Abiotic Uptake Research Articles

Uptake of Per- and Polyfluoroalkyl Substances by Fish, Mussel, and Passive Samplers in Mobile-Laboratory Exposures Using Groundwater from a Contamination Plume at a Historical Fire Training Area, Cape Cod, Massachusetts.

Aqueous film-forming foams historically were used during fire training activities on Joint Base Cape Cod, Massachusetts, and created an extensive per- and polyfluoroalkyl substances (PFAS) groundwater contamination plume. The potential for PFAS bioconcentration from exposure to the contaminated groundwater, which discharges to surface water bodies, was assessed with mobile-laboratory experiments using groundwater from the contamination plume and a nearby reference location. The on-site continuous-flow 21-day exposures used male and female fathead minnows, freshwater mussels, polar organic chemical integrative samplers (POCIS), and polyethylene tube samplers (PETS) to evaluate biotic and abiotic uptake. The composition of the PFAS-contaminated groundwater was complex and 9 PFAS were detected in the reference groundwater and 17 PFAS were detected in the contaminated groundwater. The summed PFAS concentrations ranged from 120 to 140 ng L-1 in reference groundwater and 6100 to 15,000 ng L-1 in contaminated groundwater. Biotic concentration factors (CFb) for individual PFAS were species, sex, source, and compound-specific and ranged from 2.9 to 1000 L kg-1 in whole-body male fish exposed to contaminated groundwater for 21 days. The fish and mussel CFb generally increased with increasing fluorocarbon chain length and were greater for sulfonates than for carboxylates. The exception was perfluorohexane sulfonate, which deviated from the linear trend and had a 10-fold difference in CFb between sites, possibly because of biotransformation of precursors such as perfluorohexane sulfonamide. Uptake for most PFAS in male fish was linear over time, whereas female fish had bilinear uptake indicated by an initial increase in tissue concentrations followed by a decrease. Uptake of PFAS was less for mussels (maximum CFb = 200) than for fish, and mussel uptake of most PFAS also was bilinear. Although abiotic concentration factors were greater than CFb, and values for POCIS were greater than for PETS, passive samplers were useful for assessing PFAS that potentially bioconcentrate in fish but are present at concentrations below method quantitation limits in water. Passive samplers also accumulate short-chain PFAS that are not bioconcentrated.

Phosphate Scavenging During Lava‐Seawater Interaction Offshore of Kīlauea Volcano, Hawaii

AbstractThe 2018, subaerial eruption of Kīlauea volcano, Hawaii, resulted in a 5‐km‐long stretch of coastline that actively drained lava into the ocean. Nutrients were added to the surrounding ocean through the dissolution of basaltic rock and thermal upwelling of deep water, thereby fueling a large phytoplankton bloom. Lava‐impacted, surface seawater had high suspended particle loads, and concentrations of chlorophyll, silicic acid, phosphate (Pi), nitrate, and iron that were elevated up to 12, 36, 5, 960, and 1,400 times, respectively, above the background oligotrophic levels. Widespread precipitation of iron oxyhydroxides (Feox) led to extensive scavenging of the dissolved Pi pool, similar to what occurs along mid‐ocean ridge hydrothermal systems. This scavenging transformed a “fertilization” event into a Pi sink near the coast of the ocean entry; however, nutrient data from outside the bloom suggest that Pi could also desorb from the Feox as it is dispersed into the open ocean. From lava quench experiments, we estimate that the hydration state of the Feox precipitate (H2O/Fe) was 5.2–5.7, and that the equilibrium partition coefficient of Pi into Feox (solid/liquid) was 106. In addition, 33Pi radiotracer incubations were used to differentiate between biotic and abiotic uptake of Pi at Kīlauea's ocean entry. These findings are important for understanding modern‐day volcanic fertilization events, modeling nutrient dynamics during major events in Earth history (such as oxygenation of the atmosphere and the formation of large igneous provinces), and predicting the marine response to greater continental weathering in a warming climate.

Effects of effluents from wastewater treatment plants on the abiotic and biotic uptake of phosphorus by streambed sediments

Sustained inputs of nitrogen and/or phosphorus from wastewater treatment plants (WWTPs) to aquatic environments lead to an increased risk of eutrophication. The purpose of this study was to analyze the relative proportions of biotic and abiotic processes in the uptake of phosphorus by streambed sediments and their response to exogenous carbon (sodium acetate) concentration gradients, as well as explore the effects of WWTP effluent discharges on the biotic and abiotic uptake potential of phosphorus by streambed sediments in the receiving streams. Experiments were undertaken with streambed sediments collected from four different sites in different seasons, with or without the addition of a chloroform solution (biological inhibitor), to which were added different concentrations of a source of carbon (sodium acetate). After completing the indoor simulation culture, the total uptake potential (SPUlive), abiotic uptake potential (SPUabiotic), and biotic uptake potential (SPUbiotic) of phosphorus by the sediments were calculated. The SPUlive values of the sediments in the receiving section of the WWTP effluent were higher than those at the control site and gradually decreased with the flow direction. A larger amount (c. 79.04–98.11%) of the added phosphorus was taken up abiotically by the sediments with no added carbon. The SPUbiotic value of all sampling sites increased with the increase in exogenous carbon concentration by the addition of acetate, and accordingly the maximum contribution rate of the biotic uptake of phosphorus in sediments was 14.83–36.40%. Although WWTP effluents can increase the risk of release of phosphorus from sediments to the overlying water, the abiotic and biotic uptake potential of phosphorus by sediments is significantly increased by sediment–nutrient interactions. There may be more serious carbon limitations in the uptake of phosphorus by streambed sediments downstream of WWTPs than those at the reference site.

Enantioselective degradation of dufulin pesticide in water: Uptake, thermodynamics, and kinetics studies.

Kudzu (Pueraria thunbergiana) plant extract impregnated sediments were used for abiotic and biotic uptakes and biodegradation. The optimized conditions were 25 μg L-1 concentration, 7 days for abiotic uptake and 56 days for biotic uptake and biodegradation, dose 2 g L-1 , 7 pH, and 35°C temperature. The amount removed of dufulin was 32.6% in abiotic conditions while these were 90% in the case of biotic uptake and biodegradation. Enantioselective biodegradation indicated that S-(+)-enantiomer degraded faster (90%) than R-(-)-enantiomer (87%). The data for abiotic and biotic uptakes and biodegradation followed well Langmuir, thermodynamics, and kinetics models. All these processes followed pseudo first-order kinetics. It was observed that biodegradation was three times responsible for dufulin removal than simple sorption uptake (abiotic and biotic). The abiotic and biotic uptakes and biodegradation were quite fast and endothermic nature. The developed method may be used to remove the racemic and enantiomeric dufulin in water.

REPLY TO A.V. SMAGIN: V. WHAT IS WRONG WITH AN “ABIOTIC PAPER” AND DO WE ALWAYS NEED TO TAKE INTO ACCOUNT THE ABIOTIC GAS ABSORPTION BY SOIL?

A paper of prof. A.V. Smagin [2007] is analyzed (both from outer scientometric and inner meaningful points of view). In this paper he considers the abiotic absorption of gases by organogenic soils. In this regard, claims of the author of the article to the work of V. M. Stepanenko and his colleagues on the modeling of methane emissions from lakes on the territory of permafrost are also discussed. An idea that (in contrast to the views of A.V. Smagin) a necessity to account for abiotic uptake depends on properties of modeled object is formulated. In particular, if blocks of climate models are developed (like the Stepanenko model), which should work on timescales of 103÷104 hours and more, it makes no sense to take into account the abiotic uptake that occurs within significantly shorter time intervals and concerns an extremely small amount of methane (compared to its total amount, which is released within the indicated 103-104 hours). In addition potential uncertainties of deep soil chamber technique that could be generated by abiotic absorption and biogenic oxidation of methane are discussed.

Process Understanding of Soil BVOC Fluxes in Natural Ecosystems: A Review

AbstractBiogenic volatile organic compounds (BVOCs) can be released from soils to the atmosphere through microbial decomposition of plant residues or soil organic carbon, root emission, evaporation of litter‐stored BVOCs, and other physical processes. Soils can also act as a sink of BVOCs through biotic and abiotic uptake. Currently, the source and sink capabilities of soils have not been explicitly accounted for in global BVOC estimates from the terrestrial biosphere. In this review, we summarize the current knowledge of soil BVOC processes and aim to propose a generic framework for modelling soil BVOCs based on current understanding and data availability. To achieve this target, we start by reviewing measured sources and sinks of soil BVOCs and summarize commonly reported compounds. Next, we strive to disentangle the drivers for the underlying biotic and abiotic processes. We have ranked the list of compounds, known to be emitted from soils, based on our current understanding of how each process controls emission and uptake. We then present a modelling framework to describe soil BVOC emissions. The proposed framework is an important step toward initializing modelling exercises related to soil BVOC fluxes. Finally, we also provide suggestions for measurements needed to separate individual processes, as well as explore long‐term and large‐scale patterns in soil BVOC fluxes.

Potential for Phosphorus Uptake by Bed Sediments and Its Response to Carbon Additions in the Shiwuli River, Chaohu Lake Basin

Surficial sediments were collected from five sampling sites in the mainstream of the Shiwuli River along an urban-rural gradient in the Chaohu Lake basin during July 2017 (summer) and January 2018 (winter). The total uptake (SPUlive), abiotic uptake (SPUkill), and biotic uptake (SPUbiotic) of phosphorus by sediments were measured, and uptake responses to different carbon sources (i. e., sodium acetate, glucose, and a mixture of both) were explored quantitatively through incubation experiments. The results showed that SPUlive had obviously spatiotemporal variations across the five sites, and SPUkill was higher than that of SPUbiotic. Under no carbon added, the mean values of SPUkill were 3.016 μg·(g·h)-1 and 3.368 μg·(g·h)-1, and the average values of SPUbiotic were 0.784 μg·(g·h)-1 and 0.323 μg·(g·h)-1 in summer and winter, respectively. Moreover, significant differences were found in abiotic phosphorus uptake between the two months. In the presence of carbon addition, both the value of SPUbiotic and the contribution rate of biotic phosphorus uptake showed a distinct increase. In general, the magnitude and rate of biotic uptake of phosphorus by sediments was highest when sodium acetate was added, followed by glucose, while the effect of mixed carbon was the worst. The responses of biotic phosphorus uptake to carbon addition suggested that the uptake potential of phosphorus by sediments in Shiwuli River was restricted by the carbon availability to some degree.

Biotic and Abiotic Uptake of Phosphorus in Benthic Sediments of Suburban Streams Under Intense Human Disturbance Scenario

To reveal the impact of land use change on the phosphorus uptake in benthic sediments of suburban streams, a headwater stream in the urban fringe of Hefei City was selected and a set of benthic sediments was collected monthly from the chosen stream reach from June to November 2016. An incubation method was applied to explore the biotic and abiotic uptake of phosphorus in benthic sediments under intense human disturbance scenario. Results showed that the uptake potentials in summer were higher than those in autumn, both for total (including biotic and abiotic) and abiotic uptake of phosphorus. Furthermore, both of these uptakes were distinctly higher for the third sampling site, which is adjacent to the sewage outlet, than those for the other sites. For all six sampling sites, the contribution rate of biotic uptake of phosphorus was significantly greater than that of abiotic uptake, both in summer and autumn. The monthly variations in potentials and contribution rates of phosphorus uptake indicated that intense human disturbance via land use change had a great impact on the biotic uptake of phosphorus in benthic sediments of the suburban stream.

Mass mortality of a dominant invasive species in response to an extreme climate event: Implications for ecosystem function

AbstractImpacts of invasive species on ecosystems are often context dependent, making empirical assessments difficult when climatic baselines are shifting and extreme events are becoming more common. We documented a mass mortality event of the Asian clam, Corbicula fluminea, an abundant invasive clam, which has replaced native mussels as the dominant filter‐feeding bivalve in the southeastern United States. During an extremely hot and dry period in the summer of 2012, over 99% of Corbicula died in our 10‐km study reach of the Broad River, Georgia. Because Corbicula were the only filter‐feeding organism in the ecosystem with substantial biomass, their death led to the nearly complete cessation of ecosystem services provided by filter‐feeding bivalves. We estimate that following the mass mortality event, turnover time within the sampling reach (reach volume/total filtration) rose from approximately 5 h to over 1200 h. In addition to the loss of filtering capacity, concentrations of total dissolved phosphorus (TDP) and soluble reactive phosphorus (SRP) were also higher in areas where die‐off was occurring than in an upstream area without mortality. Mass balance calculations and a manipulative mesocosm experiment predicted TDP and SRP concentrations much higher than our observed values, suggesting that rapid biotic or abiotic uptake of phosphorus may have occurred. Our study demonstrates that climate change can increase the temporal variability of populations of aquatic organisms that provide key ecosystem functions, and highlights that even pulsed, short‐lived events can markedly affect systems of reduced diversity.

Intelligence in Ecology: How Internet of Things Expands Insights into the Missing CO2Sink

Arid region characterizes more than 30% of the Earth’s total land surface area and the area is still increasing due to the trends of desertification, yet the extent to which it modulates the global C balance has been inadequately studied. As an emerging technology, IoT monitoring can combine researchers, instruments, and field sites and generate archival data for a better understanding of soil abiotic CO2uptake in arid region. Images’ similarity analyses based on IoT monitoring can help ecologists to find sites where the abiotic uptake can temporally dominate and how the negative soil respiration fluxes were produced, while IoT monitoring with a set of intelligent video recognition algorithms enables ecologists to revisit these sites and the experiments details through the videos. Therefore, IoT monitoring of geospatial images, videos, and associated optimization and control algorithms should be a research priority towards expanding insights for soil abiotic CO2uptake and a better understanding of how the uptake happens in arid region. Nevertheless, there are still considerable uncertainties and difficulties in determining the overall perspective of IoT monitoring for insights into the missing CO2sink.

Impact of Veterinary Pharmaceuticals on the Agricultural Environment: A Re-inspection.

The use of veterinary pharmaceuticals (VPs) is a result of growing animal production. Manure, a great crop fertilizer, contains a significant amount of VPs. The investigation of VPs in manure is prevalent, because of the potential risk for environmental organisms, as well as human health. A re-evaluation of the impact of veterinary pharmaceuticals on the agricultural environment is needed, even though several publications appear every year. The aim of this review was to collate the data from fields investigated for the presence of VPs as an inevitable component of manure. Data on VP concentrations in manure, soils, groundwater and plants were collected from the literature. All of this was connected with biotic and abiotic degradation, leaching and plant uptake. The data showed that the sorption of VPs into soil particles is a process which decreases the negative impact of VPs on the microbial community, the pollution of groundwater, and plant uptake. What was evident was that most of the data came from experiments conducted under conditions different from those in the environment, resulting in an overestimation of data (especially in the case of leaching). The general conclusion is that the application of manure on crop fields leads to a negligible risk for plants, bacteria, and finally humans, but in future every group of compounds needs to be investigated separately, because of the high divergence of properties.

Spatial decoupling of soil nitrogen cycling in an arid chenopod pattern ground

Patterned ground is a characteristic landscape form in arid zones across the globe and is caused by the redistribution of runoff. The vegetation is concentrated in groves, which receive runoff water from the bare soil surface of the intergroves. Despite many soil chemical and physical investigations, biogeochemical cycles are not described for this landscape form. This study focuses on the distinct features of the nitrogen (N) and carbon (C) cycle in intergrove and grove areas of chenopod pattern-ground soils of the Australian rangelands. The N concentration of grove soils is low compared with the intergrove soil because of a close link between the N cycle in the topsoil and the plant primary production. In grove soils, denitrification including emission of N2O dominated the N cycle, whereas in intergrove soils, abiotic N2O uptake is the sole fate of atmospheric N2O. The intergrove soils appear to be generally poor in bacterial quantity and diversity, and lacking denitrification by bacteria, which has an impact on the C cycle as well. Production of CO2 and consumption of CH4 were substantially lower than grove soils. There was partitioning of key biogeochemical processes between the intergrove and grove soils, which results in a spatially decoupled soil N and C cycle in arid chenopod, pattern-ground ecosystems.

In Vitro Biological Control of Branch Canker (Macrophoma theiocola) Disease of Tea

Antagonist microorganisms, such as Trichoderma spp. have long been recognized as biological agents, for the control of plant disease and for their ability to increase root growth and development, crop productivity, resistance to abiotic stresses, and uptake and use of nutrients. An attempt was made to evaluate the in vitro biocontrol of branch canker (Macrophoma theicola) of tea plants by Trichoderma spp. Isolation of Trichoderma spp. and M. theiocola was done carefully. Pure culture of Trichoderma spp. and M. theiocola and their morphological characteristics were studied at different intervals. Five M. theiocola and five Trichoderma isolates were collected from mature tea plants and tea soils respectively of Bangladesh Tea Research Institute (BTRI) main farm area. The cultural morphology and antagonistic potentiality of Trichoderma spp. against branch canker pathogen (M. theiocola) were taken into consideration. Trichoderma spp. controls the growth of M. theiocola at different intervals. After 24 hour growth rate of Trichoderma was 9.3% and M. theiocola was 0.88%. The antagonistic potentialities of isolated Trichoderma against pathogens (M. theiocola) were observed at different intervals (24-120 hrs) and the percentage of inhibition was 82% which were observed after five days (120 hours) of inoculation. The Trichoderma spp. antagonizes the pathogens by several mechanisms such as antibiosis, competition, mycoparasitism or other form of direct exploitation. From this study it was revealed that, the Trichoderma spp. was highly effective to control the isolates of M. theiocola that is responsible for branch canker in tea cultivation.

Didymosphenia geminata invasion in South America: Ecosystem impacts and potential biogeochemical state change in Patagonian rivers

The diatom Didymosphenia geminata has emerged as a major global concern, as both an aggressive invader of rivers and streams in the southern hemisphere, and for its ability to form nuisance blooms in oligotrophic systems in its native range. South American D. geminata blooms were first documented in Chilean Patagonia in May 2010, and have spread to over five regions and three provinces, in Chile and Argentina respectively. The Patagonian invasion represents a distinct challenge compared to other regions; not only are affected systems poorly characterized, but also a general synthesis of the nature and magnitude of ecosystem impacts is still lacking. The latter is essential in evaluating impacts to ecosystem services, forms the basis for a management response that is proportional to the potentially valid threats, or aids in the determination of whether action is warranted or feasible. Based on a revision of the recent literature, some of the most significant impacts may be mediated through physical changes: substantially increased algal biomass, trapping of fine sediment, altered hydrodynamics, and consequent effects on biogeochemical states and processes such as redox condition, pH and nutrient cycling in the benthic zone. Surveys conducted during the early invasion in Chile show a strong correlation between benthic biomass and associated fine sediments, both of which were one–two orders of magnitude higher within D. geminata blooms. Experimental phosphorous amendments showed significant abiotic uptake, while interstitial water in D. geminata mats had nearly 10–20 fold higher soluble reactive phosphorous and a pronounced pH cycle compared to the water column. A dominant and aggressive stalk-forming diatom with this combination of characteristics is in sharp contrast to the colonial cyanobacteria and bare gravel substrate that characterize many Patagonian streams. The potential displacement of native benthic algal communities with contrasting functional groups, increased primary producer biomass, and fine benthic sediment accumulation, all may have a significant effect on stream nutrient cycling and ecosystem function, in Patagonia and elsewhere where nuisance blooms have been reported.

Retention of Dissolved Inorganic Nitrogen by Foliage and Twigs of Four Temperate Tree Species

Nitrogen (N) retention by tree canopies is believed to be an important process for tree nutrient uptake, and its quantification is a key issue in determining the impact of atmospheric N deposition on forest ecosystems. Due to dry deposition and retention by other canopy elements, the actual uptake and assimilation by the tree canopy is often obscured in throughfall studies. In this study, 15N-labeled solutions ( $$ ^{15} {\text{NH}}_{4}^{ + } $$ and $$ ^{15} {\text{NO}}_{3}^{ - } $$ ) were used to assess dissolved inorganic N retention by leaves/needles and twigs of European beech, pedunculate oak, silver birch, and Scots pine saplings. The effects of N form, tree species, leaf phenology, and applied $$ {\text{NO}}_{3}^{ - } $$ to $$ {\text{NH}}_{4}^{ + } $$ ratio on the N retention were assessed. Retention patterns were mainly determined by foliar uptake, except for Scots pine. In twigs, a small but significant 15N enrichment was detected for $$ {\text{NH}}_{4}^{ + } $$ , which was found to be mainly due to physicochemical adsorption to the woody plant surface. The mean $$ {{^{15} {\text{NH}}_{4}^{ + } } \mathord{\left/ {\vphantom {{^{15} {\text{NH}}_{4}^{ + } } {^{15} {\text{NO}}_{3}^{ - } }}} \right. \kern-\nulldelimiterspace} {^{15} {\text{NO}}_{3}^{ - } }} $$ retention ratio varied considerably among species and phenological stadia, which indicates that the use of a fixed ratio in the canopy budget model could lead to an over- or underestimation of the total N retention. In addition, throughfall water under each branch was collected and analyzed for $$ ^{15} {\text{NH}}_{4}^{ + } $$ , $$ ^{15} {\text{NO}}_{3}^{ - } $$ , and all major ions. Net throughfall of $$ ^{15} {\text{NH}}_{4}^{ + } $$ was, on average, 20 times higher than the actual retention of $$ ^{15} {\text{NH}}_{4}^{ + } $$ by the plant material. This difference in $$ ^{15} {\text{NH}}_{4}^{ + } $$ retention could not be attributed to pools and fluxes measured in this study. The retention of $$ ^{15} {\text{NH}}_{4}^{ + } $$ was correlated with the net throughfall of K+, Mg2+, Ca2+, and weak acids during leaf development and the fully leafed period, while no significant relationships were found for $$ ^{15} {\text{NO}}_{3}^{ - } $$ retention. This suggests that the main driving factors for $$ {\text{NH}}_{4}^{ + } $$ retention might be ion exchange processes during the start and middle of the growing season and passive diffusion at leaf senescence. Actual assimilation or abiotic uptake of N through leaves and twigs was small in this study, for example, 1–5% of the applied dissolved 15N, indicating that the impact of canopy N retention from wet deposition on forest productivity and carbon sequestration is likely limited.

River phosphorus cycling: Separating biotic and abiotic uptake during short-term changes in sewage effluent loading

Medium to small scale point sources continue to threaten river ecosystems through P loadings. The capacity and timescales of within-river processing and P retention are a major factor in how rivers respond to, and protect downstream ecosystems from, elevated concentrations of soluble reactive P (SRP). In this study, the bio-geochemical response of a small river (∼40 km 2 catchment area) was determined before, during and after exposure to a fourteen day pulse of treated sewage effluent using an upstream reach as a control. A wide array of approaches (batch and column simulations to in-situ whole stream metabolism) allowed independent comparison and quantification, of the relative contribution of abiotic and biotic processes in-river P cycling. This enabled, for the first time, separating the relative contributions of algae, bacteria and abiotic sorption without the use of labelled P (radioisotope). An SRP mass balance showed that the ecosystem switched from a P sink (during effluent inputs) to a P source (when effluent flow ceased). However, 65–70% of SRP was retained during the exposure time and remained sequestered two-weeks after-effluent flow ceased. Batch studies treated with biocide gave unrealistic results, but P uptake rates derived by other methods were highly comparable. Downstream of the effluent input, net P uptake by algae, bacteria and sediment (including the biofilm polysaccharide matrix) were 0.2 (±0.1), 0.4 (±0.3), and 1.0 (±0.9) mmol m −2 day −1 during effluent exposure. While autotrophic production did not respond to the effluent exposure, heterotrophic production increased by 67% relative to the control and this translated into a 50% increase in biological P uptake rate. Therefore, both biological and abiotic components of stream ecosystems uptake P during exposure to treated sewage effluent P inputs, and maintain a long ‘memory’ of this input in terms of P storage for considerable timescales after loading.

Changes in abiotic and biotic phosphorus uptake across a gradient of stream condition

AbstractDegraded streams have been shown to retain fewer nutrients than un‐modified streams. The aim of this project was to investigate the relative importance of abiotic and biotic pathways of phosphorus uptake by epilithic communities in un‐modified and modified streams. This was investigated through a series of filterable reactive phosphorus (FRP)‐uptake experiments in two streams of the Torrens River Catchment, South Australia. Total benthic FRP uptake was assessed as the loss of FRP to un‐sterilized epilithic communities (kT), abiotic uptake was the loss to sterilized epilithic communities (kA) and biotic uptake (kB) was the difference between total and abiotic uptake. It was hypothesized that un‐modified reaches would have higher kA and kB than degraded and engineered reaches. Overall, kT, kA and kB were greatest in un‐modified reaches, but this pattern was not consistent across seasons. kT and kB were greatest in the un‐modified reaches in autumn–winter and late spring, but not in winter–spring. Differences in kB were best explained by phosphorus availability in the water column and the period of continuous flow. kA was greatest in the un‐modified reaches in autumn–winter, greatest in the degraded reaches in winter–spring, but similar in the un‐modified reaches and degraded reaches in late spring. kA was most dependent upon the background FRP concentration, but also the attached organic matter in the un‐modified reaches. The project demonstrated that several impacts of changes in land‐use can alter the affinity of biotic and abiotic processes for phosphorus, which will have implications for in‐stream nutrient availability and downstream ecosystems. Copyright © 2009 John Wiley & Sons, Ltd.

Processing of antifouling paint particles by Mytilus edulis

Particles of spent antifouling paint collected from a marine boatyard were ground and subsequently administered to the filter-feeding bivalve, Mytilus edulis, maintained in static aquaria. Concentrations of Cu and Zn were measured in seawater throughout a 16 h feeding phase and a 24 h depuration phase, in rejected and egested particles collected during the respective phases, and in the organisms themselves at the end of the experiments. Concentrations and distributions of Cu and Zn in processed particles indicated that M. edulis was able to ingest paint particles, regardless of whether nutritionally viable silt was present, and no mechanism of particle discrimination was evident. Enrichment of Cu and Zn in the visceral mass of individuals and in the aqueous phase during depuration supported these assertions, although elevated concentrations in other compartments of the organism (e.g. shell, gill) suggested that biotic and abiotic uptake of aqueous metal was also important.

Abiotic uptake of gases by organic soils

Methodological and experimental studies of the abiotic uptake of gaseous substances by organic soils were performed. The static adsorption method of closed vessels for assessing the interaction of gases with the solid and liquid soil phases and the dynamic method of determining the sorption isotherms of gases by soils were analyzed. The theoretical substantiation of the methods and their practical implementations on the basis of a PGA-7 portable gas analyzer (Russia) were considered. Good agreement between the equilibrium sorption isotherms of the gases and the Langmuir model was revealed; for the real ranges of natural gas concentrations, this model can be reduced to the linear Henry equation. The limit values of the gas sorption (Langmuir monolayer capacity) are typical for dry samples; they vary from 670–4000 g/m3 for methane and oxygen to 20 000–25 000 g/m3 for carbon dioxide. The linear distribution coefficients of gases between the solid and gas phases of organic soils (Henry constants) are 8–18 units for poorly sorbed gases (O2, CH4) and 40–60 units for CO2. The kinetics of the chemicophysical uptake of gases by the soil studied is linear in character and obeys the relaxation kinetic model of the first order with the corresponding relaxation constants, which vary from 1 h −1 in wet samples to 10 h −1 in dry samples.

Relating phosphorus uptake to changes in transient storage and streambed sediment characteristics in headwater tributaries of Valley Creek, an urbanizing watershed

Summary Phosphorus uptake dynamics were examined in two small streams in the Valley Creek watershed, located in an urbanizing area approximately 30 km west of Philadelphia, Pennsylvania, USA. The goal of this research was to examine how phosphorus uptake is influenced by temporal changes in bed sediment characteristics and transient storage in streams within an urbanizing watershed. We conducted tracer studies with a conservative solute, observed phosphorus uptake in situ and in laboratory experiments, and measured fine bed sediment grain size distributions and chemical compositions at both sites. At the Morehall Rd. site, the total laboratory and in situ uptake rates were related to the silt–clay ( d d in situ uptake rate was also related to the sediment magnesium content and the transient storage exchange rate and area. At the Sheldrake Rd. site, the phosphorus uptake rates observed in situ and in the laboratory were not significantly related to any of the measured stream or sediment characteristics. However, the areal average uptake (uptake flux), was related to the transient storage exchange rate. In addition, the abiotic contribution to in situ uptake was evaluated by comparing the in situ and laboratory measured uptake rates. The total abiotic in situ uptake rate was found to be related to the bed sediment silt–clay content and the transient storage residence time, while the abiotic uptake flux was related to the transient storage residence time. Overall, these urbanizing streams were less efficient at removing phosphorus from the water column than forested streams in non-urban settings.