Intensive Anthropogenic Activities Research Articles

A review on toxic metal pollution and source-oriented risk apportionment in road dust of a highly polluted megacity in Bangladesh.

Heavy metal enrichment in road dust has resulted from intensive anthropogenic activity, particularly urbanization, industrial activities and traffic emission, posing a hazard to urban ecosystems and human health. To promote optimal road dust management in urban environments, it is necessary to assess the possible ecological and health impact of toxic elements in road dust. In a heavily populated megacity like Dhaka, Bangladesh, large-scale risk assessments of contamination in road dust with heavy metals are limited. The present study aims at presenting a concentration of twenty-five metals in road dust (Na, K, Cs, Rb, Mg, Ca, Sr, Ba, Al, Zn, Cd, Pb, As, Sb, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr and W) in Dhaka megacity. We used a critical source-based positive matrix factorization model, source-oriented potential ecological risks and health risks. Out of the studied metals, Na, Ca, Zn, Cd, Cu, Zr and W exceeded the shale value. About 73%, 48%, 29% and 32% of sampling sites showed a higher level of pollution based on PLI, NIPI, PER and NIRI, respectively. PMF model identified that Cd (85.3%), Cr (62.4%), Ni (58.2%), Zn (81.8%) and Mn (65.9%) in road dust were primarily attributed to traffic emission, fuel combustion, metal processing, transport sources and natural sources, respectively. Fuel combustion and metal processing posed considerable and high risks based on modified potential ecological risk and NIRI. Based on health hazards, traffic emission posed a high cancer risk in adult males (29%), whereas transport sources contributed to females (21%) and children (23%).

Extreme rainfall-related accelerations in landslides in Danba County, Sichuan Province, as detected by InSAR

Landslides are frequent mountainous geohazards induced by multiple factors, such as extreme rainfall, river erosion, and intense anthropogenic activities. On 17 June 2020, a rainstorm hit Danba County, Sichuan Province, and triggered the catastrophic Aniangzhai landslide. The impact of this rainstorm on landslide kinematics in this region has seldom been investigated. We used a time-series interferometric synthetic aperture radar (InSAR) analysis to map the active slopes in Danba County using one ascending (2015–2021) and one descending (2018–2021) Sentinel-1 dataset. A total of 36 landslides (63.1 km2) were detected along riverbanks. The time series of eastward and vertical displacements during 2018–2021 were retrieved by integrating the ascending and descending Sentinel-1 datasets. The maximum eastward and vertical displacement rates obtained are 229 and −75 mm/yr, respectively. Seasonal accelerations are correlated with concentrated rainfall. We suggest that the 2020 rainstorm and the abundant precipitation during the water year 2020 altered the long-term displacement trends of active landslides. We further constrained the volumes of the Niela and Gaoding landslides in the order 3.6–6.9 × 107 m3 and 5.4–6.0 × 108 m3, respectively, using 2D displacement rates and mass conservation equations. Our results demonstrate that multi-temporal and multi-orbit InSAR measurements can provide insights into the evolution and mechanism of landslides.

Distribution characteristics of airborne bacterial community in different anthropogenic activity regions across Nanchang, China

Bacteria are widely dispersed in the atmosphere by attaching on the particulate matters (PM), which have profound implications for public health and global climate. The association between anthropogenic activity and airborne bacteria remains unclear. To reveal it, the bacterial diversity and community structures of PM2.5 collected from five different anthropogenic activity regions in Nanchang, China, were compared. We found that bacteria in UPM and SPM with relatively intensive anthropogenic activities had higher richness and diversity than the other three regions, which was confirmed by the strongly positive correlations between richness/diversity indices and PM10/NO2 concentrations. Moreover, the phyla Actinobacteria and Deinococcus-Thermus were enriched in UPM and SPM, and several soil-sourced genera such as Deinococcus, Rumbellimicrobium, and Blastococcus, were also dominant in UPM and SPM. Mantel test and correlation analysis showed that human-related air pollutants were one main reason for the disparities of airborne bacterial community (r = 0.26, p < 0.01). And the above taxa in UPM and SPM showed significantly correlation with air pollutants, while several dominant taxa such as Cyanobacteria in TPM and Chloroflexi in FPM had no obvious relationship. The results suggested that the disturbance of intensively anthropogenic activities facilitated some soil derived bacteria to enter into the air. Notably, part of them such as Kocuria, Arthrobacter, and Paracoccus, were human opportunistic pathogens. This work further our understanding of anthropogenic activity impacts on airborne bacteria, especially human pathogens.

Cross-media transfer of nitrogen pollution in the fast-urbanized Greater Bay Area of China: Trends and essential control paths

For urban agglomerations in the bay area, which concentrate multiple environmental elements and intense anthropogenic activities, comprehensive control of nitrogen pollution is particularly challenging due to diverse cross-media migration and transformation forms of nitrogen pollutants. Existing studies on urban nitrogen metabolism mainly focused on quantification of nitrogen flux, without systematic consideration of physiochemical changes of nitrogen between environmental media. This study conducted a dynamic simulation of nitrogen cross-media metabolism in urban agglomeration over 30 consecutive years, and recognized the types, quantities, and trends of cross-media transfer of nitrogen pollution as well as pollution control paths based on ecological network analysis and scenario analysis. Taking the Guangdong-Hong Kong-Macao Greater Bay Area as the case, results show that during its fast-urbanized stage in 1989–2018, more than 25% of the total nitrogen pollution emissions were transferred from other media. The higher degree of imbalance between the socioeconomic system and the soil in the nitrogen metabolic network emphasizes the increased pressure and necessity of pollution control of nitrogen in the solid state with urban development. Promoting fertilizer reduction and sludge land use are priority paths for collaborative control of cross-media nitrogen pollution. The study provides methods to systematically analyze the features of cross-media transfer of nitrogen pollution at the city level, and accordingly propose paths aiming at sustainable urban nitrogen management with multi-media integrity and synergy.

Long-Term Spatiotemporal Changes in Ecosystem Services Caused by Coastal Wetland Type Transformation in China’s Hangzhou Bay

Coastal wetlands provide essential ecosystem services, while usually experiencing land transformation or degradation mainly due to intense anthropogenic activities and climate changes. Understanding the changes in wetlands ecosystem services is essential to decision makers for generating sound coastal planning. Hangzhou Bay is rich in wetland resources, and the urbanization of Hangzhou Bay in the past three decades has caused fundamental changes in the wetlands in the region. Based on the remote sensing images of the Hangzhou Bay area from 1990 to 2020, this paper analyzes the land use situation of the Hangzhou Bay area in seven periods. This paper calculates the area transfer matrix of various types of wetlands. It uses the InVEST model to evaluate the changes in the function of wetland ecosystem services in the Hangzhou Bay area. Hangzhou Bay wetlands show a trend of transferring natural wetlands to artificial and non-wetlands from 1990 to 2020. Carbon stocks fell by 14.24%. The annual water production decreased by 33.93% and then returned to the original level. The area of habitat degradation increased by 79.94%. The main influencing factors are paddy field degradation, increase in non-wetland area, and decrease in sea area. This paper proposes that the development and construction of farmland in the “red line” area and established wetland reserves are prohibited, and to strengthen the training of wetland management personnel, establish a sound decision-making consultation mechanism, and increase the scientific research expenditure on wetlands in the region.

Potentially toxic elements in the soils of Campi Flegrei (south Italy) and the immediate surroundings: Spatial distribution, origin and probabilistic human health risk

Campi Flegrei is an active volcanic field in south Italy where the potentially toxic elements (PTEs) are of growing concern because the intensive anthropogenic and volcanic activities might pose adverse human health effects. In this article, 394 topsoils (0–15 cm) are collected for instrumental analysis of the <2 mm fraction. The geochemical maps indicate that higher concentrations of Pb, Zn, Cd, Cr, Hg, Ni and Sb are related to the urban area, but greater levels of As, Tl, Co, Cu, Se and V are observed in the other parts. A robust principal component analysis detected: (1) the Pb–Zn–Hg–Cd–Sb–Cr–Ni association that probably highlights anthropogenic activities such as heavy traffic load and fossil fuel combustion in the urbanized area; (2) the Al–Fe–Mn–Ti–Tl–V–Co–As–U–Th association that mostly reveals the contribution of pyroclastic deposits; and (3) the Na–K–B association that feasibly indicates the weathering degree. The probabilistic health risk modeling for the children under 6 years old shows negligible Pb and Zn non-carcinogenic risk and unexpected Pb carcinogenic risk for exposure through soil ingestion. However, for the inhalation pathway, the children aged <1 year old have the highest chance (90%) of acceptable (i.e. between 1E-6 and 1E-4) Pb carcinogenic health risk. This should not be overlooked because Naples is under high environmental pressure and previous studies reported the increased Pb and Zn quantities in soil over a 26-year timespan. Overall, the results of geostatistical interpolation, compositional data analysis and probabilistic health risk modeling potentially uncover the link between soil geochemistry and human health.

A multiscale air quality and health risk modelling system: Design and application over a local traffic management case study

Air pollution is nowadays a serious public health problem worldwide, especially in urban areas, due to high population density and intense anthropogenic activity. This paper aims to present the development of a modelling tool suitable for simulating multiscale air quality and health impacts - the modair4health system, and its application to an urban case study. The modair4health system includes the online model WRF-Chem, which provides meteorological and air quality fields from regional to urban scales, and the computational fluid dynamics model VADIS, which uses the urban WRF-Chem outputs to simulate the flow and pollutant dispersion in urban built-up areas. A health module based on World Health Organization (WHO) methodologies was also integrated into the system to quantify physical and economic health impacts resulting from air quality changes.The system was applied over a local case study, which represents one of the busiest road traffic areas of the city of Coimbra in Portugal, to assess its operationality in estimating NO2 concentrations and health impacts, by testing two traffic management scenarios. This scenario analysis considered a 4-domain nesting approach, with the finer resolution (4 m) domain focusing on the local case study and on two simulation periods, for which short-term health impacts were estimated. Spatially, the air quality and health greatest benefits were simulated around roads, where higher emission reductions were estimated, but they were also strongly influenced by the urban structure, local weather and population affected.The modair4health system has revealed to be an important multiscale modelling tool for integrated air quality and health assessment, able to support decision makers by facilitating the choice of cost-effective air quality and health management strategies and decisions. Moreover, its user-friendly interface allows to quickly test other urban air pollution control policies and the easy adaptation and application to other case studies considering regional to local atmospheric influences.

Bioaccumulation of heavy metals in estuaries in the southwest Atlantic Ocean.

The southwestern Atlantic Ocean is home to highly productive regions, composed of a mosaic of both protected and anthropogenically impacted areas, including the estuaries of Paranaguá, Cananéia, and Santos. In this study, concentrations of metals were measured in sediments and in marine organisms, collected from these three Brazilian estuaries. The higher concentrations of metals in the sediments from the Santos estuary are due to having the greatest intensity of anthropogenic activities. There is bioaccumulation of As, Cu, Ni, and Pb in benthic invertebrates, As in fish, and Se and Zn in all studied trophic groups. Comparing the biota among estuaries, levels were highest for Cr, Cu, Pb, Se, and Zn in Paranaguá, As in Cananéia, and Ni in Santos; results justified due to anthropogenic activities, natural sources, and geochemical and hydrodynamics characteristics of each region that affect the bioavailability of metals. The results showed that these regions of the Atlantic present higher levels of metals in the biota than several coastal regions worldwide, and signal that food security may be compromised. Highlighting the need for better impact assessment, monitoring, and managing is deemed necessary as these regions are globally recognized as hotspots of biodiversity and are considered priority areas for conservation.

Preliminary investigation of saline water intrusion (SWI) and submarine groundwater discharge (SGD) along the south-eastern coast of Andhra Pradesh, India, using groundwater dynamics, sea surface temperature and field water quality anomalies.

Intensive anthropogenic activities along the coastal plains of Andhra Pradesh (such as urbanisation, agriculture and aquaculture) rely extensively on coastal fresh groundwater resources that are pumped at unsustainable rates causing groundwater decline and water quality problems due to saline water intrusion. Hydrogeological studies are imperative to implement groundwater conservation strategies in coastal Andhra Pradesh, which is experiencing a severe freshwater shortage due to overexploitation and saline water intrusion as well as clean water loss through the aquifer system close to the coastal plains. An attempt is made in this study to demarcate the submarine groundwater discharge (SGD) and saline water intrusion (SWI) zones adopting a three-tier validation system, i.e. groundwater dynamic, LANDSAT resultant sea surface temperature (SST) variance and site-specific water characteristics along the southeast coast of Andhra Pradesh, India. A total of 234 water samples (139 porewater, 31 groundwater and 64 seawater samples) were evaluated along ~ 450km southeast coastline of Andhra Pradesh. In situ porewater physio-chemical parameters, i.e. EC, TDS, pH, DO, temperature, and salinity, at every 1km except non-accessible areas and groundwater for every 5km were analysed and used for identification of SGD zones in the study area. The hydraulic gradient values vary from - 11 to 250m in post-monsoon and - 14 to 250m in pre-monsoon. And sea surface temperature anomaly for 2017, 2018 and 2019 varies between 21-39°C, 15-34°C and 20-39°C. Three districts out of the four districts studied (Krishna, Guntur and Nellore) were shown to be prone to SWI, whereas Prakasam district was susceptible for SGD. For the first time, this kind of preliminary study was carried out in the coastal Andhra Pradesh region, and it will serve as a basis for the meticulous analysis of the fresh and saline water mixing zones/process as well as to develop and manage the groundwater resources along the water-stressed coastal plains of Andhra Pradesh, India.

Uncovering ecological regime shifts in the Sea of Marmara and reconsidering management strategies

Ecosystem regime shifts can alter ecosystem services, affect human well-being, and trigger policy conflicts due to economic losses and reductions in societal and environmental benefits. Intensive anthropogenic activities make the Sea of Marmara ecosystem suffer from nearly all existing available types of ecosystem pressures such as biological degradation, exposure to hydrological processes, nutrient and organic matter enrichment, plastic pollution, ocean warming, resulting in deterioration of habitats. In this study, using an integrated ecosystem assessment, we investigated for the first time the historical development and ecosystem state of the Sea of Marmara. Multivariate analyses were applied to the most comprehensive and unique long-term data sets of 9 biotic and 15 abiotic variables for ecosystem state and drivers respectively, from 1986 to 2020. Observed changes were confirmed by detecting shifts in the datasets. The Sea of Marmara ecosystem was classified into three regimes: i) an early initial state regime under the top-down control of predatory medium pelagic fish and fisheries exploitation until mid-1990s, ii) a transitional regime between mid-1990s and mid-2010s as from ecosystem restructuring, and iii) an alternate state late regime with prevailing impacts of climate change from mid-2010s until 2020. During the 20 years transitional regime, three different phases were also characterized; i) the 1st phase between mid-1990s and early 2000s with its gradual change in ecosystem state from a decrease in predators and significant shift in physical drivers of the ecosystem, ii) the 2nd phase between 2000 and mid-2000s with a strong shift in ecosystem state, an ongoing increase in climate indices and fishing mortality, and a gradual decrease in water quality; and iii) the 3rd phase between mid-2000s and mid-2010s with the reorganization of the ecosystem dominated by small pelagic fish and ameliorated water quality. During late regime, we observed that most of the biotic variables, mainly fish biomass, and climate variables did not return to their initial state despite the improvement in some abiotic variables such as water quality. We identify these observed changes in the SoM ecosystem as a non-linear regime shift. Finally, we also developed concrete suggestions for improved regional management.

Mammals’ abundance in Lingga Isaq Hunting Park Landscape, Aceh

Hunting-park is a conservation area with the unique attraction of periodically hunting in terms of wildlife management. Lingga Isaq Hunting-Park (LIHP) is one of 13 hunting parks in Indonesia. However, the utilization of LIHP as a hunting park is still facing obstacles; two of which are conflicts of interest among authorities and no data of the animals, especially mammals – the most hunted creatures in the park. Therefore, a study was conducted to identify the mammalian abundance and distribution. This data would be usefull as essential decision-making for hunting-tourist attractions in LIHP. This study used the transect method, with 12 transect strips evenly distributed in those four function areas; three per each. We found 11 species of mammalian that belonging to 8 families. The protected forest had the highest biodiversity value (H’=1.50), while other use areas had the lowest biodiversity value (H’=1.16). Macaca fascicularis had the highest abundance (23 individu), while Sus scrofa was the most evenly distributed mammal in the whole landscape. Protected forests and other utilization areas have the highest habitat similarity, identified as having intense anthropogenic activities. The protected forest also has habitat similarity with hunting-park as both areas are legally protected. Nevertheless, there are only Cervus unicolor, Muntiacus muntjak, and Sus scrofa that are highly recommended for hunting tourism attractions.

Solar reflective properties of porcelain tiles for UHI mitigation: effect of highly reflective frits in the engobe's formulation

The 2030 Agenda for Sustainable Development charts the course for transforming the world socially, economically, and environmentally by 2030. Cities represent a critical issue in this transformation: the population growth and the intense anthropogenic activity make them centers of strong environmental impact. For instance, cities have become Urban Heat Islands (UHIs) due to the significant increase in temperatures caused by pollution and heat produced by human activities. The urgency to make cities sustainable from an environmental point of view urges the search for innovative solutions to counter this phenomenon. One of those solutions is reflective tiles, as they absorb less heat and stay cooler than traditional materials and are considered an effective mitigation technique against the UHI phenomenon. This study investigated the obtaining of solar reflective ceramic tiles through the modification of the engobe's formulation. To achieve this goal, a glass-ceramic frit with high solar reflectance (SR) property (0.95) was incorporated into the formulation of a commercially available ceramic engobe. To verify whether the modified engobe can be used to prepare solar reflective cool color ceramic tiles, the tiles were decorated in quadrichromy by ink-jet printing according to the four-color CMYK color model. The Gray Scale (GS) printing system was used to investigate five different printing intensities. The results suggest that when a glass-ceramic frit with a high intrinsic SR value is incorporated into the formulation of an industrial engobe, it can raise its SR value, passing from 0.69 to 0.75. However, the productive process used to obtain ceramic tiles limits the SR values due to crystallization. It was also found that ink-jet decoration negatively affects the solar reflective property of the tiles prepared with the new engobe due to its coverage by the inks and their mineralogical composition. Thus, the results presented in this work evidence that changing the engobe's formulation is not enough to obtain ceramic tiles with high solar reflective properties.

Linking anthropogenic burning activities to magnetic susceptibility: Studies at Brazilian archaeological sites

AbstractThis study provides the first survey of Brazilian magnetic susceptibility (MS) data from varying archaeological and geological contexts, including open‐air sites, quartzite, and limestone rockshelters, and Amazonian dark earths. Our MS analyses associated with archaeological findings allow us to propose MS values as proxies of intense anthropogenic burning activities for archaeological sites with (i) systematic use of large hearth lit in the same places; (ii) systematic burns and highly diverse uses; (iii) higher diversity use with few fire activities and knapping playing an essential role; and (iv) incipient human activities and the initial use of the archaeological site. Our data are limited to understanding anthropogenic burning activities and cannot be extended to reveal other archaeological aspects. The results have implications for understanding human occupation in a large area with numerous archaeological sites. This study was the first step in distinguishing archaeological fires from natural fires and provided a new perspective for further research that attempts to identify distinct types of human fires.

Innovative electrochemical process for a total removal and/or separation of soluble heavy metals

This study aims to extend an innovative electrochemical process for a total elimination and/or separation of different soluble heavy metals. This objective is very important because today the water pollution, due to intense anthropogenic activities by toxic chemical substances and heavy metals in particular, becomes a serious problem for environment and human health. In this context, we have developed recently an efficient electrochemical process for removing soluble Pb(II) as adherent oxide(s) films on conductive substrate, leading to reach directly acceptable concentration levels for the environment and drinking water, and even in a complex medium. In the present study, this electrochemical process of depollution was extended to remove separately other heavy metals, and to recover them in the form of adherent films according to the same principle. The adequate parameters were researched and tested for each heavy metals present alone before to be applied on a synthetic aqueous solution containing a mixture of the studied heavy metals such as Pb(II), Cu(II), Ni(II), and Cd(II). In complement, some tests were performed with success on effluents, coming from wastewater plant (WWTP) containing different heavy metals, confirming the real interests of this innovative electrochemical treatment. These all results are very promising for future applications either for wastewater depollution either for very easy separation of different heavy metals, which generally requires complex and energy consuming chemical steps.

Seasonal and diel patterns in singing activity of humpback whales migrating through Bermuda

Humpback whales (Megaptera novaeangliae) produce song and non-song vocalisations, which allows their presence to be detected through passive acoustic monitoring. To determine the seasonal and diel acoustic presence and acoustic behaviour of humpback whales at the migratory stopover site off Bermuda, three hydrophones were deployed between March 2018 and April 2019 on Challenger Bank and the Bermuda platform. Song was the predominant vocalisation type encountered, with 65% of song recordings containing whale chorus and a clear seasonal trend of humpback whale occurrence in the spring and winter months from late December to mid-May. A strong diel pattern in singing activity was detected. Singing activity significantly increased at night relative to the daytime (p&amp;lt;0.01), whilst twilight periods were characterised by intermediate levels of singing. The song structure encountered in spring 2018 consisted of 18 units, 6 themes and 5 transitional phrases. The high occurrence of whale chorus and the strong seasonal and diel patterns of male humpback whale singing activity highlights the importance of Bermuda not just on their northward migration during spring, as described historically, but also on their southward migration during winter. Bermuda therefore constitutes a two-way migratory stopover site for humpback whales. The present study also provides Bermuda’s planning authorities with better constraints on the duration and intensity of anthropogenic activities in these waters.

Reconstruction, assessment, and calibration of potential toxic elements (PTEs) in a 3500-year-long sedimentary record off the northern coast of Shandong Peninsula, China

The marine environment of coastal Shandong Peninsula has been significantly influenced by anthropogenic activities due to the rapid industrialization and economic development in the past decades. However, the sedimentary records of PTEs in the North Yellow Sea have rarely been reported. In this study, a 209-cm-long sediment core was collected off the northern coast of Shandong Peninsula, analyzed for grain size and elemental compositions, and assessed using EF, Igeo and several numerical Sediment Quality Guidelines (SQGs). The EF and Igeo results suggested that sediment profile could be slightly to moderately polluted with As and Sb, while ecological risk assessment using SQGs showed that As, Cr, Sb and Ni in the sediment profile may have a moderate incidence of toxicity. Our results highlighted the nonnegligible ecological risk of Sb in sediments of North Yellow Sea, and great importance should be attached to the fact that many PTEs may also pose a potential ecological risk to the aquatic organisms, even though their concentrations meet the standards of the Marine Sediments Quality (MSQ). Moreover, the reconstructed PTEs record showed a dramatic increase over the past 250 years, which could be related to the intense anthropogenic activities since the Industrial Revolution. The multivariate statistical analysis results indicated that Co, Cr, Cu, Pb, Ni and Zn may be mainly related to the natural origin, while As and Sb could be influenced by both natural weathering sources and anthropogenic activities. This study provides more insights into the historical record of PTEs in the North Yellow Sea, and lays foundation for future comparison of PTEs sedimentary records.

The Impacts of Nitrogen Pollution and Urbanization on the Carbon Dioxide Emission from Sewage-Draining River Networks.

Carbon dioxide (CO2) emissions from river water have sparked worldwide concerns due to supersaturate CO2 levels in the majority of global rivers, while the knowledge on the associations among nitrogen pollution, urbanization, and CO2 emissions is still limited. In this study, the CO2 partial pressure (pCO2), carbon and nitrogen species, and water parameters in sewage-draining river networks were investigated. Extremely high pCO2 levels were observed in sewage and drainage river waters, such as Longfeng River, Beijing-drainage River, and Beitang-drainage River, which were approximately 4 times higher than the averaged pCO2 in worldwide rivers. Correlations of carbon/nitrogen species and pCO2 indicated that carbon dioxide in rural rivers and sewage waters primarily originated from soil aeration zones and biological processes of organic carbon/nitrogen input from drainage waters, while that in urban rivers and lakes was mainly dominated by organic matter degradation and biological respiration. Enhanced internal primary productivity played critical roles in absorbing CO2 by photosynthesis in some unsaturated pCO2 sampling sites. Additionally, higher pCO2 levels have been observed with higher NH4+-N and lower DO. CO2 fluxes in sewage waters exhibited extremely high levels compared with those of natural rivers. The results could provide implications for assessing CO2 emissions in diverse waters and fulfilling water management polices when considering water contamination under intense anthropogenic activities.

Simulating the Changes of Invasive Phragmites australis in a Pristine Wetland Complex with a Grey System Coupled System Dynamic Model: A Remote Sensing Practice

Biological invasion has been one of the reasons that coastal wetlands gradually lose their ecological services. The current study investigates the spread of a commonly found invasive species in coastal wetlands in Northeastern US, the Phragmites australis. Within a relatively pristine wetland complex in coastal New Jersey, we collected high-resolution multispectral remote sensing images for eight years (2011–2018), in both winter and summer seasons. The land cover/land use status in this wetland complex is relatively simple, contains only five identifiable vegetation covers and water. Applying high accuracy machine learning algorithms, we are able to classify the land use/land cover in the complex and use the classified images as the basis for the grey system coupled system dynamics simulative model. The simulative model produces land use land cover change in the wetland complex for the next 25 years. Results suggest that Phragmites australis will increase in coverage in the future, despite the stable intensity of anthropogenic activities. The wetland complex could lose its essential ecological services to serve as an exchange spot for nekton species from the sea.

Recurrent droughts increase risk of cascading tipping events by outpacing adaptive capacities in the Amazon rainforest

Tipping elements are nonlinear subsystems of the Earth system that have the potential to abruptly shift to another state if environmental change occurs close to a critical threshold with large consequences for human societies and ecosystems. Among these tipping elements may be the Amazon rainforest, which has been undergoing intensive anthropogenic activities and increasingly frequent droughts. Here, we assess how extreme deviations from climatological rainfall regimes may cause local forest collapse that cascades through the coupled forest-climate system. We develop a conceptual dynamic network model to isolate and uncover the role of atmospheric moisture recycling in such tipping cascades. We account for heterogeneity in critical thresholds of the forest caused by adaptation to local climatic conditions. Our results reveal that, despite this adaptation, a future climate characterized by permanent drought conditions could trigger a transition to an open canopy state particularly in the southern Amazon. The loss of atmospheric moisture recycling contributes to one-third of the tipping events. Thus, by exceeding local thresholds in forest adaptive capacity, local climate change impacts may propagate to other regions of the Amazon basin, causing a risk of forest shifts even in regions where critical thresholds have not been crossed locally.

Heavy metal distribution in Chinese coastal sediments and organisms: Human impacts, probabilistic risks and sensitivity analysis

Chinese coastal sediments and organisms are faced with heavy metal contamination. Current investigation revealed that Chinese coastal sediments contained 1.95-21.9, 0.03-0.62, 4.06-102, 1-90.9, 0.01-0.73, 0.11-58.9, and 7.3-153 mg/kg of As, Cd, Cr, Cu, Hg, Pb, and Zn, respectively. Due to more intensive anthropogenic activities (i.e., industrial sewage, domestic wastewater, energy consumption, and pesticide usage), sediments in the East China Sea and South China Sea had higher ecological risks. The average concentrations (wet weight) of Cd and Cu were 0.30 mg/kg and 7.52 mg/kg, respectively, in invertebrates of Chinese coastal zones, significantly higher than those in fish (Cd: 0.06 mg/kg; Cu: 1.70 mg/kg). However, higher average concentrations of Cr (0.47 mg/kg) and Hg (0.039 mg/kg) were observed in fish than invertebrates. Overall, the health risks from seafood ingestion were low. The sensitive analysis of the Monte Carlo simulation suggested that metal concentration was the most sensitive factor affecting the health risk assessment of a given metal, with the contribution rates of 64.6%-88.6%. However, seafood ingestion rate was the most sensitive factor affecting the combined health risk of all seven metals, with the contribution rate of 48.7%, followed by concentrations of As (25.3%), Cd (11.7%), Cu (6.9%), Hg (5.1%), and others.