TOXICITY OF ZINC COMPOUNDS TO AQUATIC ANIMALS, WITH SPECIAL REFERENCE TO FISH

Occurrence, distribution, and ecological risk assessment of heavy metals in Chao Phraya River, Thailand

Understanding heavy metals in rivers is crucial, as their presence and distribution impact water quality, ecosystem health, and human well-being. This study examined the presence and levels of nine heavy metals (Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) in 16 surface water samples along the Chao Phraya River, identifying Fe, Mn, Zn, and Cr as predominant metals. Although average concentrations in both rainy and dry seasons generally adhered to WHO guidelines, Mn exceeded these limits yet remained within Thailand's acceptable standards. Seasonal variations were observed in the Chao Phraya River, and Spearman's correlation coefficient analysis established significant associations between season and concentrations of heavy metals. The water quality index (WQI) demonstrated varied water quality statuses at each sampling point along the Chao Phraya River, indicating poor conditions during the rainy season, further deteriorating to very poor conditions in the dry season. The hazard potential index (HPI) was employed to assess heavy metal contamination, revealing that during the dry season in the estuary area, the HPI value exceeded the critical threshold index, indicating the presence of heavy metal pollution in the water and unsuitable for consumption. Using the species sensitivity distribution model, an ecological risk assessment ranked the heavy metals' HC5 values as Pb > Zn > Cr > Cu > Hg > Cd > Ni, identifying nickel as the most detrimental and lead as the least toxic. Despite Cr and Zn showing a moderate risk, and Cu and Ni posing a high risk to aquatic organisms, the main contributors to ecological risk were identified as Cu, Ni, and Zn, suggesting a significant potential ecological risk in the Chao Phraya River's surface water. The results of this study provide fundamental insights that can direct future actions in preventing and managing heavy metal pollution in the river ecosystem.

Using neutron activation to assess heavy metal pollution in water and sediment along Savannah River

A comprehensive study was conducted to assess heavy elemental pollution in the Savannah River, which flows through diverse landscapes encompassing agricultural, industrial, and commercial zones in South Carolina and Georgia. The investigation focused on the impacts of various anthropogenic activities on the river, potentially harming human health and aquatic ecosystems. Thirty samples, collected from the beginning of the Savannah River at Lake Hartwell to the Savannah River estuary near the Atlantic Ocean, were analyzed using Instrumental Neutron Activation Analysis. In regions of intense industrial activities, water samples exhibited elevated concentrations of elements such as Al (0.04-1.99 mg/L), Mg (0.4-5.5 mg/L), Ba (0.08-2.8 mg/L), Zn (0.017-0.9 mg/L), Cr (0.005-1.5 mg/L), and Fe (2.8-110.13 mg/L). Similarly, sediment samples near industrial areas also exhibited enhanced concentrations of heavy elements like Cr, Zr, Rb, Co, Zn, Mg, Mn, and Al. The outcome of this study has identified a spatial trend along the Savannah River, revealing major elements responsible for pollution that could disrupt the ecological environment and potentially impact human health.

Prevalence, Morpho-Histopathological Identification, Clinical Picture, and the Role of Lernanthropus kroyeri to Alleviate the Zinc Toxicity in Moron labrax

The present context is a pioneer attempt to verify the ability of copepod, Lernanthropus kroyeri (L. kroyeri), to uptake and accumulate heavy metals. We primarily assess the prevalence of the parasite in various seasons and its clinical signs, as well as post-mortem changes in sea bass (Moron labrax). The morphological features of the parasite using a light microscope, the bioaccumulation of heavy metals in the tissues of both L. kroyeri and M. labrax (gills, muscles) using Flame Atomic Absorption Spectrometry, and the histopathological alterations were monitored. Fish (n = 200) were obtained from Ezbet Elborg and examined for the parasite, L. kroyeri. The results revealed that the total infection was recorded at 86%. The infested fish exhibited excessive mucous and ulceration at the site of attachment. The post-mortem lesion in the gills revealed a marbling appearance with destructed filaments. Various heavy metals (Zn, Co, Cu, and Cd) were detected in the tissues of L. kroyeri and M. labrax and, surprisingly, L. kroyeri had the ability to uptake and accumulate a high amount of Zn in its tissues. Infested fish accumulated a lower concentration of Zn in their tissue compared with the non-infested ones. Within the host tissue, the accumulation of Zn was higher in the gills compared with the muscles. The histopathological findings demonstrated scattered parasitic elements with the destruction of the gill lamellae. Taken together, we highlight the potential role of L. kroyeri to eliminate Zn and it can be utilized as a bio-indicator for metal monitoring studies for sustaining aquaculture.

Genotoxic, biochemical and histological biomarkers of subacute concentrations of paraquat and glyphosate in Nile Tilapia

The use of herbicides for increased food production may pose risk to non-target organisms. This study evaluated the acute toxicity, genotoxic, biochemical, and histological biomarkers of subacute concentrations of paraquat and glyphosate in Oreochromis niloticus (Nile Tilapia) for 28 days following standard methods. Glyphosate (96 hLC50 value-1.23 mg/L) was 9x more toxic than paraquat (96 hLC50 value-11.20 mg/L) against O. niloticus. Average micronucleated cells were significantly higher in the erythrocytes of O. niloticus exposed to the higher (1.12 mg/L) concentration of paraquat at day 14, both subacute concentrations of paraquat at day 28, and lower concentration (0.01 mg/L) of glyphosate at days 14 and 28 compared to the other treatments and controls. Biochemical biomarkers (MDA and GST) activities were significantly higher at both subacute concentrations of the herbicides in the exposed fish compared to the controls at day 28 only. GSH activity was significantly higher in the 0.11 mg/L paraquat concentration while SOD activity was significantly lower at both subacute concentrations of glyphosate in exposed fish compared to controls at day 28. Histological alterations observed were mild to severe shortening of the gill primary lamellar and hepatic portal inflammation of exposed fish compared to the controls. This study demonstrates the risk to non-target organisms due to herbicides’ run-off from agricultural farmlands into aquatic ecosystems at environmentally relevant or subacute concentrations. Sensitization on the responsible use of pesticides is recommended to promote responsible consumption and production and sustain life below water (United Nations Sustainable Development Goals 12 and 14 respectively).

Genotoxicity and Trace Elements Contents Analysis in Nile Tilapia (Oreochromis niloticus) Indicated the Levels of Aquatic Contamination at Three Egyptian Areas

The toxic waste and pollutants of heavy metals continuously pollute freshwater aquatic reservoirs, which have severe implications on aquatic life and human health. The present work aims to evaluate trace elements (Zn, Mn, Cu, Cd, and Pb) along with three sites, Mariout Lake, Abbassa, and River Nile Aswan in Egypt, using Nile tilapia (Oreochromis niloticus) as bioindicator. The quality assurance, health-risk assessment, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), quantitative polymerase chain reaction (qPCR), and micronucleus test were performed to investigate the effect of different trace elements on Hsp70 gene level and micronuclei formation. We observed the highest expression of Hsp70 protein band of 70 KD and stress-responsive Hsp70 gene in the liver followed by gills of Nile tilapia caught from Mariout and Abbassa, but the lowest expression was in Nile tilapia caught from Aswan. Obvious micronuclei were observed under the microscope in erythrocytes, and their number was gradually decreased in the following manner: Mariout > Abbassa > Aswan. Noticeably, Cu, Zn, and Mn contents were low. Still, Pb and Cd contents were higher than the toxicity level recommended by the Food and Agriculture Organization (FAO), The World Health Organization (WHO), and the European Commission (EC). These results showed that Hsp70's appearance at the two levels of mRNA and protein is an effective indicator for aquatic pollution besides the aberration at the chromosome level represented in the micronucleus test. Furthermore, these results showed that Nile tilapia of the Aswan region had comparatively low trace elements contamination and were suitable for consumption.

Role of Zinc Oxide in the Compounding Formulation on the Growth of Nonstoichiometric Copper Sulfide Nanostructures at the Brass-Rubber Interface

Tire technology has evolved substantially by the introduction of brass-coated steel cords (BCSCs) in radial tires. The durability of radial tires is dependent on the integrity of the brass-rubber interface composed predominantly of nonstoichiometric copper sulfide (Cu_2-x S, where x = 1 to 2) nanostructures whose morphology and characteristics are dependent upon the crucial rubber additive, ZnO. Its higher concentration impacts environmental sustainability, while at lower levels, there is insufficient bonding between steel and the rubber thus affecting tire's safety. This brings in the need for an optimum ZnO concentration to be used in radial tires and is thus the theme of the present work. The changes in the properties of interfacial nanostructures such as morphology, thickness, crystallinity, and chemical composition were studied at various ZnO concentrations. We adopted our previously reported methodology, the "brass mesh experiment", to investigate the thickness of nanostructures at varied ZnO concentrations using transmission electron microscopy (TEM). Significant results were obtained from field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman imaging and X-ray photoelectron spectroscopy (XPS). In conjunction with a more practical experimental technique, namely the measurement of pull-out force (POF), it has been concluded that 9 parts per hundred rubber (PHR) ZnO is essential for the optimum growth of nanostructures and is considered to be the optimum for the composition studied. We believe that the scientific approach outlined in the manuscript would help the tire- and the material science communities to widen the knowledge of understanding sustainability in tire industries. It is estimated that the optimization presented here can save $400-450 million for the tire industry and 2.4 million tons of ZnO per year.

Trace and Major Elements Concentration in Fish and Associated Sediment-Seawater, Northern Shores of the Persian Gulf

The concentration of 19 metal and non-metal elements in two fishes (Liza subviridis and Sphyraena jello) and associated sediment-seawater from the northern part of the Persian Gulf was measured. The samples were gathered from two industrial ports, one commercial port, and one residential port. The metal accumulation in the muscle and liver of fishes was evaluated. Nickel (mean 362.07-712.83 μg/g) and chromium (mean 470.00-691.47 μg/g) in sediment and zinc (mean 9.01-31.15 μg/L) and arsenic (mean 18.22-22.14 μg/L) in seawater had the most abundancy among studied elements. The accumulation of elements in S. jello (a pelagic species) was higher than L. subviridis (a demersal species). For both species, major elements of S and Mg and trace elements of Fe, Al, Si, Zn, and Cu showed highest accumulation. Also, fish samples from Emam Hassan Port were more contaminated than other stations. Ecological indexes values have revealed a low to moderate elemental pollution of sediment and fish samples in the north part of the Persian Gulf.

Exposure to sublethal concentrations of zinc pyrithione inhibits growth and survival of marine polychaete through induction of oxidative stress and DNA damage

Effects of zinc pyrithione (ZnPT) and inorganic Zn (ZnCl₂) were evaluated on a marine polychaete at sublethal concentrations for 14 days. ZnPT decreased the burrowing activity and AChE activity with higher acute toxicities, implying its cholinergic effect. Both ZnPT and ZnCl₂ increased MDA levels at higher concentrations, suggesting lipid peroxidation and oxidative stress. In the ZnPT-treated polychaete, enzymatic activities of CAT and SOD were elevated with an increase in DNA damage, whereas the levels of GSH, GPx, GR, and GST were decreased. However, in the ZnCl₂-treated polychaete, the level of GSH and enzymatic activities of CAT, SOD, GPx, GR, and GST were significantly elevated to resist cellular damage. During 97 days depuration experiment, significant mortality and growth retardation were observed in the ZnPT-exposed polychaete. Overall, ZnPT was found to be more toxic than ZnCl₂ with the harmful impact on antioxidant defense system and DNA stability in marine polychaete.

Toxicity profile of choline chloride-based deep eutectic solvents for fungi and Cyprinus carpio fish

An investigation on the toxicological assessment of 10 choline chloride (ChCl)-based deep eutectic solvents (DESs) towards four fungi strains and Cyprinus carpio fish was conducted. ChCl was combined with materials from different chemical groups such as alcohols, sugars, acids and others to form DESs. The study was carried out on the individual DES components, their aqueous mixture before DES formation and their formed DESs. The agar disc diffusion method was followed to investigate their toxicity on four fungi strains selected as a model of eukaryotic microorganisms (Phanerochaete chrysosporium, Aspergillus niger, Lentinus tigrinus and Candida cylindracea). Among these DESs, ChCl:ZnCl2 exhibited the highest inhibition zone diameter towards the tested fungi growth in vitro, followed by the acidic group (malonic acid and p-toluenesulfonic acid). Another study was conducted to test the acute toxicity and determine the lethal concentration at 50 % (LC50) of the same DESs on C. carpio fish. The inhibition range and LC50 of DESs were found to be different from their individual components. DESs were found to be less toxic than their mixture or individual components. The LC50 of ChCl:MADES is much higher than that of ChCl:MAMix. Moreover, the DESs acidic group showed a lower inhibition zone on fungi growth. Thus, DESs should be considered as new components with different physicochemical properties and toxicological profiles, and not merely compositions of compounds.

Coupled effects of hydrodynamics and biogeochemistry on Zn mobility and speciation in highly contaminated sediments

Porewater transport and diagenetic reactions strongly regulate the mobility of metals in sediments. We executed a series of laboratory experiments in Gust chamber mesocosms to study the effects of hydrodynamics and biogeochemical transformations on the mobility and speciation of Zn in contaminated sediments from Lake DePue, IL. X-ray absorption spectroscopy (XAS) indicated that the oxidation of surficial sediments promoted the formation of more mobile Zn species. Bulk chemical measurements of porewater, overlying water, and sediment also suggested that this process liberated aqueous metals to porewater and facilitated Zn efflux to the overlying water. In addition, sediment resuspension events increased the release of aqueous metals to both surficial porewater and the overlying water column. XAS analysis indicated that resuspension increased dissolution of Zn-sequestering mineral phases. These results show that both steady slow porewater transport and rapid episodic resuspension are important to the release of metal from fine-grained, low-permeability contaminated sediments. Thus, information on metals speciation and mobility under time-varying overlying flow conditions is essential to understanding the long-term behavior of metals in contaminated sediments.

Evaluation of toxicity and biodegradability for cholinium-based deep eutectic solvents

The first study investigating the toxicity of cholinium-based DESs on freshwater fish or fungi and the biodegradability of EAC-based DESs.

Respiratory distress and behavioral changes induced by sodium cyanide in the fresh water TELEOST, Cyprinus carpio (Linnaeus)

An acute toxicity (LC50) test using a static renewal bioassay method was conducted to determine the toxicity of sodium cyanide in freshwater exotic carp, Cyprinus carpio exposed for 96 h to different concentrations of sodium cyanide. The acute toxicity value was found to be 1 mg/L; one third of the LC50 (0.33 mg/L) was selected as the sublethal concentration for subacute studies. Behavioral patterns were observed in lethal (1, 2, 3, and 4 d) and sublethal concentrations (1, 5, 10, and 15 d). Cyprinus carpio in toxic media exhibited irregular, erratic, and darting swimming movements, hyperexcitability, loss of equilibrium, and sinking to the bottom, which might be due to inhibition of cytochrome c oxidase activity and decreased blood pH. The combination of cytotoxic hypoxia with lactate acidosis depresses the central nervous system and myocardium, the most sensitive critical sites for anoxia, resulting in respiratory arrest and death. A decrease in oxygen consumption (-28.36 to -78.28%; -14.22 to -47.25%) was observed at both lethal and sublethal concentrations of sodium cyanide respectively. Fish at the sublethal concentration were found under stress, but that was not fatal.

Determination of toxic elements in waters and sediments from River Subin in the Ashanti Region of Ghana

Waters and sediments of Subin River, which flows through the industrial and commercial areas of Kumasi in the Ashanti region of Ghana, were geochemically investigated to ascertain heavy metal pollution levels due to anthropogenic activities. The study shows preoccupying pollution levels that constitute a threat to public and ecological systems. The waters of Subin River are neutral to slightly basic, inferred from pH values of 6.89-7.65). Electric conductivity (EC) of the waters ranges from 822 to 1,821 mus/cm and the range of total dissolved solids (TDS) is from 409 to 913 mg/l. Toxic elements contents of sediments and waters from 10 sites along the river were analysed by instrumental neutron activation analysis (INAA), and Al, As, Cd, Cr, Cu and Zn were determined. The concentrations of Al, As, Cd, Cr, Cu and Zn in the waters range between 4.02-15.18, 0.007-0.16, 0.002-0.05, 0.001-0.019, 1.32-7.04 and 4.28-10.2 mg/l, respectively. The contamination factors (CF) computed for the elements indicate that with the exception of sampling site S10, the sediments are polluted with Cd. Chromium contamination in the sediments is observed at S6 and S7, where the CF values were 1.39 and 1.52, respectively. The pollution load indices (PLI) were low (<1) and ranged from 0.14 to 0.75, suggesting that the overall sediment column of the river is not polluted.

Mathematical modeling of leachates from ash ponds of thermal power plants

The present study describes the development of empirical models for the prediction of various trace metals i.e., Mn, Cu, Fe, Zn and Pb found in the leachates generated from the ash ponds of various thermal power plants. The dispersion phenomenon of these trace metals followed first order reaction rate kinetics. The empirical models for individual trace metals derived from the lab scale models data correlate well with the real field data with regression coefficients varying from 0.93 to 0.98. The predicted concentrations of the trace metals varied within +/-3% of the observed values in the leachates generated from the ash ponds of four thermal power plants with standard deviation varying from 0.001 to 0.032. The empirical models derived from the study can be applied for prediction of trace metals in leachates generated from similar thermal power plants.

The effects of zeta cypermethrin on the gills of common guppy Lebistes reticulatus

Effects of lethal and sublethal concentrations 15, 20, 26 and 35 μg/l of zeta cypermethrin on the gills of common guppies (L. reticulatus) were examined by light microscopy during 96 h exposure. The most common changes at all doses of zeta cypermethrin are the lifting of epithelial layer from gill lamellae and some necrosis. Besides the exudation, hyperplasia and the shortening of secondary lamellae were other histopathological effects. The 96 h LC(50) value for zeta cypermethrin to the L. reticulatus was determined 21.35 μg/l.

Bioconcentration of atrazine, zinc and iron in the blood of Tilapia sparrmanii (Cichlidae)

1. The bioconcentration of atrazine, zinc and iron in the blood of Tilapia sparrmanii has been determined separately in each of six exposure groups. 2. An increased bioconcentration of atrazine in the blood occurred with an increased exposure concentration. 3. With exposure to zinc, there was a gradual decrease in bioconcentration of zinc in the blood of T. sparrmanii with an increased concentration in the water. 4. A similar tendency was observed during iron exposure, except that the decrease in bioconcentration was not significant.

Toxic substances in rivers and streams

Many of the toxic substances entering freshwaters today are those which were present several decades ago, but others have become significant recently. The effects of toxicants in flowing waters are modified by unidirectional transport and dispersion which afford the potential for a degree of 'self-purification'. The chemical quality of the receiving water also affects toxicity. Biological factors also contribute to the ultimate effect of pollutants. The potential for accumulation of toxic substances within tissues increases the significance of certain pollutants which may be present in water even though ambient concentrations are very low. The biota of flowing waters may be restored, following catastrophic entry of pollutants, by drift from unaffected regions upstream. The range of potential toxic substances is very extensive and includes inorganic poisons, organic poisons, heavy metals, pesticides and PCBs. Metals, pesticides and PCBs have the greatest potential for bioaccumulation. Few generalisations can be made regarding the effects of toxic substances on the biota. Each species tends to respond to different toxicants in different ways and even at different stages in its life-history. Toxicity tests conducted under controlled laboratory conditions sometimes produce conflicting results: it is not then to be unexpected that field observations should sometimes vary widely. Determinations of toxicity in laboratory tests must be applied with caution to field conditions and it is not wise to extrapolate findings to other species or environments.

Toxicity in Tilapia zilli and Clarias lazera (Pisces) induced by zinc, seasonally

Subadult teleosts, Tilapia zilli and Clarias lazera, were exposed in laboratory bioassays to lethal and sublethal concentrations of zinc, seasonally (at range of temperature between 9.3 +/- 1.5 and 25 +/- 1 degree C). It appears that Tilapia is more susceptible to Zn than Clarias and both species are more resistant to Zn toxicity at lower temperature (during winter). To determine the uptake and tissue distribution of Zn in the two species, gill, liver and muscles were analysed at moderate temperature (during spring). After a 96 hr exposure period, Zn was decreased in the following order: gill greater than liver greater than muscle.

Analysis of the effects of zinc pollution on the macro-invertebrate populations of the Afon Crafnant, North Wales

The study of the input draining from mine-waste into the Afon Crafnant, N. Wales, revealed that the most significant pollutant was zinc. The concentrations of zinc were monitored during 1978 and 1979, and spot samples were concentrated and analysed for lead, copper, cadmium, iron, cobalt, manganese and nickel. Analysis was by flame atomic absorption specto-scopy. The 'total' zinc concentration of the input was about 4 mg Zn/l which was diluted by the Afon Crafnant to give mean annual concentrations of 213 μg Zn/l and 146 μg Zn/l for 1978 and 1979 respectively at a site 60 metres downstream of the input. The numbers of individuals and number of taxa in the macro-invertebrate community were reduced at these concentrations. The taxa affected werePhagocata vitta,Erpobdella octoculata, Oligochaeta,Ithytrichia lamellaris, Simuliidae,Ancylus fluviatilis andRithrogena semicolorata. Several commonly used diversity indices failed to show differences between the macro- invertebrate communities at the affected and control sites whereas a modified version of Chandler's Biotic Score (detailed in this paper) revealed both the acute effects at higher concentrations and the chronic effects at lower concentrations.

The effect of zinc on the ultrastructure of the trunk muscle of the larva of Clupea harengus L

The ultrastructural changes in the trunk muscle tissue of Clupea harengus L. larvae, hatched from eggs exposed to four different concentrations of zinc (0.5, 2.0, 6.0 and 12.0 ppm), were examined by morphometric analysis. The surface-to-volume ratio of the mitochondrial cristae was significantly reduced with increasing zinc concentrations. At concentrations of 2.0, 6.0 and 12.0 ppm zinc, the relative volumes of the mitochondria increased significantly and individual mitochondria were swollen. At concentrations 2.0, 6.0 and 12.0 ppm zinc, the relative volumes of the myofibrils decreased significantly. At concentrations of 6.0 and 12.0 ppm zinc the sarcoplasmic reticulum showed significant swelling, and in specimens treated in 12.0 ppm zinc the sarcoplasm contains fewer ribosomes.

Oxygen consumption of the dogfish gill tissue following zinc treatment

1. Oxygen consumption of the dogfish gill tissue has been determined by manometric techniques following different treatments with zinc sulphate. 2. Exposure of the animals to subacute and acute zinc concentrations affects gill tissue respiration. 3. No significant differences in oxygen consumption were found between subacutely treated fish (10 ppm for 4 and 21 days) ad 80 ppm (LC50 48hr) for 24hr exposed animals. 4. Fish treated with 175 ppm (LC50 24hr) for 14 hr greater inhibition of gill tissue respiration than subacutely treated animals. 5. Results are discussed in relation to Zn accumulation in the gill system following the same treatment with zinc sulphate.

Critical species, including man, within the biosphere

The protection of critical ecosystems appears to be a sounder management strategy than the protection of critical species. Environmental quality-control systems designed to protect ecosystems are described. These quality-control systems will make it possible to optimize the ability of ecosystems to assimilate and transform wastes and protect them from degradation.

Effects of Copper on Gammarus pseudolimnaeus, Physa integra, and Campeloma decisum in Soft Water

Three invertebrate species were subjected to acute (96-hr), followed by long-term (6-week) copper exposures under continuous-flow bioassay conditions. Survival, growth, reproduction, and feeding were the responses used for measuring toxicant effects. The average 96-hr median tolerance limits (TLm) values for Campeloma decisum, Physa integra, and Gammarus pseudolimnaeus were 1.7, 0.039, and 0.020 mg/liter total copper, respectively. The total copper concentration having no effect after 6 weeks exposure for all three species was between 8.0 and 14.8 μg/liter. The newly hatched amphipods obtained from the second 6-week study were exposed to copper for 9 additional weeks, and grew to the adult stage only in copper concentrations ≤ 4.6 μg/liter. After 5 weeks exposure to a water system, survival of newly hatched Gammarus was markedly reduced when copper concentrations were between 12.9 and 6.2 μg/liter.