Seedlings of Psidium guajava cv. Pedro Sato were distributed into four open-top chambers: two with ambient CO2 (∼390 ppm) and two with elevated CO2 (∼780 ppm). Monthly, five individuals of each chamber were collected, separated into root, stem and leaves and immediately frozen in liquid nitrogen. Chemical parameters were analyzed to investigate how guava invests the surplus carbon. For all classes of phenolic compounds analyzed only tannins showed significant increase in plants at elevated CO2 after 90 days. There was no significant difference in dry biomass, but the leaves showed high accumulation of starch under elevated CO2. Results suggest that elevated CO2 seems to be favorable to seedlings of P. guajava, due to accumulation of starch and tannins, the latter being an important anti-herbivore substance.

Zearalenone (ZEA) is an estrogenic toxin produced by Fusarium strains, that is widely present in crops, and endangers the reproductive system of animals. Tannic acid (TA) is a natural polyphenolic substance that is widespread in the roots, stems, and leaves of plants, and has special pharmacological activity. This study was designed to investigate the therapeutic effect of TA on ZEA-induced ovarian damage in mice and to explore the molecular mechanism involved. Ninety healthy Kunming female mice were divided into six equal groups. All the groups but the control group were administered daily with ZEA [10 mg/kg body weight (bw)] orally, for 7 days, to induce damage to the reproductive system. Some groups were also administered with TA (50, 100, and 200 mg/bw) for 7 days. Mice were euthanized 24 h later to allow for collection of serum and ovaries. TA can effectively alleviate the appearance of congestion and redness of the ovary, caused by ZEA, and increase the number of healthy growing follicles. Moreover, the estrogen content and the levels of MDA and ROS in the ovaries can be effectively reduced by TA. It can also reduce the apoptosis of ovarian cells, decreases the protein expression of the estrogen receptor, Fas, Fasl, caspase-3, caspase-8, caspase-9, and Bax, and increases the protein expression of Bcl-2. Our study indicates that TA reduces the strong estrogen and oxidative damage induced by ZEA, and these therapeutic effects may be partially mediated by the death receptor and mitochondrial apoptosis signaling pathway.

Mitigation of air pollution by plants is a well-established phenomenon. Trees planted on the roadside are known to reduce particulate matter pollution by about 25%. In an urban ecosystem, especially in a metropolitan city such as Delhi, roadside trees are constantly exposed to air pollution. We, therefore, evaluated the effect of air pollution on a common Indian roadside tree, Neem (Azadirachta indica), and its associated microbes in areas with high and low levels of particulate matter (PM) pollution in Delhi. We hypothesized that alteration in the air quality index not only influences plant physiology but also its microbiome.A 100-fold increase in the number of epiphytic and 10–100 fold increase in endophytic colonies were found with 1.7 times increase in the level of pollutants. Trees in the polluted areas had an abundance of Salmonella, Proteus and Citrobacter, and showed increased secondary metabolites such as phenols and tannins as well as decreased chlorophyll and carotenoid. The number of unique microbes was positively correlated with increased primary metabolites.Our study thus indicates that, alteration in air quality affects the natural micro-environment of plants. These results may be utilized as sustainable tools for studying plant adaptations to the urban ecosystem.

The effects of four types of dissolved organic matters (DOM) on the bioconcentration of perfluoroalkyl substances (PFASs) in Chironomus plumosus larvae have been studied. The PFASs included perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA). The DOM included humic acid (HA), fulvic acid (FA), tannic acid (TA), and a protein, peptone (PEP), and their concentrations ranged from 0 to 50 mg L−1. The results showed that, upon bioconcentration equilibrium, the body burdens of longer perfluoroalkyl chain PFASs (PFOS, PFDA, PFUnA and PFDoA) decreased with PEP and HA concentrations while increased with FA and TA concentrations. When FA and TA concentrations increased from 0 to 50 mg L−1, body burdens of these PFASs increased by 7.5%–148.8% and 5.7%–37.1%, respectively. However, the DOM had no significant impact on the body burdens of shorter perfluoroalkyl chain PFASs (PFOA and PFNA). All of the four types of DOM lowered not only the uptake rate constants (ku) of PFASs due to the decrease of freely dissolved PFAS concentrations, but also the elimination rate constants (ke) due to the inhibition effect of DOM on the PFAS elimination from the larvae. The reduction in the two constants varied with both DOM and PFAS types. In the presence of PEP and HA with larger molecular weights, the ku values decreased more than ke, leading to the decreased body burdens of longer perfluoroalkyl chain PFASs. As for FA and TA with smaller molecular weights, the ke values decreased more than ku, resulting in increased body burdens of longer perfluoroalkyl chain PFASs. This study suggests that the effects of DOM on PFAS bioconcentration depend not only on the concentration but also on the molecule weight of DOM, which should be considered in the bioavailability assessment of PFASs.

The properties of carbon nanotubes (CNTs) functionalized with –OH and –COOH groups during simulated water treatment with H2O2 and/or UV were tested. There following properties of CNTs were investigated: specific surface area, elemental composition (CHN), dynamic light scattering, Raman spectroscopy, X-ray photoelectron spectroscopy and changes in the CNTs structure were observed using transmission electron microscopy. Treatment of CNTs with H2O2 and/or UV affected their properties. This effect, however, was different depending on the functionalization of CNTs and also on the factor used (UV and/or H2O2). H2O2 plays a key role as a factor modifying the surface of CNT-OHs, whereas the properties of CNT-COOHs were most affected by UV rays. A shortening of the nanotubes, exfoliation, the opening of their ends, and changes in the surface charge were observed as a result of the action of UV and/or H2O2. The changes in observed parameters may influence the stability of the aqueous suspensions of CNTs.

Trivalent chromium [Cr(III)] and tannins serve as necessary substances in leather processing and coexist in tannery site, which lead to the chromium contamination in site soil when disposed improperly. However, coexisting tannins are very likely to complex with Cr(III) and affect its properties, ultimately changing the mobility of chromium in soil. In this study, tannic acid (TA) was selected to investigate the complexation with Cr(III) and the influence on the solubility and sorption of Cr(III) in soils. Then, the transport behavior and mechanism of Cr(III)-TA complexes in soil was clarified. Dialysis results showed that the increase of TA concentration and solution pH promoted the formation of complexed Cr(III). The results of UV–Vis absorption spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations indicated that the adjacent ionized phenolic hydroxyls in TA functioned as the binding sites with Cr(III) to form the Cr–O bonds and the degree of complexation increased with pH. The Cr(III)-TA complexes had higher solubility than free Cr(III) at pH ≥ 6.0. Batch sorption experiments demonstrated that the sorption capacity of Cr(III)-TA to soils with different pH was always lower than that of free Cr(III). These reasons led to the stronger mobility of Cr(III)-TA in soil columns than Cr(III). Our research reveals that the enhanced mobility of Cr(III) in soils coexisting with TA.

Dissolved organic matter (DOM) may alter the sorption of hydrophobic organic contaminants (HOC) to metal oxide nanoparticles (NPs), but the role of DOM and NP types is poorly understood. Here, phenanthrene sorption was quantified on four types of nano-TiO2 (three rutile, one anatase), and a bulk, raw TiO2 powder. Prior to the sorption experiments, these nanoparticles were coated using four different organic materials: Lignin (LIG), tannic acid (TAN), Congo red (CON), and capsorubin (CAP). Lignin, tannic acid, congo red and capsorubin coating substantially enhanced phenanthrene sorption to various TiO2 particles. After coating with a specific DOM, Kd values by the DOM-coated TiO2 particles on percent organic carbon content and surface area (SA) basis (Koc/SA) generally followed the order: TiO2 NPs with hydrophobic surfaces > bulk TiO2 particles > other TiO2 NPs. Different Koc/SA values of various DOM-TiO2 complexes resulted from distinct conformation of the coated DOM and aggregation.

Tibouchina pulchra (Cham.) Cogn. (Melastomataceae) is a native tree species from the southeast region of Brazil. This early successional species significantly contributes to the characteristic physiognomy and structure of the Atlantic Rain Forest. Saplings were exposed to carbon filtered air (CF), ambient non–filtered air (NF), and ambient non–filtered air +40 ppb ozone (NF+O3), 8 h per day during two months, using open top chambers (OTC). The AOT40 values at the end of the experiment were 48, 910 and 12 895 ppb h–1, respectively for each treatment. After 25 days of exposure, interveinal red stippling appeared in plants in the NF+O3 chamber (AOT40=3 871 ppb h–1). In the NF chamber, symptoms were observed only after 60 days of exposure (AOT40=910 ppb h–1). No changes were observed for total phenolic contents when comparing ozone treatments. However, amounts of tannins and flavonoids were different among treatments. NF+O3 and NF treatment showed enhanced contents of flavonoids, when tannins seem to be reduced after ozone fumigation (p<0.01). Results suggest alteration on phenolic metabolism when saplings are ozone fumigated; those responses, considered T. pulchra, seem to occur before leaf injury appeared, once contents of flavonoids and tannins are also altered by NF treatment (AOT40=910 ppb h–1). This study demonstrates that total phenolic and tannins contents of saplings of T. pulchra also decreased when exposed to ozone. The same alterations were observed for T. pulchra after industrial air pollution, suggesting the reduction on total phenolic and tannins probably is a characteristic response of T. pulchra to presence of any kind of pollutant.

Tannic acid (TA) was employed as a novel colorimetric iron ion sensor. TA showed highly selective recognition for only Fe²⁺ and Fe³⁺ among a range of tested metal ions such as Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Hg²⁺, and Pb²⁺. In the presence of these metal cation solutions, only Fe²⁺ and Fe³⁺ solutions underwent impressive color change detectable with the naked eye from colorless to purple and gray, respectively. Surprisingly, TA behaves as a highly selective sensor upon chemical oxidation of iron (Fe²⁺ and Fe³⁺) cations. In addition, various sensor applications of TA were performed. For this, TA-impregnated silica gel, alumina oxide sheet, and filter paper were used. Each test strip showed very high selectivity for iron ions. The detection limit of the sensor for Fe²⁺ and Fe³⁺ was found to be 1.0 × 10⁻⁶ M, and the association constant Kₐ was determined as 4.05 × 10⁴ M⁻¹ and 1.80 × 10⁷ M⁻¹. The order of ion binding power was determined to be Fe³⁺ > Fe²⁺ by UV-Vis spectroscopy. These discernable color changes due to the complexion of TA with Fe²⁺ and Fe³⁺ demonstrated the utilization of TA to selectively detect these metal cations. The use of tannic acid as a complexing agent that can detect Fe (II) and Fe (III) metal ions in environmental waters by colorimetry and spectrophotometry.

In this work, metal sorption onto grape stalks waste structural compounds and extractives has been studied for determining their role in Cr(VI), Cu(II) and Ni(II) metal sorption. For this purpose, a sequential extraction of extractives and other compounds from the lignocellulosic material has been carried out. The resulting solid samples obtained in the different extraction processes were used as sorbents of Cr(VI), Cu(II) and Ni(II). Sorption results were discussed taking into account the elemental composition and polarity of the solid extracts. Results indicated that tannins and polyphenols are involved in chromium reduction and sorption. Lignin and celluloses are involved in chromium, Cu(II) and Ni(II) sorption. FTIR analysis confirmed the involvement of lignin moieties in the studied metal ions sorption by grape stalks waste. This study presents a new approach on metal sorption field as the knowledge of the role of the sorbent chemical compounds is essential to determine the key sorbent compounds in the sorption process.