Non-polluted Sites Research Articles

Environmental and population influences on mummichog (Fundulus heteroclitus) gut microbiomes.

The mummichog fish, a common resident of North America's east coast estuaries, has evolved the ability to survive in waters contaminated with toxic chemicals that would typically be deadly. Our study investigates how living in and adapting to these toxic environments may affect their gut microbiomes. We compared mummichogs from a polluted area in Massachusetts with those from a non-polluted site and found significant differences in their gut microbes. Interestingly, when we raised the next generation of these fish in a lab, these differences disappeared, suggesting that the environment plays a more crucial role in shaping the gut microbiome than genetics. Understanding these changes helps shed light on how animals and their associated microbiomes adapt to pollution, which can inform conservation efforts and our broader understanding of environmental impacts on host-microbe dynamics.

Comparative analysis of biodiversity, physiology, and anatomical adaptations in riparian flora exposed to industrial pollution stress

Anthropogenic activities such as industrial pollution of water bodies possess threat to floras leading to extinction and endangerment. This study investigates the impact of industrial pollution on vegetation along River Chenab and its associated drains. Rivers and channels transporting industrial effluents have been determined to be significantly contaminated. The contamination was evidenced by the acidic and alkaline nature of industrial effluents, salinity, total dissolved solids, and the sodium absorption ratio. The research revealed that the pollution in the region severely impacts the native vegetation, resulting in a marked decline in density, frequency, relative density, and relative frequency across 10 sites, including three drain sites and one non-polluted site. Four plant species, Calotropis procera, Eclipta alba, Phyla nodiflora, and Ranunculus sceleratus exhibited tolerance to pollution and were present at all sites during all seasons. Anatomical modifications, such as increased root aerenchyma and vascular bundles, enabled these plants to thrive in polluted environments. The study highlights the importance of these species in phytoremediation and their potential for use in restoring degraded ecosystems.

Prediction of soil organic carbon and total nitrogen affected by mine using Vis–NIR spectroscopy coupled with machine learning algorithms in calcareous soils

The utilization of visible-near infrared (Vis–NIR) spectroscopy presents a nondestructive, fast, reliable and cost-effective approach to predicting total nitrogen (TN) and organic carbon (OC) levels. This study employed a combination of Vis–NIR spectroscopy, partial least-squares regression (PLSR), and support vector machine (SVM) models to investigate the effects of mining on TN and OC stocks in both the topsoil (0–10 cm) and subsoil (10–40 cm). 105 soil samples were collected from agricultural areas near an iron mine, polluted, moderately-polluted, and non-polluted sites. Results indicated that soils at the non-polluted site had the highest of soil OC stocks (7.5 kg m–2) and total nitrogen (2.5 kg m–2), followed by the moderately-polluted site. Furthermore, it was observed that soils from the polluted site displayed the highest spectral reflectance. The spectral bands in the range of 500–700 nm showed the strongest correlation with soil organic carbon content. Notably, the SVM method utilizing Vis–NIR spectroscopy provided superior predictions for both subsoil and topsoil organic carbon and total nitrogen compared to the PLSR methods. Additionally, SVM demonstrated better performance in predicting topsoil soil organic carbon (R2 = 0.87, RMSE = 0.13%, and RPD = 2.8) and total nitrogen (R2 = 0.91, RMSE = 0.13%, and RPD = 2.4) compared to the subsoil, owing to the larger OM content in the topsoils.

Differential DNA methylation and metabolite profiling of Atlantic killifish (Fundulus heteroclitus) from the New Bedford Harbor Superfund site

Atlantic killifish (Fundulus heteroclitus) is a valuable model in evolutionary toxicology to study how the interactions between genetic and environmental factors serve the adaptive ability of organisms to resist chemical pollution. Killifish populations inhabiting environmental toxicant-contaminated New Bedford Harbor (NBH) show phenotypes tolerant to polychlorinated biphenyls (PCBs) and differences at the transcriptional and genomic levels. However, limited research has explored epigenetic alterations and metabolic effects in NBH killifish. To identify the involvement of epigenetic and metabolic regulation in the adaptive response of killifish, we investigated tissue- and sex-specific differences in global DNA methylation and metabolomic profiles of NBH killifish populations, compared to sensitive populations from a non-polluted site, Scorton Creek (SC). The results revealed that liver-specific global DNA hypomethylation and differential metabolites were evident in fish from NBH compared with those from SC. The sex-specific differences were not greater than the tissue-specific differences. We demonstrated liver-specific enriched metabolic pathways (e.g., amino acid metabolic pathways converged into the urea cycle and glutathione metabolism), suggesting possible crosstalk between differential metabolites and DNA hypomethylation in the livers of NBH killifish. Additional investigation of methylated gene regions is necessary to understand the functional role of DNA hypomethylation in the regulation of enzyme-encoding genes associated with metabolic processes and physiological changes in NBH populations.

Micro-morphological adaptations and tolerance assessment of selected vascular plant species exposed to vehicular exhausts

The vehicular exhausts on roadsides negatively affect living organisms and disturb their environment. These negative impacts of vehicular exhausts on plants demand a scientific investigation of roadside plants in Abbottabad, Pakistan. So, this observational and experimental study was conducted to evaluate the effect of vehicular exhausts on morphology, epidermal structure and biochemical characteristics of leaves of plants near roadsides and compared with the non-polluted site. The quantitative morphological parameters: leaf area, length of petiole and vein-to-vein difference along with anatomical attributes such as stomata and epidermal cells were recorded. Compared to non-polluted areas, the chlorophyll content of plant leaves from polluted areas was higher. The results indicate that vehicular exhaust negatively affects leaf morphology and increases the Stomatal number at adaxial (front surface) of leaves. The air pollution tolerance index evaluated Melia azedarach and Salix angustifolia as tolerant tree species and Rumex dentatus, Amaranthus viridis and Sonchus hydrophilus as tolerant herbaceous species. In order to survive in polluted environments, this study demonstrated that plants go through adaptive processes.

Seasonal variation of biochemical parameters and air pollution tolerance index (APTI) of selected plant species in Delhi city, and detailed meta-analysis from Indian metropolitan cities

Plants act as the primary barrier to atmospheric pollution. Thus, while considering the role of plants in restricting air pollutants, one of the environmental tools used to assess tolerant plant species is the Air Pollution Tolerance Index (APTI). We conducted a study in Delhi during the pre-and post-monsoon seasons at polluted (Nehru Nagar) and non-polluted (Pusa Road) sites to assess the site-specific and seasonal variation of biochemical parameters (ascorbic, pH, relative water content, and chlorophyll) and APTI. Two-way ANOVA, Pearson's test, and Principal Component Analysis (PCA) were performed for the statistical analysis. Also, a detailed meta-analysis of biochemical parameter and their influence on APTI based on published literature in metropolitan cities of India has been performed. The study conducted in Delhi at a non-polluted site found higher APTI in the pre-monsoon than post-monsoon season. In addition, the maximum ascorbic acid content of 2.47 mg/g (Azadirachta indica A.Juss) and 1.37 mg/g (Ficus benjamina L) was reported at polluted and non-polluted sites, respectively, during pre-monsoon. The detailed meta-analysis of published literature revealed that plants' chlorophyll and ascorbic acid content were more at polluted sites than at non-polluted sites and substantially impacted APTI calculation. Linear regression showed a significant correlation of ascorbic acid (Mangifera indica L, R2 = 0.9670) and chlorophyll content (Polyalthia longifolia (Sonn.), R2 = 0.958) with APTI. Also, in the PCA test, measured characteristics of different species were strongly correlated, with 72.55% of overall variability. Furthermore, the meta-analysis revealed the average APTI of the plants in the following order Ficus benghalensis L > Polyalthia longifolia > M.indica > A. indica > Delonix regia (Boj. ex Hook) > Ficus religiosa L. A substantial seasonal, site-specific variation and statistically significant differences in the biochemical parameters of plants were observed. These results could be used to classify plant species as air pollution sinks and bioindicators.

Assessment of halophyte plant phenotypic responses under heavy metals pollution. Implications for monitoring and phytoremediation

While phytoremediation is a highly valued practice to address local pollution problems, the use of early biomarkers of stress is useful for monitoring environments since they allow us to take measures before deleterious effects are irreversible. In this framework the goals are: to evaluate the pattern of leaf shape variation of Limonium brasiliense plants related to a metal soil gradient in the San Antonio salt marsh; to assess whether seeds from sites with different pollution levels show the same pattern of leaf shape variations under optimal growing conditions; and to compare the growth, the Pb accumulation pattern, and the leaf shape variation pattern of plants germinated from seeds originated in sites with different pollution levels in response to an experimental Pb rise. The results obtained from leaves collected in the field showed that the leaf shape changed depending on the soil metal levels. Plants germinated from seeds collected at the different sites expressed all the variation in leaf shape independently of the origin site, and the mean shape of each site was close to the consensus. Instead, when looking for the leaf shape components that maximize the differences between the sites from a growth experiment exposed to an increase in Pb in the irrigation solution, the pattern of variation found in the field disappeared. That is, only plants from the polluted site did not show variations in leaf shape in response to Pb additions. Finally, Pb accumulation in the roots was highest in plants germinated from seeds from the site where the soil pollution is greater. That suggests that seeds of L. brasiliense from polluted sites are better to use in phytoremediation practices, specifically to stabilize Pb in its roots whilst plants from the non-polluted site are better to detect pollutant soils using the leaf shape as an early biomarker.

Toxicological impact of water pollutants on DNA and tissues of inhabitant fish Labeo dyocheilus of River Kabul, Khyber Pakhtunkhwa, Pakistan

This investigation evaluated pollution in River Kabul and impact on DNA and histology of intestine, gills, liver, and muscle of Labeo-dyocheilus. Water and fish samples were collected from non-polluted site of Warsak Dam and polluted sites of Amanghar industrial zone and Nowshera city. Sequence of physicochemical parameters in water samples A, B and C was TDS >TSS >EC >TA >Cl >Na >K >pH and heavy metals was Zn >Pb >Cd >Ni >Fe >Mn >Cu >Cr. The parameters in samples A, B and C except TSS were below NEQS proposed limits. The investigation determined geno-toxicological impact of water pollutants in different tissues. DNA damage cells like TCS and comet classes (0, 1, 2, 3, 4) were determined in intestine, gills, liver, and muscle. Sequence of comet classes in tissues was class 0> class 4> class 3> class 2> class 1. Trend of DNA damage in tissues was intestine >liver >gills >muscle. The study investigated histopathological impacts of water pollutants in intestine, liver, gills, and muscle. Trend of lesions in tissues was liver >intestine >gills >muscle. The study confirmed high levels of pollutants like heavy metals and physicochemical parameters in River Kabul, and geno-toxicological and histopathological disorders of water pollutants in Labeo-dyocheilus.

Bacteriophages diversity in India's major river Ganga: a repository to regulate pathogenic bacteria in the aquatic environment.

Bacteriophages are key viruses that can kill thousands of harmful microbes generally present at polluted sites. Such bacteriophages are abundantly present in the river Ganga, where millions of people in India and abroad drink its water and take baths every day for spiritual reasons. Besides bacteriophages, several pathogenic and zoonotic microbes are present in the river Ganga. It is interesting to study the diversity and abundance of bacteria and their respective phages present in polluted or non-polluted sites. Thus, the metagenomics study was carried out at the most polluted sites of river Ganga near Kanpur and non-polluted sites at Farakka, which harbors several harmful bacteria and their phages. The results revealed a significantly higher percentage of Microviridae phage family, ssDNA viruses, and Mimiviridae virus family near Kanpur than Farakka. In addition, compared to Kanpur, Farakka has a more significant percentage of Myoviridae, an unidentified phage family, and Retroviridae viral families. Despite heavy drainage of untreated and contaminated effluents from the leather industry, pesticide industry, paper mills, metropolitan cities, and other sources, the vast number of said phages kills several harmful pathogenic microbes in polluted sites to maintain the Ganga water's healing power or natural sterility. In a polluted aquatic environment, the varieties of bacteriophages were identified in the Ganga and their interaction with the microbial host. The taxonomic diversity of several bacteriophages found in pathogenic host systems was investigated to get exceptional knowledge of these small viruses in the aquatic environment.

Anthropogenic pollution gradient along a mountain river affects bacterial community composition and genera with potential pathogenic species

Mountain regions in Poland are among the most frequently visited tourist destinations, causing a significant anthropogenic pressure put on the local rivers. In this study, based on numbers of 9 microorganisms, content of 17 antibiotics and 17 physicochemical parameters, we determined a pollution gradient in six sites along Białka, a typical mountain river in southern Poland. The E.coli/Staphylococcus ratio varied evidently between polluted and non-polluted sites, indicating that the possible utility of this parameter in assessing the anthropogenic impact on river ecosystems is worth further investigation. Then, using next generation sequencing, we assessed the changes in bacterial community structure and diversity as a response to the pollution gradient. Proteobacteria and Bacteroidetes were the most abundant phyla in the majority of samples. Actinobacteria were the most abundant in the most pristine (groundwater) sample, while Firmicutes and Verrucomicrobia were more prevalent in polluted sites. Bacterial diversity at various levels increased with water pollution. Eleven bacterial genera potentially containing pathogenic species were detected in the examined samples, among which Acinetobacter, Rhodococcus, and Mycobacterium were the most frequent. At the species level, Acinetobacter johnsonii was most prevalent potential pathogen, detected in all surface water samples, including the pristine ones. Two bacterial taxa—genus Flectobacillus and order Clostridiales showed very distinct variation in the relative abundance between the polluted and non-polluted sites, indicating their possible potential as biomarkers of anthropogenic impact on mountain river waters.

The effects of environmental stressors on gonad biomarkers of a sentinel marine bivalve, Mytilus galloprovincialis

ABSTRACT The aim of this work is to investigate the effects of environmental stressors on male reproductive biomarkers in sentinel species of bivalves inhabiting Annaba estuaries, considered to be reservoirs receiving industrial, agricultural, and domestic discharges. Male Mytilus galloprovincialis were collected in four seasons from a non-polluted site (S1) and two other locations receiving untreated sewage (S2) and a mixture of contaminants (S3). Testicular sperm concentration, motility, velocity, the amplitude of lateral head displacement (ALH), the beat cross frequency (BCF), spermatozoan DNA fragmentation, and histological profiles were evaluated. Individuals from S2 and S3 have diminished sperm concentration, motility, velocity, ALH and BCF, along with a significantly increased spermatozoan DNA fragmentation that was much higher in S3. Testicular tissues demonstrated histo-pathological alterations in mussels subjected to anthropogenic activities during the four seasons. In conclusion, reproductive biomarkers of male mussels were both spatially and temporally variable, which is probably correlated to pollution types and the changing seasonal stressors.

Seasonal and spatial variations in microplastics abundances in St. Andrew Bay, Florida

Wastewater treatment plants (WWTPs) cause approximately 25 % of microplastics (MPs) in the marine environment. While research on MPs in WWTP effluent has demonstrated that an abundance of particles enter the marine environment, little effort has gone to assessing MP abundances in coastal sediments to determine their seasonal and spatial variability. Here, we assessed MP abundances in sediments at sites of WWTP outflow and at non-polluted sites over six consecutive seasons within the St. Andrew Bay system in Northwestern Florida. We showed that MP abundances were highest at one of the WWTP sites, where they increased with increasing distance away from the input source (3.16 ± 1.59 MP/kg to 34.03 ± 11.69 MP/kg sediment dry weight). We also found that mean MP abundances were highest in the winter (12.41 ± 3.56 MPs/kg sediment dry weight) and lowest in the spring (2.17 ± 0.63 MPs/kg sediment dry weight). Therefore, while WWTPs differentially retain MPs in their removal processes, MP pollution in the St. Andrew Bay system shows seasonal dynamics like other studies. Although average MP abundance in surface sediments (0–5 cm) was higher than in subsurface sediments (5–10 cm) at all sites, this difference was not as substantial as has been found in other studies. Based on mean MP abundance in surface sediments, we estimate that there are 30 billion MPs within the surface layer of sediment in the St. Andrew Bay system, and that the particles export to the Gulf of Mexico because of seasonal flushing between the winter and spring. The distributions of MPs in the system were also likely driven by extreme weather events that occurred in the bay system during 2018 and 2020, which acts as a cautionary tale for coastal urban ecosystems in the face of sea level rise and climate change.

Condition Factor, Hepato-somatic Index and Gonado-somatic Index of Fish, Channa punctatus Collected from Sawan Nallaha, Balrampur, U.P.

Biomarkers are measurements within an organism that respond to environmental changes andare used as bio-monitoring tools that reflect physiological changes induced by exposure topollutants. The condition factor (K), hepatosomatic index (HSI) and gonado-somatic index(GSI)of fish, Channa punctatus was used to assess the effects of industrial pollutant stress. Forthis study, Channa punctatus was collected from Sawan Nallaha, a small lotic waterbody inall the seasons (Summer, monsoon and Winter). Fish collected from the non-polluted site hadthe higher condition factor (K) HSI and GSI as compared to fish collected from polluted sitethat received the industrial effluent and domestic sewage. K, HSI and GSI are simple and costeffectivebio-monitoring tool and can be used in pollution monitoring.

Marginal lands and fungi - linking the type of soil contamination with fungal community composition.

SummaryFungi can be found in almost all ecosystems. Some of them can even survive in harsh, anthropogenically transformed environments, such as post‐industrial soils. In order to verify how the soil fungal diversity may be changed by pollution, two soil samples from each of the 28 post‐industrial sites were collected. Each soil sample was characterized in terms of concentration of heavy metals and petroleum derivatives. To identify soil fungal communities, fungal internal transcribed spacer 2 (ITS2) amplicon was sequenced for each sample using Illumina MiSeq platform. There were significant differences in the community structure and taxonomic diversity among the analysed samples. The highest taxon richness and evenness were observed in the non‐polluted sites, and lower numbers of taxa were identified in multi‐polluted soils. The presence of monocyclic aromatic hydrocarbons, gasoline and mineral oil was determined as the factors driving the differences in the mycobiome. Furthermore, in the culture‐based selection experiment, two main groups of fungi growing on polluted media were identified – generalists able to live in the presence of pollution, and specialists adapted to the usage of BTEX as a sole source of energy. Our selection experiment proved that it is long‐term soil contamination that shapes the community, rather than temporary addition of pollutant.

Hemp Cultivation in Soils Polluted by Cd, Pb and Zn in the Mediterranean Area: Sites Characterization and Phytoremediation in Real Scale Settlement

Polluting activities affect, directly or indirectly, large areas of agricultural lands. Metal polluted soils could be managed by phytoremediation using hemp (Cannabis sativa L.). To know the phytoremediation capability of industrial hemp in metal polluted soils under semiarid environments, an experimental project with the support of local farmers was conducted in Sardinia (Italy). This work was carried out in three main steps: (i) identification and selection of the study sites, (ii) field trials, at local farms, both on contaminated and non-polluted sites, (iii) evaluation of heavy metals contents accumulated in the different parts of the plants. Five study sites were chosen. Three of them were severely polluted by heavy metals. Concentrations of Zn and Cd in plants generally were positively correlated with soil content and were different in each part of the plant. The higher values of Zn and Cd were detected in leaves of plants grown in polluted sites (Zn > 950 mg kg−1 and Cd > 6.8 mg kg−1). High values of Pb were also detected in plants grown in non-contaminated soils: this contamination may be due to atmospheric deposition related to polluting sources far to the cultivation.

Ecogenotoxicological studies for an early toxicity screening and monitoring in Epinephalus chlorostigma and Scamberomorus commerson

The study was planned to investigate DNA fragmentation in fish to screen aquatic toxicity and in Epinephalus chlorostigma and Scamberomorus commerson collected from Red sea near Jizan, Saudi Arabia from three locations “(Corniche North park: “16.92161, 42.54631; Jizan Port: 16.874, 42.54952” N and Jizan Economic City: 17.26589, 42.34738“ ”)“ were used as a case study for the application of comet assay. The study area of the Red Sea is polluted due to anthropogenic activities and the disposal of wastes from multiple sources. Comet and micronucleus assays were used to detect genotoxicity in these fish species harvested from three sites. The concentration of Pb, Cr, Zn, Mn, Cu, Cd, Sn, and Hg was higher in the water samples collected from the polluted site compared to the non-polluted site of the Red sea. Comet assay for S. commerson showed significant (p < 0.05) genetic damage about 44.33 ± 3.03% DNA in comet tail at site S1. It was subsequently reduced to 31.71 ± 3.52% and 22.11 ± 2.52% at sites S2 and S3. E. chlorostigma also showed significant DNA in comet tail as 17.34 ± 2.19%, 11.87 ± 3.01%, and 36.41 ± 3.98% at site S1-S3, respectively. Significant (p < 0.05) DNA damage was observed in the fishes procured from non-polluted locations and upstream locations. The micronucleus induction in E. chlorostigma was recorded as 23.20 ± 4.19 and 2.20 ± 0.58%, respectively, non-polluted and polluted sites. S. commerson exhibited significant differences between polluted and non-polluted sites (44.80 ± 3.73 and 8.20 ± 2.20‰) polluted and upstream (44.80 ± 3.73 and 20.60 ± 4.02‰), respectively. A significant difference was obtained between E. chlorostigma and S. commerson for nuclear abnormalities S. commerson showed higher frequencies for nuclear deformities than E. chlorostigma. S. commerson showed substantial micronucleus induction frequencies collected from an area of low pollution intensity (upstream). This study showed that E. clorostigma and S. commerson could be successfully used as a bioindicator to determine the health of the Red Sea through the most specific assays such as comet and micronucleus tests as an early warning and to devise the monitoring strategies to ensure a safe supply of fish for human consumption.

Effect of metal pollution from mining on litter decomposition in streams

Litter decomposition is critical to stream biogeochemical cycles. Metal pollution from past or present mining activities seriously threatens stream ecosystems. However, its effects on litter decomposition in streams remain unclear. A field litterbag experiment was conducted to determine the direct (i.e., via changes in stream water quality: a mine-affected vs. forest stream) and indirect (i.e., via changes in litter traits: polluted vs. non-polluted litter) effects of metal pollution from mining activities on leaf litter decomposition (total vs. microbial-driven) and the associated microbial activity and community composition in streams. Platanus acerifolia leaf litter collected from a polluted and a non-polluted site was enclosed in fine and coarse mesh bags and incubated in a mine-affected stream and a forest stream. The litter from the polluted site had a higher Pb, Zn, Cd, N, soluble sugar concentrations, specific leaf area and pH, and lower leaf toughness and lignin concentration than the litter from the non-polluted site. After incubation in situ, litter mass loss did not significantly differ between streams, but the mine-affected stream had a greater impact on total-driven decomposition rates than microbial-driven decomposition rates. Polluted litter had a significantly higher decomposition rate than non-polluted litter. The decomposition potential of polluted litter produces faster nutrient cycling and supports higher microbial colonization. Litter traits and decomposer community type modulate the influence of metal pollution on litter decomposition. The results suggest that the indirect effects of mining activities on litter decomposition were stronger than the direct effects.

Phenotypic responses to oil pollution in a poeciliid fish

Pollution damages ecosystems around the globe and some forms of pollution, like oil pollution, can be either man-made or derived from natural sources. Despite the pervasiveness of oil pollution, certain organisms are able to colonise polluted or toxic environments, yet we only have a limited understanding of how they are affected by it. Here, we analysed phenotypic responses to oil pollution in guppies (Poecilia reticulata) living in oil-polluted habitats across southern Trinidad. We analysed body-shape and life-history traits for 352 individuals from 11 independent populations, six living in oil-polluted environments (including the naturally oil-polluted Pitch Lake), and five stemming from non-polluted habitats. Based on theory of, and previous studies on, responses to environmental stressors, we predicted guppies from oil-polluted waters to have larger heads and shallower bodies, to be smaller, to invest more into reproduction, and to produce more but smaller offspring compared to guppies from non-polluted habitats. Contrary to most of our predictions, we uncovered strong population-specific variation regardless of the presence of oil pollution. Moreover, guppies from oil-polluted habitats were characterised by increased body size; rounder, deeper bodies with increased head size; and increased offspring size, when compared to their counterparts from non-polluted sites. This suggests that guppies in oil-polluted environments are not only subject to the direct negative effects of oil pollution, but might gain some (indirect) benefits from other concomitant environmental factors, such as reduced predation and reduced parasite load. Our results extend our knowledge of organismal responses to oil pollution and highlight the importance of anthropogenic pollution as a source of environmental variation. They also emphasise the understudied ecological heterogeneity of extreme environments.

Heavy metals uptake by the global economic crop (Pisum sativum L.) grown in contaminated soils and its associated health risks.

The aim of the present investigation was to determine the concentration of heavy metals in the different organs of Pisum sativum L. (garden pea) grown in contaminated soils in comparison to nonpolluted soils in the South Cairo and Giza provinces, Egypt, and their effect on consumers’ health. To collect soil and plant samples from two nonpolluted and two polluted farms, five quadrats, each of 1 m2, were collected per each farm and used for growth measurement and chemical analysis. The daily intake of metals (DIM) and its associated health risks (health risk index (HRI) were also assessed. The investigated heavy metals were cadmium (Cd), arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), manganese (Mn), zinc (Zn), silver (Ag), cobalt (Co) and vanadium (V). Significant differences in soil heavy metals, except As, between nonpolluted and polluted sites were recorded. Fresh and dry phytomass, photosynthetic pigments, fruit production, and organic and inorganic nutrients were reduced in the polluted sites, where there was a high concentration of heavy metals in the fruit. The bioaccumulation factor for all studied heavy metals exceeded 1 in the polluted sites and only Pb, Cu and Mn exceeded 1 in the nonpolluted sites. Except for Fe, the DIM of the studied heavy metals in both sites did not exceed 1 in either children or adults. However, the HRI of Pb, Cd, Fe, and Mn in the polluted plants and Pb in the nonpolluted ones exceeded 1, indicating significant potential health risks to consumers. The authors recommend not to eat garden peas grown in the polluted sites, and farmers should carefully grow heavy metals non-accumulating food crops or non-edible plants for other purposes such as animal forages.

Anthropogenic nitrogen pollution in mangrove ecosystems along Dar es Salaam and Bagamoyo coasts in Tanzania

Mangroves are among the most productive coastal ecosystems; however, they are prone to anthropogenic pollution due to their land-sea interface position. We used stable nitrogen isotopes and spectrophotometric nitrate analysis to study the anthropogenic pollution in five mangrove ecosystems in Tanzania, including two polluted (Mzinga and Kizinga), one moderate (Kunduchi) and non-polluted (Mbegani and Ras Dege) sites. Also, we tested the suitability of mangrove leaves, roots, sediment, and gastropod as indicators of anthropogenic nitrogen pollution using stable δ15N isotope analysis. Results revealed higher than 10‰ δ15N values in all analysed components and the highest nitrate concentrations of 16.44 mg L−1 in the interstitial waters at the polluted sites, indicating anthropogenic nitrogen inputs. The δ15N enrichment increased in the order: non-polluted < moderate < polluted. The polluted sites are fed by freshwater creeks and probably receive high loads of domestic sewage from the surrounding communities, industries, and agricultural effluents. Therefore, to protect mangrove ecosystems, proper waste and wastewater management upstream are recommended.