Combined Effects Of Cadmium Research Articles

Comprehensive multi-omics investigation of sub-chronic toxicity induced by Cadmium and Triazophos Co-exposure in hook snout carps (Opsariichthys bidens)

The coexistence of heavy metals and pesticides poses a critical challenge in agricultural ecosystems. Traditional toxicity assessments often focus only on the individual impacts of either pesticides or heavy metals. Here, the untargeted metabolomics and 16 S rRNA sequencing were used to assess the individual and combined effects of cadmium (Cd) and triazophos (TRI) on hook snout carps (Opsariichthys bidens). Cd caused much more serious impacts on hepatic metabolism and gut microbiota than those in TRI. Combined Cd and TRI exposure synergistically affected hepatic metabolism, causing mitochondrial dysfunction and even oxidative damage. Simultaneously, 16 S rRNA sequencing highlighted significant variations in the composition and abundance of gut microbiota. A noteworthy connection emerged between these distinct microbiota profiles and disruptions in energy metabolism, ultimately leading to disorders in metabolites. These findings enhanced the understanding of risks posed by heavy metals and pesticides, providing insights for better environmental risk assessments of aquatic organisms.

Combined effects of cadmium and simulated acid rain on soil microbial communities in the early cultivation of Populus beijingensis seedlings

The combined cadmium (Cd) and acid rain pollution poses a significant threat to the global ecological environment. Previous studies on the combined adverse effects have predominantly focused on the aboveground plant physiological responses, with limited reports on the microbial response in the rhizosphere soil. This study employed Populus beijingensis seedlings and potting experiments to simulate the impacts of combined mild acid rain (pH=4.5, MA) or highly strong acid rain (pH=3.0, HA), and soil Cd pollution on the composition and diversity of microbial communities, as well as the physiochemical properties in the rhizosphere soil. The results showed that Cd decreased the content of inorganic nitrogen, resulting in an overall decrease of 49.10 % and 46.67 % in ammonium nitrogen and nitrate nitrogen, respectively. Conversely, acid rain was found to elevate the content of total potassium and soil organic carbon by 4.68 %-6.18 % and 8.64–19.16 %, respectively. Additionally, simulated acid rain was observed to decrease the pH level by 0.29–0.35, while Cd increased the pH level by 0.11. Moreover, Cd alone reduced the rhizosphere bacterial diversity, however, when combined with acid rain, regardless of its intensity, Cd was observed to increase the diversity. Fungal diversity was not influenced by the acid rain, but Cd increased fungal diversity to some extend under HA as observed in bacterial diversity. In addition, composition of the rhizosphere bacterial community was primarily influenced by the inorganic nitrogen components, while the fungal community was driven mainly by soil pH. Furthermore, “Metabolism” was emerged as the most significant bacterial function, which was markedly affected by the combined pollution, while Cd pollution led to a shift from symbiotroph to other trophic types for fungi. These findings suggest that simulated acid rain has a mitigating effect on the diversity of rhizosphere bacteria affected by Cd pollution, and also alters the trophic type of these microorganisms. This can be attributed to the acid rain-induced direct acidic environment, as well as the indirect changes in the availability or sources of carbon, nitrogen, or potassium.

Combined effects of cadmium and sulfamethoxazole on Eisenia fetida: Insights into accumulation, subcellular partitioning, biomarkers and toxicological responses

Cadmium (Cd) and sulfamethoxazole (SMX) frequently coexist in farmlands, yet their synergistic toxicological impacts on terrestrial invertebrates remain unexplored. In this study, earthworms were exposed to artificial soils percolated with Cd (5 mg/kg), SMX (5 mg/kg) or combination of them for 7 days, followed by a 12-day elimination phase in uncontaminated soil. The uptake of Cd and SMX by the earthworms, along with their subcellular distribution, was meticulously analyzed. Additionally, a suite of biomarkers—including superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and weight loss—were evaluated to assess the health status of the earthworms and the toxicological effects of the Cd and SMX mixture. Notably, the cotreatment with Cd and SMX resulted in a significantly higher weight loss in Eisenia fetida (41.25 %) compared to exposure to Cd alone (26.84 %). Moreover, the cotreatment group exhibited substantially higher concentrations of Cd in the total internal body, fraction C (cytosol), and fraction E (tissue fragments and cell membranes) in Eisenia fetida compared to Cd alone counterparts. The combined exposure also significantly elevated the SMX levels in the total body and fraction C compared with the SMX-only treated earthworms. Additionally, Eisenia fetida subjected to the combined treatment showed markedly increased activities of SOD, CAT, and MDA compared to those treated with Cd alone. The effect addition indices (EAIs), ranging from 1.00 to 2.23, unequivocally demonstrated a synergistic effect of the combined treatments. Interestingly, relocating the earthworms to clean soil did not mitigate the observed adverse effects. These findings underscore the increased risk posed by the Cd-SMX complex to terrestrial invertebrates in agricultural areas.

Individual and combined effects of cadmium and lead exposure in rats

ABSTRACT The exposure of humans and animals to environmental compounds is rarely restricted to a single chemical. Cadmium (Cd) and lead (Pb) are two heavy metals known to be the most toxic. Deleterious effects of each metal alone are well documented. Unfortunately, very few studies were conducted to determine their combined effect. Four groups of Wistar rats were treated intravenously for 15 days. The control group received physiological saline solution; groups 2 and 3 were treated with Cd chloride and lead acetate, respectively ; and the treatment group 4 received a combined treatment of Cd and Pb . A significant decrease was recorded for hematological parameters , with an increase in white blood cells and an inhibition in δ-ALAD level. Cell injury in the livers and kidneys was clearly shown by the significant elevation of the biochemical markers. Cd and Pb induced oxidative stress and had adverse health effects at lower exposure levels than previously thought.

Single and combined effects of cadmium, microplastics, and their mixture on whole-body serotonin and feeding behaviour following chronic exposure and subsequent recovery in the freshwater leech, Nephelopsis obscura

Microplastics and metals are contaminants detected in many freshwater systems globally. Interactions of microplastics with other contaminants including cadmium poses potential threats to the health of aquatic organisms including Nephelopsis obscura, a predatory leech species that is widespread and serves important ecological and economic roles. The feeding biology of N. obscura has been well-described, including that serotonin regulates feeding behaviour. Further, exposure to cadmium has been found to cause decrease whole-body concentrations of serotonin. The influence that microplastic contamination and co-contamination of cadmium and microplastics has on N. obscura is unknown. The present study had three objectives: (1) to determine if water or sediment contaminated with cadmium, microplastics, or their mixture resulted in greater cadmium uptake by N. obscura, (2) to assess effects of chronic (21-day) exposure of N. obscura to waterborne cadmium, microplastics, and their mixture on bioaccumulation of cadmium, concentrations of serotonin, and feeding behaviour (latency to feeding, time spent feeding, and distance moved), and (3) to reassess the bioaccumulation of cadmium, concentrations of serotonin, and feeding behaviour following transfer to an uncontaminated environment for a one-week recovery period. This study revealed that access to and presence of sediment is protective against cadmium uptake and that cadmium is more readily accumulated from waterborne sources, even in environments where both sediment and surface water are contaminated. After 21-days of exposure to waterborne cadmium, microplastics, and their mixture, accumulation of cadmium, decreased concentrations of serotonin, and impaired feeding behaviours were greatest in leeches from the co-exposures compared to leeches from either single contaminant exposure group. Finally, after one week of depuration and recovery in freshwater following the 21-day exposures, concentrations of serotonin and feeding behaviour were restored in individuals from the microplastic exposure; however, cadmium-exposed individuals continued to show decreased concentrations of serotonin and behavioural deficits. The co-exposure of leeches to cadmium and microplastics resulted in additive effects to serotonin synthesis and feeding behaviour; however, this study demonstrated that leeches were able to recover from microplastic toxicity within a week whereas cadmium toxicity persisted.

Combined effects of cadmium and nanoplastics on oxidative stress, histopathology, and intestinal microbiota in largemouth bass (Micropterus salmoides)

As a momentous emerging contaminant, nanoplastics (NPs) can pose as vectors for other environmental pollutants, leading to their migration, spreading throughout ecosystems and converting their toxicity. However, research on the combined effects of NPs and cadmium (Cd) on aquatic animals is still in its infancy, especially freshwater carnivore fish. Therefore, we investigated the combined effects of NPs and Cd in water on growth performance, oxidative stress, histopathology, and intestinal microbiota in juvenile Micropterus salmoides (initial weight: 14.67 ± 0.08 g). Analyses were done on control group (unexposed to NPs or Cd), 10 μg/L Cd group, 100 μg/L NPs group, and 10 μg/L Cd + 100 μg/L NPs group for 19 days, and fish were sampled on day 7 and 19. Our analyses revealed that the combined exposure to NPs and Cd significantly reduced feed intake after 7-day exposure and caused poor growth after 19-day exposure (P < 0.05). Combined exposure to NPs and Cd markedly triggered oxidative stress and oxidative damage in liver. After 7-day exposure, two-way ANOVA showed a significant interaction between Cd and NPs for SOD, CAT, GSH and MDA. After 19-day exposure, two-way ANOVA showed a significant interaction between Cd and NPs for MDA. Histological abnormalities in gills, livers, and intestines were observed after exposure to Cd and NPs, alone or in combined. Furthermore, combined exposure damaged the liver ultrastructure and caused intestinal microbiota dysbiosis. Overall, by combining physiological and 16S rRNA sequencing analysis, a better understanding of the potential risks posed by nanoplastic and heavy metal pollution in freshwater carnivores has been obtained. The toxicity of co-exposure to NPs and Cd is higher than that of NPs and Cd alone.

Separate and combined effects of cadmium (Cd) and nonylphenol (NP) on growth and antioxidative enzymes in Hydrocharis dubia (Bl.) Backer.

Cadmium (Cd) is considered a priority pollutant, and nonylphenol (NP) is a common organic pollutant in water environments. However, the ecological risks of combined Cd and NP pollution have not been fully elucidated. In this study, the effects of Cd, NP, and Cd-NP on the growth and physiology of Hydrocharis dubia (Bl.) Backer were studied. The results indicated that Cd-NP joint toxicity is concentration-dependent. The joint toxicity of Cd and NP on H. dubia was antagonistic when the concentrations of Cd + NP were 0.01 + 0.1/1mg/L. At 0.5 + 0.1/1mg/L, Cd and NP had a strong synergistic effect on H. dubia. In addition, plant growth was significantly inhibited, and the chlorophyll contents were significantly reduced under Cd, NP, or Cd-NP exposure. The plant's antioxidant enzyme system was destroyed. The activities of superoxide dismutase (SOD) and catalase (CAT) were significantly decreased under NP-only exposure. The activity of SOD was significantly decreased under Cd-only and under joint exposure. Compound pollution exceeded the oxidative defense capacity of the plants, so the H2O2 content increased significantly. Our results indicated that the ecotoxicity of NP combined with Cd may be exacerbated in aquatic environments and cause obvious damage to H. dubia.

Morphological, physiological and biochemical responses to combined cadmium and drought stress in radish (Raphanus sativus L.)

Drought and heavy metal stress are among the most important stress factors that negatively affect plant growth. This study was carried out to determine the individual and combined effects of cadmium (Cd) and drought stress on growth (plant leaf area, stem and root diameter, shoot and root fresh weight, shoot and root dry weight), physiological [electrolyte leakage (EL), leaf relative water content (LRWC)] and biochemical [antioxidant enzyme activity, hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, sucrose and mineral element content] parameters of radish. In the study, four Cd concentrations (0 mg kg−1, 100 mg kg−1, 150 mg kg−1 and 200 mg kg−1), three irrigation levels (100%, 75% and 50% of field capacity—FC) were used. Leaf area, stem and root diameter, shoot and root fresh weight, shoot and root dry weight, LRWC, chlorophyll a, chlorophyll b and total chlorophyll content decreased with increased level of drought and Cd stress, but EL has increased. The effect of water deficit on these parameters was more detrimental than heavy metal stress; however, the stress-related damage was greater under combined stress conditions. In addition, H2O2, MDA, proline and sucrose content of radish leaves increased with increased water deficit and Cd stress levels. POD, CAT and SOD enzyme activities of radish leaves under combined stresses increased more than individual stress conditions. There was a significant increase in the content of Cd in the plant leaves and roots under Cd stress compared to the control. This increase in leaves was more pronounced than roots. Although individual drought and Cd stress negatively influenced radish growth and development, the damage was greater with the simultaneous occurrence of these two stress factors.

Single and Combined Effects of Cadmium and Lead on Seed Germination and Early Seedling Growth in &lt;i&gt;Rhus typhina&lt;/i&gt;

Single and Combined Effects of Cadmium and Lead on Seed Germination and Early Seedling Growth in &lt;i&gt;Rhus typhina&lt;/i&gt;

The individual and combined effects of cadmium, polyvinyl chloride (PVC) microplastics and their polyalkylamines modified forms on meiobenthic features in a microcosm

A microcosm experiment was carried out to study the ecotoxicity and interactions between heavy metals and polyvinyl chloride microplastics. Fifteen treatments were tested and results were examined after one month. In details, this work aims to study the ecotoxicological effects of cadmium (10 and 20 mg kg−1 Dry Weight DW), polyvinyl chloride (PVC) and its modified forms; PVC-DETA (PD) and PVC-TETA (PT) (20 and 40 mg kg−1 DW), separately and in mixtures, on meiofauna from Bizerte lagoon (NE Tunisia) with focus on nematode features. The results obtained showed that individual treatments were toxic for meiofauna and particularly for free-living nematodes. No clear trends characterized the numerical responses but significant reductions were observed for diversity indices. Moreover, the binary combinations of contaminants have a lesser toxic effect compared to their individual effects. This effect could be related to the high-capacity chelating ability of PVC and its polymers against cadmium.

Combined effects of cadmium and oil sludge on sorghum: growth, physiology, and contaminant removal.

The physiological and biochemical responses of Sorghum bicolor (L.) Moench. to cadmium (Cd) (30mgkg-1) and oil sludge (OS) (16gkg-1) present in soil both separately and as a mixture were studied in pot experiments. The addition of oil sludge as a co-contaminant decreased Cd entry into the plant by almost 80% and simultaneously decreased the stimulation of superoxide dismutase (SOD) and peroxidase. The decrease in glutathione reductase (GR) activity and the increase in glutathione-S-transferase (GST) activity under the influence of oil sludge indicated that its components were detoxified by conjugation with glutathione. Cd additionally activated the antioxidant and detoxifying potential of the plant enzymatic response to stress. This helped to enhance the degradation rate of oil sludge in the rhizosphere, in which the participation of the root-released enzymes in the degradation could be possible. Cd increased the extent of soil clean-up from oil sludge, mainly owing to the elimination of paraffins, naphthenes, and mono- and bicyclic aromatic hydrocarbons. The mutual influence of the pollutants on the biochemical responses of sorghum and on soil clean-up was evaluated. The results are important for understanding the antistress and detoxification responses of the remediating plant to combined environmental pollution.

Single and Combined Effects of Cadmium and Aroclor 1254 on Oxidative Stress in Gills of Mytilus coruscus

Both polychlorinated biphenyls (PCBs) and cadmium (Cd) can be frequently found in marine ecosystems and have detrimental effects on marine organisms, especially on filter-feeding marine mussels. Although biological responses to single metal or PCB exposure in mussels have been well-studied, information about oxidative stress is still limited, especially in different tissues in mussels. Considering the variety of contaminants existing in the actual marine environment, the exposures of the marine mussel Mytilus coruscus to Cd2+ alone (0.194, 0.388, and 0.775 mg/L) and Aroclor 1254 alone (0.005, 0.010, and 0.050 mg/L) and the co-exposures of the marine mussel Mytilus coruscus to Cd2+ (0.194 and 0.388 mg/L) and Aroclor 1254 (0.005 and 0.010 mg/L) were tested in an 8-day exposure experiment followed by a 7-day acclimation experiment. The alterations in superoxide dismutase, catalase, glutathione peroxidase, and malondialdehyde levels in the gills of the mussels were assessed. The effects of the depressed antioxidant were induced by the exposures of Cd2+ and Aroclor 1254 and their co-exposures. All exposures resulted in an initial increase and then a reduction in antioxidant enzyme activities. The range and rate of the antioxidant enzyme activities were positively correlated with stress duration and the concentration of the stress material. The effect of combined stress was stronger than that of each individual stressor. The valuable information for future investigations of stress response mechanisms, especially in relation to tissue functions in marine organisms, has been provided by the results and experimental model. The study of combined pollution effects has more scientific significance for marine pollution monitoring.

Evaluation of single and combined effects of cadmium and micro-plastic particles on biochemical and immunological parameters of common carp (Cyprinus carpio)

The growing accumulation of microplastics (MPs) in aquatic environments is a global concern. MPs are capable to interact with other environmental contaminants, including heavy metals, altering their toxicity. The aim of the study was to investigate the sub-lethal effects of cadmium chloride (Cd) alone and in combination with MPs on common carp (Cyprinus carpio). Multi-biomarkers, including plasma biochemical parameters and intrinsic immunological factors, were measured after 30 days of exposure. Exposure to Cd or NPs reduced the plasma activities of acetylcholinesterase (AChE) and gamma-glutamyl-transferase (GGT) and increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). Exposure to both compounds enhanced the observed effects except for AST activity and ALP at the highest concentrations, whereas evidenced an antagonistic interaction in ALT. Plasma total protein, albumin, and globulin levels were decreased, and the levels of glucose, triglyceride, and cholesterol levels increased mainly in the Cd groups with no additional effects derived from the co-exposure to both stressors. Lysozyme and alternative complement (ACH50) activities and the levels of total immunoglobulins, and complement C3 and C4 in fish exposed to Cd and MPs were lower than those in the control group and this decrease was more significant by the mixture of both compounds. These findings showed that the exposure to Cd or MPs alone is toxic to fish altering the biochemical and immunological parameters. Moreover, these alterations are even greater when the Cd and the MPS are combined suggesting synergistic effects in increasing Cd toxicity and vice versa.

Physiological responses of Elaeocarpus glabripetalus seedlings exposed to simulated acid rain and cadmium

Combined effects of cadmium (Cd) and acid rain on physiological characteristics in Eleocarpus glabripetalus seedlings were investigated under controlled conditions. The single Cd treatment and the combined Cd and acid rain treatment increased growth at low Cd concentrations, while decreased growth and photosynthesis at high Cd2+ concentrations. A low Cd2+ concentration (50 mg kg-1) combined with different acid rain treatments increased the seedling biomass. A high Cd2+ concentration (100 mg kg-1) under different acid rain treatments significantly decreased the biomass, the Fe content, chlorophyll fluorescence and photosynthetic parameters. Relative electric conductivity, malondialdehyde (MDA) content and peroxidase (POD) activity were increased while the reduced glutathione (GSH) content and catalase (CAT) activity were significantly lower at high Cd2+ concentration under acid rain. The results indicated that the combination of a high concentration of Cd2+ and acid rain aggravated the toxic effect of Cd2+ or acid rain alone on the growth and physiological parameters of E. glabripetalus due to serious damage to the chloroplast structure. These results provide novel insights into the combined effects of Cd2+and acid rain on woody plants and might also serve as a guide to evaluate forest restoration and biological safety in areas with Cd2+and acid rain pollution.

Individual and combined effects of cadmium and polycyclic aromatic hydrocarbons on the phytoremediation potential of Xanthium sibiricum in co-contaminated soil

ABSTRACTSoil contamination with heavy metals and organic pollutants continues to cause major ecological damage and human health problems. Phytoremediation offers a highly promising technology for the recovery of sites contaminated with mixed pollutants. In this study, we performed a greenhouse experiment to investigate the individual and combined effects of cadmium (Cd) and polycyclic aromatic hydrocarbon (PAH) contamination on the growth of Xanthium sibiricum, and also the ability of this species to accumulate and remove Cd and to reduce PAHs over a period of 75 days. Our results demonstrated that individual or combined contamination by Cd and PAHs showed no significant differences to the control treatment except in the high Cd treatment. The reduction of PAH concentration in the soil with the passage of time was similar in the presence or absence of plants. At higher levels of Cd, the removal of pyrene decreased in both planted and non-planted soils; however, this effect might be due to the higher Cd content. Soil dehydrogenase and polyphenol oxidase activities showed that soil contamination did not have a significant effect on the removal of PAHs. Overall, our results suggest that X. sibiricum might be a suitable species for use in the phytoremediation of contaminated soils.

Combined effects of cadmium and tetrabromobisphenol a (TBBPA) on development, antioxidant enzymes activity and thyroid hormones in female rats

Tetrabromobisphenol A (TBBPA) is one of the world's most widely used brominated flame retardants (BFRs) and considered as persistent halogenated contaminant. E-wastes contain a range of toxic chemicals, including BFRs and heavy metals, exerting adverse impacts to human health and environment. Nevertheless, comprehensive evaluation on combined toxicity of these co-existing pollutants is limited. This study conducted a subchronic effects of cadmium and TBBPA on the development and antioxidative defense system as well as thyroid functions in female rats through single and combined exposure at environmentally relevant doses for a 20-day consecutive administration. Body indexes, histopathology, redox status, and thyroid hormones levels were assessed. Slower body weight gains and reduced ovary weight (20.8% and 32.4% for combined and single-Cd exposures, respectively) were observed with significant variation from controls in high dose treatments. Co-exposure resulted in a slight enhancement in TSH levels compared to control (by 7.6% for high dose) without significance. TBBPA-Cd interactions are involved in the changes of kidney weight as well as the induction of SOD activities and MDA levels. The disturbances in the redox status may be a result of an independent effect of Cd and/or TBBPA and also of their interaction. The results implied under these treatment, kidney was more sensitive with significant increased organ coefficient and alteration for antioxidative indices (increasing by 46% for SOD activity). This study represents the toxic effects of Cd and TBBPA co-exposure through oral administration in pubertal rats, which may provide useful information for health risk assessment for young exposed individuals.

Combined effects of cadmium and salinity on juvenile Takifugu obscurus: cadmium moderates salinity tolerance; salinity decreases the toxicity of cadmium.

Obscure puffer Takifugu obscurus, a species of anadromous fish, experiences several salinity changes in its lifetime. Cadmium (Cd) is a toxic heavy metal that can potentially induce oxidative stress in fish. The present study aimed to detect the combined effects of Cd (0, 5, 10, 20 and 50 mg L−1) and salinity (0, 15 and 30 ppt) on juvenile T. obscurus. Results showed the juveniles could survive well under different salinities; however, with Cd exposure, the survival rates significantly decreased at 0 and 30 ppt. At 15 ppt, tolerance to Cd increased. Cd exposure clearly induced oxidative stress, and the responses among different tissues were qualitatively similar. Salinity acted as a protective factor which could reduce the reactive oxygen species and malondialdehyde levels. In addition, salinity could enhance the antioxidant defense system, including superoxide dismutase, catalase and glutathione. Na+/K+–ATPase activity significantly decreased under Cd exposure in gill, kidney and intestine. These findings indicated that Cd could moderate the adaptability of juvenile T. obscurus to high salinity and low salinity played a protective role upon Cd exposure. Thus, the role of salinity should be considered when evaluating the effect of heavy metals on anadromous and estuarine fishes.

Summation of subthreshold impulses in case of separate and combined effects of cadmium and immobilization stress, considering typology of behavior of experimental animals.

The aim of the work was to study dynamics of changes of summation-threshold index under the combined impact of cadmium and immobilization of animals depending on the typological characteristics of animal behavior. The studies were conducted on white rats, previously divided into groups of and ones by terms of horizontal activity in the test open field. In each group the experiments were planned according to the scheme of orthogonal design 2 2 . Summation-threshold index was studied by Speransky S.V. method. It was found that the summation-threshold index increases on the day 10 of experiments under the action of a cadmium only in groups of active and passive animals; this testifies to inhibition processes in the CNS. The effect of cadmium, immobilization and their combined action on day 30 of experiments leads to the reduction in the of studying parameter in both groups of animals; this testifies to excitation of the CNS. The animals are more susceptible to immobilization stress, the ones - to the action of cadmium. The combined action of stress factors on day 10 is characterized by desensitization, on day 30 – by unidirectional interdependent action and less than by additive effect. The processes of inhibition and excitation in the central nervous system depend on type of animal behavior, type and duration of exposure to the stress factor. The results may be taken into account when assessing adaptation process, correction, and adaptation depending on the type of behavior.

Combined effects of cadmium and ozone on photosynthesis of Lycopersicon esculentum

Tomato (Lycopersicon esculentum Mill. cv. Pearson) plants were grown in growth chambers for 25 days with cadmium (Cd) and then exposed briefly to ozone (O3). Gas exchange, chlorophyll a fluorescence, and pigment composition were analysed in leaves at the end of the treatment to assess the effects of a single pollutant and their combination on photosynthesis. The CO2 assimilation rate was dramatically reduced in plants subjected to the combined treatment, while the single effect of Cd appeared less severe than that of O3. The decline of CO2 photoassimilation found in all O3-exposed plants was attributed to both stomatal and nonstomatal limitations. Tomato plants seemed to detoxify Cd to a great extent, but this resulted in growth suppression. In response to O3 exposure, the plants protected their photosystems by heat dissipation of excess energy via the xanthophyll cycle. Cd combined with O3 affected adversely this cycle resulting in an increase in photosynthetic performance under the same experimental light conditions.

Evaluation of effects of exposure conditions on the biological responses of Gammarus pulex exposed to cadmium

This study was conducted to determine the single and combined effects of cadmium (Cd) exposure at different concentrations and durations on biological responses in Gammarus pulex. The animals were exposed to 4, 8, 16 or 32 μg l−1 of CdCl2 for 24, 48, 72 or 96 h, respectively. Cd accumulation, protein content, malondialdehyde content (MDA) and three antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were studied. The results were analyzed with two-way analysis of variance (two-way ANOVA) to assess the significance of the effects of exposure concentration and duration and their combined effects. The highest accumulation of Cd was found as 15.07 μg g−1 at 32 μg l−1 and 96-h Cd exposure. There was a significant correlation between accumulated Cd concentration and MDA and protein content and GPx activity. Although there was no significant synergistic effect of duration and concentration on Cd accumulation, a significant synergy of duration and concentration was observed in all other studied parameters. Interestingly, with the exception of GPx activity, the effect of concentration was greater than the effect of duration for all studied parameters. GPx activity showed that duration had a greater effect than concentration. Additionally, both SOD and GPx are more effective than CAT during Cd stress. The results of this study may be useful for understanding the relationship between organisms and environmental toxins.