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Mining activities cause severe nitrogen pollution in watersheds, yet our understanding of the transport pathways, transformation processes, and control mechanisms of nitrate (NO3–) in these areas is limited. Based on nearly 4-year observations of groundwater and river in China’s largest ion-adsorption rare earth mining watershed, we revealed the dynamics of NO3–and its drivers using stoichiometry-based load model, molecular biological, and multi-isotope approaches. Results indicated that the NO3–dynamics were jointly controlled by sources (precipitation, terrestrial inputs, and sediment supply) and processes (hydrological and biological). The monthly NO3–export load from the 444.4 km2watershed was 3.72 × 105kg. Groundwater (36 ± 26%) and soil nitrogen (25 ± 17%) were the primary exogenous sources of NO3–. Baseflow was the main hydrological pathway for legacy nitrogen into the river, contributing 66.8% of the NO3–load. Coupled nitrification-denitrification were key biological processes affecting the NO3–transformation, with denitrification contributing 58%. Burkholderiawere most associated with NO3–transformation. Dissolved organic carbon and oxygen were major drivers affecting the NO3–production and consumption. This study highlights effective control and management strategies for nitrogen pollution in mining-affected watersheds, considering not only reducing nitrogen inputs but also integrating hydrological pathways and nitrogen transformation mechanisms.

Autonomous sensory meridian response (ASMR) describes an atypical multisensory experience of calming, tingling sensations in response to a specific subset of social audiovisual triggers. To date, the electrophysiological (EEG) correlates of ASMR remain largely unexplored. Here we sought to provide source-level signatures of oscillatory changes induced by this phenomenon and investigate potential decay effects—oscillatory changes in the absence of self-reported ASMR. We recorded brain activity using EEG as participants watched ASMR-inducing videos and self-reported changes in their state: no change (Baseline); enhanced relaxation (Relaxed); and ASMR sensations (ASMR). Statistical tests in the sensor-space were used to inform contrasts in the source-space, executed with beamformer reconstruction. ASMR modulated oscillatory power by decreasing high gamma (52–80 Hz) relative to Relaxed and by increasing alpha (8–13 Hz) and decreasing delta (1–4 Hz) relative to Baseline. At the source level, ASMR increased power in the low-mid frequency ranges (8–18 Hz) and decreased power in high frequency (21–80 Hz). ASMR decay effects reduced gamma (30–80 Hz) and in the source-space reduced high-beta/gamma power (21–80 Hz). The temporal profile of ASMR modulations in high-frequency power later shifts to lower frequencies (1–8 Hz), except for an enhanced alpha, which persists for up to 45 min post self-reported ASMR. Crucially, these results provide the first evidence that the cortical sources of ASMR tingling sensations may arise from decreases in higher frequency oscillations and that ASMR may induce a sustained relaxation state.

Periphyton can play an important role for biogeochemical processes in large regulated rivers. The development of benthic algae during low flow periods are especially suitable in braided sections, near bank zones and shallow areas. Light availability, fine sediment accumulation and flow velocity are assumed to be the main factors controlling periphyton growth, while the effect of water level fluctuations in large rivers is often neglected. However, the latter could also have severe impacts on the development of benthic algae. The present study aims to analyse how short term (hourly and daily) water level fluctuations influence the periphyton development and species richness and how desiccation stress affects the specific primary production. An in-situ experiment was conducted for one month on a Danube River bank in the free-flowing stretch of the river east of Vienna. Plates with artificial substrates were exposed at several defined depths along a fluctuating water level gradient. A short term laboratory experiment was also conducted to assess the effect of drying and rewetting on benthic algal production. Our results showed the benthic chlorophyll-a content was 40 to 60 times lower and diatom species were 5 times fewer at a desiccation-affected zone compared with the permanently-immersed zone. However, after a short term flow pulse lasting 3 days, the differences between the two zones were alleviated. In the laboratory experiment, the benthic algal community from two different colonisation stages with different chlorophyll-a content and species composition (days 12 and 21 of development) were capable of efficient photosynthesis for 2 and 5 hours of desiccation, respectively, followed by no measurable photosynthetic activity for an additional hour. Complete recovery of photosynthesis took 3 and 5 hours after rehydration. The results of this study showed that the periphyton on a riparian zone of a large regulated river is a very dynamic community with a high capacity for resilience with regard to the highly fluctuating environmental conditions. Furthermore, short-term desiccation stress should be considered as an important form of disturbance that affects algal communities in altered river systems.

We used a hydromorphological model to assess areas of potential high denitrification rates and nitrous oxide release in a frequently and an infrequently connected floodplain system of the Danube River under different river discharge conditions. Based on the model's projections, the decoupled floodplain was predicted to have more areas of high potential denitrification during mean and elevated discharge, but with more sites dominated by incomplete denitrification, resulting in higher N2O emission. In the restored floodplain, frequently inundated, the model predicted that lower rates of denitrification would occur at lower river discharge levels, dominated by complete denitrification, resulting in N2 rather than N2O production. During an annual flood (5300 m3s-1), flooding both floodplains, the restored floodplain was predicted to have more areas of high potential denitrification activity than the decoupled floodplain. The model outputs suggest that floodplains subject to frequent inundations can effectively and efficiently use nitrate input from the main river channel, resulting in complete denitrification. Restoration measures should attempt to promotefrequent inundation periods in order to fully realize the high denitrification potential of floodplain systems.

In northeastern Austria, marshlands have been turned into the most productive arable land of the country. As a result, most headwater streams show structurally degraded channels, lacking riparian buffer zones, which are heavily loaded with nutrients from the surrounding crop fields. The present study examines whether longitudinally restricted riparian forest buffers can enhance the in‐stream nutrient retention in nutrient‐enriched headwater streams. We estimated nutrient uptake from pairwise, short‐term addition experiments with 15NH4, NH4, PO4, and NaCl within reaches with riparian forest buffers (RFB) and degraded reaches (DEG) of the same streams. Riparian forest buffers originated from the conservation of the pristine vegetation or from restoration measures. Hydrologic retention was calculated with the model OTIS‐P on the basis of conductivity break‐through curves from the salt injections. A significant increase in surface transient storage was revealed in pristine and restored RFB reaches compared with DEG reaches due to the longitudinal step‐pool pattern and the frequent occurrence of woody debris on the channel bed. Ammonium uptake lengths were significantly shorter in RFB reaches than in DEG reaches, resulting from the higher hydrologic retention. Uptake velocities did not differ significantly between RFB and DEG reaches, indicating that riparian forest buffers did not affect the biochemical nutrient demand. Uptake of 15NH4was mainly driven by autotrophs. Net PO4uptake was not affected by riparian forest buffers. The study shows that the physical and biogeochemical effects of riparian forest buffers on the in‐stream nutrient retention are limited in the case of highly eutrophic streams.

The retention efficiency of a specific reach is one key factor controlling the dynamics of particulate organic matter (POM) in running waters. Floodplains enhance the retention of riverine POM, thereby altering its structure and diagenetic state, and constitute a substantial autochthonous source. Hydrological connectivity between the river and its floodplains determines the impact of floodplains for the POM dynamics of the entire river. The elemental and isotopic (d13C, d15N) composition and microbial utilisation of POM was investigated in relation to hydrological connectivity in the Danube River and two floodplain segments, one of which was isolated, the other dynamically connected. The latter had been subjected to river restoration measures. An increased integration in the riverine network was the effect of the restoration. Within both floodplains, isolated, disconnected and connected conditions were distinguished depending on the location of inflow areas and the riverine water level. Hydrological connectivity, expressed as water age, significantly influenced the quantity and composition of POM in the dynamic floodplain. Carbon isotopic composition of POM clearly separated riverine and connected conditions from those disconnected and isolated, the latter representing autochthonous material mainly derived from plankton. At disconnection, the maximum contribution of phytoplankton to POC was determined (54.5% ± 28.8 SE), which also supported the highest bacterial productivity (4.61µgCl-1h-1 ± 0.55 SE). Connected conditions were characterised by relatively enriched, allochthonous POM (d13C: -23.27‰ ± 0.98 SE). In the isolated floodplain, high standing stocks of aquatic macrophytes developed which act as 'sinks' of carbon for the river. Restoration efforts like the Danube restoration project, which increase hydrological connectivity, enhance the importance of autochthonous POM and its further transformation by re-establishing dynamically connected floodplains in regulated, temperate large rivers.

The relationship between network structure and dynamics is one of the most extensively investigated problems in the theory of complex systems of recent years. Understanding this relationship is of relevance to a range of disciplines—from neuroscience to geomorphology. A major strategy of investigating this relationship is the quantitative comparison of a representation of network architecture (structural connectivity, SC) with a (network) representation of the dynamics (functional connectivity, FC). Here, we show that one can distinguish two classes of functional connectivity—one based on simultaneous activity (co-activity) of nodes, the other based on sequential activity of nodes. We delineate these two classes in different categories of dynamical processes—excitations, regular and chaotic oscillators—and provide examples for SC/FC correlations of both classes in each of these models. We expand the theoretical view of the SC/FC relationships, with conceptual instances of the SC and the two classes of FC for various application scenarios in geomorphology, ecology, systems biology, neuroscience and socio-ecological systems. Seeing the organisation of dynamical processes in a network either as governed by co-activity or by sequential activity allows us to bring some order in the myriad of observations relating structure and function of complex networks.

The region of whole Zea mays plants most susceptible to Agrobacterium–mediated transfer of infectious maize streak virus has been identified. Injection of a suspension of bacterial cells in meristematic tissues at or close to the apex gives a high proportion of plants showing viral symptoms, whereas inoculations in non–meri–stematic tissues give few or no symptomatic plants. We have developed a simple, reliable, sensitive and rapid assay for the transfer of DNA from Agrobacterium to plant, which allows a large number of independent inoculations to be screened.

For about two decades, river restoration is high on the scientific and political water management agenda, as measures are needed to improve the ecological situation of river systems and the adjacent landscape elements. Thus, implementing of measures in the frame of river restoration is an issue integrating ecological, social and economic aspects. While aquatic ecologists and river engineers restore ecosystem services lost by hydromorphological alterations, economic policy aims to mitigate flood damage by restoring lost retention areas. Hence, an intelligent river basin management links these two issues together to create a ?win-win? situation for a sustainable use. Considering the still existing large near natural floodplains in the Danube and the Elbe (as compared e.g. to the River Rhine), a wise strategy would be not to repeat the mistakes of the past and not to destroy these areas by disconnecting lateral connectivity through rip-rap banks and flood protection levees and channelization at high costs, just to restore them some time later at high costs again. Rather we recommend to evaluate the ecosystem services of these hotspots of biodiversity and ?hydrological lungs and kidneys? of the landscape so as to evidence their economic value. In this way, hard pressures of future infrastructure projects (navigation, hydroelectric power) and land use (urban and industrial development) should be kept out of floodplains, while soft use by eco-tourism (recreation, camping, education) and sustainable agriculture (cattle grazing meadows) should be encouraged.