High Concentrations Of Cadmium Research Articles

Increased removal of cadmium by Chlamydomonas reinhardtii modified with a synthetic gene for γ-glutamylcysteine synthetase

Bioremediation with genetically modified microalgae is becoming an alternative to remove metalloids and metals such as cadmium, a contaminant produced in industrial processes and found in domestic waste. Its removal is important in several countries including Mexico, where the San Luis Potosi region has elevated levels of it. We generated a construct with a synthetic gene for γ-glutamylcysteine synthetase and employed it in the chloroplast transformation of Chlamydomonas reinhardtii. In dose-response kinetics with media containing from 1 to 20 mg/L of cadmium, both the transplastomic clone and the wild-type strain grew similarly, but the former removed up to 32% more cadmium. While the growth of both decreased with higher concentrations of cadmium, the transplastomic clone removed 20 ± 9% more than the wild-type strain. Compared to the wild-type strain, in the transplastomic clone the activity of glutathione S-transferase and the intracellular glutathione increased up to 2.1 and 1.9 times, respectively, in media with 2.5 and 10 mg/mL of cadmium. While 20 mg/L of cadmium inhibited the growth of both, the transplastomic clone gradually duplicated. These results confirm the expression of the synthetic gene gshA in the transformed strain as revealed in its increased removal uptake and metabolic response.

Identification of Durum Wheat Cultivars and Their Tetraploid Relatives with Low Cadmium Content.

SUMMARYIn this study, 71 durum wheat cultivars (Triticum durum Desf.), 22 emmer wheat (Triticum dicoccum L.) and 11 wild emmer (Triticum dicoccoides L.) genotypes were genetically characterized to determine the alleles associated with high cadmium (Cd) content. After genotypic characterization, 14 cultivars selected among all genotypes with low and high Cd content were phenotyped by a pot experiment to verify the genotypic data. Identification of 32 durum wheat, one emmer wheat and four wild emmer genotypes showed that they have alleles associated with high Cd content, while 68 genotypes of which 39 durum wheat, 21 emmer wheat and 7 wild emmer cultivars had alleles associated with low Cd content, respectively. Moreover, phenotypic data obtained from pot experiment were similar to the molecular data. To sum up, the marker successfully classified durum wheat cultivars into either high or low accumulators and these results can be safely used in breeding programs to improve new durum wheat cultivars with alleles associated with low Cd content. Due to routine use of phosphorus fertilizers in agricultural areas and other anthropogenic factors related to Cd toxicity, new durum wheat cultivars with low Cd content should be urgently developed for safe production of macaroni or other types of wheat products for human and animal consumption.

Biochemical and morphological responses to cadmium-induced oxidative stress in Cladophora glomerata

This study aimed to assess the effect of cadmium Cd2+ concentrations on biovolume, pigments, malondialdehyde MDA , hydrogen peroxide, proline, total phenolic compounds, total protein, and total carbohydrate contents of Cladophora glomerata . Cultivations of the alga 8.0 ± 0.1 g as fresh weight were exposed to 7.5, 15, 30, and 60 mg/L of Cd2+ ions in 500 mL flasks containing 400 mL of the medium on a shaker at 120 rpm for 7 days. Results of Fourier transform infrared analyses indicated that the amide, anionic, and amino groups had significant rolesin the binding of Cd2+ on C. glomerata. The detrimental effects of the Cd2+ dose not only observed the morphology of the algal cell but also changed the biochemical compounds of C. glomerata. Growth gradually decreased when the alga was exposed to Cd2+ at 15 and 60 mg/L in comparison with the control. High Cd2+ ions concentrations decreased in chlorophyll-a from 14.27 mg/g in control to 9.97 mg/g at 60 mg/L Cd and protein content from 43.60 mg/g in control to 21.66 mg/g at 60 mg/L Cd in the treated cells compared to the control group, whereas they increased stress molecules e.g., MDA and proline as biomarkers in the response mechanisms of algae to Cd2+ exposure. Results indicated that this alga had wide tolerance to high cadmium concentrations, and the stress compounds in the alga with exposure of Cd2+ seemed to be parameters as a biomarker for metal-induced oxidative stress.

Agricultural use suitability assessment and characterization of municipal liquid sludge: Based on South Africa survey

Sludge recycling as an agricultural resource has gained great attention worldwide. This is exacerbated by the ever-rising municipal wastewater production and the realization of its potential as a soil amendment resource. Sludge suitability assessment and characterization is crucial to prompt informed decisions regarding its use on agricultural lands. Liquid sludge samples were collected from eighteen wastewater treatment plants (WWTPs) employing three different treatment processes in South Africa. Samples were analysed for physical and chemical parameters. Sludges' pH ranged from 4.5–9.5. Heavy metals concentrations were below the threshold level except for two waste activated sludge (WAS) which were downgraded to class B due to high Lead (Pb) content. Two anaerobically digested (AnD) sludges were downgraded to classes B and C because of high Pb and Cadmium (Cd) concentrations respectively. Electrical conductivity (EC) was above the 200 mS m−1 threshold in AnD and in one of aerobically digested (AeD) sludges whilst WAS had ≤100 mS m−1. Nitrogen (N): Phosphorus (P) ratios of the sludges were <8. Application of biosolids with low N:P ratio based on crop N requirements would lead to P pollution. Sustainable sludge application options were either to apply dry sludge based on crop N or P requirements and supplement the nutrient deficit with other fertilizer sources. The use of current liquid sludge as irrigation water to meet crop water needs and or applying dry sludge at 10 tons ha−1 options showed that such options are unsustainable and would add excess nutrients above crop need which would result in agroecosystems pollution. The study findings suggest that, supposedly these liquid sludges are used for irrigation, they should be diluted with fresh water or deficit irrigation should be implemented to limit nutrient load.

Consequences of trace metal cocktail exposure in zebra finch (Taeniopygia guttata) and effect of calcium supplementation.

Trace metal elements are significant stressors in urban areas. Their harmful effects on physiological parameters are demonstrated, but current laboratory studies are not representative of wild chronic exposure to a trace metal cocktail. Calcium can reduce the accumulation and toxicity of several metals, but soil acidification in cities leads to a decrease in bioavailability of this element. The objective of this study was to investigate the accumulation and toxicity of a trace metal cocktail representative of urban exposure on passerine birds, and test the importance of calcium availability on these toxic effects. We exposed zebra finches (Taeniopygia guttata) to a cocktail of seven metals and one metalloid in drinking water, with or without calcium supplementation. We monitored the concentration of metals in the blood and feathers, and their effects on oxidative status and telomere length. The metal cocktail led to higher concentration of all elements in the feathers, and of arsenic and lead in the blood. Birds with a higher concentration of cadmium, arsenic and lead in the feathers had shorter telomeres, but no impact of the cocktail was detected on oxidative status. Birds of the 'calcium' group and the 'calcium and metal' group accumulated higher concentrations of zinc, chromium and nickel in feathers. The 'calcium and metal' group also accumulated lower concentrations of arsenic and lead in feathers compared to the 'metal' group. Our results suggest that chronic exposure to a cocktail of metals at low concentrations has deleterious effects on birds, which can be limited through calcium intake.

Nutrient Composition and Heavy Metals Content of Three Leafy Vegetables ( Amaranthus Cruentus L., Lactuca Sativa L., Solanum Macrocarpon L.) in Porto-Novo, Republic of Benin

The interest of leafy vegetables has increased in recent years, mainly because of health benefits due of their nutritional compounds. Knowledge of the nutrients of vegetables is necessary to better value them in the diet of the population. The aim of this study was to determine the nutrients of three green leafy vegetables cultivated and consumed at Porto-Novo. For this purpose, using standard methods, carbohydrates, protein, fat, crude fibre, ash, calcium, potassium, magnesium, iron and zinc were determined in 24 samples of Amaranthus cruentus L., Solanum macrocarpon L. and Lactuca sativa L. and were compared. Also, heavy metals (Pb, Cd) contents of these vegetables and of soils were compared. The significant difference between nutrients of leafy vegetables was tested by ANOVA. Lactuca sativa L. has the highest water content, Amaranthus cruentus L. has the highest content of proteins, ash, fibre, zinc, calcium and potassium while the Solanum macrocarpon L. has the highest content of fat and iron. Solanum macrocarpon L. has the highest lead content while Amaranthus cruentus L. has the highest cadmium content. These results show that leafy vegetables could provide an important part of nutritional requirements for the adequate protection against diseases. The results suggest that Amaranthus cruentus L. has the high content of nutrients followed by Solanum macrocarpon L. and Lactuca sativa L.. Cadmium and lead found in vegetables of this study in Porto-Novo must be monitored and managed to prevent adverse consequences on human health.

Cadmium behavior in a karst environment hydrological cycle

Karst regions are important water providers, supplying approximately 25% of the world population. These areas present higher vulnerability to contamination due to hydrodynamics, which hampers the natural depuration of these waters until reaching the underground environment. High concentrations of cadmium (Cd) are observed in the São Miguel watershed, state of Minas Gerais, Brazil. This toxic element is generally and predominantly released into the atmosphere by burning materials that have Cd in their composition, potentially contaminating surface and groundwater. Therefore, the objective of the study is to map Cd concentrations in the hydrological cycle of the São Miguel karst watershed and, through natural background level values (NBL 90%) of rainwater, surface water and groundwater, to understand the seasonal behavior of this element, and to identify the most vulnerable areas to contamination. To achieve this goal, rainwater, surface, and groundwater seasonal monitoring were conducted in 87 sampling stations. A total of 335 samples were collected, distributed over a watershed area of 520km2. Concentrations of cadmium above 1μg/L were found in 21.49% of samples during the rainy season. The origin and distribution of Cd were related to rainfall. For rainwater samples, 90% presented Cd concentration of 3.06μg/L. When these waters precipitate, they contaminate surface waters (NBL 90% = 1.50μg/L) and groundwater (NBL 90% = 2.81μg/L). This study presented a hydrochemical cycle map and proposed NBL values of Cd for surface water and groundwater, helping to understand how the environment is contaminated by this element.

Copper and cadmium administration induce toxicity and oxidative stress in the marine flatworm Macrostomum lignano

The contamination of coastal regions with different toxicants, including heavy metal ions such as copper and cadmium jeopardize health and survival of organisms exposed to this habitat. To study the effects of high copper and cadmium concentrations in these marine environments, we used the flatworm Macrostomum lignano as a model. This platyhelminth lives in shallow coastal water and is exposed to high concentrations of all toxicants that accumulate in these sea floors. We could show that both, cadmium and copper show toxicity at higher concentrations, with copper being more toxic than cadmium. At concentrations below acute toxicity, a reduced long-term survival was observed for both metal ions. The effects of sublethal doses comprise reduced physical activities, an increase in ROS levels within the worms, and alterations of the mitochondrial biology. Moreover, cell death events were substantially increased in response to sublethal concentrations of both metal ions and stem cell activity was reduced following exposure to higher cadmium concentrations. Finally, the expression of several genes involved in xenobiotic metabolism was substantially altered by this intervention. Taken together, M. lignano has been identified as a suitable model for marine toxicological studies as it allows to quantify several relevant life-history traits as well as of physiological and behavioral read-outs.

Axenic cyanobacterial (Nostoc muscorum) biofilm as a platform for Cd(II) sequestration from aqueous solutions

An environment friendly approach towards heavy metal remediation from water is the need of the hour. A novel approach to heavy metal bioremediation from water was attempted using axenic cultures of the photoautotrophic cyanobacterium, Nostoc muscorum immobilised on to glass surface through the formation of biofilms. Being a biofilm, it exhibited much higher cellular integrity than cell suspension cultures when exposed to high concentrations of cadmium, and could also withstand the harsh conditions prevalent in industrial effluents. Being a photosynthetic organism, culturing of N. muscorum as a biofilm was achieved with minimal requirements, such as water with minerals, light and stationary conditions, which also enabled ease of scalability. The strong adherence of the N. muscorum biofilm to the glass surface was beneficial as (i) no diffusion of cell mass on to the media was observed even with the use of top-end stirrer, (ii) no expensive separation techniques were required for separation of biomass from the treated solution, and (iii) direct contact of the solution containing metals to the active components on biofilm surface allowed better interaction. The N. muscorum biofilm exhibited the capability to sequester Cd(II) in the pH range 5–9, concentration range <0.05 ppm to 100 ppm and from different waste waters. Sequestration of Cd(II) resulted in cell surface changes, the mode of sequestration being chemisorption through the >C=O and >C=N functional groups, and followed the Langmuir's adsorption isotherm. It is proposed to use the N. muscorum biofilm as a potential green technology for waste water treatment in future.

Modeling the Spatial Distribution of Soil Heavy Metals Using Random Forest Model—A Case Study of Nairobi and Thirirka Rivers’ Confluence

Modeling the spatial distribution of soil heavy metals is important in determining the safety of contaminated soils for agricultural use. This study utilized 60 topsoil samples (0 - 30 cm), multispectral images (Sentinel-2), spectral indices, and ancillary data to model the spatial distribution of heavy metals in the soils along the Nairobi River. The model was generated using the Random Forest package in R. Using R2 to assess the prediction accuracy, the Random Forest model generated satisfactory results for all the elements. It also ranked the variables in order of their importance in the overall prediction. Spectral indices were the most important variables within the rankings. From the predicted topsoil maps, there were high concentrations of Cadmium on the easterly end of the river. Cadmium is an impurity in detergents, and this section is in close proximity to the Nairobi water sewerage plant, which could be a direct source of Cadmium. Some farms had Zinc levels which were above the World Health Organization recommended limit. The Random Forest model performed satisfactorily. However, the predictions can be improved further if the spatial resolutions of the various variables are increased and through the addition of more predictor variables.

JAPANESE KNOTWEED (REYNOUTRIA JAPONICA) AS A PHYTOREMEDIATOR OF HEAVY METALS

Recently, plant remediation techniques - phytoremediation - have been developed. Japanese Knotweed (Reynoutria japonica), is an invasive species with negative impacts on the environment and the economy. In order to assess the tolerance of highly invasive weeds to heavy metals, an experiment was conducted in which this plant was grown in control soil and in soils contaminated with different concentrations of Pb, Cd. The content of heavy metals in the soil did not eliminate the ability of Reynoutria japonica roots to regenerate. In soil contaminated with any concentration of Pb, the shoots of this plant grew at a similar rate as the control plants, and had the same morphological characteristics. Higher concentrations of cadmium and lead Cd (100, 200 mgkg-1), Pb (2000 mgkg-1) have extended rhizome regeneration compared to control plants. In soils contaminated with lower concentrations of Cd or Pb shoots grew at a similar rate as control plants. Chemical analysis of heavy metal content showed that this weed accumulated large amounts of metals when grown in soil contaminated with heavy metals A relatively high intake of Cd, aboveground plants. At a cadmium concentration of 100 mg kg-1, more than 537 times the amount of cadmium accumulated in the aboveground part of the plant, as opposed to that in control. The ability of Japanese Knotweed (Reynoutria japonica), to regenerate from parts of the rhizome, to grow and develop under stressful conditions in the presence of heavy metals indicates a high tolerance to heavy metals. Key words: Japanese Knotweed (Reynoutria japonica), phytoremediation, heavy metal accumulation

Quantification of heavy metals in canned tomato paste sold in Ubani-Umuahia, Nigeria

In recent years there has been an increase in the contaminations of heavy metals on the environment. Government and private organization have shown their interest in the effect of dietary exposure to several heavy metals. These heavy metals have been implicated in the etiology of many diseases with high risk to humans. Canned tomatoes paste is one of the important health deterioting factors to human health in Ubani-Umuahia, Nigeria. In this study atomic absorption spectrophotometer was used to screen for nine heavy metals concentration in ten different brands of canned tomatoes paste sold at Ubani-Umuahia market in Nigeria. Human risk assessment was calculated using the collated data to evaluate the predictive risk of human health after the consumption of canned tomatoes paste. Results shows that lead and nickel were not detected in all the canned tomatoes. In comparison low concentrations of copper, iron, and manganese were notated but high concentrations of chromium and cadmium were detected in all the tested tomatoes pastes. Cobalt and zinc concentration was notated lower than permissible limit. The daily intake of copper, cobalt, manganese, chromium, cadmium, nickel, iron, zinc and lead were below their tolerable values in canned tomatoes. The predicted lifetime for carcinogens to occur was less than one (&lt;1). Copper, cobalt, iron, and zinc were below the acceptable value for non-cancer risk with HQ &lt;1.The risk of incurring cancer by ingesting canned tomatoes was within the lifetime predicted a range of (1.0E-6 to 1.0E-4). Finds suggest that prolong and persistent consumption of these heavy metals may cause toxicity and consequential heath challenges.&#x0D; J. bio-sci. 28: 1-11, 2020

BIOPHILE ELEMENTS AND HEAVY METALS IN ARTEMISIA FRIGIDA WILLD. AND ARTEMISIA JACUTICA DROB.

Biophile microelements (copper, zinc, manganese, iron, nickel) and heavy metals (lead, cadmium) in the aerial part of Artemisia frigida Willd. and Artemisia jacutica Drob. of Russian (areas of the Republic of Buryatia) and Mongolian flora was presented in this paper. The quantitative content of the elements in the samples collected in 2008, 2015–2018 was studied using atomic absorption method performed on a SOLAAR M6 after preliminary decomposition by dry mineralization, and inductively coupled plasma atomic emission method (ICP) on a Profile Plus spectrometer after decomposition of samples in the MARS 6 microwave system. The content of the same elements in the aerial part of the same species of Artemisia varied in a wide range, which was consistent with the literature data. In addition, the Principle component analysis of the elemental composition of A. frigida and A. jacutica was presented in this paper. The biplot showed the impact of forest fires that took place on the territory of Buryatia in 2015. So this year was characterized by a high concentration of lead, cadmium, nickel, copper and iron in studied samples. Also, the biplot showed the elements content versus plant species. In general, the content of toxic (lead, cadmium, nickel) and vital elements (copper, zinc, iron, manganese) was within the normal concentration. Therefore, the aerial part of A. frigida and A. jacutica of Buryatian (Russia) and aimaks (Mongolia) flora can be considered as promising plant raw materials for using in medical practice.

Silicon application affects cadmium translocation and physiological traits of Lallemantia royleana under cadmium stress

To study the interaction of different concentrations of cadmium and silicon on physiological traits of Lallemantia royleana a factorial experiment was conducted based on a completely randomized design. Experimental treatments were different concentrations of cadmium (0, 2.5, 5 and 10 mg L−1) in the absence (-Si) or presence (+Si) of silicon with a concentration of 1 mmol L−1. Based on results the highest amount of shoot Cd content (84.1 mg kg−1 DW) measured in -Si treatments was measured when the highest concentration of Cd (10 mg Cd L−1) was utilized. In all of the + Si treatments shoot Cd content decreased. The highest translocation factor (0.195) was observed in 2.5 mg Cd L−1 treatment without Si application and as a result of increasing Cd concentration in plant growth medium, the translocation factor decreased significantly. In + Si treated plants the translocation factor of Cd compared with –Si treated plants significantly decreased. Increasing the cadmium concentration up to 2.5 mg.L−1 did not have a significant effect on relative water content, leaf area, Chlorophyll a, and catalase activity. At the highest concentration of cadmium, the activity of peroxidase, catalase and superoxide dismutase in + Si plants compared with -Si plants increased about 23%, 55% and 30%, respectively. Silicon reduced the negative effects of cadmium on plant growth either by increasing the activity of antioxidant enzymes or decreasing Cd translocation to shoot. Therefore, application of silicon for increasing growth and to produce healthier plants under cadmium stress with a concentration of 5 mg L−1 is recommended.

The effect of cadmium exposure on the cytoskeleton and morphology of the gill chloride cells in juvenile mosquito fish (Gambusia affinis)

One of the wide spread aquatic organisms in the rivers of Indonesia is the mosquito fish (Gambusia affinis (Baird and Girard, 1853)). Mosquito fish are invasive species that can adapt to environmental changes, also they act as bioindicator species for polluted environments. The study aims to determine the effects of the exposure to cadmium on the cytoskeleton and morphology of the gill’s Chloride Cells (CCs) in the mosquito fish. In cadmium treated mosquito fish (0.03 mg/L for 28 days), the immuno-fluorescent light microscope showed strong absorption of actin stain and strong primary MT antibody uptake in CC and apical epithelia. Scanning electron microscopy observations showed a change in microfilament organized at the CC's apex, with the appearance of some actin filament aggregates. Higher cadmium concentrations (0.03 and 0.015 mg/L) did not alter such reorganization. Microtubules weren’t significantly affected by similar exposures. SEM analysis showed that cadmium exposure induced a significant increase in CC's surface area. After 28 days, the density of CC also increased. It was observed that there is an increase of CC's surface area, although the CC density didn’t increase significantly. The results of this study confirmed the cytotoxic effects of cadmium on mosquito fish.

Depuration of cadmium from Chlamys farreri by ZnSO4, EDTA-Na2 and sodium citrate in short time.

In view of high content of cadmium (Cd) in Chlamys farreri, a commercial edible shellfish species, depurating Cd from Chlamys farreri is an important topic nowadays, especially in short time. Therefore, three kinds of additives were introduced into seawater respectively, i.e. ZnSO4, EDTA-Na2, sodium citrate, to depurate Cd from Chlamys farreri. The alteration of Cd content in separate organs was investigated under several treatments with high depuration efficiency. The results showed that Cd was depurated exceeding 20% within 12h by the combination of 0.15g/L sodium citrate, 0.28g/L ZnSO4, and 0.42g/L EDTA-Na2. No obvious increase of Cd was observed in the adductor muscles, while Cd decreased in the other part, so the reduction of Cd in the whole organism of Chlamys farreri may occur. Cd reduction was found in the following organs: the digestive gland, kidney, gill, and mantle. Furthermore, Cd migration to gonad from other tissues was noticed.

Protective role of citric acid against oxidative stress induced by heavy metals in Caenorhabditis elegans.

The adverse effects of heavy metals, such as cadmium, zinc, and copper, occur due to the generation of reactive oxygen species (ROS). The use of Caenorhabditis elegans for the purposes of conservation and biomonitoring is of great interest. In the present study, ROS, malondialdehyde (MDA), and citric acid levels and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in a model organism were tested to study toxicity. C. elegans was exposed to three different concentrations of cadmium (CdCl2, 5, 10, 50 μM), zinc (ZnSO4, 10, 100, 500 μM), and copper (CuSO4, 10, 100, 500 μM) for 3 days. ROS levels increased by 1.3- to 2.1-fold with increasing metal concentrations. The MDA content increased by approximately 7-, 5-, 2-fold after exposure to high concentrations of cadmium, zinc, and copper, respectively. Furthermore, the citric acid content increased by approximately 3-fold in the cadmium (Cd, 5 μM), zinc (Zn, 10 μM), and copper (Cu, 100 μM) treatment groups compared to that in untreated C. elegans. Therefore, citric acid may play an important role in heavy metal detoxification. Excess citric acid also slightly increased the LC50 by 1.3- to 2.0-fold, basic movements by 1.0- to 1.5-fold, decreased the ROS content by 2.4- to 2.1-fold, the MDA content by 4- to 2-fold, the SOD activity by 9- to 3-fold, the GPx activity by 4.0- to 3.0-fold, and the mRNA expression levels of GPxs by 3.2- to 1.8-fold after metals treatment. And it is most significantly in the alleviation of citric acid to cadmium. This study not only provides information to further understand the effects of heavy metal exposure on ROS, MDA, GPx, SOD, and citric acid in worms but also indicates that supplemental citric acid can protect animals from heavy metal stress and has broad application prospects in decreasing oxidative damage caused by heavy metals.

The concentration of selected elements in the placenta according to selected sociodemographic factors and their effect on birth mass and birth length of newborns

Background and aimsThe placenta is a remarkable organ which provides critical transport functions between the maternal and fetal circulations during pregnancy. The demand for mineral components increases during the gestational period, therefore, an appropriate intake of minerals, such as calcium, phosphorus, potassium, magnesium, iron, zinc, copper, and manganese, determines the correct growth and development of a fetus. The aim of the study was to assess the concentration of selected elements in the placenta, and to assess the impact of their concentrations on the birth weight and birth length of newborns. The second aim of the study was to assess the influence of selected sociodemographic factors on the concentration of elements in the placenta. ResultsThe study demonstrated that the age of mothers affected the concentration of Ca and Mn in the placenta, and their habit of tobacco smoking during the gestational period was associated with higher concentrations of Ca, P, K, Mg, Fe, Cu, and Cd in the placental tissue. The results also showed that concentrations of K, Fe, Zn, and Mn in the placental tissue affected birth length. Furthermore, the association was demonstrated between a higher Cd concentration in the placenta (≥ 0.0503 μg/g) and the birth anthropometric parameters of neonates. ConclusionsSmoking during pregnancy and environment pollution are the factors that affects the concentration of elements in the placenta and contributes to their high accumulation in the placenta. Smoking during pregnancy causes an increased concentration of cadmium in the placenta which has negative health effects for the newborn. Women living in a big city or village had a higher concentration of cadmium in their placentas compared to women living in smaller cities. The significant influence of some elements (K, Fe, Zn, Cu and Cd) on the newborn’s birth parameters was also demonstrated. The results of our research indicate the importance of the mother’s lifestyle in providing the placenta with elements, which affects the growth of the fetus.•The placenta is an organ that is responsible for the proper course of pregnancy and fetal development.•The demand for mineral components increases during the gestational period, therefore, an appropriate intake of minerals determines the correct growth and development of a fetus•Increased exposure to arsenic, cadmium and lead during the gestational period can induce miscarriage, premature delivery, risk of fetal death, inhibition of intrauterine growth and development of the fetus, and low birth parameters.

Bioaccumulation of heavy metals in the dice snake Natrix tessellata (Reptilia, Colubridae) from ecosystems of different anthropogenic loads in modern conditions of the steppe Dnieper area

We studied the peculiarities of bioaccumulation and distribution of heavy metals (cadmium, lead, zinc and copper) in the bone tissue, liver and kidneys of the dice snake Natrix tessellata (Laurenti, 1768) inhabited ecosystems under different anthropogenic loads in 2015-2016. Mature individuals were caught in anthropogenically transformed ecosystems of the sanitary-protective zone of the Dniprovska Thermal Power Plant (SPZ DTPP) (48.402°N, 35.111°E, n = 7), coastal ecosystems of the National Nature Park «Velykyi Luh» (47.443°N, 35.149°E, n = 8) and in the Maiorka gully ecosystems (48.260°N, 35.170°E, n = 7). The gross content of metals in the organs of N. tessellata was determined after their dry ashing in a muffle furnace. Determination of the trace elements was performed by atomic absorption spectrophotometry. Among the studied trace elements, zinc has the highest concentrations in the liver, kidneys and bones of N. tessellata. The kidneys and liver are characterized by such amount of concentrations: Zn&gt; Cu&gt; Pb&gt; Cd, but bone tissue has the following ratio Zn&gt; Pb&gt; Cu&gt; Cd. The highest concentration of cadmium is found in the kidneys, and the lowest one – in the bones of snakes. There are the highest contents of lead and copper in the snakes’ liver, but the lowest in the kidneys and bones. The lead bioaccumulations in organs of snakes from different ecosystems are dissimilar. Zinc content in bones is higher than in kidneys and liver, but the lowest concentration is found in the kidneys. It has been found that the highest contents of toxic metals (Cd, Pb) were in the kidneys and liver of the snakes dwelled in the SPZ DTPP ecosystems in comparison with both studied natural ecosystems. In addition, snakes caught in anthropogenically transformed ecosystems of SPZ DTPP are characterised by increased zinc content in all studied organs and enlarged copper concentration in the kidneys. Considering the obtained results on the metals bioaccumulation, the dice snake can be considered as a potential bio-indicator of environmental pollution by heavy metals.

River toxicity assessment using molecular biosensors: Heavy metal contamination in the Turag-Balu-Buriganga river systems, Dhaka, Bangladesh

Pollution in rapidly urbanising cities and in delta systems is a serious problem that blights the lives and livelihoods of millions of people, damaging and restricting potable water supply and supplies to industry (Whitehead et al, 2015, 2018). Employing new technology based on luminescent molecular biosensors, the toxicity in the rivers around Dhaka in Bangladesh, namely the Turag, Tongi, Balu and Buriganga, has been assessed. Samples taken at 36 sites during medium and low flow conditions and during the Bishwa Ijtema Festival revealed high levels of cell toxicity, as well as high concentrations of metals, particularly aluminium, cadmium, chromium, iron, zinc, lithium, selenium and nickel. Chemical analysis also revealed low dissolved oxygen levels and anoxic conditions in the rivers at certain sites. The bacterial molecular biosensors were demonstrated to be fast, with results in 30 min, robust and a highly sensitive method for the assessment of water toxicity in the field. Furthermore, the biosensor toxicity analysis correlated with the metals data, and a multivariate regression relationship was developed relating toxicity to key metals, such a selenium, zinc and chromium. The resulting model has been validated against split samples and the Bishwa Ijtema Festival data. The combination of modelling and the molecular biosensor technology provides a new approach to detecting and managing pollution in urban river systems.