With the aim of investigating the effects of carbonaceous sorbent amendment on plant health and end point contaminant bioavailability, plant experiments were set up to grow maize (Zea mays) in soil contaminated with polycyclic aromatic hydrocarbons (PAHs) and metals. Maize and pine derived biochars, as well as a commercial grade activated carbon, were used as amendments. Plant growth characteristics, such as chlorophyll content and shoot to root biomass, improved with sorbent amendment to varying extents and contaminant uptake to shoots was consistently reduced in amended soils. By further defining the conditions in which sorbent amended soils successfully reduce contaminant bioavailability and improve plant growth, this work will inform field scale remediation efforts.

Rhizosphere effects on the distribution of PBDEs in e-waste contaminated soils were investigated. The geometric means of the PBDEs in the rhizosphere and non-rhizosphere soils were 32.6 ng/g and 12.2 ng/g, whereas the geometric means of the PBDEs in vegetable shoots and roots were 2.15 ng/g and 3.02 ng/g, respectively. PBDEs in soil at different distances from the root surface may first rise appreciably and then decrease to a non-rhizosphere level for long-term contaminated soils. Different PBDE compositions in roots and shoots indicated that PBDEs in shoots may be mainly taken up from the air. The ratios of BDE99/100 and BDE153/154 in plants and their corresponding soils were different. The bioaccumulations of BDEs 100 and 154 were much higher than those of BDEs 99 and 153, respectively. This indicated that the bioaccumulation was selective and influenced by the substitution pattern, with ortho-substituted isomers being more prevalent than meta-substituted isomers.

The increase of seawater desalination plants may affect seagrasses as a result of its hypersaline effluents. There are some studies on the salinity tolerance of seagrasses under controlled laboratory conditions, but few have been done in situ. To this end, Cymodocea nodosa shoots were placed during one month at four localities: two close to a brine discharge; and the other two not affected by the discharge, and this experiment was repeated four times. The results obtained showed a decrease in growth and an increased mortality at the localities affected by the brine discharge. An increase was detected in the percentage of horizontal shoots in respect to vertical shoots at the impacted localities. It is probably that not only the average salinity, but also the constant salinity fluctuations and slightly higher temperatures associated with the brine that may have caused physiological stress thus reducing C. nodosa growth and survival.

We investigated impacts of Macondo MC252 oil from the Deepwater Horizon (DWH) spill on the common reed Phragmites australis (Cav.) Trin. ex Steud., a dominant species of the Mississippi River Delta. In greenhouse experiments, we simulated the most common DWH oiling scenarios by applying weathered and emulsified Macondo oil to aboveground shoots at varying degrees of coverage (0–100%) or directly to marsh soil at different dosages (0–16Lm−2). P. australis exhibited strong resistance to negative impacts when oil was applied to shoots alone, while reductions in above- and belowground plant growth were apparent when oil was applied to the soil or with repeated shoot-oiling. Although soil-oiling compromised plant function, mortality of P. australis did not occur. Our results demonstrate that P. australis has a high tolerance to weathered and emulsified Macondo oil, and that mode of exposure (aboveground versus belowground) was a primary determinant of impact severity.

The potential use of the arsenic-tolerant woody leguminous species Anadenanthera peregrina (L) Spegazzini for rehabilitating arsenic (As)-contaminated areas was studied. In an As (539.33 mg/kg)-contaminated soil experiment, plants were able to accumulate arsenic in their roots with a low transfer index to the shoot. Inoculation with arbuscular mycorrhizal fungi (AMF) amplified this behavior and improved both biomass production and the phosphorus concentration in the shoot. AMF inoculation not only improved A. peregrina plant growth but also protected the shoot against As toxicity. Aside from the AMF inoculation, the addition of organic matter reduced the soil pH, thus improving the ability of the roots to accumulate arsenic. The majority (81 %) of the variations in As accumulation in A. peregrina roots were explained by the effects of the organic matter and soil pH as well as AMF treatments, as found by a principal component analysis. A. peregrina promoted phytostabilization through As root sequestration. Therefore, A. peregrina plants inoculated with AMF in the presence of organic matter are recommended to rehabilitate degraded areas of soil contaminated with arsenic.

The accumulation of metals and nutrients in biosolid-amended soils and the risk of their excess uptake by plants is a topic of great concern. This study examines the elemental uptake and accumulation in five vegetable plants grown on biosolid-applied soils and the use of spectral reflectance to monitor the resulting plant stress. Soil, shoot, root, and fruit samples were collected and analyzed for several elemental concentrations. The chemical concentrations in soils and all the plant parts increased with increase in applied biosolid concentrations. The Cu and Zn concentrations in the plant shoots increased in the order of collard < radish < lettuce < tomato < pepper. The Cu and Zn concentrations accumulated significantly in the fruits of the tomato plants compared to other plants. Among all the plants, the shoot concentration factor (SCF) of Zn was significantly higher for pepper plants, indicating increase in uptake of Zn. The shoot relative uptake index (SRUI) of Cu and Zn increased in the order of collard < radish < lettuce < tomato < pepper. The shoot dry weight and spectral reflectance of the radish plants in the near-infrared (NIR) region (800–1,300 nm) decreased significantly with increase in biosolid concentration compared to other plants. Increase in plant stress with increase in biosolid dose was evident in radish plants through significant reduction in Normalized Difference Vegetative Index (NDVI). This study indicates the potential use of spectral reflectance as a tool for the screening and monitoring of stress-sensitive plant species and their physiology and as a result, indirectly assesses the chemical concentrations in soils and plants.

The extent of endosulfan sulfate removal from soils by different planting pattern with sweet corn (Zea mays), cowpea (Vigna sinensis), and cucumber (Cucumis sativus) either cultivated alone or together was investigated in pot experiments. Endosulfan sulfate was removed to the greatest extent in the treatment in which sweet corn was grown alone; only 11.3 and 27.2 % of the initial endosulfan sulfate remained in rhizospheric and bulk soil, respectively, of sweet corn grown alone at day 60. Endosulfan sulfate was also removed from soil to a great extent in treatments where cucumber or cowpea was grown alone; only 30.3 and 38.8 % of endosulfan sulfate remained in their respective rhizospheric soil after 45 days. However, cucumber did not tolerate the toxicity of endosulfan sulfate well and died around 50–55 days when it was cultivated either alone or together with another plant. Cultivation of sweet corn and cowpea together was less effective in removing endosulfan sulfate from soil; about 41.7 and 52.3 % of endosulfan sulfate remained in their respective rhizospheric soils after 60 days. The results showed that single cultivation of the plants was the most efficient way to remediate endosulfan sulfate-contaminated soil in this study. Endosulfan sulfate was detected in both the root and shoot of plants but given the low levels found, bioaccumulation was judged to be a relatively minor factor in endosulfan sulfate removal from soil.

In agricultural areas, pesticides can enter receiving waterbodies by means of agricultural runoff and pollute these systems. Constructed wetlands are capable of removing several pollutants including pesticides. Unfortunately, few studies are from South America, and therefore, information is urgently needed on pesticide mitigation in agricultural runoff by native plants. To this aim, an experimental setup of polypropylene tubs was used, which were planted with two types of native plants (Nymphaea amazonum and Eleocharis mutata). Mesocosms were exposed to low (10 μg/l) and high (30 μg/l) target concentrations of lambda-cyhalothrin, while for imidacloprid, a low (60 μg/l), high (180 μg/l), and an extra high (1,000 μg/l) dose, were applied using batch experiments of 2 weeks each. Removal efficiencies for lambda-cyhalothrin from the water phase showed 100 % removal at 72 h for both low and high target concentrations for N. amazonum mesocosms, while for E. mutata mesocosms, a 100 % removal was observed at 48 h for mesocosms exposed to low target concentrations and for high target concentrations at 72 h. For imidacloprid, a 100 % removal was observed for E. mutata and 86 % for N. amazonum mesocosms exposed to low target concentrations (60 μg/l) at 216 h. For the highest dose (1,000 μg/l), the removal efficiency was on average 72 % at 216 h for both types of mesocosms. Statistical two-way ANOVA analysis (α = 0.05) showed that the removal of lambda-cyhalothrin was independent of the dose applied and the plant type, while for imidacloprid, removal was dependent on the dose applied and independent of the plant type. After the experimental period, analyses of the plants and sediment showed that 48.5 % of the applied amount of lambda-cyhalothrin was detected in the sediment and 0.4 % in plant material (shoots and leaves), while the amount in roots was below the limit of detection for N. amazonum mesocosms. For E. mutata mesocosms, 44.6 % of lambda-cyhalothrin was detected in sediment and 0.5 % in roots. For N. amazonum mesocosms, 78.9 % of the applied amount of imidacloprid was retained in plants (plant material and roots) and 17.31 % in sediment, while for E. mutata mesocosms only 0.5 % of imidacloprid was detected in plant material and roots. In this experiment, the DT₅₀of lambda-cyhalothrin in the water phase of both types of mesocosms was on average 1 day, while for imidacloprid, this was calculated to be around 1–10 days. The results obtained provide necessary information for the construction of a field scale wetland capable of efficient removal of pesticides in agricultural runoff.

The outstanding biological performance and non-food utilization of bioenergy grass possibly make it to be the best candidate for phytoremediation of heavy metal-contaminated soil, but evidence is limited. In this study, we conducted pot experiments to quantify the performance of two promising energy grasses, Arundo donax and Miscanthus sacchariflorus, in the phytoremediation of Zn- and Cr-contaminated soil. The results showed that (1) the biomass and root length of the two grasses were firstly increased and then kept stable or slightly decreased with increasing soil Zn/Cr concentration, implying that the two grasses had strong tolerance to Zn/Cr contamination; (2) the Zn/Cr concentration in the grass roots was two to seven times of that in the shoots, while both of them were positively correlated with the Zn/Cr concentration in soil; (3) the total accumulation of Zn/Cr in the grass (shoots + roots) was firstly determined by their concentration in the shoots and secondly determined by the shoots’ biomass, indicating that most of the Zn/Cr could be removed from contaminated soil by harvesting the aboveground parts; (4) the accumulating amount of the two grasses for Zn were 17.5 and 12.1 mg plant⁻¹, respectively; while the accumulating amount for Cr were 3.9 and 2.9 mg plant⁻¹, respectively. Taken together, the two energy grasses had strong tolerance and high accumulating ability for Zn/Cr, and therefore, they are promising candidates for the phytoremediation of Zn-/Cr-contaminated soil.

The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical–physical properties. After the amendment of Cu (5 or 10 mg Cu l⁻¹) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg⁻¹DW, more than three times higher than in S. alba (31.56 mg Cu kg⁻¹DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to threefold to fourfold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.