Concentration and Biomagnification of Heavy Metals in Biota of the Coastal Marine Areas of Tanzania

The concentrations of heavy metals （As, Hg, Cr, Pb and Zn） were measured in the macroalgae, macrobenthos and fish from the Tanzanian coastal marine environment in order to ascertain the biomagnification using stable isotopes of C and N. Macroalgae samples from the central marine areas of the Tanzanian coast had higher mean concentrations of Hg （0.17 ± 0.01 μg/g） and Cr （23.7 ± 4.15 μg/g） compared to other locations. Higher concentration of Hg （0.06 ±0.02 μg/g） was detected in the Ulva fasciata close to the Msimbazi Creek in Dares Salaam, whereas the highest concentration of Cr （45.5 ± 6.83 μg/g） was found in Ulva petrusa near Dares Salaam port. The crab Portunus pelagicus collected from Pangani river estuary contained 411.5 ± 13.04 μg/g of Zn. The other metals were uniformly distributed in macrobenthos from the entire coast. Mercury and lead in the biota were found to biomagnify along the Arius dussumieri and Lethrinus lentjan food chains as suggested by the significant positive relationships between log-pollutant concentrations in fish muscle tissues vs. 615N signatures. Zinc in muscle tissues was found to be transferred along the food webs although no biomagnification was observed. Arsenic and chromium were found to decrease with the rise of the trophic position. Metal concentrations in macroalgae, macrobenthos and fish were compared with quality guidelines values by FAO （Food and Agricultural Organization） in 1983 and they all were below permissible limits for human consumption.δ

Polycyclic Aromatic Hydrocarbons and Selected Heavy Metals in Some Oil Polluted Sites in Delta State Nigeria

Concentrations of selected heavy metals, nutrient elements and PAHs in farms and produce (cassava tubers and oil bean seeds) from 4-year-old crude oil impacted areas (Ekore and Uduvwoku) and a non-oil-impacted area (Okpe), all in Ughelli South Local Government Area, Delta State, Nigeria, were investigated to ascertain degree of risk posed. A random sampling design was chosen with three replications. Results obtained revealed significantly (P < 0.05) elevated (mg·kg-1) Cd (0.240, 0.140) and Cr (1.327, 3.122) in cassava samples for Ekore and Uduvwoku respectively in comparison to non-detectable amount for those of non-impacted source and exceeded set WHO limits of 0.1 and 0.05 mg·kg-1 respectively. Although PAHs were low, oil spill increased available levels by factor of 2.5 and 5 for Ekore and Uduvwoku respectively. Again, Cd and Cr exceeded WHO limit for study impacted soils. Available N, P and K decreased (%) by 56.1, 28.5 and 2.4 for Ekore and 82.9, 39.9 and 45.5 for Uduvwoku Cassava samples. Nutrient profiling in oil bean revealed % reduction in avaliable N, P and K by 33.7, 47.7 and 57.9 and 28.9, 76.3 and 39.8 for Ekore and Uduvwoku samples respectively. For oil bean, Cd and Cr did not differ markedly between polluted samples but exceeded WHO limits. Other studied contaminants fell within limits. In soils, available N, P and K decreased (%) by 39.6, 79.1 and 27.4 for Ekore and 53, 88.1 and 45.5 for Uduvwoku samples. Low pH of 5.3 and 5.7 in Ekore and Uduvwoku respectively may increase the leachability of Cr into groundwater. Biopersistent Cd and Cr were found to biomagnify up the food chain and may impair major processes. Although PAHs were relatively low, their % composition was more of High Molecular Weight that was less readily biodegraded by indigenous microorganisms, and hence can persist in the environment as carcinogens.

Exposure to Dioxins and Furans at the Bormeh Kingtom Dumpsite in the Western Area of Sierra Leone

Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.

DDT and Its Metabolites in Fresh Water Fish Samples

Twenty two fresh water fish samples namely Puntius sarana （Shawrputi）, Cyprinus carpio （Karp）, Oreochromis niloticos （Telapia）, Channa punctatus （Taki）, Wallogonia attu （Boal）, Eutropiichthys vacha （Bacha）, Macrognathus aculiatus （Baim）, Ailia coila （Kajoli）, Mystus cavasisus（Gulsa）, Ompok pabda （Pabdha）, Corica soborna （Kachki）, Mystus vittatus （Tengra）, Glossogobius giuris （Baila）, Macrobrachium malcolmsli （Chingri）, Amblypharyngodon microlepis （Mola）, Anabas testudineus （Koi）, Macrognathus aculiatus （Baim）, Channa striatus （Shole）, Heteropnueste fossilis （Shing）, Puntius sophore （Small Puti） and Pseudambassis ranga （Telapia） were collected from two rivers and one cultured fish pond. The samples were extracted by QuEChERS method, cleaned up with conc. H2SO4 treatment and cleaned extracts were analyzed by GC-ECD. Small size cultured rui fish sample which did show detectable amount of DDT and its metabohtes was used for the recovery experiments. Percent recovery was found to be in the range of 70%-113%. Amount of total DDTs were found to be 54.34, 48.81, 62.09, 54.72,78.81, 60.07, 47.0, 42.7, 26.31, 10.36, 25.32, 12.96, 20.10, 12.78, 17.65, and 4.71, 8.58, 11.3 and 19.01 ng/g in gulsa, pabhda, baila, bacha, baim, small purl, tengra, chanda, kachki, boal, taki, chingri, mola, shole, shing, koi, swarpurl, karp and telapia fish samples, respectively. However, the residual amounts of DDTs in all the fish samples were below maximum residue limit （MRL of DDTs in fish 5.0 mg/kg） according to Codex Alimentarius Commission. The ratios of 4,4＇-DDT/DDTs were in the range of 0.03-0.44 which indicated that exposure to DDT is not due to recent use.

Bioaccumulation of Mercury in Fish Species from Different Trophic Level

Mercury （Hg） is an environmental pollutant, and can bioaccumulate and biomagnify in the food web. Twenty four fish samples of different tropic level i.e., Herbivore, Omnivore and Carnivore were collected from two contaminated rivers, the Megna and the Buriganga which surround the Dhaka division for the assessment of toxic Hg. Fourteen samples were found to contain Hg in the range of 0.01-0.09 mg/kg. The highest Hg （0.09 mg/kg） was found in the Carnivore, Bele （Glossogobius giuris）. However, all fish species had lower amount of Hg than the maximum Hg limit （0.5 mg/kg for fish） set by World Health Organization （WHO）. Among all the fish species, the order of bioaccumulation was carnivore 〉 omnivore 〉 herbivore. Kajoli （Ailia coila）, Shing （Heteropnuestes fossilis）, Rui （Labeo rohita）, Chewa （Tryauchen vagine）, Rita （Rita rita）, Hilsha （Tenualosa ilisha）, Small Puti （Puntius sophore）, Bacha （Eutropiichthys vacha） and Chingri （smallprawn） were not found to contain any Hg which indicated that fish species from these rivers are safe for human consumption.

Nanomaterials in Soil Environment: A Review

Nanomaterials(NMs)have become an integral part of our daily life,and their extensive production will only increase with the increasing time.These NMs exhibit significant contrast regarding dimension,reaction,and structure.The most important aspect of the NMs is that these can be easily manipulated and engineered to custom-suit different functions/industries.Owing to their dynamic nature,these NMs behave differently when introduced in any medium.In soil,the behavior of NMs is significantly controlled by the interactions of nanomaterials with soil phases.Although NMs are deemed beneficial for human-use,yet these also carry lethal effects.Moreover,there is a dearth of adequate research for the interactions among nanomaterials and soil physicochemical properties;their accumulation-dissolution dynamics in soil-plant systems;and their long term influence on soil health.Several NMs induce physiological stress when introduced inside the body.Thus,various researchers have devised green pathways for producing NMs,although their wide applicability is still questionable.Although the domain of nanotechnology is greatly explored,yet there remain several grey areas which need to be addressed for sustainable utilization of these unique materials in the benefit of humankind.

Water temperature governs organophosphate ester dynamics in the aquatic food chain of Poyang Lake

Organophosphate esters(OPEs)are increasingly recognized as pervasive environmental contaminants,primarily from their extensive application in flame retardants and plasticizers.Despite their widespread presence,the intricacies of OPE bioaccumulation within aquatic ecosystems remain poorly understood,particularly the environmental determinants influencing their distribution and the bioaccumulation dynamics across aquatic food chains.Here we show that water temperature plays a crucial role in modulating the dispersion of OPE in the aquatic environment of Poyang Lake.We quantified OPE concentrations across various matrices,uncovering levels ranging from 0.198 to 912.622 ng L^(-1) in water,0.013e493.36 ng per g dry weight(dw)in sediment,0.026e41.92 ng per g wet weight(ww)in plankton,0.13e2100.72 ng per g dw in benthic invertebrates,and 0.31e3956.49 ng per g dw in wild fish,highlighting a pronounced bioaccumulation gradient.Notably,the intestines emerged as the principal site for OPE absorption,displaying the highest concentrations among the seven tissues examined.Among the various OPEs,tris(chloroethyl)phosphate was distinguished by its significant bioaccumulation potential within the aquatic food web,suggesting a need for heightened scrutiny.The propensity for OPE accumulation was markedly higher in benthic invertebrates than wild fish,indicating a differential vulnerability within aquatic biota.This study lays a foundational basis for the risk assessment of OPEs as emerging contaminants and underscores the imperative to prioritize the examination of bioaccumulation effects,particularly in benthic invertebrates,to inform future environmental safeguarding strategies.

Cadmium,chromium,copper,iron,lead,mercury,nickel,and zinc in freshwater fish:Assessing trophic transfer using stable isotope ratios ofδ^(15)N andδ^(13)C

Introduction The health benefits of consuming aquatic organisms are clear,given their high protein count,low saturated fats,and low cholesterol content.Fish,in particular,contains valuable nutrients(e.g.,omega-3 polyunsaturated fats),vitamins,essential elements,and is therefore considered an important part of a balanced human diet.China is a major seafood producer,accounting for 58%of global production in 2018(Crona et al.,2020).China is the largest seafood consuming country in the world,with consumption rates steadily increasing.Since the 1978 Chinese economic reform,the amount of seafood consumed per capita in China increased from 5 kg per capita in 1980 to 41 kg in 2015(Zhang et al.,2021).By 2030,the overall amount of fish consumption will likely exceed the amount of fish production in China.

Metal concentrations of insects associated with the South African Ni hyperaccumulator Berkheya coddii （Asteraceae）

The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations （Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn）. We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni （4 700-16 000μg/g） and high values （5-34μg/g） for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni （〉 500μg/g）. The large number of high-Ni heteropterans adds to discoveries of others （from California USA and New Caledonia） and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran （Stenoscepa） contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg （〉 2 800 μg/g）, one beetle with elevated Cu （〉 70 μg/g） and one heteropteran with an elevated level of Mn （〉 200 μg/g）. Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.

Assessment of heavy metal accumulation in freshwater fish of Dongting Lake,China:Effects of feeding habits,habitat preferences and body size

We measured the concentrations of Cr,Fe,Ni,Cu,Zn,Cd,Pb and Hg,and the stable isotope ratios(δ^(13)C and δ^(15)N)in 87 fish samples within 12 economic fish species collected from the Dongting Lake,the second largest freshwater lake in China.With few exceptions in concentration of Cr,most of fish species showed lower concentrations of the 8 metals than legislation thresholds.Piscivorous fishes had significantly higher values of δ^(15)N(possessing higher trophic level)and metal concentrations than planktivorous and herbivorous fishes.Moreover,demersal fishes showed higher concentrations of Cu,Zn,Cd and Pb than pelagic and benthopelagic fishes.We found positive correlations between concentrations of Fe,Pb and Hg and δ^(15)N ratio,confirming the biomagnification of the three metals through trophic transfer.In contrast,fishes showed clear growth dilution effect for Ni,Zn,Cu,Pb and Hg,indicated by the negative correlations between their concentrations and fish weight or length.Multiple regression analysis demonstrated that growth dilution and biomagnification effects simultaneously governed the metal concentrations in fish muscle,and the two effects'importance varied among different metals.The human health risk assessment indicated that all 8 metals gave target hazard quotient(THQ)values<1.0,i.e.,the estimated daily intake(EDI)of metals did not exceed the oral reference dose(Rf D),indicating a safe consumption of these fish species for consumer.Our study provides comprehensive approaches to better understand the determining processes and potential risk of heavy metals in freshwater lake fishes.

Host-herbivore studies of Stenoscepa sp. （Orthoptera：Pyrgomorphidae）, a high-Ni herbivore of the South African Ni hyperaccumulator Berkheya coddii （Asteraceae）

Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with Ni concentrations in the normal range. We conducted studies to： （i） determine the whole-body metal concentration of nymphs （including those starved to empty their guts）; （ii） compare Stenoscepa sp. nymphs against other grasshoppers in the same habitat for whole-body metal concentrations; and （iii）compare the suitability of Ni hyperaccumulator and Ni accumulator plants as food sources for Stenoscepa sp. and other grasshoppers. Stenoscepa nymphs had extremely high whole-body Ni concentrations （3 500μg Ni/g）. This was partly due to food in the gut, as starved insects contained less Ni （950 pg Ni/g）. Stenoscepa nymphs survived significantly better than other grasshoppers collected from either a serpentine or a non-serpentine site when offered high-Ni plants as food. In a host preference test among four Berkheya species （two Ni hyperaccumulators and two Ni accumulators）, Stenoscepa sp, preferred leaves of the Ni hyperaccumulator species. A preference experiment using leaves of three Senecio species （of which one species, Senecio coronatus, was represented by both a Ni hyperaccumulator and a Ni accumulator population） showed that Stenoscepa sp. preferred Ni accumulator Senecio coronatus leaves to all other choices. We conclude that Stenoscepa sp. is extremely Ni-tolerant. Stenoscepa sp. nymphs prefer leaves of hyperaccumulator Berkheya species, but elevated Ni concentration alone does not determine their food preference. We suggest that the extremely high whole-body Ni concentration of Stenoscepa nymphs may affect food web relationships in these serpentine communities.

Nickel levels in arthropods associated with Ni hyperaccumulator plants from an ultramafic site in New Caledonia

Arthropods （mainly insects） were collected from a forest site that contained at least six species of Ni hyperaccumulators. Whole body Ni analysis was performed for 12 arthropod taxa, two of which were studied at different life cycle stages. We found two Nitolerant insects. The pentatomid heteropteran Utana viridipuncta, feeding on fruits of the Ni hyperaccumulator Hybanthus austrocaledonicus, contained a mean of 2 600 μg Ni/g in nymphs and 750μg Ni/g in adults. The tephritid fly Bactrocera psidii, feeding on pulp of Sebertia acuminata fruits that contained 6 900μg Ni/g, contained 420μg Ni/g as larvae that had evacuated their guts and significantly less （65μg Ni/g） as adults. European honeybees （Apis mellifera） visiting flowers of the Ni hyperaccumulator H. austrocaledonicus contained significantly more Ni （8-fold more） than those collected from flowers of Myodocarpus fraxinifolius, a non-hyperaccumulator. Our results show that some insects feed on Ni hyperaccumulator plants and that their feeding mobilizes Ni into local food webs.

A review of chlorinated paraffin contamination in Arctic ecosystems

Chlorinated paraffins(CPs)present a complex mixture of congeners which are often analysed and assessed as short-,medium-and long-chain CPs,i.e.SSCCP(C10eC13),SMCCP(C14eC17)and SLCCP(
C18).Their complexity makes the chemical analysis challenging,in particular in terms of accurate quantification,but promising developments involving ultra-high resolution mass spectrometry have been presented lately.Most Arctic data exist for SCCPs,while LCCPs have not yet been studied in the Arctic.SSCCP concentrations in Arctic air often exceeded those of SMCCP,usually with a predominance of the most volatile C10 congeners,and of banned persistent organic pollutants(POPs),such as polychlorinated biphenyls(PCBs).The presence of SCCPs and MCCPs in Arctic air,as well as in the Antarctic and in the remote regions of the Tibetan plateau,provides evidence of their long-range transport including sufficient environmental persistence to reach the Arctic.Arctic vegetation accumulated SCCPs partly from air and partly through root uptake from soil,with consequences for the SCCP profile found in Arctic plants.No results have yet been reported for CPs in terrestrial Arctic animals.Results for freshwater sediment and fish confirmed the long-range transport of SCCPs and MCCPs and documented their bioaccumulation.Where additional PCB data were available,SPCB was usually higher than SSCCP in freshwater fish.Both SCCPs and MCCPs were widely present in marine Arctic biota(e.g.mussels,fish,seabirds,seals,whales,polar bears).In mussels and Atlantic cod,SMCCP concentrations exceeded those of SSCCP,while this was less clear for other marine species.Marine mammals and the long-lived Greenland shark roughly had SSCCP concentrations of 100e500 ng/g lipid weight,often dominated by C11 congeners.Biomagnification appeared to be more pronounced for SSCCP than for SMCCP,but more studies will be needed.Increasing SSCCP concentrations were observed in Arctic air and sediment over time,but not in beluga monitored since the 1980s.For both SCCPs and MCCPs,increasing concentrations over time have been shown in blue mussels and Atlantic cod at some,but not all stations.Indications exist of local sources of SCCPs in the Arctic,including Arctic settlements and research stations.In studies involving multiple locations,a general decrease of SCCP concentrations with increasing latitude or distance from point sources was observed as well as relatively more MCCPs at locations closer to potential CP sources.Monitoring of SCCPs and MCCPs has been initiated in some Arctic regions and will be important to assess the effect of recent regulations of SCCPs and the use of potential replacement chemicals.

Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint John River estuary

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury（MeHg） in biota from fresh to marine waters are poorly understood. Our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback（Apeltes quadracus）, invertebrates（snails,amphipods, and chironomids）, sediments, and water were collected from ten sites along the Saint John River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury（proxy for MeHg） was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur（δ34S）, carbon（δ13 C）, and nitrogen（δ15N） isotope values were measured to assess energy sources（S, C） and relative trophic level（N）. There were increases in biotic δ13C and δ34S from fresh to more saline sites and these measures were correlated with salinity.Though aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint John River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient.

Occurrence,profiles,and ecotoxicity of poly-and perfluoroalkyl substances and their alternatives in global apex predators:A critical review

Certain poly-and perfluoroalkyl substances(PFASs)exhibit significant bioaccumulation/biomagnification behaviors in ecosystems.PFASs,such as perfluorooctane sulfonate(PFOS),perfluorooctanoic acid(PFOA),perfluorohexanesulfonic acid(PFHxS)and related precursors,have elicited attention from both public and national regulatory agencies,which has resulted in worldwide restrictions on their production and use.Apex predators occupy the top trophic positions in ecosystems and are most affected by the biomagnification behavior of PFASs.Meanwhile,the long lifespans of apex predators also lead to the high body burden of PFASs.The high body burden of PFASs might be linked to adverse health effects and even pose a potential threat to their reproduction.As seen in previous reviews of PFASs,knowledge is lacking between the current stage of the PFAS body burden and related effects in apex predators.This review summarized PFAS occurrence in global apex predators,including information on the geographic distribution,levels,profiles,and tissue distribution,and discussed the trophic transfer and ecotoxicity of PFASs.In the case where legacy PFASs were restricted under international convention,the occurrence of novel PFASs,such as 6:2 chlorinated polyfluorinated ether sulfonate(6:2 Cl-PFESA)and perfluoroethylcyclohexane sulfonate(PFECHS),in apex predators arose as an emerging issue.Future studies should develop an effective analytical method and focus on the toxicity and trophic transfer behavior of novel PFASs.