Role Of Anthropogenic Activities Research Articles

Anthropogenic and Hydroclimatic Controls on the CO2 and CH4 Dynamics in Subtropical Monsoon Rivers

AbstractAnthropogenic perturbations have substantially altered riverine carbon cycling worldwide, exerting influences on dissolved carbon dioxide (CO2) and methane (CH4) dynamics at multiple levels. However, the magnitude and role of anthropogenic activities in modulating carbon emissions across entire river networks, as well as the influence of climatic controls, remain largely unresolved. Here, we explore the controlling factors of riverine CO2 and CH4 dynamics across 62 subtropical, monsoon‐influenced streams and rivers through basin‐wide seasonal measurements. We found that land use and aquatic metabolism played significant roles in regulating the spatial and temporal patterns of both gases. Increased nutrient levels and organic matter contributed to higher partial pressure of CO2 (pCO2) and CH4 (pCH4). Dissolved oxygen, stable carbon isotope of dissolved inorganic carbon, the proportion of impervious surface, catchment slope, and river width were the major predictors for pCO2. For pCH4, the major predictors were Chlorophyll a and water temperature, which influence organic matter availability and methanogenesis. Seasonal variations in pCO2 and pCH4 were strongly modulated by hydroclimatic conditions, with temperature markedly regulating river ecosystem metabolism. These findings highlight the likelihood of significant changes in riverine carbon emissions as climate changes and land use patterns evolve, thereby profoundly affecting the global carbon cycle.

Comparing the gut microbiota of Sichuan golden monkeys across multiple captive and wild settings: roles of anthropogenic activities and host factors

BackgroundCaptivity and artificial food provision are common conservation strategies for the endangered golden snub-nosed monkey (Rhinopithecus roxellana). Anthropogenic activities have been reported to impact the fitness of R. roxellana by altering their gut microbiota, a crucial indicator of animal health. Nevertheless, the degree of divergence in gut microbiota between different anthropogenically-disturbed (AD) R. roxellana and their counterparts in the wild has yet to be elucidated. Here, we conducted a comparative analysis of the gut microbiota across nine populations of R. roxellana spanning China, which included seven captive populations, one wild population, and another wild population subject to artificial food provision.ResultsBoth captivity and food provision significantly altered the gut microbiota. AD populations exhibited common variations, such as increased Bacteroidetes and decreased Firmicutes (e.g., Ruminococcus), Actinobacteria (e.g., Parvibacter), Verrucomicrobia (e.g., Akkermansia), and Tenericutes. Additionally, a reduced Firmicutes/Bacteroidetes ratiosuggested diminished capacity for complex carbohydrate degradation in captive individuals. The results of microbial functional prediction suggested that AD populations displayed heightened microbial genes linked to vitamin and amino acid metabolism, alongside decreased genes associated antibiotics biosynthesis (e.g., penicillin, cephalosporin, macrolides, and clavulanic acid) and secondary metabolite degradation (e.g., naphthalene and atrazine). These microbial alterations implied potential disparities in the health status between AD and wild individuals. AD populations exhibited varying degrees of microbial changes compared to the wild group, implying that the extent of these variations might serve as a metric for assessing the health status of AD populations. Furthermore, utilizing the individual information of captive individuals, we identified associations between variations in the gut microbiota of R. roxellana and host age, as well as pedigree. Older individuals exhibited higher microbial diversity, while a closer genetic relatedness reflected a more similar gut microbiota.ConclusionsOur aim was to assess how anthropogenic activities and host factors influence the gut microbiota of R. roxellana. Anthropogenic activities led to consistent changes in gut microbial diversity and function, while host age and genetic relatedness contributed to interindividual variations in the gut microbiota. These findings may contribute to the establishment of health assessment standards and the optimization of breeding conditions for captive R. roxellana populations.

Hydrochemical Characteristics and Water Quality Assessment of Irkutsk Reservoir (Baikal Region, Russia)

The Irkutsk Reservoir, belonging to the largest unified freshwater Baikal–Angara system, is an important source of drinking water in the region. Therefore, studies of its hydrochemical characteristics are of prime importance in deciding on the role of anthropogenic activity in water quality. The water samples were collected across the reservoir in 2007, 2012, and 2021 and then were analyzed for major ions and trace elements. The data revealed that the distribution of HCO3−, SO42−, Cl−, Ca2+, Mg2+, Na+ and K+ is stable across the reservoir. Trace element concentrations varied from 1.13 to 15.39 µg L−1 for Al, from <DL to 0.39 µg L−1 for Cr, from 0.39 to 23.12 µg L−1 for Mn, from 1.25 to 53.22 µg L−1 for Fe, from 0.005 to 0.100 µg L−1 for Co, from 0.20 to 1.98 µg L−1 for Cu, from <DL to 13.40 µg L−1 for Zn, from 0.25 to 0.48 µg L−1 for As, from 0.004 to 0.127 µg L−1 for Cd, from <DL to 0.195 µg L−1 for Sn, from <DL to 0.0277 µg L−1 for Cs, from <DL to 1.13 µg L−1 for Pb, from <DL to 0.0202 µg L−1 for Th, and from 0.27 to 0.75 µg L−1 for U. The concentrations of all major ions and trace elements in water were below the drinking water standards. CF values showed considerable and high contamination of samples with Al, Mn, Fe, Co, Cu, Cd, Sn, Pb, and Th. PLI values classified the majority of water samples as water with baseline levels of pollutants, and part of the samples was classified as either polluted or highly polluted.

Hydrogeochemical Characteristics and Evolution Processes of Karst Groundwater Affected by Multiple Influencing Factors in a Karst Spring Basin, Eastern China

Karst groundwater is an important water supply, especially in northern China. With the rapid development of China’s economy, anthropogenic activities have had a significant impact on karst groundwater formation, circulation and other processes. In this paper, the Baotu spring basin, which is closely related to anthropogenic activities, was selected as the research object to carry out a study of water chemical characteristics and evolutionary processes. And, mathematical statistics, Piper trilinear diagram, Gibbs diagram, and ion ratio methods were used to analyze the characteristics and evolution processes of groundwater. The results of this study show that the hydrogeochemical components of karst groundwater are mainly controlled by the weathering of rocks, mainly by the dissolution of carbonate rocks and silicates with the dominant cation of Ca2+ and the dominant anion of HCO3−. Considering the role of anthropogenic activities, including agricultural and industrial activities, the evolution process of karst groundwater is mainly controlled by hydrogeochemical effects such as mineral dissolution and filtration, the mixing of multiple water bodies, anthropogenic activities (domestic sewage, industrial and agricultural wastes), oxidation–reduction and cation alternating adsorption. Moreover, the influence of anthropogenic activities on the formation and evolution of karst groundwater gradually increases, leading to the rise in nitrate content in karst groundwater and accelerating carbonate rock dissolution. The research results of this paper can provide a favorable reference for environmental protection and research on karst groundwater in areas of intensive anthropogenic activity.

Exploring the Diversity and Antibiogram of the Soil around a Tertiary Care Hospital and a University Precinct in Southern India: A Pilot Study

Soil contains an enormous diversity of microorganisms and can act as a reservoir of antibiotic resistance determinants. This study identified and compared the bacterial diversity and the antimicrobial resistance profile of clinically-relevant isolates around a newly developed hospital and university precinct. Eight soil samples were collected, genomic DNA was extracted and 16S rRNA gene sequencing was performed. Bacterial isolates cultured from the soil were identified using MALDI-TOF. Antibiotic sensitivity testing (AST) was performed on a subset of isolates. The soil from both precincts were similarly diverse. Phylum Proteobacteria was prevalent in all samples and was the most abundant in one of the hospital sites. Cyanobacteria was abundant in two hospital sites closer to a sewage treatment plant. Bacterial diversity was only significantly different between two of the hospital sites. A total of 22 Gram-negative organisms were isolated by culture. AST revealed that the soil isolates from both precincts exhibited low resistance. The unidentified bacteria closer to the hospital precinct with human interactions possibly hints at the role of anthropogenic activities on the soil microbial diversity. The abundance of Proteobacteria (causing majority of human infections) and Cyanobacteria nearer to the hospital premises, comprising more immunocompromised and immunocompetent individuals, is concerning.

Geographic distribution of arsenic contamination in the Himalayan Rivers flowing through Pakistan: Implications for its natural source and effects of anthropogenic activities

Arsenic (As) in natural hydrological systems is known as a worldwide major environmental concern. A geochemical and sedimentological study was done to ascertain the origin and geographical distribution of As in surface water and fluvial sediment collected from the floodplains/basins of the River Indus and its four major tributaries that drain through the northern Pakistan. The hydrogeochemical compositions of all five rivers were similar with calcium (Ca2+) and bicarbonate (HCO3−) being the dominating ions. The concentration of As ranged from 0.62–24.05 μg/L (average 3.7 ± 3.5 μg/L, n = 61) in river water, 2.3–23.4 mg/kg (average 5.7 ± 3.9 mg/kg) in suspended sediment, and 2.0–13 mg/kg (average 4.13 ± 2.3 mg/kg) in fluvial sediment. Various approaches were used, including mineralogical, sequential extraction, geochemical, and statistical analyses to investigate the distribution, behavior, and potential sources of As in the sediment. The effect of geological factors on the distribution of As was also studied. No noticeable changes in the relative abundance of minerals were observed in the sediment at different locations along the river. Both mineralogical and statistical analyses showed that silicate minerals like muscovite, biotite, and chloride are the main As reservoir while oxides minerals like hematite and magnetite, which are minor components in the sediment are second largest As carrier. A geochemical baseline, using the normalization and cumulative frequency distribution curves was constructed for As. The estimated mean human contribution of As was 3.4% in the Indus River, 1.9% in the Jhelum River, 13.7% in the Chenab River, 17.5% in the Ravi River and 5.4% in the Sutlej River, indicating relatively higher effects of anthropogenic activity along the Chenab River and Ravi River. The almost negligible effects of anthropogenic activities were additionally confirmed through the pollution assessment parameters estimated from the geo-enrichment, contamination factors, and accumulation index analyses. The current data suggest that As transported by the Indus River and its major tributaries is accumulated in the sediment and is potentially incorporated in the sedimentary aquifers situated along the Indus Basin and surrounding areas. Based on the current study, it is concluded that the source of As is dominantly geogenic whereas the role of anthropogenic activities is considered negligible except along the Ravi River which showed relatively a higher percentage (17.5%) of human or industrial contribution.

An Invasive Ecological Study on the Flora of Soil Seed Bank and Standing Vegetation Across Diverse Anthropo-ecosystems in Indian Dry Tropics

Plant invasions in tropical ecosystems are being increasingly realized particularly in highly dynamic but fragile dry tropical ecosystems, where there is generally little ecological information on invasions in subterranean vegetation. The present study was carried out to understand the floristic composition of both seed bank and standing vegetation across a range of five diverse anthropo-ecosystems in an urban region in Indian dry tropics. A total of one hundred soil samples (each of size of 25cm×25cm from 0-5 cm and 5-10 cm depth) from five anthropic sites (vegetation of University campus, polluted Kali River bank, Brick kiln, Waste land and Road side) were analyzed for their taxonomic position, life form and bio-geographic origin of the seedling emergents in relation to the flora in standing vegetation. A total of 221 plant species (58% aliens, 34% of aliens of American origin, 75% weedy herbs) in standing vegetation spread over 54 families were recorded in standing vegetation of the study sites with more than 55% representation from eight dominant families led by Fabaceae, Poaceae and Asteraceae followed by Malvaceae, Amaranthaceae and Solanaceae. In contrast, a total of 81 seed bank flora (10 unidentified, 62% aliens, 43% of American origin, 87% herbs) distributed over 32 angiospermic families were recorded. While none of the seed bank vegetation at any site showed significant similarity with its standing vegetation indicating the minor role of seed bank flora in the regeneration of the standing plant communities above ground. However, a considerable similarity among seed banks and standing vegetation at other sites indicated a significant possible role of anthropogenic activities in the urban regions of Indian dry tropics, evinced by the largest proportion of grasses and herbs dominated by exotics, especially of American origin. These aliens through successful naturalization via seed banks may cause homogenization of floristic structure. In conclusion, the present study revealed a heavy scale of intrusion by the alien plants dominated by American elements into not only standing vegetation but also in seed banks across the anthropic sites in urban regions in Indian dry tropics which is likely to alter the standing vegetation floristic structure with a larger abundance of alien flora.

Vertical distribution and radiological risk assessment of natural radionuclides in the alluvial soil profile of south-west Punjab, India

Natural radionuclide levels are studied in alluvial sediments upto the depth of 900 cm. Eighteen profiles are selected from agricultural and undisturbed areas and analysed by gamma-ray spectrophotometer. Levels were found to vary significantly with depth and higher concentration is observed in agricultural samples till the depth of 600 cm and values are comparable after this depth, indicating role of anthropogenic activities on radionuclide enrichment in agricultural areas. However, value is higher than global average at both sites, indicating their geogenic presence. Elemental ratio and multi-statistical analysis are utilized to assess the behaviour of radionuclides involved. Radiological hazard risk assesment is also carried out.

Developing wetland landscape insecurity and hydrological security models and measuring their spatial linkages

The existing literature emphasized on the role of anthropogenic activities toward landscape insecurity of the wetlands, but in urban dominated infrastructurally advanced study area where hydrological transformation is very evident, how hydrological richness factors can control landscape insecurity was not well addressed. Therefore, the present study attempted to identify the spatial linkage between landscape insecurity and hydrological security of the wetland in a deltaic floodplain environment. 15 landscape metrics were employed for landscape insecurity and very basic hydrological phenomena of the wetlands like water presence frequency (WPF), depth of water, and seasonality were involved for hydrological security. Spatial modelling was performed with the machine learning (ML) algorithms and acceptable accuracy was obtained. Results showed on an average, 40% of the wetland area was under the insecure landscape category whereas, lower hydrological security prevailed over 60% of wetland area. A large portion of the hydrologically poor and insecure landscape of wetlands transformed to land. Landscape insecurity was found negatively associated with hydrological security. A slight positive trend was detected in the bheri (embankment of fishing) complex where few newer wetlands emerged due to manual regulation. Negative association exhibited poor hydrological security is a booster of landscape insecurity since it facilitates the spread of infrastructure causing landscape insecurity. The anthropogenic activities promoted the fragmentation and insecurity of wetlands in the outer region and simultaneously prevented the same and maintained greater hydrological security in the bheri complex gaining economic profit which argues for synchronizing conservation planning of the landscape with the local economy.

On the Role of Anthropogenic Activity and Sea‐Level‐Rise in Tidal Distortion on the Open Coast of the Yellow Sea Shelf

AbstractThis study investigates how varied coastline strategies and rising mean‐sea‐level influence tidal distortion along the open coast of the Yellow Sea shelf. The major contributors to tidal distortion were first identified. Then, the primary tidal constituents causing changes in tidal propagation and distortion in response to shoreline reconstruction management and near‐future sea‐level‐rise (SLR) were determined. The intrinsic mechanisms causing tidal duration asymmetry (TDA) were investigated and found to differ in various types of coastal systems. Specifically, the nonlinear tidal interaction between M2/M4, M2/S2/MS4 and K1/O1/M2 are the top three dominant contributors to TDA. The interactions between M2/M4 and M2/S2/MS4 are most sensitive to different coastline configurations and produce the largest evolution in tidal distortion. Two primary factors are (i) the location of the amphidromic point of the semidiurnal tides in the deep ocean, which controls the M2 and S2 energy fluxes into embayment, and (ii) the nondimensional amplitude (A/h), which importantly indicates tidal nonlinearity and determines shallow tide generation. For the coast with a progressive tidal system, tidal distortion and shallow‐water tide genesis depend mainly on the influx of semidiurnal tides from offshore, which is controlled by the position of the M2 amphidrome. For a coast with quasistanding tidal behavior, however, the scales and positions of tidal flats and shoals play vital roles in tidal distortion and the genesis of shallow‐water tides. Model simulations suggest that hardened shoreline or SLR could dampen the advection and bottom dissipation, thus reducing tidal distortion.

Modelling of underwater noise emissions by ships in Klaipėda Strait, Lithuania

One of the United Nations Sustainable Development Goals regarding “conservation and sustainable use of the oceans, seas, and marine resources” emphasizes the urgency of eliminating harmful effects on the sea and its biota, where the role of anthropogenic activities is crucial. The global trend of merchant shipping is increasing, thus enlarging underwater noise levels. As a result, greater noise can harm aquatic animals in their habitats. In the Baltic Sea, the underwater sound pressure levels are now being evaluated utilizing noise measurement, modelling, and mapping. In areas such as narrow ship passages, namely lagoons, channels, or straits, the ambient underwater noise modelling becomes very complex, even though these EU inland waters are regarded by legislation as part of the marine basin. For instance, the Klaipėda Channel (Klaipėda Strait), connecting the Baltic Sea and the Curonian Lagoon, is regarded by the national Lithuanian legislation as part of marine waters, where the environmental status should be evaluated according to the EU Maritime Strategy Framework Directive. In this narrow channel, an alternative to the modelling of ambient sound pressure levels can be applied to understand the long-term trends of vessel-sourced noise emissions. In this paper, an example of application of ship noise emission modelling for a narrow Klaipėda Harbour area is presented, along with the results obtained throughout 2015–2017. The modelled noise levels in the harbour area reached the median levels of 112.5 dB in 2015 and 102.6 dB re 1 µPa2 in 2017. The maximum emitted instantaneous sound pressure levels by ships reached 173.7 dB in 2015 and 179.4 dB re 1 µPa2 in 2017 in the area of interest.

Presence of Cyanotoxins in a Mexican Subtropical Monomictic Crater Lake

Microcystins (MCs) produced by cyanobacteria are a ubiquitous worldwide problem because some MCs can cause tumor formation and are hepatotoxic. In the Santa María del Oro crater lake, Mexico, plankton scums are recurrent during most of the year and are associated with cyanobacteria of the genera Microcystis spp. and Lyngbya spp. As some of these species are associated with the production of MCs and paralytic shellfish toxins (PSTs), samples from these scums and particulate matter were collected and analyzed for the main bloom species and toxins by a ultrahigh performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) and high performance liquid chromatography with fluorescence detection (HPLC-FLD). Results showed that the main bloom-forming species were Limnoraphis robusta and Microcystis aeruginosa, the presence of at least seven MC congeners and the absence of PSTs in the algae scums. The MCs identified were MC-WR, MC-LR, MC-LA, MC-HilR, MC-LF, MC-YR, and MC-LY. On a dry mass weight basis, MC concentrations were low and ranged between 0.15 and 6.84 μg/kg. Toxin profiles were dominated by MC-WR, MC-LR, and MC-LA, representing 94.5% of the total sample, with each analog contributing 39.8%, 38.1% and 16.5% by relative concentration, respectively. Two of the more hazardous congeners, MC-LR and MC-LA, represented 54.6% of the total MC concentration. MCs in particulate matter along the depth profile were not detected. The MC profile is linked to M. aeruginosa, and it represents the first quantitative MC congener description for this species from a Mexican water ecosystem. Since these mats are recurrent yearly, their effects on humans and wild fauna, and the possible role of anthropogenic activities that favor their presence and proliferation, need to be evaluated.

Sources and historical sedimentary record: Temporal variability of n-alkane and PAHs from the Yellow River Estuary, China

The composition and distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in suspended particulate matter (SPM) from the Yellow River and a sedimentary core from the Yellow River Estuary, China, were measured in order to determine environmental changes in the Yellow River Estuary on a regional scale. The concentration of n-alkane in SPM increased along the upper-middle-lower reaches of the Yellow River. The total concentrations of n-alkanes and PAHs in the core ranged from 0.04 to 0.86 μg g−1 (avg. 0.21 μg g−1), and from 0.04 to 0.29 μg g−1 (avg. 0.15 μg g−1) on a dry wt. basis, respectively. Understanding the temporal evolution of n-alkanes provide information on terrigenous versus aquatic productivity, oil exploration at the Shengli Oilfield, and channel diversion in the Yellow River. n-Alkanes in SPM were mainly derived from mixed sources, with terrigenous inputs dominating. PAHs in the sediment core were predominantly derived from coal and biomass combustion. The variation in PAHs levels throughout the core determines changes in energy use and socio-economic development. The temporal variability in n-alkane and PAHs and their molecular diagnostic ratios revealed a trend of regional environmental change and the role of anthropogenic activity in that environmental change.

Effects of water-borne copper and lead on metabolic and excretion rate of bahaii loach (Turcinoemacheilus bahaii)

Beyond the role of anthropogenic activities, natural sources of metal contaminations are still controversial, together counting, however, as a major threat to inland and coastal waters, becoming an even more prominent stressor for aquatic life. To address the effects of metals on the physiological response of fish, standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS) and factorial aerobic scope (FAS) as well as specific rate of ammonia excretion (Jamm) of Turcinoemacheilus bahaii were determined following different water-borne Cu2+ and Pb2+ treatments. Following LC50-96 h determination, 72 fish (BW = 1.153 ± 0.56 g and TL = 6.155 ± 0.97 cm) were exposed to different amounts of Cu2+ and Pb2+ in 9 different treatments (eight fish/treatment), including 0.910 mg l−1 Cu2+ for 24 h, 0.455 mg l−1 Cu2+ for 7d, 0.182 mg l−1 Cu2+ for 14d and 0.091 mg l−1 Cu2+ for 30 d as well as 124.430 mg l−1 Pb2+ for 24 h, 62.215 mg l−1 Pb2+ for 7d,12.443 mg l−1 Pb2+ for 14d, 6.221 mg l−1 Pb2+ for 30d and control. The SMR of fish was reduced following exposures to all Cu2+ and Pb2+ treatments (P < 0.05), except for 30d exposure as compared with the control. The MMR remained steady following all Cu2+ treatments while it was raised significantly (P < 0.05) following Pb2+ treatments at 7, 14 and 30d exposure. Although the AS showed a similar pattern to MMR, the FAS was elevated (P < 0.05) following all the treatments when compared with control. Lower Jamm were observed following all metals-treated fish in comparison with control (P < 0.05). In addition, higher (P < 0.05) levels of injuries were observed following all Cu2+ and Pb2+ treatments in gills and kidneys. The results suggest that Cu2+ and Pb2+ over the experimental period could impair the metabolic and excretory capacities, hence affecting the possible physiological performance of fish.

N-Alkanes in sediments from the Yellow River Estuary, China: Occurrence, sources and historical sedimentary record

A total of 21 surface sediments from the Yellow River Estuary (YRE) and a sediment core from the abandoned Old Yellow River Estuary (OYRE) were analyzed for n-alkanes using gas chromatography-mass spectrometry (GC-MS). n-Alkanes in the range C12-C33 and C13-C34 were identified in the surface sediments and the core, respectively. The homologous series were mainly bimodal distribution pattern without odd/even predominance in the YRE and OYRE. The total n-alkanes concentrations in the surface sediments ranged from 0.356 to 0.572mg/kg, with a mean of 0.434mg/kg on dry wt. basis. Evaluation of n-alkanes proxies indicated that the aliphatic hydrocarbons in the surface sediments were derived mainly from a petrogenic source with a relatively low contribution of submerged/floating macrophytes, terrestrial and emergent plants. The dated core covered the time period 1925–2012 and the mean sedimentation rate was ca. 0.5cm/yr. The total n-alkanes concentrations in the core ranged from 0.0394 to 0.941mg/kg, with a mean of 0.180mg/kg. The temporal evolution of n-alkanes reflected the historical input of aliphatic hydrocarbons and was consistent with local and regional anthropogenic activity. In general, the investigation on the sediment core revealed a trend of regional environmental change and the role of anthropogenic activity in environmental change.

Groundwater Arsenic Contamination in Semi-Urban Areas of Tando Muhammad Khan District: A Case Study from Deltaic Flood Plain of Sindh, Pakistan

&lt;em&gt;An attempt has been made to assess the arsenic contamination and role of anthropogenic activities on &lt;/em&gt;&lt;em&gt;its release in the groundwater of alluvial aquifers occurring on deltaic flood plain of Indus River. &lt;/em&gt;&lt;em&gt;Groundwater collected from three semi-urban union councils of Tando Muhammad Khan district &lt;/em&gt;&lt;em&gt;revealed that the groundwater has bad quality for drinking which varied in the order of UC-2 &amp;gt; UC-1 &lt;/em&gt;&lt;em&gt;&amp;gt; UC-3. Anoxia is prevalent in the aquifers of study area which is indicated by high HCO3 and low&lt;/em&gt;&lt;br /&gt;&lt;em&gt;NO3 and Fe contents. However, the natural concentration of sulphate (Mean range: 105-450 mg/L) in &lt;/em&gt;&lt;em&gt;the groundwater of study area suggested that anoxia has not reached the stage where sulphate is &lt;/em&gt;&lt;em&gt;consumed by SO4 reducing bacteria for organic matter decomposition. On the other hand elevated &lt;/em&gt;&lt;em&gt;content of Na and Cl coupled with pathogenic bacteria occurrence indicated that sewage mixing is &lt;/em&gt;&lt;em&gt;common in the study area. Elevated arsenic is reported from all there union councils which varied in&lt;/em&gt;&lt;br /&gt;&lt;em&gt;the order of UC2 &amp;gt; UC 1 &amp;gt; UC3. Arsenic is mobilized from host sediments (clays/biotite) due to the &lt;/em&gt;&lt;em&gt;prevalence of reduced environment caused by organic matter decomposition and triggered by sewage&lt;/em&gt;&lt;br /&gt;&lt;em&gt;mixing.&lt;/em&gt;

Multi-Criteria Assessment of Land Cover Dynamic Changes in Halgurd Sakran National Park (HSNP), Kurdistan Region of Iraq, Using Remote Sensing and GIS

Halgurd Sakran National Park (HSNP) is Iraq’s first designated national park, located in the Kurdistan Region, which has suffered multiple armed conflicts over the past decades. This study assesses how vegetation dynamics have affected the landscape structure and composition of the core zone of the park over the last 31 years. Spatio-temporal changes in land cover were mapped for three points in time using remote sensing, geographic information systems (GIS), and landscape metrics. Land cover changes were mapped using random forest classifications of satellite images from Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 LDCM acquired in 1984, 1998, and 2015. Five landscape pattern metrics were analysed at class and landscape levels in order to quantify landscape patterns arising from land use and land cover (LULC) change in HSNP using FRAGSTATS 4.2. These landscape pattern metrics were patch metrics, area metrics, shape metrics interspersion/juxtaposition and contagion metrics and diversity metrics. Significant changes in cultivated areas after 1991 were observed, which indicate the role of anthropogenic activities in land cover change. Areas of bare surface and forest lands declined and became more fragmented in 1984 and 1998 while, at the same time, cultivated areas increased, with a continuing fragmentation of pasture land. Internal migration of people was one of the major drivers of LULC change. The results reveal that significant LULC changes in terms of composition and spatial structure over the 31-year period have occurred in the designated protected area. Landscape metrics were able to assess the trend of spatial patchiness over the studied period. A discussion of the significance of changes in land use systems for understanding the causes and consequences of change is provided.

Historical Land‐use and Vegetation Change in Northern Kwazulu‐Natal, South Africa

AbstractThe role of anthropogenic activity is increasingly recognized as an agent of environmental change. Photographs, taken more than 130 years ago in KwaZulu‐Natal, South Africa, show a very different landscape to that viewed today. In attempting to understand some of the dynamics behind the changes in the landscape, we explored the history of land‐use in communal rangelands in KwaZulu‐Natal from the arrival of Iron Age man through to modern practices. Communal farming is frequently cited as a major cause of environmental degradation. Traditional lifestyles have been eroded by social, political and economic changes since the arrival of European explorers and settlers in the early 1800s. This may have contributed to encroachment by woody plants into the open savannas and grasslands of KwaZulu‐Natal in recent times because of increased grazing pressure and, perhaps reduced fires. Furthermore, there is decreasing dependence on wood for everyday needs due to the increased availability of electricity. Interviews with a number of community members indicate that they have noted a change in climate and in vegetation structure. Their observations have been confirmed by climate data and historic photographs. Environmental planners need to view change in a holistic manner, taking cognisance not only of the physical changes but also of the history of land‐use and human needs and to give credence to community perceptions. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Potassium: a neglected nutrient in global change

AbstractAimPotassium (K) is the second most abundant nutrient in plant photosynthetic tissues after nitrogen (N). Thousands of physiological and metabolic studies in recent decades have established the fundamental role of K in plant function, especially in water‐use efficiency and economy, and yet macroecological studies have mostly overlooked this nutrient.MethodsWe have reviewed available studies on the content, stoichiometry and roles of K in the soil–plant system and in terrestrial ecosystems. We have also reviewed the impacts of global change drivers on K content, stoichiometry and roles.ConclusionsThe current literature indicates that K, at a global level, is as limiting as N and phosphorus (P) for plant productivity in terrestrial ecosystems. Some degree of K limitation has been seen in up to 70% of all studied terrestrial ecosystems. However, in some areas atmospheric K deposition from human activities is greater than that from natural sources. We are far from understanding the K fluxes between the atmosphere and land, and the role of anthropogenic activities in these fluxes. The increasing aridity expected in wide areas of the world makes K more critical through its role in water‐use efficiency. N deposition exerts a strong impact on the ecosystem K cycle, decreasing K availability and increasing K limitation. Plant invasive success is enhanced by higher soil K availability, especially in environments without strong abiotic stresses. The impacts of other drivers of global change, such as increasing atmospheric CO2 or changes in land use, remain to be elucidated. Current models of the responses of ecosystems and carbon storage to projected global climatic and atmospheric changes are now starting to consider N and P, but they should also consider K, mostly in arid and semi‐arid ecosystems.

The role of anthropogenic activities in karst spring discharge volatility

AbstractThe traditional hydrological time series methods tend to focus on the mean of whichever variable is analysed but neglect its time‐varying variance (i.e. assuming the variance remains constant). The variances of hydrological time series vary with time under anthropogenic influence. There is evidence that extensive well drilling and groundwater pumping can intercept groundwater run‐off and consequently induce spring discharge volatility or variance varying with time (i.e. heteroskedasticity). To investigate the time‐varying variance or heteroskedasticity of spring discharge, this paper presents a seasonal autoregressive integrated moving average with general autoregressive conditional heteroskedasticity (SARIMA‐GARCH) model, whose the SARIMA model is used to estimate the mean of hydrological time series, and the GARCH model estimates its time‐varying variance. The SARIMA‐GARCH model was then applied to the Xin'an Springs Basin, China, where extensive groundwater development has occurred since 1978 (e.g. the average annual groundwater pumping rates were less than 0.20 m3/s in the 1970s, reached 1.20 m3/s at the end of the 1980s, surpassed 2.0 m3/s in the 1990s and exceeded 3.0 m3/s by 2007). To identify whether human activities or natural stressors caused the heteroskedasticity of Xin'an Springs discharge, we segmented the spring discharge sequence into two periods: a predevelopment stage (i.e. 1956–1977) and a developed stage (i.e. 1978–2012), and set up the SARIMA‐GARCH model for the two stages, respectively. By comparing the models, we detected the role of human activities in spring discharge volatility. The results showed that human activities caused the heteroskedasticity of the Xin'an Spring discharge. The predicted Xin'an Springs discharge by the SARIMA‐GARCH model showed that the mean monthly spring discharge is predicted to continue to decline to 0.93 m3/s in 2013, 0.67 m3/s in 2014 and 0.73 m3/s in 2015. Copyright © 2014 John Wiley &amp; Sons, Ltd.