Spatiotemporal evolution of dissolved organic matter (DOM) and its response to environmental factors and human activities.

The South-to-North Water Diversion East Project (SNWDP-E) is an effective way to realize the optimal allocation of water resources in China. The North Dasha River (NDR) is the reverse recharge section that receives water from the Yufu River to the Wohushan Reservoir transfer project line in the SNWDP. However, the dissolved organic matter (DOM) evolution mechanism of seasonal water transfer projects on tributary waters has not been fully elucidated. In this paper, the NDR is the main object, and the changes in the composition and distribution of spectral characteristics during the winter water transfer period (WT) as well as during the summer non-water transfer period (NWT) are investigated by parallel factor analysis (PARAFAC). The results showed that the water connectivity caused by water transfer reduces the environmental heterogeneity of waters in the basin, as evidenced by the ammonia nitrogen (NH4+-N) and total phosphorus (TP) in the water body were significantly lower (p<0.05, p<0.01) during the water transfer period than the non-water transfer period. In addition, the fluorescence intensity of DOM was significantly lower in the WT than the NWT (p<0.05) and was mainly composed of humic substances generated from endogenous sources with high stability. While the NWT was disturbed by anthropogenic activities leading to significant differences in DOM composition in different functional areas. Based on the redundancy analysis (RDA) and multiple regression analysis, it was found that the evolution of the protein-like components is dominated by chemical oxygen demand (COD) and NH4+-N factors during the WT. While the NWT is mainly dominated by total nitrogen (TN) and TP factors for the evolution of the humic-like components. This study helps to elucidate the impact of water transfer projects on the trunk basin and contribute to the regulation and management of inter-basin water transfer projects.

Improving Small-Scale Human Action Recognition Performance Using a 3D Heatmap Volume.

In recent years, skeleton-based human action recognition has garnered significant research attention, with proposed recognition or segmentation methods typically validated on large-scale coarse-grained action datasets. However, there remains a lack of research on the recognition of small-scale fine-grained human actions using deep learning methods, which have greater practical significance. To address this gap, we propose a novel approach based on heatmap-based pseudo videos and a unified, general model applicable to all modality datasets. Leveraging anthropometric kinematics as prior information, we extract common human motion features among datasets through an ad hoc pre-trained model. To overcome joint mismatch issues, we partition the human skeleton into five parts, a simple yet effective technique for information sharing. Our approach is evaluated on two datasets, including the public Nursing Activities and our self-built Tai Chi Action dataset. Results from linear evaluation protocol and fine-tuned evaluation demonstrate that our pre-trained model effectively captures common motion features among human actions and achieves steady and precise accuracy across all training settings, while mitigating network overfitting. Notably, our model outperforms state-of-the-art models in recognition accuracy when fusing joint and limb modality features along the channel dimension.

Encapsulated in sediments: eDNA deciphers the ecosystem history of one of the most polluted European marine sites.

The Anthropocene is characterized by dramatic ecosystem changes driven by human activities. The impact of these activities can be assessed by different geochemical and paleontological proxies. However, each of these proxies provides only a fragmentary insight into the effects of anthropogenic impacts. It is highly challenging to reconstruct, with a holistic view, the state of the ecosystems from the preindustrial period to the present day, covering all biological components, from prokaryotes to multicellular eukaryotes. Here, we used sedimentary ancient DNA (sedaDNA) archives encompassing all trophic levels of biodiversity to reconstruct the two century-natural history in Bagnoli-Coroglio (Gulf of Pozzuoli, Tyrrhenian Sea), one of the most polluted marine-coastal sites in Europe. The site was characterized by seagrass meadows and high eukaryotic diversity until the beginning of the 20th century. Then, the ecosystem completely changed, with seagrasses and associated fauna as well as diverse groups of planktonic and benthic protists being replaced by low diversity biota dominated by dinophyceans and infaunal metazoan species. The sedaDNA analysis revealed a five-phase evolution of the area, where changes appear as the result of a multi-level cascade effect of impacts associated with industrial activities, urbanization, water circulation and land-use changes. The sedaDNA allowed to infer reference conditions that must be considered when restoration actions are to be implemented.

Improving cleaner production of human activities to mitigate total petroleum hydrocarbons accumulation in coastal environment.

The marine coast is an important ecological transitional boundary but easily suffers from human intervention. Total petroleum hydrocarbons (TPHs) are ubiquitous along the coast. However, the influence of anthropogenic and natural factors on TPHs distribution remains unclear. This study sampled surficial sediment (N = 243) from the coasts of the largest peninsula-Leizhou Peninsula, in Southern China. We found that land-based discharge, sea traffic, and sediment type significantly (p < 0.05) drive the accumulation of TPHs. We observed that TPHs increased by 1.036 µg · g-1 (exp[αi] = exp. [0.0355]) of its original value with the addition of one more boat on the wharf. Although the average TPHs were at a moderate level (124.68, ND-1536.14, µg · g-1) and risk, 'Blue Carbon' ecosystems, i.e., mangroves (224.84, ND - 1441.13, µg · g-1, p < 0.001) were more severely polluted. Cleaner production policy should be applied to mitigate TPHs discharging trend from coastal areas.

WMNN: Wearables-Based Multi-Column Neural Network for Human Activity Recognition.

In recent years, human activity recognition (HAR) technologies in e-health have triggered broad interest. In literature, mainstream works focus on the body's spatial information (i.e. postures) which lacks the interpretation of key bioinformatics associated with movements, limiting the use in applications requiring comprehensively evaluating motion tasks' correctness. To address the issue, in this article, a Wearables-based Multi-column Neural Network (WMNN) for HAR based on multi-sensor fusion and deep learning is presented. Here, the Tai Chi Eight Methods were utilized as an example as in which both postures and muscle activity strengths are significant. The research work was validated by recruiting 14 subjects in total, and we experimentally show 96.9% and 92.5% accuracy for training and testing, for a total of 144 postures and corresponding muscle activities. The method is then provided with a human-machine interface (HMI), which returns users with motion suggestions (i.e. postures and muscle strength). The report demonstrates that the proposed HAR technique can enhance users' self-training efficiency, potentially promoting the development of the HAR area.

Human activities have reduced plant diversity in eastern China over the last two millennia.

Understanding the history and regional singularities of human impact on vegetation is key to developing strategies for sustainable ecosystem management. In this study, fossil and modern pollen datasets from China are employed to investigate temporal changes in pollen composition, analogue quality, and pollen diversity during the Holocene. Anthropogenic disturbance and vegetation's responses are also assessed. Results reveal that pollen assemblages from non-forest communities fail to provide evidence of human impact for the western part of China (annual precipitation less than 400 mm and/or elevation more than 3000 m.a.s.l.), as inferred from the stable quality of modern analogues, principal components, and diversity of species and communities throughout the Holocene. For the eastern part of China, the proportion of fossil pollen spectra with good modern analogues increases from ca. 50% to ca. 80% during the last 2 millennia, indicating an enhanced intensity of anthropogenic disturbance on vegetation. This disturbance has caused the pollen spectra to become taxonomically less diverse over space (reduced abundances of arboreal taxa and increased abundances of herbaceous taxa), highlighting a reduced south-north differentiation and divergence from past vegetation between regions in the eastern part of China. We recommend that care is taken in eastern China when basing the development of ecosystem management strategies on vegetation changes in the region during the last 2000 years, since humans have significantly disturbed the vegetation during this period.

Nutrient budgets for the Bohai Sea: Implication for ratio imbalance of nitrogen to phosphorus input under intense human activities.

Eutrophication is a global problem for coastal ecosystems, one that the Bohai Sea (BHS), China, is severely afflicted by due to rapid economic and social development over the last forty years. For sustainable nutrients management in the BHS, comprehensive budgets for Nitrogen (N) and Phosphorus (P) was characterized in 2017, and the relative contributions of river input, submarine fresh groundwater discharge, atmospheric deposition, sediment diffusion, and exchange with the Yellow Sea were quantified. The annual N and P fluxes into the BHS were 362 × 103 t and 10.4 × 103 t, respectively. The terrigenous N inputs occupied the highest proportion, while the largest P input was from sediment diffusion. The ratio of N:P was 77 for total external inputs, while that of the Yellow River was 680; both exceeded the Redfield ratio, indicating an imbalance in the nutrient structure and a P limitation in the BHS.

Dynamic characteristics of net anthropogenic phosphorus input and legacy phosphorus reserves under high human activity - A case study in the Jianghan Plain.

The increase of phosphorus (P) input related to human activities is one of the main reasons for eutrophication. Notably, in areas with high population densities and intensive agricultural activities, eutrophication has occurred frequently in the Jianghan Plain, so quantitative evaluation of anthropogenic P input is of great significance for the formulation of P pollution control measures. This study estimated net anthropogenic P input (NAPI), riverine total P exports (TP exports), and the pool of P stored in the terrestrial system (legacy P reserves) at the county scale from 1990 to 2019 in the Jianghan Plain. The results showed that NAPI increased from 2645 kg·km-2·yr-1 in 1991 to 5812 kg·km-2·yr-1 in 2014, and then decreased to 4509 kg·km-2·yr-1 in 2019. Non-point sources were the main form of NAPI, of which 75-96% came from agricultural systems. Meanwhile, P fertilizer input was the largest source of NAPI. It is worth noting that the contribution of seed P input in some counties, such as Jiangling County, is relatively high, even exceeding that of net food/feed P input. The P fertilizer application and livestock density were the main drivers for NAPI change. Only 3% of NAPI was exported into rivers, so a large amount of legacy P accumulated in the terrestrial system. An empirical model incorporating NAPI components, cultivated land area ratio, and annual precipitation was established. Based on this model, the average contribution of annual NAPI and the sum of legacy P and natural background sources to TP exports were calculated to be 71% and 29%, respectively. So it is necessary to control P pollution by improving fertilizer use efficiency and enhancing manure management. The results provide a scientific basis for targeted solutions to the sources of P nutrient and its control measures in the middle reach of the Yangtze River.

Federated Learning via Augmented Knowledge Distillation for Heterogenous Deep Human Activity Recognition Systems.

Deep learning-based Human Activity Recognition (HAR) systems received a lot of interest for health monitoring and activity tracking on wearable devices. The availability of large and representative datasets is often a requirement for training accurate deep learning models. To keep private data on users' devices while utilizing them to train deep learning models on huge datasets, Federated Learning (FL) was introduced as an inherently private distributed training paradigm. However, standard FL (FedAvg) lacks the capability to train heterogeneous model architectures. In this paper, we propose Federated Learning via Augmented Knowledge Distillation (FedAKD) for distributed training of heterogeneous models. FedAKD is evaluated on two HAR datasets: A waist-mounted tabular HAR dataset and a wrist-mounted time-series HAR dataset. FedAKD is more flexible than standard federated learning (FedAvg) as it enables collaborative heterogeneous deep learning models with various learning capacities. In the considered FL experiments, the communication overhead under FedAKD is 200X less compared with FL methods that communicate models' gradients/weights. Relative to other model-agnostic FL methods, results show that FedAKD boosts performance gains of clients by up to 20 percent. Furthermore, FedAKD is shown to be relatively more robust under statistical heterogeneous scenarios.

Emerging themes in Population Consequences of Disturbance models.

Assessing the non-lethal effects of disturbance from human activities is necessary for wildlife conservation and management. However, linking short-term responses to long-term impacts on individuals and populations is a significant hurdle for evaluating the risks of a proposed activity. The Population Consequences of Disturbance (PCoD) framework conceptually describes how disturbance can lead to changes in population dynamics, and its real-world application has led to a suite of quantitative models that can inform risk assessments. Here, we review PCoD models that forecast the possible consequences of a range of disturbance scenarios for marine mammals. In so doing, we identify common themes and highlight general principles to consider when assessing risk. We find that, when considered holistically, these models provide valuable insights into which contextual factors influence a population's degree of exposure and sensitivity to disturbance. We also discuss model assumptions and limitations, identify data gaps and suggest future research directions to enable PCoD models to better inform risk assessments and conservation and management decisions. The general principles explored can help wildlife managers and practitioners identify and prioritize the populations most vulnerable to disturbance and guide industry in planning activities that avoid or mitigate population-level effects.

The human dimension of biodiversity changes on islands.

Islands are among the last regions on Earth settled and transformed by human activities, and they provide replicated model systems for analysis of how people affect ecological functions. By analyzing 27 representative fossil pollen sequences encompassing the past 5000 years from islands globally, we quantified the rates of vegetation compositional change before and after human arrival. After human arrival, rates of turnover accelerate by a median factor of 11, with faster rates on islands colonized in the past 1500 years than for those colonized earlier. This global anthropogenic acceleration in turnover suggests that islands are on trajectories of continuing change. Strategies for biodiversity conservation and ecosystem restoration must acknowledge the long duration of human impacts and the degree to which ecological changes today differ from prehuman dynamics.

Biocultural evidence of precise manual activities in an Early Holocene individual of the high-altitude Peruvian Andes.

OBJECTIVES: Cuncaicha, a rockshelter site in the southern Peruvian Andes, has yielded archaeological evidence for human occupation at high elevation (4,480 masl) during the Terminal Pleistocene (12,500-11,200 cal BP), Early Holocene (9,500-9,000 cal BP), and later periods. One of the excavated human burials (Feature 15-06), corresponding to a middle-aged female dated to ~8,500 cal BP, exhibits skeletal osteoarthritic lesions previously proposed to reflect habitual loading and specialized crafting labor. Three small tools found in association with this burial are hypothesized to be associated with precise manual dexterity. MATERIALS AND METHODS: Here, we tested this functional hypothesis through the application of a novel multivariate methodology for the three-dimensional analysis of muscle attachment surfaces (entheses). This original approach has been recently validated on both lifelong-documented anthropological samples as well as experimental studies in nonhuman laboratory samples. Additionally, we analyzed the three-dimensional entheseal shape and resulting moment arms for muscle opponens pollicis. RESULTS: Results show that Cuncaicha individual 15-06 shows a distinctive entheseal pattern associated with habitual precision grasping via thumb-index finger coordination, which is shared exclusively with documented long-term precision workers from recent historical collections. The separate geometric morphometric analysis revealed that the individual's opponens pollicis enthesis presents a highly projecting morphology, which was found to strongly correlate with long joint moment arms (a fundamental component of force-producing capacity), closely resembling the form of Paleolithic hunter-gatherers from diverse geo-chronological contexts of Eurasia and North Africa. DISCUSSION: Overall, our findings provide the first biocultural evidence to confirm that the lifestyle of some of the earliest Andean inhabitants relied on habitual and forceful precision grasping tasks.

Association between coffee consumption and functional disability in older US adults.

The effect of coffee consumption on functional disability has been scarcely investigated. Thus, this study aimed to examine the association between coffee consumption and functional disability in older American adults. Participants (≥60 years old, n 7704) were from the National Health and Nutrition Examination Survey 2007-2016. Coffee consumption was assessed through two 24-h dietary recall interviews. Five domains of functional disability including lower extremity mobility (LEM), general physical activity (GPA), leisure and social activities (LSA), activities of daily living (ADL) and instrumental activities of daily living (IADL) were self-reported. Age- and multivariate-adjusted logistic regression models and restricted cubic spline analyses were used. Total coffee consumption was inversely associated with LEM, GPA, LSA and IADL disability. Compared with non-drinkers of total coffee, those who consumed ≥2 cups/d reported lower odds of LEM (OR 0·67, 95 % CI 0·50, 0·91), GPA (OR 0·65, 95 % CI 0·47, 0·88), LSA (OR 0·61, 95 % CI 0·45, 0·83) and IADL (OR 0·59, 95 % CI 0·44, 0·78) disability. The dose-response analyses confirmed these relationships. Intake of ≥2 cups/d caffeinated coffee was also inversely linked to GPA (OR 0·67, 95 % CI 0·48, 0·92), LSA (OR 0·66, 95 % CI 0·46, 0·93) and IADL (OR 0·57, 95 % CI 0·43, 0·75) disability, whereas the inverse association of 2+ cups/d decaffeinated coffee was only on LEM (OR 0·43, 95 % CI 0·23, 0·81) and LSA (OR 0·39, 95 % CI 0·16, 0·94) disability. The present study suggested that coffee consumption was inversely associated with functional disability in older American adults. Those associations of diverse coffee types differed across domains of functional disability.

Split-based points from the Swabian Jura highlight Aurignacian regional signatures.

The systematic use of antlers and other osseous materials by modern humans marks a set of cultural and technological innovations in the early Upper Paleolithic, as is seen most clearly in the Aurignacian. Split-based points, which are one of the most common osseous tools, are present throughout most regions where the Aurignacian is documented. Using results from recent and ongoing excavations at Geißenklösterle, Hohle Fels and Vogelherd, we nearly tripled the sample of split-based points from 31 to 87 specimens, and thereby enhance our understanding of the technological economy surrounding the production of osseous tools. Aurignacian people of the Swabian Jura typically left spit-based points at sites that appear to be base camps rich with numerous examples of personal ornaments, figurative art, symbolic imagery, and musical instruments. The artifact assemblages from SW Germany highlight a production sequence that resembles that of SW France and Cantabria, except for the absence of tongued pieces. Our study documents the life histories of osseous tools and demonstrates templates for manufacture, use, recycling, and discard of these archetypal artifacts from the Aurignacian. The study also underlines the diversified repertoire of modern humans in cultural and technological realms highlighting their adaptive capabilities.

Redefining shared symbolic networks during the Gravettian in Western Europe: New data from the rock art findings in Aitzbitarte caves (Northern Spain).

The renewal of the archaeological record, mainly through the discovery of unpublished sites, provides information that sometimes qualifies or even reformulates previous approaches. One of the latter cases is represented by the three new decorated caves found in 2015 in Aitzbitarte Hill. Their exhaustive study shows the presence of engraved animals, mainly bison, with formal characteristics unknown so far in the Palaeolithic art of the northern Iberian Peninsula. However, parallels are located in caves in southern France such as Gargas, Cussac, Roucadour or Cosquer. All of them share very specific graphic conventions that correspond to human occupations assigned basically to the Gravettian cultural complex. The new discovery implies the need to reformulate the iconographic exchange networks currently accepted, as well as their correspondence with other elements of the material culture at the same sites. Thus, we have carried out a multiproxy approach based in statistical analysis. The updated data reveals a greater complexity in artistic expression during the Gravettian that had not been considered so far, and also challenges the traditional isolation that had been granted to Cantabrian symbolic expressions during pre-Magdalenian times.

Environmental interactions between people and birds in semiarid lands of the Zapotitlán Valley, Central Mexico.

BACKGROUND: Birds have been among the most important element in lives of humans around the world, due to their presence and abundance in practically all ecosystems. Zapotitlán Salinas, a community of the Tehuacán Valley, has been a site of interest for studying ecology of bird communities, but no previous studies addressing the relationship between humans and birds have been conducted in the area. Based on their local knowledge, people of the area shape the use and conservation of local bird fauna diversity, which is being maintained or lost under the influence of factors like commerce, tourism, agriculture intensification or abandonment, public policies for conservation, environmental changes, among others. This study aims to analyze the patterns of interactions between humans and birds in a context of high biocultural diversity with a long history and facing the environmental and social challenges of semiarid areas. METHODS: Ecological sampling for documenting bird species richness was conducted from November 2015 to May 2017 in three transects that included agroforestry systems, forests, and fallow agricultural land. The method of counting by fixed radius points at 16 points within the study systems was used. Thirty in-depth interviews were conducted with local people who own land in the study areas by random sampling and choosing experts of Zapotitlán Salinas, Puebla, a semiarid natural protected area and, since 2019, recognized as Mixed World Heritage. Some visitor guides of the Helia Bravo Hollis Botanical Garden who are member of the community and local people who dedicated part of their time to catching birds were considered as local experts. They have experience in identifying birds through bird watching and listening to bird songs, as well as their knowledge on behavior and habits of the bird species occurring in their locality. We in addition conducted free listing of bird species recognized by people and interviews on ecological aspects, forms of use, and management of birds using a photographic catalog as visual stimulus. The following aspects were addressed with local people: (i) the bird species of Zapotitlán recognized by them; (ii) the biological, ecological, and behavioral knowledge about these species; (iii) the description of practices of use and management of these animals; (iv) the perceived changes regarding presence and abundance of the wild birds recognized; and (v) the regulations of these practices and uses. RESULTS: Through the ecological sampling, we identified 89 bird species, a number representing nearly 68% of all species reported for the Zapotitlán Valley. The species recorded belong to 61 genera, 26 families, and 11 orders. Local people interviewed recognized 62 morphospecies occurring in their territory, and designated them with 50 local names. The interactions of local people with birds and the knowledge related to habitats and habits varied according to people's daily life activities and the ways of inter-generational transmission of knowledge. The interactions identified respond to several motivations. The most intense are those of utilitarian nature (three types of use are recognized: nutritional, medicinal, and ornamental), while other less notorious but equally relevant are those related to the awareness and conservation of biological diversity, and aesthetic appreciation of nature. Also relevant are those interactions shaped by the people's worldview since some species are interpreted as climatic environmental predictors, amulets, or omens. CONCLUSIONS: To understand the various human-bird environmental interactions, it is necessary not only to address the utilitarian assessment that species have in a specific place but also those associated with cultural expressions and the connection between these aspects. Lifestyles, traditions, and beliefs model intangible forms of use, such as the interpretation of climate predictors. Ancient roles of birds in local culture are ongoing, and new demand of ornamental birds from cities influences catching activities but local and regional regulations have contributed to maintain them below a critical level.

Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions.

Atmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era1. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate2,3. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century4,5. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year)2,3 between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year6,7. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago8, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)-an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions9,10.

'Social screens' and 'the mainstream': longitudinal competitors of non-organized physical activity in the transition from childhood to adolescence.

BACKGROUND: Physical activity (PA) tends to decline during late childhood and adolescence. In Australia, this decline has been shown to occur particularly in non-organized PA (e.g. active play and informal sport). Using a social marketing approach, segments of youth may be identified and targeted based on their profile of alternative activities that compete with non-organized PA during the transition to adolescence. The objectives of this study were to identify and describe segments of youth whose participation in non-organized PA declined between 11 and 13 years, based on changes in other potential competing activities during this period. METHODS: Data were sourced from Waves 4 and 5 of the Longitudinal Study of Australian Children. Participation in non-organized PA and thirteen alternative activities (e.g. video games, homework, sleep) were measured using 24-h time-use diaries. Analyses were limited to participants whose non-organized PA had declined between 11 and 13 years (n = 1043). Two-stage cluster analysis was conducted and segments were described using chi-square and t-tests. RESULTS: Among the analytic sample, average non-organized PA participation declined by 87 min/day between 11y and 13y (p < 0.001). Two segments were identified (κ = 0.66). The 'Social Screens' segment (n = 143) had large increases in texting, emailing and social media use (+ 56 min/day, p < 0.001) and other internet use (+ 32 min/day, p < 0.001). Conversely, 'the Mainstream' segment (n = 900) had smaller increases in a wider range of activities, including other PA (organized PA, active transport, active chores/work) (+ 16.0 min/day, p < 0.001), homework/study (+ 9.5 min/day, p < 0.001) and electronic gaming (+ 6.7 min/day, p < 0.05). 'Social Screens' were more likely to attend public school, live in urban areas and have more advanced pubertal development (girls only). 'The Mainstream' were more likely to participate in PA and out-of-school activities. CONCLUSIONS: The 'Social Screens' segment had a much larger increase in texting, emailing, social media and other internet use, and lower participation in overall PA and out-of-school activities, compared with 'the Mainstream'. Future research may trial PA promotion strategies to replace benefits that this segment may seek in competing activities (e.g. social PA apps).

Modeling phosphorus sources and transport in a headwater catchment with rapid agricultural expansion.

Increasing riverine phosphorus (P) levels in headwaters due to expanded and intensified human activities are worldwide concerns, because P is a well-known limiting nutrient for freshwater eutrophication. Here we adopt the conceptual framework of the SPAtially Referenced Regressions On Watershed attributes (SPARROW) model to describe total phosphorus (TP) sources and transport in a headwater watershed undergoing rapid agricultural expansion in the upper Taihu Lake Basin, China. Our models, which include variables for land cover, river length, runoff depth, and pond density, explain 94% of the spatio-temporal variability in TP loads. Agricultural lands contribute the largest percentage (61%) of the TP loads delivered downstream, followed by forestland (21%) and urban land (18%). Future agricultural expansion to 15% of the total basin area is possible, which could lead to a 50% increase in TP loads. According to our analysis, an average of 24% of the total P export from the watershed landscape was intercepted in ponds. The exported amount was subsequently retained by tributaries and along the mainstem river, accounting for 14% and 43% of their inflowing loads, respectively. The remaining ∼6 tons yr-1 of TP was eventually transported into Tianmu Lake, in Southeastern China. The model identified several sub-catchments as hotspots of TP loss and thus logical sites for targeted management. Our study underscores the significance of agricultural expansion as a factor that can exacerbate headwater TP pollution, highlighting the importance of landscapes to buffer TP losses from sensitive hilly catchments. This also points to a need for an integrated management strategy that considers the spatial-varying P sources and associated transport of TP in precious headwater resources.