Assessment of heavy metals in soil, leaf litter, and their bioaccumulation in terrestrial macroinvertebrates in Sohag Governorate, Egypt.

The presence of elevated levels of heavy metals in soil poses a significant environmental concern with implications for human health and other organisms. The main objective of our study was to reduce the gap information of seasonal abundance, distribution of heavy metals in soil, leaf litter, and some macroinvertebrates in a citrus orchard (Citrus sinensis) in Sohag Governorate, Egypt. The heavy metals copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) were determined by atomic absorption spectrometry. Degree of contamination (DC) was determined for both soil and leaf litter contamination. However, the bioaccumulation factor (BAF) was estimated to determine metal accumulation in the macroinvertebrates including earwigs Anisolabis maritima, chilopoda Scolopendra moristans, spider Dysdera crocata, and earthworm Aporrectodea caliginosa. The study area had clay-loam with varying organic matter, salinity, and pH levels. The degree of contamination varied among seasons, with the highest levels typically observed in autumn in both soil and leaf litter. The soil ranged from low contamination (1.82) to high contamination levels (4.4), while the leaf litter showed extremely high (30.03) to ultra-high (85.92) contamination levels. The mean ecological risk index results indicated that the sampling area had moderate ecological risk levels for Cd (44.3), Zn (42.17), and Pb (80.05), and extremely high levels for Cu (342.5). Heavy metal concentrations in the selected fauna were the highest in autumn, and the bioaccumulation factor varied among species and seasons with some species classified as e-concentrators, micro-concentrators, and macro-concentrators of certain heavy metals. Scolopendra moristans exhibited the highest mean metal concentrations (Cd, Pb, and Zn), while Aporrectodea caliginosa had the lowest. Thus, the differences in heavy metal concentrations found in different soil taxa highlight the significance of taxing a holistic understanding of feeding mechanisms into account when evaluating the potential risk for animals that consume invertebrates.

Abundance and risk assessment of microplastics in water, sediment, and aquatic insects of the Nile River.

Microplastics (MPs) are a serious threat in freshwater environments. The ecological risk and abundance level of MPs in abiotic and biotic compartments of the Nile River haven't been systematically reported. Thus, these issues were highlighted in the present study during different seasons of the sampling year. The results showed that MP concentrations in the river ranged from 2.24 ± 0.6 to 3.76 ± 1.1 particles/L, 298 ± 63 to 520 ± 80 particles/kg dry weight, and 0.081 ± 0.051 to 4.95 ± 2.6 particles/individual in surface water, sediment, and different species of aquatic insects, respectively. All the extracted MPs are colored blue, red, and black. Fiber-shaped polyesters (<500-1500 µm) were the most common MPs in all the river compartments. MPs' dominance was observed during the summer in comparison with that in the other seasons. Environmental risk indicators indicate the high ecological risk of MPs, which are widely distributed in the Nile River. In conclusion, MP consumption by aquatic insects may not only be related to levels of environmental contamination, since other variables, such as taxon size, weight, and particular feeding behavior, may also be significant. Additionally, the presence of MPs in insects (at lower trophic levels) creates the potential for predation-based inter-trophic level transmission. Thus, higher trophic-level investigations of various feeding groups should be carried out to identify any possible harm that MPs cause to various aquatic organisms.