Search

Anthropogenic contamination of surface waters is a critical issue in urbanised catchments, especially in Mediterranean environments with scarce water resources and intermittent rivers. A combined hydro-geochemical and multivariate statistical methodology has been applied to evaluate the surface water quality of Wadi El Hatab catchment (Central Tunisia). More than half of the 28 samples collected in March 2021 exceeded WHO standards for sodium, chloride and sulphate contents. Most polluted sites are directly influenced by domestic and industrial effluents that contaminate the river for kilometers. Principal Component Analysis and Hierarchical Ascendant Classification distinguished four contamination sources: water-rock interaction, domestic wastewater, untreated industrial effluents mainly from paper mills and irrigation return. A Water Quality Index model indicated that 75% of the surface water was unsuitable for drinking purposes; while according to chemical indices such as saturation index, sodium absorption coefficient (SAR), magnesium ratio (MR) and percent sodium (%Na), 25 to 49% of samples were unsuitable for irrigation. Considering that water of Wadi El Hatab is used for vegetable irrigation, serious public health issues may arise. The investigation demonstrated that a single representative sampling campaign could be a useful way to identify contamination sources when interpreted with both statistical and geochemical tools. [ABSTRACT FROM AUTHOR]

Anthropogenic activities are responsible for degrading rivers and decreasing their capacity to offer ecosystem services. This paper reports the findings of a study carried out to assess the impacts of anthropogenic activities in Pinyinyi River water quality using physicochemical parameters. BOD, COD, phosphate, pH, EC, TDS, turbidity, DO and nitrate were analysed. Anthropogenic activities around Lake Natron Ramsar Site also documented. pH, EC, TDS, turbidity and DO measure in-situ using potentiometric method (HANNA HI 9829). Phosphate and nitrate analysed using photometric method (HACH DR/2700). BOD and COD analysed using bottle incubation method for five days (BOD incubator) and dichromate method (COD digester) respectively. Structured questionnaires used to collect data about anthropogenic activities taking place around Lake Natron Ramsar Site. DO, BOD, COD and turbidity were above the permissible limit. Phosphate, pH, EC, TDS and nitrate were within permissible limit. Irrigation, livestock keeping, fishing, bathing, washing, deforestation, water diversion, sand mining, making bricks along the river, tourist guidance, soda ash harvesting and selling soda ash are the anthropogenic activities taking place around Lake Natron Ramsar Site. River water was found to be unsafe for drinking purposes and was found to be safe for irrigation purposes. The study recommends sustainable anthropogenic activities along Pinyinyi River and mitigation measure to restore the lost ecosystem services. [ABSTRACT FROM AUTHOR]

The regions near the Tropic of Cancer are a latitudinal geographical zone with typical climatic, topographic, and human landscape features. It is necessary to explore the region's net primary productivity (NPP) dynamics as it combines complex topography, various vegetation types, and intense human activities. The study sets the transect near the Tropic of Cancer (TCT) and uses the Carnegie–Ames–Stanford (CASA) model to estimate the NPP from 2000 to 2020. After using the RESTREND method, the paper calculates and compares the relative contributions of climate variability and anthropogenic activities to NPP changes. Finally, the geographical detector (Geodetector) model is applied to evaluate how anthropogenic and natural factors affect spatial distribution patterns and NPP changes. The results indicated that the average annual NPP is 820.39 gC·m−2·yr−1 during the 21 years. In addition, when the NPP varies, it increases over the entire study area, with a slope of 4.81 gC·m−2·yr−1, particularly in the western region. Across the entire research area, 63.39% and 77.44% of the total pixels positively contribute to climate variability and human activities in NPP, with a contribution of 0.90 and 3.91 gC·m−2·yr−1, respectively. Within the western, central, and eastern regions, anthropogenic activities have a stronger impact on NPP than climate variability, particularly pronounced in the eastern region. Furthermore, vegetation cover is the dominant factor in the spatial patterns and NPP trends across the TCT and the three regions. In contrast, climate factors are shown to be less influential in NPP distribution than in the western region. The results also demonstrated that the effect of population density and the GDP on NPP gradually rises. Two-factor interaction is much larger than any individual factor, with the dominant interaction factor being vegetation cover with climatic factors. Lastly, the findings revealed that anthropogenic activities positively promote NPP accumulation across the TCT, thus highlighting the importance of human activity-led ecological restoration and ecological protection measures that contribute to regional carbon sequestration and carbon balance. [ABSTRACT FROM AUTHOR]

The macro-tidal estuary with a mountain stream is a typical estuary on China′s southeast coast, characterized by intense dynamic forces, active sediment movements, and a robust response to human activities. It demands further investigation of its evolution mechanism under both natural conditions and anthropogenic stresses. This paper takes the Jiangxinyu reach of the Oujiang River estuary as a case example to explore the river′s evolution under the influence of human activities, including effects of longitudinal dam construction, sand mining, and shoreline adjustment since the 1970s. Measured data analysis and a two- dimensional flow and sediment mathematical model were used. The results confirm that anthropogenic stresses have altered the natural periodic alternation of the river′s main and side branches. Moreover, the undercutting of the riverbed caused by sand mining from the beginning of this century has increased tidal range by 0. 5 m and tidal prism by 47%, while weakening the discharge asymmetry and sediment transport asymmetry indices by 0. 08—0. 30 and 0. 28—0. 54, respectively. The undercutting of the riverbed has also weakened the ebb and flood asymmetry. These conditions have subsequently helped slow down the shrinkage of the side branch. The evolution mechanism is dominated by both natural and human activities. Overall, the research findings may be a reference for river evolution and protection under the influence of human activities. [ABSTRACT FROM AUTHOR]

The description of sound as a form of energetic pollutant is very complex as is also its impact on aquatic life. Human activities causing continuous and implosive underwater noise, such as marine traffic, maintenance of ships, coastal tourism, marine research, military, offshore energy platforms, generation of ocean energies and construction operations are expected to increase. The paper analyses current approach to minimise the impact of underwater noise and limit its emissions, examines regulatory approach and discusses the possibilities to control this type of pollution in order to ensure the preservation of natural underwater soundscape. The timely implementation and further development of the European Marine Strategy Framework Directive and its provisions related to underwater noise is of exceptional importance for the Adriatic Sea, which is facing increasing pressure from various industries generating underwater noise. [ABSTRACT FROM AUTHOR]

Mt. Everest (Qomolangma or Sagarmatha), the highest mount on Earth and located in the central Himalayas between China and Nepal, is characterized by highly concentrated glaciers and diverse landscapes, and is considered to be one of the most sensitive area to climate change. In this paper, we comprehensively synthesized the climate and environmental changes in the Mt. Everest region, including changes in air temperature, precipitation, glaciers and glacial lakes, atmospheric environment, river and lake water quality, and vegetation phenology. Historical temperature reconstruction from ice cores and tree rings revealed the distinct features of 20th century warming in the Mt. Everest region. Meteorological observations further proved that the Mt. Everest region has been experiencing significant warming (approximately 0.33 °C/decade) but relatively stable precipitation during 1961−2018 AD. Projected results (during 2006−2099 AD) under different representative concentration pathway scenarios showed a general warming trend in the region, with larger warming occurring in winter than in summer. Meanwhile, the precipitation projections varied spatially with no significant trends over the region. Intensive glacier shrinkage was characterized by decreasing glacier areas, while glacier-fed river runoff increased. Glacial lakes expanded with increasing glacial lake areas and numbers. These findings indicated a clear regional hydrological response to climate warming. Owing to the remote location of Mt. Everest, the present atmospheric environment remained relatively clean; however, long-range transport of atmospheric pollutants from South Asia and West Asia may have substantially influenced the Mt. Everest region, resulting in increasing concentrations of pollutants since the Industrial Revolution. Anthropogenic activities have been shown to influence river and lake water quality in this remote region, especially in the downstream. The end of the vegetation growing season advanced in the northern slope and did not change in southern slope region of the Mt. Everest, and there was no significant change in start date of the growing season in the region. This review will enhance our understanding of climate and environmental changes in the Mt. Everest region under global warming. • Climate and environmental changes were synthesized in the Mt. Everest region. • Glaciers have retreated significantly, posing impacts to river runoff and glacial lakes. • Transboundary transport of atmospheric pollutants influenced the region. • TThere was no significant change in start date of the growing season. [ABSTRACT FROM AUTHOR]

Coastal morphodynamics and environmental changes have been obviously altered by global warming, sea-level fluctuations, and human activities. Palynological analysis is one of the most important tools for providing information on vegetation, climate, and environmental change, which can be relatively sensitive indicators of human activity during the Holocene. However, Holocene coastal morphodynamics and palynological evidence from the Pearl River Delta and coastal areas has not been sufficiently studied. In this paper, we carry out analyses using detailed grain-size and palynological records of pollen, spores, freshwater algae, and marine dinoflagellate cysts from Borehole QZK13 in the Pearl River Estuary (PRE), southern China. The results show information relating coastal morphodynamics, vegetation evolution, climate changes, and anthropogenic activities during the Holocene based on radiocarbon chronology. In general, the PRE experienced marine transgressive processes; sea-level and the coastline tended to migrate landward between 10,700 and 4250 cal yr BP. Meanwhile, abundant arboreal pollen (mainly Castanopsis , Quercus -evergreen, Oleaceae, and Castanea) and small amounts of non-arboreal pollen (mainly Poaceae, Cyperaceae, and Artemisia) were observed in Borehole QZK13, which suggests that subtropical evergreen broadleaved forests were distributed throughout the PRE and adjacent areas, and relatively warm and moist climatic conditions were present during the early-middle Holocene. After that, there were relatively cool and wet climatic conditions, and marine regressive processes occurred in the PRE during the Late Holocene (ca. 4250–960 cal yr BP) indicated by an abrupt increase in aquatic herbs and Dicranopteris. Moreover, we hypothesize that the Neolithic "cultural fault" in the PRE is likely related to frequent storm surges induced by extreme typhoon events that occurred ca. 3000–2700 yr BP. • Grain size, pollen, spores, freshwater algae and dinoflagellate cysts from the Pearl River Estuary were investigated. • Three major phases shown by palynological results were corresponding to the changes in vegetation and climate. • We hypothesized that the Neolithic "cultural fault" is probably related to the storm surges induced by extreme typhoon events. • Natural vegetation cover has suffered large-scale destruction by ancient humans during the Late Holocene. [ABSTRACT FROM AUTHOR]