Environmental Monitoring and Assessment最新文献

This research assesses the spatial distribution of aboveground biomass (AGB) and aboveground carbon (AGC) in evergreen forests across six socio-economic regions of Vietnam. The classification outcomes of evergreen forests utilizing the Support Vector Machine (SVM) model achieved an overall accuracy (OA) of 86.59% and CI (F1_forest) of 0.845–0.955, suggesting that evergreen forests represent over 44% of the total forest area in Vietnam. The amalgamation of diverse data sources, encompassing optical indices, radar, and topographical information, considerably enhanced the precision of AGB estimations, with the Genetic Algorithm-Adaptive Neuro Fuzzy Inference System (GA-ANFIS) model reaching an R² value exceeding 0.82. The findings indicate a cumulative AGB figure of 1,377,020.22 tons/ha, which is 2.2 times higher than the total AGC figure of 605,026.24 tons/ha. Regions characterized by lower AGB and AGC values are primarily concentrated in the Northern Midland and Mountain areas (NMR). Conversely, areas with elevated AGB and AGC values are predominantly located in the North Central and Central Coast (NCR), Central Highlands (CHR), and specific provinces within the Southeast region (SER). While the GA-ANFIS model exhibited commendable performance, a gap persists between forecasted and actual figures, with an overall discrepancy of 16,749.81 ha for AGB and 8156.6 tons/ha for AGC, likely attributable to challenges in field data acquisition, particularly in pristine and mature forest ecosystems. This study serves as an instrumental resource for extensive forest resource management and advocates for targeted restoration actions in zones exhibiting diminished AGB and AGC levels.

Water resource management of areas with shallow groundwater tables often aims at improving soil water retention and storage and at reducing greenhouse gas emissions. However, methods to quantify the effect of management measures in the field are rare. One possibility is to monitor the volumetric water content in a soil profile, to calculate the water storage change, and to upscaling the point data to the field. But how exact are the estimated values on sites with organic soils and shallow groundwater conditions? And can soil water storage changes be estimated from water content data obtained with profile probes? To test this, an EnviroScan profile probe was installed in a soil monolith of a weighable groundwater lysimeter to monitor the volumetric water contents at eight depths. The water storage changes obtained from profile probe data were compared with the reference storage change from the lysimeter. A soil specific calibration was useful especially for soil layers with higher organic matter content. Water storage changes estimated from profile probe data largely reflected the reference hydrograph of the lysimeter except for intensive drying and rapid infiltration periods. The results suggest that profile probe data can be used to quantify soil water retention; by installing multiple probes, the approach allows extending such point observation to larger lowland areas with shallow groundwater tables.

Cadmium is highly toxic, causing both bone and kidney damage in higher animals including humans. Human exposure to cadmium is a concern not only due to its toxicity but also to its ability to bioaccumulate in the body over time. Recent studies have shown that some inexpensive jewelry items purchased in the USA contain extraordinarily high concentrations of cadmium—in some cases, over 90.0% (900,000 ppm) Cd by mass. The cadmium in these items poses a hazard not only to children who may mouth or swallow pieces of jewelry, but the ultimate disposal of this jewelry in household trash can lead to the release of cadmium into the environment through landfill leachates. Of 45 high-cadmium jewelry items evaluated by the US Environmental Protection Agency’s Toxicity Characteristic Leaching Procedure (TCLP), 43 exceeded the US regulatory standard of 1 mg/L in the leachate, and the average concentration found was 546 mg/L. The maximum cadmium release in these tests was 3250 mg/L. The use of cadmium in inexpensive jewelry thus poses serious environmental hazards that can be avoided by eliminating cadmium from these products.

The COVID-19 pandemic lockdown provided a unique opportunity to assess the effects of mobility restrictions on urban air pollution. Prior studies have shown that scale and impact of these reductions varied by location and time. This study assessed how daily concentrations of PM₂.₅ and PM₁₀ changed during 2020 lockdown compared to the same period in 2019 and 2021, and evaluated how these levels aligned with the updated WHO Air Quality Guidelines and Georgia’s national standards. Daily average concentrations of PM₂.₅ and PM₁₀ were analyzed over a 63-day period (March 21 to May 22) for 2019, 2020, and 2021. Descriptive statistics, ANOVA, and pairwise post-hoc tests were used to assess changes. Exceedance rates for WHO guidelines and Georgian standards were also calculated to evaluate compliance. Average daily concentrations of PM₂.₅ and PM₁₀ declined modestly during the 2020 lockdown compared to pre-lockdown 2019, but increased significantly post-lockdown in 2021. PM₂.₅ increased from 11.7 µg/m3 in 2020 to 14.6 µg/m3 in 2021 (p = 0.010); PM₁₀ increased from 23.2 µg/m3 to 32.3 µg/m3 (p = 0.001). The proportion of days exceeding WHO values was lowest in 2020 for both PM₂.₅ (23.3%) and PM₁₀ (5.0%) but increased in 2021. Exceedances of Georgian standards remained minimal across all years. The lockdown was associated with a temporary decline in PM₂.₅ and PM₁₀ in Tbilisi, however, levels increased again in 2021, with more frequent exceedances of WHO guidelines. The consistently low exceedance under Georgia’s national standards highlights the urgency of revising thresholds and strengthening long-term air quality policies.

Heavy metal contamination in sewage sludge (SS) threatens safe agricultural reuse. This study assesses the impact of relocating tanneries from Magra El-Oyoun to Robbiki Leather City (RLC) on heavy metals especially chromium (Cr) in sludge from Cairo’s El-Gabal El-Asfar Wastewater Treatment Plant (GAWWTP). Before July 2020, Cr-rich tannery effluent caused elevated sludge Cr (median: 800 mg kg⁻¹; max: 1750 mg kg⁻¹), exceeding safe limits and posing environmental/agricultural risks. Post-relocation, Cr plummeted (median: 77 mg kg⁻¹; max: 140 mg kg⁻¹)—a > 90% reduction—bringing concentrations within safe limits. Other metals showed variable trends: Hg increased (median: 0.05 to 1.10 mg kg⁻¹) while Arsenic (As) exhibited statistically significant temporal trends (p < 0.05). No significant temporal trends were observed for nickel (Ni), cadmium (Cd), zinc (Zn), copper (Cu), and lead (Pb), with p values exceeding 0.05 and low explanatory power (R² < 0.16). All monitored metals (Hg, Ni, Cd, Zn, Cu, Pb, As) remained below permissible limits. While Cr posed historical risks that have now been resolved, the other metals—despite minor fluctuations—present no current threat. This confirms the success of industrial intervention and underscores the need for ongoing monitoring to ensure safe SS reuse.

Graphical Abstract

Road sediment is an underutilized medium in the investigation of environmental pollution, yet it serves as both a source and sink for a wide array of pollutants. In urban areas especially, contaminants present within road sediment have the potential to pose human health risks depending on the abundance, chemical, and physical nature of these contaminants as well as the duration (i.e. acute or chronic) of exposure. Las Vegas, Nevada is currently one of the fastest growing urban areas in the United States and is therefore a prime location for the investigation of potential environmental contaminants and pollutants in road sediment. Forty-six road sediment samples were collected from locations throughout the Las Vegas region, including Las Vegas, Henderson, and Boulder City. Geochemical and mineralogical characterization of the selected samples was completed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray fluorescence spectrometry (XRF). Results from these analyses indicate the presence of metal-bearing particulate matter (including metal shavings), in addition to spherules, all of which are consistent with an anthropogenic origin. Additionally, geoaccumulation index (I_geo) values determined from XRF bulk chemical data show that Cu and Zn were enriched in road sediment samples (I_geo > 1) throughout Las Vegas and are thus considered to be significant anthropogenic pollutants in the region. This study serves as the first investigation into road sediment contaminants in the region, and provides a critical framework for more detailed investigation of the source and potential human health effects of these contaminants.

The study examines six species of the genus Portulaca in China. Using geographical distribution data along with altitude and vegetation layers, we employed DIVA-GIS software to update maps for these species, systematically detailing their current distribution status and analyzing species richness. By integrating 19 environmental factors related to precipitation and temperature, we used the MaxEnt model to predict the probable distribution areas of these species and identify the key environmental factors influencing their distribution. The results show that the genus Portulaca in China exhibits a wide distribution pattern. A high consistency was observed between its current potential distribution and its actual modern distribution. Seasonal precipitation patterns and temperature variations play significant roles in shaping the potential distribution of this genus, with temperature annual range, mean diurnal range, precipitation of driest month, and precipitation of warmest quarter contributing most substantially. As climate change intensifies, the habitats of these species are likely to shift northward and expand into new areas. This study provides valuable insights into the distribution dynamics of Portulaca species and offers scientific guidance for their conservation and sustainable use.

Dumpsites represent a major environmental and public health challenge, particularly in low- and middle-income countries (LMICs). Despite increasing global waste generation, many regions still struggle to implement safe and sustainable waste management practices, resulting in significant pollution, greenhouse gas emissions, and health risks due to uncontrolled waste disposal. Dumpsites lack containment measures, allowing pollutants to migrate through environmental matrices and reach different targets (e.g., human receptors). The primary objective of this review was to evaluate existing risk assessment procedures and propose a research direction for a standardized human health risk assessment (HHRA) methodology to prioritize interventions, starting with the most dangerous dumpsites in a given territory. The paper begins by presenting an overview of dumpsites, followed by a discussion on the pathways through which pollutants may migrate from dumpsites to human receptors and the associated health risks. Citing case studies, we explore the available environmental and health risk assessment methodologies, identifying and discussing key characteristics appropriate for dumpsites with a focus on LMICs where such sites are widespread and appropriate approaches are necessary. We identify and further discuss the relative HHRA as the most practical and reliable approach. We conclude with recommendations on research and policy.

Ebullition constitutes a major pathway for methane emissions from reservoirs, particularly in tributary bays with steep depth gradients. However, methane (CH₄) bubble release characteristics remain poorly understood in Three Gorges Reservoir tributaries due to methodological limitations in quantitative monitoring. A novel underwater bubble generation device was employed to establish the target strength (TS) to bubble volume (V) relationship for echo sounder measurements. Sediment bubble release was monitored in situ in the Xiangxi River, a major tributary of the Three Gorges Reservoir (TGR). Site-specific acoustic TS-V relationships effectively enhanced the precision of acoustic bubble volume quantification. Fixed-point monitoring and comprehensive cruise surveys across depth gradients (0–70 m) revealed pronounced spatial heterogeneity in ebullition, with shallow areas (< 20 m) exhibiting fluxes 19–29 times greater than deep regions (> 40 m). A critical depth threshold of 40 m was identified, below which bubble formation is suppressed. Strong coupling between ebullition and dissolved CH₄ distributions (R² = 0.93) indicates bubble release drives dissolved methane concentrations more than sediment organic carbon content. These methodological advances provide essential tools for accurate reservoir methane emission assessments and highlight the importance of depth-dependent spatial variability in global carbon budget evaluations.

Irrigation waters can act as reservoirs and transmission pathways for antimicrobial resistant (AMR) bacteria, contributing to the broader global AMR crisis. The current extent of AMR in irrigation waters is poorly understood. This is especially true for small waters such as farm ponds. The objectives of this work were to determine if stable spatial patterns in the concentration data exist that can be used to inform monitoring design. Water sampling was conducted on 9 dates from June to September 2023 at 20 locations within an irrigation pond in Maryland, USA. The antibiotic resistant genes (ARGs) tetA and bla_CTX-M were enumerated using digital PCR (dPCR) in all collected samples. Spatial variation of tetA concentrations was time-dependent with coefficients of variation ranging from 97 to 377%. Average concentrations steadily declined throughout the observation period. Rainfall events did not result in higher concentrations of tetA. Stable spatial patterns in the concentration data were detected using the mean relative difference analysis. Samples collected at the banks contained higher tetA concentrations than those collected in the interior. Elevated ARG concentrations at bank sites were attributed to on-land activities as well as hydrological conditions within the water body. Sampling sites were identified which best represented the spatiotemporal average of the concentrations. Spatial patterns of tetA were negatively correlated with those of water temperature, electrical conductance, and pH, while correlations for all other measurements were positive. This work is the first to evaluate fine-scale spatial variation of ARGs in lentic waters used for irrigation. The results show that the choice of where to sample for AMR enumeration in ponds or lakes should not be made arbitrarily.