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The continued phosphorus (P) impairment of freshwaters and the associated risk of eutrophication raise questions regarding the efficiency of current beneficial management practices (BMPs) for improving water quality. Vegetated buffer strips (VBSs) are widely encouraged BMPs for reducing P export from agricultural land. However, there is a lack of evidence regarding the long‐term efficiency of VBSs for reducing legacy P losses. This research used soil analyses to investigate the P removal efficiency of an unmanaged VBS for controlling P loss from agricultural land in Manitoba, Canada, between 1954 and 2011. The results showed statistically significant retention of total P, Olsen extractable P, and 0.01 M CaCl2extractable P by a 5‐m wide VBS compared with field soils. We found that surface soils at 5‐m into the VBS had a significantly greater P sorption capacity and a smaller degree of P saturation (DPS) than adjacent field soils. The elevated DPS in field soils is likely associated with gradual P enrichment as a result of manure or fertilizer application over time and the strong affinity of P compounds for soil. Although P stratification in the VBS over 57 yr resulted in a significant increase (∼11%) in DPS of VBS topsoil compared with VBS subsoil, our findings do not support the saturation of VBS soils with P. However, cutting and removal of vegetation from VBS could be a useful strategy to remove P from VBS and minimize possible P remobilization associated with vegetation senescence, especially where the climate is cold and runoff is dominated by snowmelt. Vegetated buffer strips (VBSs) reduced legacy P losses from adjacent land.VBS soils had a significantly greater P sorption capacity than field soils.VBS soils had a significantly smaller degree of P saturation than field soils.VBS soils did not get saturated with P exports from adjacent land even after 57 yr.

The use of sediment color as a fingerprint property to determine sediment sources is an emerging technique that can provide a rapid and inexpensive means of investigating sediment sources. The present study aims to test the feasibility of color fingerprint properties to apportion sediment sources within the South Tobacco Creek Watershed (74 km2) in Manitoba, Canada. Suspended sediment from 2009 to 2011 at six monitoring stations and potential source samples along the main stem of the creek were collected. Reflectance spectra of sediments and source materials were quantified using a diffuse reflectance spectrometry, and 16 color coefficients were derived from several color space models. Canonical discriminant analysis was used to reclassify and downsize sediment source groups. After the linear additive test and stepwise discriminant function analysis, four color coefficients were chosen to fit the Stable Isotope Analysis in R model. Consistent with the conventional fingerprinting approach, the color fingerprint results demonstrated a switch in the dominant sediment source between the headwaters and the outlet of the watershed, with the main sources being topsoil in the upper reaches, whereas outcrop shale and stream bank materials dominated in the lower reaches. The color fingerprinting approach can be integrated with conventional fingerprints (e.g., geochemical and fallout radionuclide properties) to improve source discrimination, which is a key component for source ascription modeling. We concluded that the use of color fingerprints is a promising, cost‐effective technique for sediment source fingerprinting. Defining sources and testing the behavior of tracers are critical for sediment source apportionment.The predominant sources of river sediment varied at different reaches of the study creek.Integrating color and conventional fingerprinting techniques likely improves source apportionment.Color fingerprinting is a promising, cost‐effective technique for sediment source ascription.

On 4 August 2014, a catastrophic breach of the Mount Polley mine tailings impoundment released ~25 M m3of tailings and water and scoured an unknown quantity of overburden into the West Basin of Quesnel Lake. We document Quesnel Lake and Quesnel River observations for 2 months postspill. Breach inflows raised Quesnel Lake by 7.7 cm, equivalent to ~21 M m3. The West Basin hypolimnion was modified immediately, exhibiting increased temperature (~5°C to 6–7.5°C), conductivity (110 to 160 μS/cm), and turbidity (<1 to 200–1000 nephelometric turbidity units (NTU)). Cooscillating seiches moved West Basin hypolimnetic water both westward and eastward contaminating the Main Basin. Postspill, high‐turbidity water propagated eastward (~1 cm/s), introducing a persistent ~20 m thick layer below the thermocline and an ~30 m thick layer at the bottom. The contaminant introduction, mobilization, and bioaccumulation may pose risks to resident and anadromous fish stocks, which support recreational, commercial, and First Nations fisheries. Hypolimnetic increase in temperature and turbidity due to a mine tailings spillStratification and seiching promote and distribute fine‐grained sediment plumePhysical, biological and chemical implications for a near‐pristine lake

On 4 August 2014, a tailings dam failure at Mount Polley Mine in central British Columbia led to the largest short‐term release of mine waste into a lake ever recorded. Once released by the breach, slurry entered the smaller of Quesnel Lake’s two basins, called the West Basin, from which the lake drains northwest into the Quesnel River. An estimated 38,000 ± 11,000 tonnes of fine solids remained suspended in the West Basin on 10 September 2014, 37 days postspill. This decreased to within background levels (<300 tonnes) by June 2015, by which time ∼4,000 tonnes of sediment had flowed from the West Basin into the Quesnel River, and ∼31,000 tonnes had been transported east into the main basin, the direction opposed to the mean hydraulic gradient. Here, we evaluate sediment transport in Quesnel Lake following the Mount Polley tailings dam spill. We apply conservation of mass in two ways: using data collected between 12 August 2014 and 15 October 2020 to estimate suspended sediment mass and mass flows into and out of the West Basin; and using one‐ and two‐basin completely mixed models. Suspended sediment concentrations were highly elevated through the first three seasons postspill, then fluctuated within a gradually decreasing, seasonal cycle. The observed mass trend and an analytical mass balance model of a simplified, two‐basin system suggest that suspended sediment mass will fall to below the median prespill mass by 7 ± 5 years postspill. The largest mine waste spill into a lake to date began on 4 August 2014, at Mount Polley Mine in central British Columbia, Canada. Within the day, nearby Quesnel Lake received a volume of waste equivalent to 2% of the volume of its smaller, downstream basin, the West Basin, where the spill flowed into the lake (0.02 km3of waste into the 1 km3basin). Roughly 38,000 tonnes of fine solids remained in suspension 37 days postspill, and our study evaluated the movements of this suspended sediment in Quesnel Lake and the Quesnel River using water quality data collected between 12 August 2014 and 15 October 2020. We found that the net movement of suspended sediment was opposed to that of the hydraulic gradient through the first three seasons postspill, after which the amount of sediment fluctuated seasonally each year, greatest each autumn and spring. We assessed simplified one‐ and two‐basin mathematical models, the latter of which broadly describes the two‐phased response of Quesnel Lake’s two basins, and both of which predict a return to background suspended sediment concentration in the West Basin by about one decade postspill. About 38,000 Mg of sediment was suspended in the smaller of two lake basins 1 month after a spillFour fifths of this sediment went east into the larger basin and one tenth went north to the outflowTrends show a return to background suspended sediment levels by about 7 years after the spill About 38,000 Mg of sediment was suspended in the smaller of two lake basins 1 month after a spill Four fifths of this sediment went east into the larger basin and one tenth went north to the outflow Trends show a return to background suspended sediment levels by about 7 years after the spill

Many models of phosphorus (P) transfer at the catchment scale rely on input from generic databases including, amongst others, soil and land use maps. Spatially detailed geochemical data sets have the potential to improve the accuracy of the input parameters of catchment‐scale nutrient transfer models. Furthermore, they enable the assessment of the utility of available, generic spatial data sets for the modeling and prediction of soil nutrient status and nutrient transfer at the catchment scale. This study aims to quantify the unique and joint contribution of soil and sediment properties, land cover, and point‐source emissions to the spatial variation of P concentrations in soil, streambed sediments, and stream water at the scale of a medium‐sized catchment. Soil parent material and soil chemical properties were identified as major factors controlling the catchment‐scale spatial variation in soil total P and Olsen P concentrations. Soil type and land cover as derived from the generic spatial database explain 33.7% of the variation in soil total P concentrations and 17.4% of the variation in Olsen P concentrations. Streambed P concentrations are principally related to the major element concentrations in streambed sediment and P delivery from the hillslopes due to sediment erosion. During base flow conditions, the total phosphorus (<0.45 μm) concentrations in stream water are mainly controlled by the concentrations of P and the major elements in the streambed sediment.

A measure of soil P status in agricultural soils is generally required for assisting with prediction of potential P loss from agricultural catchments and assessing risk for water quality. The objectives of this paper are twofold: (i) investigating the soil P status, distribution, and variability, both spatially and with soil depth, of two different first‐order catchments; and (ii) determining variation in soil P concentration in relation to catchment topography (quantified as the “topographic index”) and critical source areas (CSAs). The soil P measurements showed large spatial variability, not only between fields and land uses, but also within individual fields and in part was thought to be strongly influenced by areas where cattle tended to congregate and areas where manure was most commonly spread. Topographic index alone was not related to the distribution of soil P, and does not seem to provide an adequate indicator for CSAs in the study catchments. However, CSAs may be used in conjunction with soil P data for help in determining a more “effective” catchment soil P status. The difficulties in defining CSAs a priori, particularly for modeling and prediction purposes, however, suggest that other more “integrated” measures of catchment soil P status, such as baseflow P concentrations or streambed sediment P concentrations, might be more useful. Since observed soil P distribution is variable and is also difficult to relate to nationally available soil P data, any assessment of soil P status for determining risk of P loss is uncertain and problematic, given other catchment physicochemical characteristics and the sampling strategy employed.

This study attempts to quantify the amount of fine-grained (ca.< 150 μm) sediment stored on the floodplains and on the channel bed of the non-tidal sections of the main channels in the catchment of the River Ouse (3315 km 2) and of one of its tributaries, the River Waarfe (818 km 2), in Yorkshire, UK. Caesium-137 analyses of floodplain sediment cores were used to quantify the amount of Iloodplain deposition as a result of overbank flooding during the last ca. 40 years. A combination of bulk and sectioned cores were collected along transects perpendicular to the channel at 26 sites throughout the study basins. In general, rates of overbank sedimentation decrease with distance from the channel. The average values for individual transects range between 0.010 and 0.554 g cm −2year −1. Floodplain storage along the main channels of the Ouse and Wharfe basins accounts for 60645 and 10325 t year −1, respectively, and represents a net loss from the system. The amount of fine-grained sediment stored on the channel bed was estimated by a survey undertaken in August 1996, during which the fine material deposited on the bed was resuspended and its mass estimated at 16 locations. The average values for the individual locations range between 0.017 and 0.924 g cm −2and tend to increase downstream. The total channel bed storage at the time of sampling in 1996 was estimated to be 16076 and 1866 t for the Ouse and Wharfe basins, respectively. It is assumed that channel bed storage is seasonal and that no net loss to the system occurs at the annual timescale. Floodplain storage for the Ouse and Wharfe basins represents 39 and 49%, and channel bed storage equals 10 and 9%, respectively, of the annual suspended sediment load (1995–1996) delivered to the channel system. These results have important implications for the routing of fine-grained sediment and sediment-associated contaminants in drainage basins, and for the interpretation of downstream sediment yields in terms of upstream sediment mobilisation.

Contemporary and post‐glacial rates of aeolian deposition are determined for three small catchments that straddle the alpine‐subalpine ecotone in the Pacific Ranges of the Coast Mountains of British Columbia. From process measurement over a single year, the mean annual regional (allochthonous) rate of aeolian deposition for the catchments is estimated to be approximately 11 g m−2. The average rate of annual deposition over the post‐glacial period is calculated from the soil profiles to be c. 6 g m−2, although fallout rates are likely to have varied significantly over the Holocene epoch due to changes in climate and catchment conditions. It would appear that the vegetated ground strata in these catchments are net receivers of aeolian dust fallout. Consequently, many of the soils are cumulic in nature and protect the bedrock in these catchments from subaerial weathering. These results have implications for sediment transfers in alpine and sub‐alpine environments in southwestern British Columbia.

Contemporary and post‐glacial rates of aeolian deposition are determined for three small catchments that straddle the alpine‐subalpine ecotone in the Pacific Ranges of the Coast Mountains of British Columbia. From process measurement over a single year, the mean annual regional (allochthonous) rate of aeolian deposition for the catchments is estimated to be approximately 11 g m−2. The average rate of annual deposition over the post‐glacial period is calculated from the soil profiles to be c. 6 g m−2, although fallout rates are likely to have varied significantly over the Holocene epoch due to changes in climate and catchment conditions. It would appear that the vegetated ground strata in these catchments are net receivers of aeolian dust fallout. Consequently, many of the soils are cumulic in nature and protect the bedrock in these catchments from subaerial weathering. These results have implications for sediment transfers in alpine and sub‐alpine environments in southwestern British Columbia.

The catastrophic August 2014 Mount Polley tailings spill, the second largest ever documented, sent ~18 Mm3of waste plunging to the bottom of the >100 m deep West Basin of Quesnel Lake, British Columbia, a critical West Coast salmon habitat. To understand the impact of the spill on the lake, including the fate of suspended solids, we examine changes in physical water properties over 11 years (2006–2017) using water column profiles, moored timeseries, and satellite imagery. Contaminated waters were initially largely confined to the hypolimnion; however, during autumn 2014 turnover, turbid waters were mixed to the surface, resulting in the clear blue lake turning bright green. Twelve months after the spill, the lake's temperature, conductivity, and turbidity temporarily returned to pre‐spill conditions; however, initiation of mine effluent discharge in late 2015 was associated with a subsequent 15 μS cm−1conductivity increase above historic values. Importantly, a post‐spill 1–2.5 formazin turbidity unit hypolimnetic turbidity increase was observed during spring and fall turnovers of 2015–2017, which appeared to be due to resuspension of a thin layer of unconsolidated spill‐related material from the lake bed driven by large internal seiche motions. This process implies spill contaminants may be seasonally mobilized into the water column, with potentially detrimental impacts on aquatic ecology. Our findings underscore that basin‐scale physical processes, including seasonal turnover and internal seiches, must be accounted for, even in deep lakes, to understand the long‐term impact of the ever increasing number of tailings spills into aquatic ecosystems. The catastrophic failure of the Mount Polley copper and gold mine tailings pond dam in August 2014 was, at the time, the largest mine‐related spill ever documented. The turbid torrent of mine waste plunged to the bottom of the near pristine waters of Quesnel Lake, British Columbia, critical habitat for West Coast salmon stocks. Despite the scale of the spill, there was surprisingly little visible evidence of it at the surface of the lake in the months following. But what happened below the surface? Using 11 years of water column measurements we show that as the lake mixed from top to bottom (called turnover) that autumn the contaminated deep water was brought to the surface, abruptly changing the color of the clearblue lake to an abnormal bright green color—a change readily visible from space. Since the spill the turbidity of the lake has increased during spring and autumn turnover, apparently due to resuspension of spill material off the lake bottom driven by basin‐scale wave oscillations. This process, and the ongoing discharge of excess mine waste water directly into the lake, raises concerns over the seasonal mobilization of mine contaminants and their impact on aquatic ecosystems. Quesnel Lake turned bright green when turbid spill material trapped in the hypolimnion mixed to the surface during autumn 2014 turnoverSeasonal turbidity increases since the spill are likely due to resuspension of spill‐related bottom sediment by internal seichesPhysical dynamics are key to understanding the long‐term impact of acute and chronic mine spills even in deep aquatic systems