Cadmium stress in rice: toxic effects,tolerance mechanisms,and management: a critical review

Cadmium (Cd) is one of the main pollutants in paddy fields, and its accumulation in rice (Oryza sativa L.) and subsequent transfer to food chain is a global environmental issue. This paper reviews the toxic effects, tolerance mechanisms, and management of Cd in a rice paddy. Cadmium toxicity decreases seed germination, growth, mineral nutrients, photosynthesis, and grain yield. It also causes oxidative stress and genotoxicity in rice. Plant response to Cd toxicity varies with cultivars, growth condition, and duration of Cd exposure. Under Cd stress, stimulation of antioxidant defense system, osmoregulation, ion homeostasis, and over production of signaling molecules are important tolerance mechanisms in rice. Several strategies have been proposed for the management of Cd-contaminated paddy soils. One such approach is the exogenous application of hormones, osmolytes, and signaling molecules. Moreover, Cd uptake and toxicity in rice can be decreased by proper application of essential nutrients such as nitrogen, zinc, iron, and selenium in Cd-contaminated soils. In addition, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce Cd stress in rice. Selection of low Cd-accumulating rice cultivars, crop rotation, water management, and exogenous application of microbes could be a reasonable approach to alleviate Cd toxicity in rice. To draw a sound conclusion, long-term field trials are still required, including risks and benefit analysis for various management strategies.     

Modeling plant response to tropospheric ozone: a critical review

The advantages and disadvantages, benefits and limitations, of a number of published mathematical models representing the effects of ozone on crops and native vegetation are described. Several levels of modeling are addressed: word models, graphic models, mathematical models, and computer simulation implementation. Special attention is given to evaluating: (1) how the interaction between ozone exposure and vegetation effects is quantified, (2) the status of field testing of the model, and (3) the adequacy of information for enabling other investigators to replicate the model for further testing. Original contributions, not previously published, are made in this evaluation in the form of: (1) graphic model flow charts for published models, (2) clarification of mathematical equations for existing models, (3) graphic forms of functional relations comprising portions of models, and (4) graphic displays of model output performance versus observed data. The models that are evaluated cover acute exposure-response models, statistical and mechanistic-process models, including a partial model of ambient exposure versus ozone flux, and uptake. They also cover chronic exposure statistical approaches, including time-series modeling, mechanistic-process models, 'disintegrated' models of forest system simulations, chronic flux density-uptake-response, and models for regional effects assessment in forests and agricultural lands.     

Studies on cadmium toxicity in plants: a review

This review emphasises cadmium toxicity on plants with regards to ecological, physiological and biochemical aspects. Cadmium toxicity in plants and problems concerning tolerance and ecological performance are discussed briefly. Efforts have been made to compare the relative sensitivity of various plant groups including micro-and macro-flora. This review may help in interdisciplinary studies to assess the ecological significance of metal stress.     

Lead tolerance in plants: strategies for phytoremediation

Lead (Pb) is naturally occurring element whose distribution in the environment occurs because of its extensive use in paints, petrol, explosives, sludge, and industrial wastes. In plants, Pb uptake and translocation occurs, causing toxic effects resulting in decrease of biomass production. Commonly plants may prevent the toxic effect of heavy metals by induction of various celular mechanisms such as adsorption to the cell wall, compartmentation in vacuoles, enhancement of the active efflux, or induction of higher levels of metal chelates like a protein complex (metallothioneins and phytochelatins), organic (citrates), and inorganic (sulphides) complexes. Phyotochelains (PC) are synthesized from glutathione (GSH) and such synthesis is due to transpeptidation of γ-glutamyl cysteinyl dipeptides from GSH by the action of a constitutively present enzyme, PC synthase. Phytochelatin binds to Pb ions leading to sequestration of Pb ions in plants and thus serves as an important component of the detoxification mechanism in plants. At cellular level, Pb induces accumulation of reactive oxygen species (ROS), as a result of imbalanced ROS production and ROS scavenging processes by imposing oxidative stress. ROS include superoxide radical (O₂ ^.?), hydrogen peroxide (H₂O₂) and hydroxyl radical (^·OH), which are necessary for the correct functioning of plants; however, in excess they caused damage to biomolecules, such as membrane lipids, proteins, and nucleic acids among others. To limit the detrimental impact of Pb, efficient strategies like phytoremediation are required. In this review, it will discuss recent advancement and potential application of plants for lead removal from the environment.     

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis

Since sewage discharges can significantly contribute to the contaminant loadings in coastal areas, it is important to identify sources, pathways and environmental sinks. Sterol and fatty alcohol biomarkers were quantified in source materials, suspended sediments and settling matter from the Ria Formosa Lagoon. Simple ratios between key biomarkers including 5beta-coprostanol, cholesterol and epi-coprostanol were able to identify the sewage sources and effected deposition sites. Multivariate methods (PCA) were used to identify co-varying sites. PLS analysis using the sewage discharge as the signature indicated approximately 25% of the variance in the sites could be predicted by the sewage signature. A new source of sewage derived organic matter was found with a high sewage predictable signature. The suspended sediments had relatively low sewage signatures as the material was diluted with other organic matter from in situ production. From a management viewpoint, PLS provides a useful tool in identifying the pathways and accumulation sites for such contaminants.     

Spontaneous abortion in women occupationally exposed to inhalational anesthetics: a critical systematic review

Environmental Science and Pollution Research - Occupational exposure to inhalational anesthetics has been associated with health problems, including reproductive issues. Considering the scarcity...     

Heavy metal tolerance of rice plants (Oryza sativa L.) to some metal oxides at the critical levels

The toxicity of metal oxides (CdO, ZnO, PbO) were compared with each other and the critical levels of metal uptake by rice plants were determined. The order of metal toxicity to rice plants is CdO greater than ZnO greater than PbO. The highest concentration obtained for unpolished rice was 4.97 micrograms/g at the Cd 10,000 ppm in soil. This values is higher than every other we have seen in the reports for treatment with CdO. We are able to find out that the concentration of 10,000 ppm Cd in the form of CdO in the critical one towards rice plant. By contrast, such damage was not observed at even higher levels of ZnO and PbO were considered to have low toxicity toward rice plant. Also, a negative correlation between Zn or Cu accumulation in rice plants and Cd concentration in soil was found.     

Aquatic plants and ecotoxicological assessment in freshwater ecosystems: a review

Environmental Science and Pollution Research - This paper reviews the current state-of-the-art, limitations, critical issues, and new directions in freshwater plant ecotoxicology. We selected...     

Approaches to assess the oral bioaccessibility of persistent organic pollutants: a critical review

Oral bioaccessibility, also known as in vitro gastrointestinal extraction or the physiologically based extraction test (PBET), is an important tool when assessing the risk to humans from persistent organic pollutants (POPs) (and metals). The approach seeks to mimic the processes of human food digestion and thereby assess the bioavailability of POPs (and metals) from materials consumed either accidentally or intentionally in the diet. In vitro conditions are created to simulate various actions in the stomach and intestines (although some methods also include the mouth compartment). This paper reviews the current status of oral bioaccessibility with respect to the release of POPs from soil and related samples of environmental importance. Particular emphasis is placed on the parameters that influence gastrointestinal extraction including gastric and intestinal pH, enzymes, bile salts, food constituents and residence time. In addition, important developments in the use of in vitro gastrointestinal extraction are highlighted. These developments include the use of epithelial Caco-2 cells to mimic the intestinal cell lining, the potential for biotransformation of POPs into estrogenic metabolites as a result of colon microbiota, and the use of in vivo studies to validate existing approaches.     

Bibliometric analysis of studies involving e-waste: a critical review

Environmental Science and Pollution Research - The correct destination of waste is an essential factor for sustainable development. Electronic waste, which is very toxic, is the type of waste with...     

Use of freshwater plants for phytotoxicity testing: a review

Phytotoxicity data for aquatic plants have served a relatively minor role in regulatory decisions concerning the environmental hazard of most potential contaminants. A variety of phytotoxicity tests have been conducted with freshwater green algae, duckweed, blue-green algae, diatoms and rooted macrophytes (whole plants and seeds). Several test methods have been standardized for microalgae which are used primarily with chemicals, effluents, contaminated sediment elutriates and hazardous waste leachates. Current scientific understanding concerning the phytotoxic effects of these contaminants is based mostly on results for a few green algae. The greatest limitation of these results is their uncertain environmental relevance due to the large interspecific variation in response of standard algal test species and the unrealistic experimental test conditions. Results of the few field validation toxicity tests conducted to resolve this uncertainty have been chemical-specific and unpredictable. Aquatic vascular plants have been used less frequently than algae as test species. Duckweeds have been used more often than rooted submersed species but the uncertain nature of their sensitivities relative to animal and other plant species has limited their use. Regulatory interest in wetland protection, contaminated sediment evaluations and sediment quality criteria development will result in increased use of whole rooted plants and their seeds as test species. Overall, regardless of the test species, if phytotoxicity data are to be more available and effective in the hazard assessment process, additional information concerning species sensitivity, and environmental relevance of the results will be needed.     

Aqueous carbonation of peridotites for carbon utilisation: a critical review

Environmental Science and Pollution Research - Peridotite and serpentinites can be used to sequester CO2 emissions through mineral carbonation. Olivine dissolution rate is directly proportional...     

Auxin induced stress tolerance in algae

IAA effect on responses of West African algae Caloglosa, Bostrychia, Rhizoclonium and the fresh water alga Pithophora to different growth conditions was examined in growth chamber experiments. The auxin (2.28 x 10(-5) M) caused growth increase of 2.3- and 2.6-fold in Caloglossa and 1.6 and 1.7 in Rhizoclonium, respectively, in sea water and 1:1 diluted sea water/Erdschreiber medium. In Bostrychia pronounced deterioration of growth was noticed in the control samples between 16 and 32 days in culture. The cultures maintained an active growth, however, in the presence of IAA. IAA also allowed Pithophora to withstand salinity: Compared to growth in fresh water, a 65% growth inhibition was recorded in 1:1 diluted sea water in the absence of auxin and a slight growth stimulation when the auxin was present. Pithophora and Rhizoclonium also maintained higher rates of growth in extremal temperatures of 10 and 45 degrees C when the auxin was present.     

Agriculture and deforestation in the tropics: a critical theoretical and empirical review

Despite the important role that tropical forests play in human existence, their depletion, especially in the developing world, continue relentlessly. Agriculture has been cited as the major cause of this depletion. This paper discusses two main theoretical underpinnings for the role of agriculture in tropical deforestation. First, the forest biomass as input in agricultural production, and second, the competition between agriculture and forestry underlined by their relative marginal benefits. These are supported by empirical evidence from selected countries in Africa and South America. The paper suggests a need to find a win-win situation to control the spate of tropical deforestation. This may imply improved technologies in the agriculture sector in the developing world, which would lead both to increased production in the agriculture sector, and would also help control the use of tropical forest as an input in agriculture production.     

污水处理厂出水中常见抗生素光降解去除规律研究进展

残留的抗生素和新产生的抗生素代谢产物会通过不同的途径进入到环境中,污染环境,诱导产生一些耐药和变异的超级细菌,严重危害人类健康.梳理分析了污水处理厂出水中常见的抗生素种类,阐述了光降解抗生素的反应机理和影响抗生素光降解的因素,并从高效光转化材料的制备、光降解产物的精准识别和降解产物的生物毒性评估角度提出开展后续研究的建...     

Mechanisms of silicon-mediated alleviation of abiotic stresses in higher plants: a review

Although silicon (Si) is the second most abundant element both on the surface of the Earth's crust and in soils, it has not yet been listed among the essential elements for higher plants. However, the beneficial role of Si in stimulating the growth and development of many plant species has been generally recognized. Silicon is known to effectively mitigate various abiotic stresses such as manganese, aluminum and heavy metal toxicities, and salinity, drought, chilling and freezing stresses. However, mechanisms of Si-mediated alleviation of abiotic stresses remain poorly understood. The key mechanisms of Si-mediated alleviation of abiotic stresses in higher plants include: (1) stimulation of antioxidant systems in plants, (2) complexation or co-precipitation of toxic metal ions with Si, (3) immobilization of toxic metal ions in growth media, (4) uptake processes, and (5) compartmentation of metal ions within plants. Future research needs for Si-mediated alleviation of abiotic stresses are also discussed.     

Transmission of SARS-CoV-2 virus and ambient temperature: a critical review

Environmental Science and Pollution Research - The coronavirus disease 2019 (COVID-19) pandemic has brought unprecedented public health, and social and economic challenges. It remains unclear...     

Physiological responses,tolerance, and remediation strategies in plants exposed to metalloids

Environmental Science and Pollution Research - Metalloids are a subset of particular concern to risk assessors and toxicologists because of their well-documented potential hazards to plant system....     

Microplastics in urban waters and its effects on microbial communities: a critical review

Environmental Science and Pollution Research - Microplastic (MP) pollution is one of the emerging threats to the water and terrestrial environment, forcing a new environmental challenge due to the...