Although post-combustion emissions from power plants are a major source of air pollution, they contain excess CO₂ that could be used to fertilize commercial greenhouses and stimulate plant growth. We addressed the combined effects of ultrahigh [CO₂] and acidic pollutants in flue gas on the growth of Alternanthera philoxeroides. When acidic pollutants were excluded, the biomass yield of A. philoxeroides saturated near 2000 μmol mol⁻¹ [CO₂] with doubled biomass accumulation relative to the ambient control. The growth enhancement was maintained at 5000 μmol mol⁻¹ [CO₂], but declined when [CO₂ rose above 1%, in association with a strong photosynthetic inhibition. Although acidic components (SO₂ and NO₂) significantly offset the CO2 enhancement, the aboveground yield increased considerably when the concentration of pollutants was moderate (200 times dilution). Our results indicate that using excess CO₂ from the power plant emissions to optimize growth in commercial green house could be viable. Diluted post-combustion emission gas from fossil fuel fired power plants stimulate the growth of C₃ plant.

The effects on the growth of tomato seedlings and cadmium accumulation of earthworm mucus and a solution of amino acids matching those in earthworm mucus was studied through a hydroponic experiment. The experiment included four treatments: 5 mg Cd L⁻¹ (CC), 5 mg Cd L⁻¹ þ 100 mL L⁻¹ earthworm mucus (CE), 5 mg Cd L⁻¹ þ 100 mL L⁻¹ amino acids solution (CA) and the control (CK). Results showed that, compared with CC treatment, either earthworm mucus or amino acids significantly increased tomato seedling growth and Cd accumulation but the increase was much higher in the CE treatment compared with the CA treatment. This may be due to earthworm mucus and amino acids significantly increasing the chlorophyll content, antioxidative enzyme activities, and essential microelement uptake and transport in the tomato seedlings. The much greater increase in the effect of earthworm mucus compared with amino acid treatments may be due to IAA-like substances in earthworm mucus.

High O3 levels, driving uptake and challenging defense, prevail on the Canary Islands, being associated with the hot and dry summers of the Mediterranean-type climate. Pinus canariensis is an endemic conifer species that forms forests across these islands. We investigated the effects of ozone on photosynthesis and biochemical parameters of P. canariensis seedlings exposed to free-air O3 fumigation at Kranzberg Forest, Germany, where ambient O3 levels were similar to those at forest sites in the Canary Islands. The twice-ambient O3 regime (2xO3) neither caused visible injury-like chlorotic or necrotic spots in the needles nor significantly affected violaxanthin, antheraxanthin and zeaxanthin levels and the de-epoxidation state of the xanthophyll cycle. In parallel, stomatal conductance for water vapour, net photosynthesis, intercellular CO2 concentration, chlorophyll fluorescence parameters, as well as antioxidant levels were hardly affected. It is concluded that presently prevailing O3 levels do not impose severe stress on P. canariensis seedlings.

Stomatal ozone uptake, determined with the Jarvis' approach, was related to photosynthetic efficiency assessed by chlorophyll fluorescence and reflectance measurements in open-top chamber experiments on Phaseolus vulgaris. The effects of O₃ exposure were also evaluated in terms of visible and microscopical leaf injury and plant productivity. Results showed that microscopical leaf symptoms, assessed as cell death and H₂O₂ accumulation, preceded by 3-4 days the appearance of visible symptoms. An effective dose of ozone stomatal flux for visible leaf damages was found around 1.33 mmol O₃ m⁻². Significant linear dose-response relationships were obtained between accumulated fluxes and optical indices (PRI, NDI, ΔF/Fm'). The negative effects on photosynthesis reduced plant productivity, affecting the number of pods and seeds, but not seed weight. These results, besides contributing to the development of a flux-based ozone risk assessment for crops in Europe, highlight the potentiality of reflectance measurements for the early detection of ozone stress. Ozone stomatal fluxes affect leaf cell viability, photosynthetic performance, optical properties and crop yield of bean.

In coastal marshy lands, halogen bromide concentration is reported to be generally higher than in the inland soils where, annual halophytic species naturally grow. The effect of bromide on plant responses is relatively less known. The objectives of this study were to assess the effect of sodium bromide (NaBr) on growth, photosynthetic pigments, tissue ions content and changes in enzymes activity in Salicornia brachiata, a salt marsh halophyte. Presence of NaBr in the root medium induced 200 percent increase in fresh mass and 30% increase in dry mass, compared to untreated control. Relative water content also increased significantly with NaBr treatment. Increase in fresh and dry mass was not associated with high photosynthetic efficiency as evidenced by decrease in photosynthetic pigments accumulation. However, inorganic ion analysis revealed that S. brachiata accumulated Na⁺ as a primary osmotica. The concentration of Na⁺ in NaBr treated plants was ~4 fold higher than that measured in untreated controls and this was associated with significant reduction in K⁺, Ca²⁺, Mg²⁺ contents. Bromide content also increased significantly and accounted for 20 to 50 percent of dry weight. In addition, significant differences in the activities of superoxide dismutase (SOD), peroxidase (POX), catalase (CAT) and ATPase were observed in bromide treated plants. For the first time bromide tolerance in coastal halophyte was reported and the results suggest that bromide was not toxic to S. brachiata for growth and metabolism even at 600 mM. concentration and suggest that the species can be used in phytoremediation of bromide contaminated soils.

In order to assess as to whether treated textile effluent could be safely used to irrigate some winter vegetables, growth room experiments were conducted. Varying levels of treated and untreated textile effluents were applied to germinating seeds of some winter vegetables and their effect was evaluated on germination and early growth stage using seed germination, growth, and biochemical attributes. From the results, it was obvious that textile effluent reduced seed germination and early growth of all vegetables. However, this effect was more pronounced at the highest concentration of textile effluent. Furthermore, treated textile effluent did not show any inhibitory effect on seed germination of all vegetables. Photosynthetic pigments such as chlorophyll a and b, and protein contents were higher in the leaves of all vegetable plants irrigated with treated textile effluent than those of supplied with untreated textile effluents. It has been observed that heavy metals were lower in concentration in treated textile effluent as compared with untreated textile effluent. However, germination and growth responses of all three vegetables were different to treated or untreated textile effluents. Furthermore, the Raphanus sativus ranked as tolerant followed by Brassica campastris and Brassica napus based on germination and growth responses. In conclusion, in view of shortage of water, textile effluent could safely be used for irrigation to vegetables after proper processing.

The effects of bentazon and molinate, two selective herbicides recommended for integrated weed management in rice, were studied in Anabaena cylindrica, an abundant cyanobacterium isolated from a Portuguese rice field agro-ecosystem. Comparative effects of both herbicides on A. cylindrica were estimated under laboratory conditions by measuring its dry weight yield, photopigments, and carbohydrate and protein contents in a time- and dose-dependent exposure throughout 72 h. Photosynthesis and respiration were also monitored. The results revealed that both herbicides exerted a pleiotropic effect on the cyanobacterium at the range of concentrations tested (0.75-2 mM). Growth, chlorophyll a, carotenoids and phycobiliproteins were more adversely affected by molinate than by bentazon. Cyanobacterial growth inhibitions of over 50% were observed after 48 h when 1.5-2 mM of molinate were applied. Bentazon concentrations ranging from 0.75 to 2 mM did not significantly modified chlorophyll a content with time, however, considerable reductions in chlorophyll a, carotenoids and specially phycobiliproteins were observed with molinate. Protein content increased with both herbicides although the effect was particularly noticeable with the highest concentration of molinate. Herbicide effects on carbohydrate content were contrasting: molinate increased this organic fraction whereas bentazon decrease it. Photosynthesis and respiration were inhibited by both herbicides and higher molinate concentrations (1.5-2 mM) completely ceased O₂ evolution after 48 h. Since A. cylindrica is abundant in Portuguese rice fields and could be used as an inoculum source in rice biofertilization programs, their protection from potential residual effects of herbicides is fundamental for a correct management of local soil fertility.

Effects of elevated arsenic (As) concentrations on hydroponic Kalmi (Ipomoea aquatica L.) were investigated. Plants were treated with 0, 10, 25, and 50 μM As in the greenhouse for 14 days. Arsenic was added from sodium meta-arsenite (NaAsO₂). Visible toxicity symptom could not easily be recognized without visible growth reduction. Little brown spots on the leaf blade were found at 50 μM As treatment. Dry matter yields decreased by 18.8%, 43.2%, and 78.2% in leaves; 23.6%, 56.4%, and 81.8% in stems; and 11.0%, 28.6%, and 63.7% in roots in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentrations increased in leaves (except in 50 μM As treatment), stems, and roots with increasing As concentrations in the medium. Roots contained 12.7, 11.3, and 10.5 times higher As concentrations as compared to stems and 15.5, 15.9, and 52.8 times higher as compared to leaves in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentration followed the trend of roots > stems > leaves. Kalmi concentrated unaccepted levels of As in leaf and stem tissues for human consumption in the As-treated plants. Based on 10% dry weight (DW) reduction, the critical toxicity level (CTL) of As in the leaves was 7.02 and 23.6 μg g⁻¹ DW in stems.

Background, aim, and scope The success of phytoextraction depends upon the identification of suitable plant species that hyperaccumulate heavy metals and produce large amounts of biomass using established agricultural techniques. In this study, the Mediterranean saltbush Atriplex halimus L., which is a C4 perennial native shrub of Mediterranean basin with an excellent tolerance to drought and salinity, is investigated with the main aim to assess its phytoremediation potential for Pb and Cd removal from contaminated soils. In particular, the influence of soil salinity in metal accumulation has been studied as there is notable evidence that salinity changes the bioavailability of metals in soil and is a key factor in the translocation of metals from roots to the aerial parts of the plant. Materials and methods Three pot experiments were conducted under greenhouse conditions for a 10-week period with A. halimus grown in soil artificially polluted with 20 ppm of Cd and/or 800 ppm of Pb and irrigated with three different salt solutions (0.0%, 0.5%, and 3.0% NaCl). Soil measurements for soil characterization were performed with the expiration of the first week of plant exposure to metals and NaCl, and at the end of the experimental period, chlorophyll content, leaf protein content, leaf specific activity of guaiacol peroxidase (EC 1.11.1.7), shoot water content, biomass, and Cd and Pb content in the plant tissues were determined. Additionally, any symptoms of metal or salt toxicity exhibited by the plants were visually noted during the whole experimental period. Results The experimental data suggest that increasing salinity increases cadmium uptake by A. halimus L. while in the case of lead there was not a clear effect of the presence of salt on lead accumulation in plant tissues. A. halimus developed no visible signs of metal toxicity; only salt toxicity symptoms were observed in plants irrigated with 3% NaCl solutions. Chlorophyll content, leaf protein content, shoot water content, and biomass were not negatively affected by the metals; instead, there was even an increase in the amount of photosynthetic pigments in plants treated with both metals and salinity. The specific activity of guaiacol peroxidase seems to have a general tendency for increase in plants treated with the metals in comparison with the respective controls but a statistically significant difference exists only in plants treated with the metal mixture and saline conditions. Discussion The data revealed that lead and cadmium accumulation in plant tissues was kept generally at low levels. Salinity was found to have a positive effect on cadmium uptake by the plant and this may be related to a higher bioavailability of the metal in soil due to decreased Cd sorption on soil particles. On the other hand, salinity did not influence in a clear way the uptake of Pb by the plant probably because of lead's limited mobility in soils and plant tissues. Cd and Pd usually decrease the chlorophyll content and biomass and change water relations in plants; however, A. halimus was found not to be affected indicating that it is a Cd- and Pb-tolerant plant. Guaiacol peroxidase activity as one of the parameters expressing oxidative damage and extent of stress in plants was not generally found to be significantly affected under the presence of metals in most plants suggesting that the extent of stress in plants was minimal, while only for plants treated with the metal mixture and low salinity the enzyme activity was elevated confirming that this enzyme serves as an antioxidative tool against the reactive oxygen species produced by the metals. Conclusions Atriplex halimus L. is a Pb- and Cd-tolerant plant but metal concentrations achieved in plant tissues were kept generally at low levels; however, metal accumulation in shoots, especially for Cd, considered together with its high biomass production, rapid growth, and deep root system able to cope with poor structure and xeric characteristics of several polluted soils suggest that this plant deserves further investigation. Recommendations and perspectives Phytoextraction by halophytes is a promising alternative for the remediation of heavy metal contaminated sites affected by salinity since saline depressions often indicate sites of industrial effluents accumulation, contaminated by heavy metals, including Pb and Cd. Halophytes are also promising candidates for the removal of heavy metals from non-saline soils. Furthermore, the use of such plants can be potentially viewed as an alternative method for soil desalination where salt is removed from the soil instead of being washed downwards by water or other solutions.

Lake Tasaul on the Black Sea coast is highly eutrophic, but not strongly contaminated (heavy metals, PAHs, and organochlorine pesticides). Cyanophytes dominate phytoplankton by 67-94% and form frequent algal blooms. High primary production (up to 270 mg Cass/m².h) and algal biomass (maximum chlorophyll a concentration 417 μg/l) may be controlled by light, as Secchi depth is often below 1 m. The main tributary, Casimcea River, provides high quantities of suspended matter and about 3 tons TP/year and 660 tons TN/year. Based on chemical and biological analysis as well as fishery investigations, we provide recommendations for Lake Tasaul rehabilitation.