Total Sediment Research Articles

Complex patterns of phosphorus delivery in the Lake of the Woods watershed

Lake of the Woods (LoW) is a large, transboundary lake that continues to experience harmful algal blooms despite large declines in phosphorus (P) inputs from point sources. Tributary runoff is considered the largest source of P to the lake; however, there are few monitoring data within the Canadian portion of the basin (∼60% of total area), to guide management. To address this gap, we monitored five rivers of contrasting land use within the lower Rainy River region, an acknowledged “hot spot” of P delivery in the basin. Total P (TP) concentrations were consistently high at all five rivers (volume-weighted range: 19–215 μg/l) despite differences in agriculture across sites (7–27%), suggesting ‘natural’ background P levels are high in this landscape. Furthermore, TP concentrations were strongly correlated with total suspended sediment and geogenic metals, iron (Fe) and aluminum, and TP was especially high during events (>400 μg/l) indicating erosion is an important source of P delivery. However, equally high TP and Fe during periods of slow, stagnant flow in the summer and under winter ice suggest erosion is not the only source of P. Instead, we suggest redox release of P from streambed sediment is also important. This observation is significant, because internal P release within the tributaries, especially during the summer could ‘seed’ downstream algal blooms. The strong sensitivity of TP to both high and low flow conditions indicates that frequent, all-season, multi-year measurements are needed to understand the mechanisms of P delivery in this basin.

ASSESSMENT OF STEADY FLOW BEHAVIOUR OF KULSI RIVER USING HEC-RAS AND QGIS

Sediment transport study is important tools of Kulsi River in the context of river bank erosion, Sedimentation, and water quality management. The initiation of computer technologies has enabled engineers to resolve sediment transport equations through computer simulations. In this study, it is intended to carry out a sediment transport study in the Kulsi River reach with the help of Hydrologic Engineering Centre-River Analysis System (HEC-RAS) and Quantum Geographic information System (QGIS). From the analysis of the model, total sediment erosion and deposition were obtained at different cross sections between the study reach. Kulsi river is Southern tributary of Brahmaputra and it’s originate in Meghalaya (2538N, 9138E) and after travelling 12 km its enter Assam from the place of its origin and linked with Brahmaputra at Nagarbara in Kamrup Metro. The initial version of this sediment model will leverage the wide range of hydraulic capabilities existing in HEC-RAS to compute a series of steady flow profiles used to develop hydrodynamic parameters for sediment transport. In this model where sufficient data is not available, So QGIS and remote sensing used as tools for extraction of bed profile of Kulsi River. HEC-RAS and QGIS are the Software used in this study. This study is carried out to simulate the process of erosion and sedimentation using HEC- RAS model to assess sedimentation and erosion processes in 2.5 Km stretch of Kulsi River from upstream to downstream. The model was calibrated manually for hydraulic parameters of river flow and then sediment transport model was simulated from January 2016 to December 2016. Key Words: Steady flow, HEC-RAS 5.05, QGIS, TCX converter.

Spatial Trends and Drivers of Bedload and Suspended Sediment Fluxes in Global Rivers

AbstractBedload is notoriously challenging to measure and model; its dynamics, therefore, remains largely unknown in most fluvial systems worldwide. We present results from a global scale bedload flux model as part of the WBMsed modeling framework that well predict the distribution of water discharge, suspended sediment and bedload. The sensitivity of bedload predictions to river slope, particle size, discharge, river width, and suspended sediment were analyzed, showing the model to be most responsive to spatial dynamics in river discharge and slope. The relationship between bedload and total sediment flux is analyzed globally, and for representative longitudinal river profiles (Amazon, Mississippi, and Lena Rivers). The results show that while the proportion of bedload decreases from headwaters to the coasts, there is considerable variability between basins and along river corridors. The topographic and hydrological longitudinal profiles of rivers are shown to be the key drivers of bedload trends, with fluctuations in slope controlling its more local dynamics. Estimates of water and sediment fluxes to global oceans from 2,067 largest river outlets (draining 67% of the global continental area) are provided. Estimated water discharge at 30,579 km3/y corresponds well to past estimates; however, sediment flux is higher. Total global particulate load of 17.8 Gt/y is delivered to global oceans, 14.8 Gt/y as washload, 1.1 Gt/y as bedload, and 2.6 Gt/y as suspended bed material. The largest 25 rivers are predicted to transport more than half of the total sediment flux to global oceans.

Changes to the structure and function of microbial communities in Spartina alterniflora and Kandelia obovata sediments as a factor of stand age

The effects of Kandelia obovata introduction and Spartina alterniflora invasion on the microorganisms are very important for coastal ecology and restoration. MiSeq sequencing of the 16S rRNA gene and Tax4Fun predictive functional profiles were used to investigate the diversity estimators, community structures and potential metabolic functions of benthic bacteria in surface sediments of coastal wetlands invaded by S. alterniflora and artificially planted with K. obovata at stand ages of 2-, 8-, 11-, 16- and 60-years on Ximen Island, Yueqing Bay, China. The results showed that the sediment bacterial richness was significantly decreased in 60-year K. obovata stands compared with younger K. obovata stands and S. alterniflora stands. The age of K. obovata and specie of exotic plants formed distinct bacterial communities and functional structures in sediments, respectively. With increasing plantation of K. obovata, the bacterial communities shifted from the class Anaerolineae, the genus Sulfurovum, and bacteria involved in sulfate reduction as abundant taxa to higher proportions of bacteria involved in degradation of plant polysaccharide and nitrate reduction. The shift in bacterial community structures was mainly driven by changes in sediment total organic matter, total nitrogen, total phosphorus, ammonium concentrations, pH and temperature. The community functions also changed from nitrogen fixation to more nitrate reduction and denitrification processes. Compared with 60-year K. obovata, S. alterniflora was occupied by higher proportions of the phylum Bacteroidetes, the orders Rhodobacterales, Flavobacteriales and Desulfuromonadales, and total nitrogen, total phosphorus concentrations and sediment temperature were major environmental factors affecting the variation. Among the major sulfur cycling processes examined, higher potential of dissimilatory sulfate reduction was observed in S. alterniflora. Our results indicated that K. obovata introduction has a greater effect on the bacterial community diversity and structure than S. alterniflora invasion. This study could improve the understanding of microbial processes and potential functions of K. obovata introduction and S. alterniflora invasion and provide reference in the restoration and management of the coastal wetlands.

Suspended sediment transport in a tropical river basin exhibiting combinations of land uses/land covers and hydroclimatic conditions: Case study of upper Athi Basin, Kenya

Study regionThe Upper Athi River Basin (Lat: 1°25′17.61°S and Long: 37°15′29.55°E) in Kenya, East Africa. Study focusThe effects of land use/land cover type on suspended sediment concentrations and yield were investigated in the upper Athi river basin in Kenya. The suspended sediment concentrations and yield, river discharges, water levels and flow velocities were monitored in stations established at the outlets of sub-basins and also at the outlet of the main basin in period 2012–2015. New hydrological insightsThe magnitude of river discharge in the upper Athi river basin is not only a function of the magnitude of rainfall, but combination of land uses/land covers determined the magnitude of sediment yield in the sub-basins. The highest sediment yield occurred in a semi-arid sub-basin dominated by savannah grassland and livestock grazing. The lowest occurred in the high rainfall sub-basins dominated by forest with mixed farming and settlements. Significant sediment transport commenced at an effective river discharge of 405 m3s−1 which is a frequent discharge event resulting in significant sediment load transport in most rainy seasons and years. The magnitude of suspended sediment discharge is a function of the magnitude of rainfall such that the greatest sediment transport occurs during the long rainy seasons (54%) as compared to 41% during the short rainy season. The total annual suspended sediment load in the basin ranged 2.11–3.77 × 106 tons.yr−1 and sediment production rate ranged 205–366 tons.km−2.year−1.

Acoustic based assessment of cross-sectional concentration inhomogeneity at a suspended sediment monitoring station in a large river

Establishing and operating a harmonized sediment monitoring system along large rivers such as the Danube River is a challenging international task. As an element of such a system, a new monitoring site with state-of-the-art instrumentation is currently under development in the Upper-Hungarian section of the Danube River. The monitoring station will consist of a near-bank optical backscatter sensor and a horizontal acoustic Doppler current profiler (H-ADCP). As previous studies showed, the suspended sediment concentration (SSC) that is continuously measured with near-bank sensors can significantly enhance the temporal resolution of sediment transport monitoring. However, sediment plumes from tributary inflows upstream of the monitoring station can alter the detected near-bank concentrations, eventually biasing the sediment load estimation. Such an influence is likely in the cross-section of the planned monitoring station, therefore, a thorough preliminary analysis of the cross-sectional variation of the SSC was performed, based on expeditionary sediment measurement campaigns. Between 2018 and 2021 24 campaigns were carried out at different hydrological regimes, where physical sediment samplings together with fixed and moving boat ADCP measurements were performed. The cross-sectional variability of SSC and its influence on the sediment load estimations were assessed based on the moving boat ADCP measurements, after calibrating the backscatter signal with more than 500 physical samples. Based on the results, we identified different cross-sectional patterns of the SSC which is apparently governed by: (i) the actual hydrological situation considering both the main river and the tributary, and (ii) the local river morphology. Based on our findings, we suggested a correction method that accounts for the above effects, using which the near-bank SSC can be reliably converted into total suspended sediment load.

Assessment of Annual Erosion and Sediment Yield Using Empirical Methods and Validating with Field Measurements—A Case Study

To implement soil conservation approaches, it is necessary to estimate the amount of annual sediment production from a watershed. The purpose of this study was to determine the erosion intensity and sedimentation rate from a watershed by employing empirical models, including the modified Pacific Southwest Inter-Agency Committee (MPSIAC), the erosion potential method (EPM), and Fournier. Moreover, the accuracy of these empirical models was studied based on field measurements. Field measurements were conducted along two reaches of Babolroud River. Total sediment transport, including suspended load and bed load, was predicted. Bed load transport rate was measured using a Helly–Smith sampler, and suspended load discharge was calculated by a sediment rating curve. The results of this study indicate that the erosion intensity coefficient (Z) of the Babolroud watershed is 0.54, with a deposition rate of 166.469 m3/(km2.year). Due to the existence of unusable crops, the highest amount of erosion appeared in the northern region of the watershed. The results using the EPM and MPSIAC models were compared with field measurements and indicated that both models provided good accuracy, with differences of 22.42% and 20.5% from the field results, respectively. Additionally, it could be concluded that the Fournier method is not an efficient method since it is unable to consider the erosion potential.

Forest fire effects on stream water quality at continental scales: a meta-analysis

Forested watersheds supply over two thirds of the world’s drinking water. The last decade has seen an increase in the frequency and intensity of wildfires that is threatening these source watersheds, and necessitating more expensive water treatment to address degrading water quality. Given increasing wildfire frequency in a changing climate, it is important to understand the magnitude of water quality impacts following fire. Here, we conducted a meta-analysis to explore post-fire changes in the concentrations of nitrogen (N) and phosphorus (P) species, dissolved organic carbon, and total suspended sediments in 121 sites around the world. Changes were documented over each study’s respective duration, which for 90% of sites was five years or fewer. We find concurrent increases in C, N and P species, highlighting a tight coupling between biogeochemical cycles in post-fire landscapes. We find that fire alters N and P speciation, with median increases of 40%–60% in the proportion of soluble inorganic N and P relative to total N and P. We also found that fire decreases C:N and C:P ratios, with median decreases ranging from 60% to 70%. Finally we observe a ‘hockey stick’-like response in changes to the concentration distribution, where increases in the highest concentration ranges are much greater than increases at lower concentrations. Our study documents strong heterogeneity in responses of water quality to wildfire that have been unreported so far in the literature.

An inclusive multiple model for predicting total sediment transport rate in the presence of coastal vegetation cover based on optimized kernel extreme learning models.

Predicting sediment transport rate (STR) in the presence of flexible vegetation is a critical task for modelers. Sediment transport modeling methods in the coastal region is equally challenging due to the nonlinearity of the STR-vegetation interaction. In the present study, the kernel extreme learning model (KELM) was integrated with the seagull optimization algorithm (SEOA), the crow optimization algorithm (COA), the firefly algorithm (FFA), and particle swarm optimization (PSO) to estimate the STR in the presence of vegetation cover. The rigidity index, D50/wave height, Newton number, drag coefficient, and cover density were used as inputs to the models. The root mean square error (RMSE), the mean absolute error (MAE), and percentage of bias (PBIAS) were used to evaluate the capability of models. This study applied the novel ensemble model, and the inclusive multiple model (IMM), to assemble the outputs of the KELM models. In addition, the innovations of this study were the introduction of a new IMM model, and the use of new hybrid KELM models for predicting STR and investigating the effects of various parameters on the STR. At the testing level, the MAE of the IMM model was 22, 60, 68, 73, and 76% lower than those of the KELM-SEOA, KELM-COA, KELM-PSO, and KELM models, respectively. The IMM had a PBIAS of 5, whereas the KELM-SEOA, KELM-COA, KELM-PSOA, and KELM had PBIAS of 9, 12, 14, 18, and 21%, respectively. The results indicated that the increasing drag coefficient and D50/wave height had decreased the STR. From the findings, it was revealed that the IMM and KELM-SEOA had higher predictive ability for STR. Since the sediment is one of the most important sources of environmental pollution, therefore, this study is useful for monitoring and controlling environmental pollution.

Influence of Rainfall Intensity and Slope on Runoff and Sediment Reduction Benefits of Fine Mesh Net on Construction Spoil Deposits

Fine mesh nets (FMNs) are commonly used as a mulch material to control soil erosion in construction spoil deposits. Here, three rainfall intensities (60–120 mm·h−1) and seven slope gradients (5–35°) were considered in relation to an FMN’s function of reducing soil erosion on spoil deposits. Soil surfaces covered with an FMN (NS) were prepared in 2 m × 0.5 m soil boxes, with a smooth surface (SS) as the control. Runoff and sediment reduction benefits (RRB and SRB, respectively) were used to quantify the role of the FMN in soil erosion reduction. The FMN performed better in controlling the total sediment yield (mean SRB: 35.9%) compared with total runoff (mean RRB: 5.3%). There was a difference in runoff between SS and NS under a low rainfall intensity (60 mm·h−1; p < 0.05). SS and NS on different slopes generated similar runoff, with significantly different sediment yields (p < 0.05). The benefits of the FMN basically decreased with increases in the rainfall intensity and slope, although the RRB fluctuated on different slopes. The results demonstrate that the soil and water conservation benefits of the FMN on spoil deposits were influenced by the rainfall intensity and slope. The effectiveness of FMNs in soil erosion control needs further investigation in the context of local climates.

Species Sensitivity Distributions of Benthic Macroinvertebrates in Fludioxonil-Spiked Sediment Toxicity Tests.

The fungicide fludioxonil, given its physicochemical properties, potentially accumulates and persists in sediments. Fludioxonil has a widespread agricultural use to control various fungal diseases. Its residues may cause toxic effects to benthic aquatic fauna, thereby impacting ecosystem service functions of aquatic ecosystems. To assess the potential environmental effects of fludioxonil in the sediment compartment of edge-of-field surface waters, sediment-spiked single-species toxicity tests with benthic macroinvertebrates were performed. In all experiments artificial sediment was used with an organic carbon content of 2.43% on dry weight basis. The single-species tests were conducted with 8 benthic macroinvertebrates covering different taxonomic groups typical for the Yangtze River Delta, China. The 28d-EC10 and 28-LC10 values thus obtained were used to construct species sensitivity distributions (SSDs). In addition, our dataset was supplemented with 28d-EC10 and 28-LC10 values for 8 different benthic invertebrates from a study in the Netherlands that used field-collected sediment. Based on SSDs constructed with 28d-EC10 or 28d-LC10 values hazardous concentrations to 5% of the species tested (HC5's) were obtained. The HC5 values based on the toxicity tests from China were lower than those from the Netherlands, although 95% confidence bands overlapped. The HC5 values derived from the separate datasets from China and the Netherlands, as well as from the combined dataset, were compared to the Tier-3 Regulatory Acceptable Concentrations (RAC) for fludioxonil and the benthic invertebrate community derived from a sediment-spiked outdoor microcosm experiment conducted in the Netherlands. The HC5 values obtained appeared to be lower than this Tier-3 RAC when expressed in terms of total sediment concentration, but not always when expressed in terms of pore water concentrations.

Seagrasses and local environment control the bacterial community structure and carbon substrate utilization in brackish sediments

Seagrasses are complex benthic coastal ecosystems that play a crucial role in organic matter cycling and carbon sequestration. However, little is known about how seagrasses influence the structure and carbon utilization potential of benthic bacterial communities. This study examined the bacterial communities in monospecific and mixed meadows of seagrasses and compared with bulk (unvegetated) sediments from Chilika, a brackish water coastal lagoon of India. High-throughput sequencing of 16S rRNA genes revealed a vegetation effect in terms of differences in benthic bacterial community diversity, composition, and abundances in comparison with bulk sediments. Desulfobacterales, Chromatiales, Enterobacteriales, Clostridiales, Vibrionales, and Acidimicrobiales were major taxa that contributed to differences between seagrass and bulk sediments. Seagrasses supported ∼5.94 fold higher bacterial abundances than the bulk due to rich organic carbon stock in their sediments. Co-occurrence network demonstrated much stronger potential interactions and connectedness in seagrass bacterial communities compared to bulk. Chromatiales and Acidimicrobiales were identified as the top two keystone taxa in seagrass bacterial communities, whereas, Dehalococcoidales and Rhizobiales were in bulk communities. Seagrasses and local environmental factors, namely, water depth, water pH, sediment salinity, redox potential, total organic carbon, available nitrogen, sediment texture, sediment pH, and sediment core depth were the major drivers of benthic bacterial community composition. Carbon metabolic profiling revealed that heterotrophic bacteria in seagrass sediments were much more metabolically diverse and active than bulk. The utilization of carbon substrate guilds, namely, amino acids, amines, carboxylic acids, carbohydrates, polymers, and phenolic compounds was enhanced in seagrass sediments. Metabolic mapping predicted higher prevalence of sulfate-reducer and N2 fixation metabolic functions in seagrass sediments. Overall, this study showed that seagrasses control benthic bacterial community composition and diversity, enhance heterotrophic carbon substrate utilization, and play crucial roles in organic matter cycling including degradation of hydrocarbon and xenobiotics in coastal sediments.

Effects of rock fragment coverage on soil erosion: Differ among rock fragment sizes?

The presence of rock fragments can change land cover and thus profoundly perturb soil erosion process. This study aimed to identify the effects of rock coverage on soil erosion, and how such effects were influenced by rock fragment sizes. A series of simulated rainfall experiments were applied to erosion plots with two initial soil moisture contents (dry run and wet run), under rock fragment coverage (15%, 30%, 45%, 60%) composed of eight different fragment sizes (0.7, 1.1, 3.0, 5.5, 12.0, 18.8, 26.4, 36.0 cm) from May to September in 2021. The results show that total runoff and sediment concentration increased with rock fragment size. When rock fragments with the sizes were less than 12.0 cm, the total runoff and sediment concentration were respectively 0.81–16.02% and 16.45–50.88% lower than the bare soil. Consequently, the soil loss decreased exponentially with rock fragment coverage. When rock fragment with the sizes were large than 12.0 cm, they decreased sediment concentration by 7.91–33.32% in the dry run, but increased the total runoff by 0.26–10.28% and sediment concentration by 9.33–82.91% in the wet run. As a result, the soil loss ratio firstly enhanced as rock fragment coverage up to 45% and then declined at the rock fragment coverage of 60%. Our findings demonstrate that the effects of rock fragment coverage on soil erosion are rock fragment size dependent. This can help to better parameterize the effects of rock fragment coverage in current soil erosion models, in turn providing guiding information for soil erosion control in stony regions.

Linking rill development characteristics to sediment production on different coarse-textured granite topsoils

The sheet and rill erosion phases dominate the erosion process of the catchment area and up-slope of Benggang (a special gully) area, and its evolution has a vital impact on erosion characteristics in the erosion feedback loop. Here, the rill development processes, morphological characteristics and corresponding soil loss were investigated by laser scanning on the four coarse-textured granite topsoils defined as WH, TC, GX, and CT for the counties of Wuhua, Tongcheng, Ganxian, and Changting in China, respectively. A soil flume (3 × 0.8 m) at a slope gradient of 16.7% was treated with rainfall-inflow at the upslope inflow rate of 2 L min−1 and rainfall intensity of 90 mm h−1. Results showed that soil erosion rate increased with erosion evolution (sheet erosion, rill advance, and rill maturity phases). A comparison of the four different soils exhibited that the soil erosion rate showed a downtrend with the increase of soil clay and gravel contents. Specifically, the CT soil with high clay and gravel content showed the minimal soil erosion rate (0.024 kg m−2 min−1), rill density (0.95 m m−2), headward erosion rate (0.41 cm min−1), and surface evolution rate. The maximal soil erosion rate and rill depth were observed on the WH slope, with the rill headward erosion rate reaching the maximum of 20.59 cm min−1. Despite no significant difference in the geomorphologic comentropy of the four soils, their variation trend and rate could reflect dynamic changes in erosion. The total sediment transport efficiency was improved by rill formation and development, with rill erosion contributing to about 70% of total soil loss for the four soils. This study can enrich our understanding of the rill erosion process and surface morphology of coarse-textured topsoils.

Improper Maintenance Activities Alter Benefits of Urban Stormwater Treatment in a Temperate Constructed Wetland in NSW, Australia

Constructed wetlands (CWs) are an effective means to treat nutrient and sediment pollution in urban stormwater runoff to minimise impact on receiving waterways. Maintenance of devices is recognised as a major contributing factor to performance. There is a lack of evidence-based guidance on maintenance activities to optimise treatment, due to a paucity of data from long-term field studies into CW performance before and after maintenance. In this study, the nutrient and sediment removal efficiency (% RE) of a CW was evaluated by calculating removal efficiencies of nitrogen (N), phosphorus (P) and total suspended sediment (TSS) following a long-term sampling program under baseflow and event flow conditions. Sampling was carried out before, during and after maintenance. Maintenance involved removing all aquatic vegetation and 200–300 mm of sediments over a 3-week period, aiming to improve the wetland’s performance. Assessment of dissolved and particulate nutrient fractions allowed a comprehensive investigation into drivers of nutrient removal efficiency. Under baseflow conditions differences in inflow and outflow pollutant concentrations were used to calculate removal efficiency and pollutant loads were used during event flow conditions. Before maintenance, during baseflow conditions the wetland was removing total N (36% RE) but exporting total P (-52% RE) and total sediment (-94% RE). During event-flow conditions all target pollutants were being removed (total N 63% RE, total P 25% RE and TSS 69% RE). phosphorusDuring maintenance, the device continued to remove total N (18% RE) but the physical disturbance of the maintenance resulted in mass export of total P (-120% RE) and total sediment (−2,000% RE) over a short time period, effectively undoing previous treatment. After maintenance, during baseflow conditions, the wetlands’ ability to treat total N decreased (28% RE), improved for total P (1% RE), and became a chronic source of suspended sediment (−127% RE). During event flow conditions, total N was no longer being treated (−19%) but total P and total suspended sediment were being retained (74%, 80% RE respectively). This study showed that the physical disturbance resulting from large-scale maintenance activities can potentially reverse years’ worth of treatment if not adequately planned and carried out with suitable controls.

Effects of crop residue on wind erosion due to dust storms in Hotan Prefecture, Xinjiang, China

In arid and semiarid areas with frequent dust storms, reasonable planting modes and crop residue measures could prevent dust storms that originate from local farmlands and address key factors for wind erosion control. The considered crop residue modes included all harvesting with no residue in a Cyperus esculentus L. (C.) monoculture setting (AH), retention of 1 ridge and harvesting of 3 ridges in a C. monoculture setting (RH), and all harvesting with retention of Setaria italica (L.) Beauv. var. germanica (Mill.) Schrad (S.) residue in an intercropping setting of 6S. ridges and 9C. ridges (ARS). The aerodynamic roughness z0 and friction velocity u* were measured with handheld anemometers, and sediment fluxes were measured by combining multichannel sand collectors under different crop residue modes. The results indicated that the total aeolian sediment flux increased with distance away from the final belt of crop residue under both the RH and ARS modes. S. residue reduced the total aeolian sediment flux by more than 50% compared to C. residue at a distance of 4.5 m away from the residue belt during the dust storm. The sand transported height under both the RH and ARS modes was lower than that under the AH mode, and the distance required for sand to be transported to the same flux behind the S. residue belt was more than that behind the C. residue belt. The frontal area index (FAI) is a parameter that can better reflect the wind erosion control ability of C. and S. residues. S. residue attained a higher wind weakening ability than C. residue according to the positive relationship between z0, u* and FAI. During the dust storm, the relationship between the total aeolian sediment flux and FAI changed from significant to insignificant as the sand transported height exceeded C. residue height. Using standing crops intercropping with C. can provide both income from C. and wind erosion control from standing crop residues. The results can provide useful guidance for local C. harvest and planting design.

Trends Analysis of Simultaneously Extracted Metal Copper Sediment Concentrations from a California Agricultural Waterbody including Historical Comparisons with Other Agricultural Waterbodies

The objectives of this study were to: (1) assess annual, seasonal and spatial trends in simultaneously extracted metal copper (SEM copper) sediment concentrations in an agricultural California waterbody (Cache Slough) sampled over three years and two seasons (spring and fall); (2) determine the relationship between SEM copper sediment concentrations and precipitation; (3) compare the SEM copper sediment concentrations from Cache Slough with other agricultural streams and (4) compare trends in SEM copper with total copper sediment concentrations previously reported from this waterbody. Sediment samples for SEM copper analysis were collected by boat. Regression analysis, Analysis of Variance, T-test procedure and the Fisher LDS method were used for statistical analysis of data. The results from this study showed that mean seasonal SEM copper sediment concentrations from Cache Slough ranged from 18.6 to 30.1 µg/g dw. SEM copper sediment concentrations were not reported to increase over time in this agricultural waterbody where copper was used as a fungicide, although some spatial differences in SEM copper sediment concentrations were reported. Seasonal analysis showed no significant differences in SEM copper sediment concentrations for both spring and fall for two years, but spring concentrations were statistically higher than fall concentrations for the last year of the study. There were no statistically significant relationships between SEM copper sediment concentrations and precipitation for the three-year period, based on an analysis by year and season. A comparative analysis of total copper and SEM copper from Cache Slough showed that the range of mean seasonal concentrations of SEM copper was much lower, and more sites showed declining trends for SEM copper than for total copper. Increasing trends were not reported at any of the sites for either SEM copper or total copper. A comparison of SEM copper data from Cache Slough was reported to be similar to concentrations reported for other water bodies influenced by agricultural use. Additional multiple year studies in other geographic areas assessing trends in SEM copper sediment concentrations with a comprehensive spatial scale are recommended.

Disproportionate and chronic sediment delivery from a fluvially controlled, deep‐seated landslide in Aotearoa New Zealand

AbstractPast research has highlighted the importance of sediment delivery from multiple‐occurrence regional landslide events triggered by storms or earthquakes. Herein, we examine delivery from a more persistent source of sediment, that of a large, slow‐moving landslide in the soft‐rock hill country of Aotearoa New Zealand. We map and monitor the 80‐ha Rangitikei Landslide from 2015 to 2019 using time‐lapse photography, ground surveys, photogrammetry, and piezometers. We show that the landslide can be divided into several zones with distinctive movement patterns, but all zones respond to river erosion. The fastest zone moves more than 10 m per year in a flow‐like fashion, while other zones move 0.01 m per year via slow sliding. Movement occurs all year round, but is two to three times faster in winter and spring. While rainfall and associated groundwater change are commonly attributed to landslide movement patterns, our data show that river flow correlates closely with the weekly to seasonal variability in movement of the landslide toe. This suggests that fluvial erosion can play an important role in the movement dynamics of highly coupled landslides. We estimate an annual sediment yield to the Rangitikei River of at least 40 000 tonnes, in this first quantification of sediment delivery from an active soft‐rock landslide in Aotearoa. This volume implies 7% of the total catchment suspended sediment yield is derived from 0.03% of the contributing catchment area, demonstrating the disproportionate effect of this (and likely other) deep‐seated landslide(s) as a source of sediment in the Rangitikei catchment. Sediment delivery is more continuous than the episodic supply of multiple‐occurrence regional landslide triggering events, and by delivering mostly fine‐grained sediment, it has a potentially large impact on water quality.

Spatiotemporal variations of total suspended sediment concentrations in the Peace-Athabasca Delta during 2000 to 2020

Total suspended sediments (TSS) are an important water quality indicator. The spatiotemporal distribution patterns of TSS concentrations in summer in the Peace-Athabasca Delta (PAD) remain unclear between 2000 and 2020. Among empirical and machine learning models, the random forest (RF) model exhibits the best performance for the PAD with a coefficient of determination, normalized root-means-square error, and relative root-mean-square error of 0.92, 7.51%, and 27.36%, respectively. Our study analyzes the spatiotemporal TSS distribution based on 21 years of Landsat remote sensing data and the RF model. The results showed that the TSS concentrations of the Peace River were elevated in 2000, 2016, 2019, and 2020. The long-term TSS concentration distribution in the PAD showed a decreasing trend from west to east, and the TSS concentrations ranged from 6 to 80 mg/L level and remained stable in Lake Athabasca during the investigated period. Moreover, 57.14% of the PAD area exhibited no significant change between 2000 and 2020. The results of our study provide detailed information for the local government on the TSS concentrations in the PAD.

Вплив клітинної терапії на динаміку маркерів запалення в крові щурів з ад’ювантним артритом

The purpose of the study was to investigate the dynamics of inflammation in blood of the rats with adjuvant arthritis under the conditions of generalized and local administration of cryopreserved multipotent mesenchymal stromal cells from adipose and cartilage tissues. Materials and methods. A model of adjuvant arthritis in male rats was induced by subplantar administration of Freund’s complete adjuvant. On the 7th day of modeling, experimental animals were administered: control group – saline; experimental group 1 and 2 – cryopreserved multipotent mesenchymal stromal cells from adipose or cartilaginous tissue locally; experimental group 3 and 4 – cryopreserved multipotent mesenchymal stromal cells from adipose or cartilaginous tissue generalized. Groups of intact animals served as control. On days 14, 21 and 28 erythrocyte sedimentation rate was determined in blood, and content of total protein, C-reactive protein and rheumatoid factor were measured in serum. Results and discussion. In the control group of animals, the inflammatory process was pronounced, as evidenced by a significant increase in the studied parameters throughout the observation period. The use of cryopreserved multipotent mesenchymal stromal cells from adipose and cartilaginous tissues led to the restoration of the total protein content and erythrocyte sedimentation rate on the 28th day of observation, as well as positive dynamics in the level of C-reactive protein and rheumatoid factor. Generalized administration of cells had a more pronounced therapeutic effect compared to the animals with local one. A comparative assessment of the use of cryopreserved multipotent mesenchymal stromal cells from adipose and cartilaginous tissues showed the absence of significant changes in the studied parameters both with studied ways of cell administration. These data can be used to justify and develop methods of treating arthritis in clinical practice. But important issue that needs further research is the determination of cell immunity in the animals with adjuvant arthritis and treatment of cryopreserved multipotent mesenchymal stromal cells from adipose and cartilage tissues. Conclusion. Cell therapy with the use of cryopreserved multipotent mesenchymal stromal cells from the investigated sources provided by both local and generalized administration to animals with adjuvant arthritis has a modulating effect on the course of inflammation