Watershed Ecology and the Environment最新文献

Aquatic habitats serve as pollutant reservoirs and experience massive pollution disasters due to anthropogenic pressure. The effect of the Water-Soluble Fraction (WSF) of burnt tire ash (BTA) was investigated on Clarias gariepinus juvenile using blood biomarkers as well as liver and gill histology. The model fish were exposed to 5 % (0.56 g/L), 10 % (1.12 g/L) and 20 % (2.24 g/L) of 96-hr LC₅₀ (11.2 g/L) value of BTA sub-chronic doses during the experiment. Hematological indices, the liver, and gill histology were studied throughout the 28-day exposure study, which was followed by a 14-day post-exposure trial. The studies revealed that BTA-exposed fish had reduced red blood cells, packed cell volume, and hemoglobin levels with time, whereas white blood cells and leukocyte numbers increased. Concentration-dependent histopathologic abnormalities such as hyperplasia, telangiectasis, hemorrhage, desquamation, lamellar edema, and vacuolation were observed in the gill of the affected fish, in contrast to the control. Likewise, the presence of histopathologic abnormalities in the liver of BTA-exposed fish, such as vacuolar degeneration, hyperplasia, dilated portal vein, pyknotic nucleus formations, hypertrophy hepatocytes, and aggregated macrophages, was concentration-dependent. Following apparent histologic deformities that persisted in the tissues after recovery, healing from BTA exposure was only partial. C. gariepinus is an essential bioindicator of burnt tire ash’s ecotoxicological impact. Point and non-point traces of burnt-tire ash to the aquatic systems may harm aquatic animal species, thus necessitating preventative actions.

Potentially toxic elements (PTEs) are naturally available in the environment; however, anthropogenic activities encourage their high concentration, posing environmental and human health risks. The ecotoxicological status, source apportionment and health risk assessment of PTEs (Iron (Fe), Nickel (Ni), Cadmium (Cd), Selenium (Se), Zinc (Zn), Lead (Pb), Chromium (Cr) and Copper (Cu)) in creeks (Fibiri and Iwoama) along Bonny River were examined through laboratory analysis (American Public Health Association standard), indicators and statistical techniques. The PTEs concentration of surface water and sediment for both creeks exceeded the WHO allowable limit, and the surface water trended as Cr > Pb > Fe > Ni > Cd > Zn > Cu > Se for Fibiri creeks, Fe > Cr > Pb > Ni > Cd > Zn > Cu > Se for Iwoama creek while the sediment trended as Fe > Pb > Ni > Cr > Zn > Cd > Cu > Se for both creeks. The contamination factor (CF) of the creek’s sediment showed low CF (Zn and Cu), moderate CF (Ni, Pb and Cr) and very high CF (Fe and Cd), while risk index status ranged from low risk (Ni, Zn, Pb, Cr and Cu), moderate risk (Fe) and significantly high risk (Cd). The human health risk revealed that children could be exposed to potential non-carcinogenic effect (HI > 1) with Zn (1.64 and 2.03), and the Total Carcinogenic Risk (TCR) for children indicated high carcinogenic risk (TCR > 1 × 10⁻⁴) for Ni, Pb, Cr and Cd of the creeks’ environmental mediums. The similarity in the trend and status of the creeks suggested that both environments are exposed to similar anthropogenic activities impact.

In highly modified and managed systems the balance of freshwater inputs discharged to estuarine systems are important to maintain salinity balances and thus estuarine function. However, the availability of freshwater is highly dependent on upstream water management to provide flood protection whilst meeting freshwater demand for people and the environment. In South Florida, water is managed by a water control plan with Lake Okeechobee at the center. Currently, water levels within the lake are managed based on the Lake Okeechobee Regulation Schedule of 2008. The new regulation schedule, Lake Okeechobee System Operating Manual (LOSOM), updates water management rules while attempting to balance the needs of downstream systems; salinity and water quality in the Caloosahatchee and Saint Lucie (northern) estuaries; and more water for the southern Everglades. This study evaluates LOSOM relative to ecologically significant performance measures for the northern estuaries. Overall, the proposed regulation schedule is expected to provide a more sustainable flow regime to the estuaries by reducing stressful and damaging discharge events. Moreover, new management rules combined with new infrastructure are expected to reduce low discharge events to the Caloosahatchee estuary and reduce stress on key indicator species such as Vallisneria americana during the wet season. This regulation schedule provides improved conditions for the estuaries at the expense of higher Lake Okeechobee stages. Future restoration and water management will maintain the benefits afforded to the estuaries while at the same time reducing the impacts to Lake Okeechobee resulting in a more sustainable and resilient system.

The impact of an earthquake on river water quality is massive, and the quality of life and environment typically changes as a result of a quick drop in the environment system. A 6.0 magnitude earthquake struck the Ranau area of Sabah, Malaysia, in 2015, affecting the Liwagu River’s water quality. Satellite data on earthquakes, coupled with local water quality data collecting, allows for an accurate assessment of water quality parameters. As a result, the Sabah Water Department provided secondary water quality data from Bambangan and Kimolohing on the Liwagu River. Following that, turbidity, color, pH, electric conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), nitrate (NO₃⁻), iron (Fe), manganese (Mn), aluminum (Al), alkalinity, hardness, chloride (Cl-), and sulfate (SO₄²⁻) were chosen. The investigation discovered unusually high turbidity and color in the water on June 17, 2015, as well as elevated levels of Al, Fe, and Mn. DO concentrations plummeted to 3.8 mg/L on the same day. Statistical analyses, employing the Kruskal-Wallis test, identified significant parameters—Fe (0.001) and Mn (0.001) at both stations, turbidity (0.001), and color (0.003) in Kimolohing, and Al (0.027) in Bambangan. Recovery in water quality took two weeks to two months, with iron and manganese requiring over six months for restoration. The earthquake didn’t solely dominate the impact but altered pollution sources to the river. The discussion highlights the synthesis of spatial and temporal dynamics enabled by the integration of ground and satellite data. This approach not only refines retrospective analyses but also propels us into predictive modeling, enhancing preparedness for future seismic events. The study’s holistic environmental impact assessment extends beyond water quality, unraveling cascading effects on ecosystems, soil, and vegetation. Informed decision-making for sustainable resource utilization emerges as a pivotal outcome, emphasizing the interconnectedness of seismic activity, rainfall patterns, and water quality. The study serves as a blueprint for future environmental assessments, emphasizing multifaceted approaches to understand and mitigate the complex impacts of seismic events on water resources.

The expansion of saline-alkali paddy fields, coupled with the application of large amounts of nitrogen (N) fertilizers, has given rise to a host of environmental concerns. While N and carbon (C) are vital indicators for assessing soil fertility, their dynamic characteristics in saline-alkali paddy soil remain obscure. To address this knowledge gap, we established paddy mesocosms with five distinct N-fertilizer treatments: control without N-fertilizer (CK), urea (U), urea with inhibitors (UI), organic–inorganic compound fertilizer (OCF) and C-based slow-release fertilizer (CSF). The objective was to monitor the dynamic changes of various N and soil organic-C (SOC) during a 137-day rice growing season, and to clarify the microbiological characteristics. By the end of the rice growing season, soil ammonia-N (NH₄⁺-N) concentrations were UI > OCF > CSF > U > CK, and UI had a significant difference (p < 0.05) with all the other four treatments. Soil nitrate-N (NO₃⁻-N) concentrations in OCF and CSF treatments were 5.64 ± 1.25 mg kg⁻¹ and 6.81 ± 0.29 mg kg⁻¹, respectively, significantly (p < 0.05) higher than U and UI treatments. NH₄⁺-N showed a negative correlation with NO₃⁻-N regardless of the N-fertilizer types, and a significant (p < 0.01) positive relationship with alkali-hydrolyzable N (AHN). A significant (p < 0.01) positive relationship existed between total-N (TN) and Bacteria 16S rRNA gene. The SOC had a significant (p < 0.05) positive relationship with mcrA gene. During the entire rice growing season, CSF treatment had lower mean TN and SOC concentrations than all the other treatments, and exhibited the highest TN and total organic-C (TOC) content in rice. In summary, the UI can increase the residual NH₄⁺-N in saline-alkali paddy fields, and the CSF is a better choice for growing rice.