mg/kg) mostly exceeding the maximum permissible level (MPL) for agricultural land use (1 mg/kg). Sequential extraction procedure indicates that even Tl is predominantly retained in the residual fraction, significant levels of Tl are still present in the geochemically mobile fractions. Besides, metals like Cu, Cd, Mn, and Co are mostly distributed in the labile fractions. Almost all metal (loid)s in edible parts of the vegetables exceed their corresponding MPL for consumption. The chronic daily intake (CDI) and hazard quotient (HQ) values calculated for inhabitants at different ages indicate non-negligible Tl risks via consumption of local vegetables, especially for children. Therefore, it is critical to establish effective measures for hazardous waste management and enforceable regulations in Tl-polluted area to mitigate potential severe impacts of Tl on human health through food chain.

In an attempt to evaluate the behavior of Dechlorane plus (DP) in soil-vegetable systems, this work investigated the uptake and translocation of DP by vegetables and the dissipation of DP in soil under greenhouse and conventional conditions. To address human dietary exposure to DP, estimated dietary intake via vegetable consumption was calculated. The uptake potential indexes of DP from soil into root for tomato and cucumber cultivated under different conditions ranged from 0.089 to 0.71. The ranges of uptake potential indexes of DP from resuspended soil particles into stem, leaf and fruit were 0.68–0.78, 0.27–0.42 and 0.39–0.75, respectively. The uptake potential indexes in greenhouse vegetables were generally higher than those in conventional vegetables when the vegetables had been planted in contaminated soil, indicating that greenhouse enhanced the uptake of DP with a high soil concentration by vegetables. The translocation factor (TF) values of DP in vegetables were in the range of 0.022–0.17, indicating that DP can be transported from root to fruit even though it has a high octanol water partition coefficient (KOW). The half-lives of DP dissipation in soil ranged from 70 to 102 days. The dissipation of DP in greenhouse soil was slightly slower than that in conventional soil. Higher estimated dietary intake (EDI) values of DP via greenhouse vegetables were observed due to the higher concentration of DP in greenhouse vegetables than conventional vegetables. These results suggested that greenhouses should not be adopted for vegetable production in contaminated regions.

Irrigation of crop plants with microcystins (MCs) contaminated water could be a threat to human health via bioaccumulation. Despite the fact MCs bioaccumulation in crop plants is well documented, MCs depuration, as well as the mechanism involved remains unclear. The objectives of the present study were to investigate the bioaccumulation and depuration of microcystin-LR (MC-LR) in lettuce (Lactuca sativa L.) and spinach (Spinacia oleracea L.), as well as to explore the role of glutathione (GSH) biosynthesis in MC-LR depuration. The tested plants were irrigated with deionized water containing 10 μg L⁻¹ MC-LR for 12 days (bioaccumulation), and subsequently, with either deionized water only or deionized water containing 0.5 mM buthionine sulfoximine (BSO, a specific inhibitor of GSH biosynthesis) for 12 days (depuration). After bioaccumulation period, highest concentrations of MC-LR found in lettuce and spinach were 114.4 and 138.5 μg kg⁻¹ dry weight (DW) respectively. Depuration rates of MC-LR in lettuce and spinach were 9.5 and 8.1 μg kg⁻¹ DW d⁻¹, which deceased to 3.7 and 4.6 μg kg⁻¹ DW d⁻¹ in treatments with BSO application. GSH content in both lettuce and spinach were not significantly affected during depuration without BSO; whereas after treatment with BSO, GSH content significantly decreased by 36.0% and 24.7% in lettuce and spinach on 15 d, and the decrease remained on 18 d and 21 d in lettuce. Moreover, during the bioaccumulation period, activities of glutathione reductase (GR) and glutathione S-transferase (GST) were enhanced in both plants. Our results suggested that GSH biosynthesis played an important role in MC-LR depuration in the tested plants. Concerning human health risk, most of the estimated daily intake (EDI) values during the bioaccumulation period exceeded the tolerable daily intake (TDI) guideline. However, the risk could be alleviated by irrigating with MCs-free water for a certain amount of time before harvest.

This paper reports the results of a joint project carried out by three regional environmental agencies of Italy to evaluate long-range mercury (Hg) transport from the abandoned Mt. Amiata Hg district in southern Tuscany (the third largest worldwide site for Hg production) to the fluvial ecosystems of the Paglia and Tiber rivers. Most of the work focused on stream sediments, surface waters and soils. A preliminary survey of Hg0 content in air was also conducted. Data obtained by public health authorities on Hg in vegetables and fish were also included.The highest Hg concentrations (up to thousands of μg/g Hg) were observed in stream sediments and soils directly impacted by Hg mine runoff. Although progressive Hg dilution was observed from north to south along the river, sediments and soils show anomalous Hg levels for over 200 km downstream of Mt. Amiata, testifying to an extreme case of long-range Hg contamination. A pervasive redistribution of Hg is observed in all sediment compartments. Presumably, the width of the impacted fluvial corridor corresponds to the entire alluvial plains of the rivers. The floodplains can be considered new sources for downstream Hg redistribution, especially during large flood events. On the other hand, results from water, air, and vegetable sampling indicate low potential for human exposure to Hg.The extent and distribution of the contamination makes remediation not viable. Therefore, people and human activities must coexist with such an anomaly. On the technical side, the most urgent action to be taken is better definition of the exact extent of the contaminated area. On the management side, it is necessary to identify which public institution(s) can best deal with such a widespread phenomenon. According to the precautionary principle, the impact of the contamination on human activities in the affected areas should be considered.