Changes In Nutrient Concentrations Research Articles

Annual changes in water quality and sportfish community structure following commercial harvest of common carp and bigmouth buffalo

Martin A. Simonson, Michael J. Weber, Grace M. Wilkinson and Andrew R. Annear. 2023. Annual changes in water quality and sportfish community structure following commercial harvest of common carp and bigmouth buffalo. Lake Reserv Manage. XX:XXX–XXX. Commercial harvest of common carp (Cyprinus carpio; hereafter carp) and bigmouth buffalo (Ictiobus cyprinellus; hereafter buffalo) populations had little detectable effect on shallow lake ecosystems. We tested whether carp and buffalo biomass removal affects limnological variables and fish community metrics across 6 shallow, natural lakes of northwestern Iowa using mixed effects models. Annual commercial harvest of carp ranged from 0 to 71 kg/ha; annual harvest of buffalo ranged from 0 to 356 kg/ha. Biomanipulation (i.e., commercial harvest) of carp was associated with decreases in soluble phosphorus and nitrogen concentrations, but not total phosphorus or nitrogen. Buffalo harvest was unrelated to annual changes in nutrient concentrations but was associated with reductions in chlorophyll a and phycocyanin concentrations. Secchi disk transparency and total suspended solids were unrelated to carp and buffalo harvest. Carp harvest was associated with reduced biomass of large cladocerans but no other zooplankton biomass densities; buffalo harvest was unrelated to zooplankton biomass. Species richness and rake density of aquatic macrophytes were unrelated to carp and buffalo harvest. Carp and buffalo harvest was unrelated to changes in most indices of sportfish abundance, condition, and size distribution. Our results suggest harvest of carp and buffalo <71 kg/ha has little effect on abiotic and biotic ecosystem components on short time scales and highlights the challenges associated with shallow lake restoration.

Changes in Nutrient Concentration Resulting From Floods and Their Impact on the Estuary–Sea Continuum

AbstractEvaluating the contribution of rivers to coastal seas in the Earth system and accurately predicting marine environmental responses to climate change are crucial for mitigating and addressing future natural disasters, especially those related to extreme hydrological events, such as fluvial floods. The Changjiang (Yangtze) River Estuary (CRE) and the East China Sea continuum, known for high environmental stress, complex marine dynamic processes, and frequent flood events, were selected to determine the compound impacts of a severe flood that persisted for the whole of July 2017. We conducted three cruise surveys before and after this flood event. Our surveys revealed that the phosphate concentration in the channel of the CRE declined from 2 to &lt;1 μM during the flood, while the nitrate concentration remained stable. We applied a coupled physical‐biogeochemical model to determine the spatio‐temporal influence of floodwater (freshwater from upstream during flood events). During the initial rising discharge stage, surface phytoplankton blooms triggered by enhanced stratification consumed phosphate and significantly increased the N:P ratio in the sea. The ratio was restored as the blooms diminished, but remained elevated due to lower phosphate floodwater in the northeastward area within the low‐salinity river plume. Model experiments also showed that phytoplankton biomass and N:P ratio in the flood plume region were sensitive to the riverine phosphate concentration inputs during the flood event.

Consistent microbial and nutrient resource island patterns during monsoon rain in a Chihuahuan Desert bajada shrubland

AbstractIn dryland soils, spatiotemporal variation in surface soils (0–10 cm) plays an important role in the function of the “critical zone” that extends from canopy to groundwater. Understanding connections between soil microbes and biogeochemical cycling in surface soils requires repeated multivariate measurements of nutrients, microbial abundance, and microbial function. We examined these processes in resource islands and interspaces over a two‐month period at a Chihuahuan Desert bajada shrubland site. We collected soil in Prosopis glandulosa (honey mesquite), Larrea tridentata (creosote bush), and unvegetated (interspace) areas to measure soil nutrient concentrations, microbial biomass, and potential soil enzyme activity. We monitored the dynamics of these belowground processes as soil conditions dried and then rewetted due to rainfall. Most measured variables, including inorganic nutrients, microbial biomass, and soil enzyme activities, were greater under shrubs during both wet and dry periods, with the highest magnitudes under mesquite followed by creosote bush and then interspace. One exception was nitrate, which was highly variable and did not show resource island patterns. Temporally, rainfall pulses were associated with substantial changes in soil nutrient concentrations, though resource island patterns remained consistent during all phases of the soil moisture pulse. Microbial biomass was more consistent than nutrients, decreasing only when soils were driest. Potential enzyme activities were even more consistent and did not decline in dry periods, potentially helping to stimulate observed pulses in CO2 efflux following rain events observed at a co‐located eddy flux tower. These results indicate a critical zone with organic matter cycling patterns consistently elevated in shrub resource islands (which varied by shrub species), high decomposition potential that limits soil organic matter accumulation across the landscape, and nitrate fluxes that are decoupled from the organic matter pathways.

Changes in nutrient concentration and water level affect the microbial loop: a 6-month mesocosm experiment

Changes in nutrient concentration and water level affect the microbial loop: a 6-month mesocosm experiment

An evaluation of long-term physical and hydrochemical measurements at the Sylt Roads Marine Observatory (1973–2019), Wadden Sea, North Sea

Abstract. The Sylt Roads pelagic time series covers physical and hydrochemical parameters at five neighboring stations in the Sylt–Rømø bight, Wadden Sea, North Sea. Since the beginning of the time series in 1973, sea surface temperature (SST), salinity, ammonium, nitrite, nitrate, and soluble reactive phosphorus (SRP) have been measured twice a week. The other parameters were introduced later (dissolved silicate (Si) since 1974, pH since 1979, dissolved organic nitrogen (DON) since 1996, dissolved organic phosphorus (DOP) since 2001, chlorophyll a since 1979, and suspended particulate matter (SPM) since 1975), and in the case of dissolved oxygen, were already discontinued (1979–1983). In the years 1977, 1978, and 1983, no sampling took place. Since the start of the continuous sampling in 1984, the sea surface temperature in the bight has risen by +1.11 ∘C, with the highest increases during the autumn months, while the pH and salinity decreased by 0.23 and 0.33 units, respectively. Summer and autumn salinities are generally significantly elevated compared to spring and winter conditions. Dissolved nutrients (ammonium, nitrite, nitrate, and SRP) have displayed periods of intense eutrophication (1973–1998) and de-eutrophication since 1999. Silicate has shown significantly higher winter levels since 1999. Interestingly, phytoplankton parameters did not mirror these large changes in nutrient concentrations, as a seasonal comparison of the two eutrophication periods showed no significant differences with regard to chlorophyll a. This phenomenon might be triggered by an important switch in nutrient limitation during the time series. With regard to nutrients, the phytoplankton was probably primarily limited by silicate until 1998, while, since 1999, the SRP limitation has become increasingly important. All data are available in Rick et al. (2017b–e, 2020a–o) from https://doi.org/10.1594/PANGAEA.150032, https://doi.org/10.1594/PANGAEA.873549, https://doi.org/10.1594/PANGAEA.873545, https://doi.org/10.1594/PANGAEA.873547, https://doi.org/10.1594/PANGAEA.918018, https://doi.org/10.1594/PANGAEA.918032, https://doi.org/10.1594/PANGAEA.918027, https://doi.org/10.1594/PANGAEA.918023, https://doi.org/10.1594/PANGAEA.918033, https://doi.org/10.1594/PANGAEA.918028, https://doi.org/10.1594/PANGAEA.918024, https://doi.org/10.1594/PANGAEA.918034, https://doi.org/10.1594/PANGAEA.918029, https://doi.org/10.1594/PANGAEA.918025, https://doi.org/10.1594/PANGAEA.918035, https://doi.org/10.1594/PANGAEA.918030, https://doi.org/10.1594/PANGAEA.918026, https://doi.org/10.1594/PANGAEA.918036, and https://doi.org/10.1594/PANGAEA.918031.

Multigenerational variation in the nutrients and digestion of western flower thrips (Frankliniella occidentalis) depends on the nutritive quality of different foods

Western flower thrips (WFTs), Frankliniella occidentalis (Thysanoptera, Thripidae), is one of the most serious pests that attack rose flowers. Little is known about the effect of different parts of the rose flower on nutritional contents and digestive enzyme activities in thrips. This study assessed variations in the nutritional contents and digestive enzyme activities in the second-instar larvae and adults WFTs fed on 3 food types (rose petals, rose flowers, and honey solution + kidney bean pods) for multiple generations. The highest contents of soluble sugar (in 10% honey solution + kidney bean pods), amino acid (in rose flowers), and protein (in rose flowers) were observed, respectively. Soluble sugar and protein contents in the second-instar larvae and adults fed on rose petals decreased in the F1 generation but increased in the F2 generation and remained at higher levels until the F7 generation. Feeding of thrips with 3 food types increased the lipid content in the F1 generation, which peaked in the F2 generation and remained high until the F7 generation. In most cases, α-amylase and trypsin activities significantly decreased in the F1 generation after feeding on rose petals and then prominently increased in the F2 generation. In contrast, chymotrypsin activity remarkably increased and peaked in the F1 generation after second-instar larvae thrips fed on rose petals. There were correlations among the contents of 3 nutrient related positively with the activities of α-amylase and trypsin in WFTs second-instar larvae and adults, respectively. Overall, variations in the nutrient properties of the 3 food types caused changes in nutrient contents and digestive enzyme activities in thrips.

Long-term changes in Nutrient Concentration and Fluxes from the Godavari Estuary: Role of River Discharge and Fertilizer Inputs

Long-term changes in Nutrient Concentration and Fluxes from the Godavari Estuary: Role of River Discharge and Fertilizer Inputs

Agricultural Pressures on the Quality of Ground and Surface Waters in Catchments of Artificial Reservoirs

Changes in nutrient concentrations in groundwater were investigated to determine the impact of agriculture on water quality in artificial lakes. The study covered three reservoirs in an agricultural area of Wielkopolska (central-western part of Poland). Assessing the agricultural impact required a network of piezometers around the reservoirs, used to determine the degree of groundwater pollution from nutrients supplied to the reservoirs. Moreover, the analysis covered the quality of water in streams flowing into the reservoirs, and in the reservoirs themselves. Field research was conducted every month of the growing season from March to November. The analysis covered land inclination, ground permeability, and soil type. Detailed objectives included: (1) assessment of the agricultural impact on the chemical parameters of ground and surface water quality, and (2) evaluation of the impact of different sources of agricultural pollution on water quality in artificial reservoirs in regards to their management. This study revealed high dynamics of nutrient concentrations, particularly for nitrates and phosphates, in groundwater and surface water. A significant effect of maize cultivation on an increase in nitrate concentrations in the groundwater of the catchment of the Przebędowo Reservoir was evidenced, as well as a substantial effect of the functioning of an animal farm on the quality of groundwaters in the catchment of the Lachotka Reservoir. The nutrient load of agricultural origin in the catchment of the Miedzichowo Reservoir was relatively low. Our study revealed elevated amounts of nutrients such as nitrogen and phosphorus, detected more frequently in groundwater than in running waters, which confirms our hypothesis of the importance of groundwater analysis in detecting the source of pollution of the studied lakes. High nutrient concentrations recorded in groundwater leached from arable fields were also observed in the summer period, failing to confirm the hypothesis that the greatest effect of factors would be related to the spring effect of arable fields on water quality (lack of compact vegetation cover, high water level, etc.). Our study also indicated a greater importance of the type of land use than lithology or permeability of deposits.

Contrasting effects of nitrogen fertiliser application on the performance of closely related grasshoppers through changes in plant nutrient concentrations

Abstract Global environmental changes mediated by anthropogenic processes can affect the nutrient status of plants, with important consequences for the performance and dynamics of insect herbivores that feed on them. While it is well documented that insects from different feeding guilds (e.g., sap‐feeders and leaf‐chewers) can respond differently to altered food resources due to their distinct physiological and ecological characteristics, little is known about how ecologically similar insect species from the same feeding guild respond to changes in food nutrient status. Using nitrogen (N) fertiliser, the authors examined the effects of N inputs on two sympatric grasshopper species, Euchorthippus cheui and E. unicolor, that share the same host food plant, Leymus chinensis grass. The authors examined the effects of fertilisation on the individual feeding behaviour, performance and abundance of the two grasshopper species. The nutrient (protein) content of L. chinensis leaves was enhanced by fertilisation during the entire season. However, E. cheui and E. unicolor exhibited differing growth rates, development and body size responses to fertilisation. E. cheui preferred L. chinensis leaves from high‐N fertilised treatments, while E. unicolor preferred leaves from low‐N fertilised treatments. Moreover, fertilisation increased the abundance of E. cheui but had no significant effect on the abundance of E. unicolor in the field. The findings imply that effective management and conservation strategies for insects should target the needs of individual species rather than species groups or communities as a whole because nutritional and environmental requirements are often species‐specific.

Comparison of Nutritional Value between Broiler Feather Flour and Fermented Broiler Feather Flour

The aim of this study was to acknowledge the change in the nutrient content of fermented feather flour use a mixture of yeast tape and yeast bread. Feather flour used is a waste broiler feather flour obtained from the Oesao Presidential Market, Kupang Regency. Trial method used was a direct methods and fermented result through proximate analysis would be compared with before fermented. The design used was complete randomized design with 2 treatments and 3 replications. The treatment tested were R0: Broiler feather flour without fermented and R1: fermented broiler feather flour used yeast tape and yeast bread. Variable observed were the change in nutrient content in form of dry matter, crude protein, crude fat, crude fiber and material extract without nitrogen feather meal after fermented. Statistical analysis showed significant result (P&lt;0.05) on variables and fermented used yeast tape and yeast bread could increase crude protein and crude fat with could reduce content of crude fiber, carbohydrates and material extract without nitrogen feather meal. The conclusion of this study was yeast tape and yeast bread could increase the nutrients in feather flour that could be used as indgredients mixed diet.

Nutrients and Environmental Factors Cross Wavelet Analysis of River Yi in East China: A Multi-Scale Approach.

The accumulation of nutrients in rivers is a major cause of eutrophication, and the change in nutrient content is affected by a variety of factors. Taking the River Yi as an example, this study used wavelet analysis tools to examine the periodic changes in nutrients and environmental factors, as well as the relationship between nutrients and environmental factors. The results revealed that total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen (NH4+-N) exhibit multiscale oscillation features, with the dominating periods of 16-17, 26, and 57-60 months. The continuous wavelet transform revealed periodic fluctuation laws on multiple scales between nutrients and several environmental factors. Wavelet transform coherence (WTC) was performed on nutrients and environmental factors, and the results showed that temperature and dissolved oxygen (DO) have a strong influence on nutrient concentration fluctuation. The WTC revealed a weak correlation between pH and TP. On a longer period, however, pH was positively correlated with TN. The flow was found to be positively correct with N and P, while N and P were found to be negatively correct with DO and electrical conductance (EC) at different scales. In most cases, TP was negatively correlated with 5-day biochemical oxygen demand (BOD5) and permanganate index (CODMn). The correlation between TN and CODMn and BOD5 was limited, and no clear dominant phase emerged. In a nutshell, wavelet analysis revealed that water temperature, pH, DO, flow, EC, CODMn, and BOD5 had a pronounced influence on nutrient concentration in the River Yi at different time scales. In the case of the combination of environmental factors, pH and DO play the largest role in determining nutrient concentration.

Utilization of Fermentation Lemna as a Feed Source on the Growth of Sangkuriang Catfish (Clarias Sp.)

This research aims to determine the nutritional content and the best treatment for the addition of Lemna sp. fermented for the growth of sangkuriang catfish. The research was conducted from February to August 2022, in Aquaculture Laboratory of the Fisheries and Marine Science Faculty, Universitas Padjadjaran. The method used in this research is experimental, and is of a Completely Randomized Design (CRD). It consists of four treatments and four repetitions, namely treatment A (control) treatment B (10% fermented lemna + 90% commercial feed), Treatment C (20% fermented lemna + 80% commercial feed), and Treatment D (30% fermented lemna + 70% commercial feed). Parameters observed were changes in nutrient content of lemna, daily growth rate, feed conversion ratio, survival rate, and water quality. Data were analyzed using ANOVA analysis of variance and if there was a significant difference, Duncan test was performed with a 95% confidence level, while changes in nutrients in lemna and water quality were analyzed descriptively. The results of the proximate analysis showed that the fermented lemna using BIOM-S probiotics experienced changes in the nutritional content, namely an increase in protein content from 25.24% to 33.66% and a decrease in crude fiber from 11.93 to 9.13%. Based on the results of this research, the treatment C (20% fermented lemna + 80% commercial feed) the best results in a daily growth rate at 1.92%/day, a feed conversion ratio at 1.41, and a survival rate of up to 97.5%.

Advances and future research in ecological stoichiometry under saline-alkali stress.

Saline-alkali stress is a serious abiotic factor which negatively impacts agricultural production and the ecological environment. Thus, improving the development of saline-alkali soil and reducing the effects of saline-alkali stress is a key issue for sustainable agricultural development and environmental protection. As such, it is unsurprising that researchers have lately focused on how to improve saline-alkali soil, increase the agricultural yield of saline-alkali land, and promote the adaptive growth of plants in saline-alkali soil. This paper reviews the latest research concerning nutrient content changes in saline-alkali soil, along with the associated changes in key nutrients in plants, to summarize which methods are most effective for improving the plant growth under saline-alkali stress. Finally, the prospects for alleviating saline-alkali stress and improving saline-alkali soil are put forward as a theoretical foundation for the stabilization of plant growth in saline-alkali soil, expansion of arable land area, crop yield improvement, and effective environmental protection.

Tropical cyclones: what are their impacts on phytoplankton ecology?

Following the passage of a tropical cyclone (TC) the changes in temperature, salinity, nutrient concentration, water clarity, pigments and phytoplankton taxa were assessed at 42 stations from eight sites ranging from the open ocean, through the coastal zone and into estuaries. The impacts of the TC were estimated relative to the long-term average (LTA) conditions as well as before and after the TC. Over all sites the most consistent environmental impacts associated with TCs were an average 41% increase in turbidity, a 13% decline in salinity and a 2% decline in temperature relative to the LTA. In the open ocean, the nutrient concentrations, cyanobacteria and picoeukaryote abundances increased at depths between 100 and 150m for up to 3months following a TC. While at the riverine end of coastal estuaries, the predominate short-term response was a strong decline in salinity and phytoplankton suggesting these impacts were initially dominated by advection. The more intermediate coastal water-bodies generally experienced declines in salinity, significant reductions in water clarity, plus significant increases in nutrient concentrations and phytoplankton abundance. These intermediate waters typically developed dinoflagellate, diatom or cryptophyte blooms that elevated phytoplankton biomass for 1-3months following a TC.

Grassland Reseeding: Impact on Soil Surface Nutrient Accumulation and Using LiDAR-Based Image Differencing to Infer Implications for Water Quality

Long-term phosphorus (P) accumulation in agricultural soils presents a challenge for water quality improvement. P is commonly elevated in soils managed for intensive livestock production due to repeated overapplication of slurry and fertilisers. High legacy nutrient accumulations result in poor water quality via transport pathways such as surface runoff, subsurface drainage, and soil erosion. To achieve environmental water quality targets, improved management strategies are required for targeting and reducing excess agricultural P sources. Reseeding of old swards is known to improve grassland productivity and enhance overall soil health. However, soil disturbance associated with reseeding could have positive and negative impacts on other soil functions that affect the nutrient balance (including improved microbial activity, but also increasing the potential for sediment and nutrient losses). This study investigates the impact of reseeding and inversion tillage in addressing soil surface nutrient surpluses and identifies potential trade-offs between production, environment (through soil erosion and associated sediment and nutrient losses), and soil health. At a study site in the Blackwater catchment in Northern Ireland, we collected high-resolution (35 m) gridded soil samples pre- and post-reseeding for nutrient analyses and combined this with GIS-based interpolation. We found that decreases in sub-field scale surface nutrient content (0–7.5 cm depth) occurred following tillage and reseeding, but that this was spatially variable. In addition, the magnitude of changes in nutrient content was variable between P and other sampled nutrients. LiDAR-based image differencing indicated variability in the magnitude of soil erosion and sediment loss also at sub-field scale. Information on the identified deposition and erosion zones (from LiDAR analysis) was combined with mass wasting data to determine accumulation rates and losses of nutrients in-field and confirmed some of the identified patterns in soil surface nutrient content changes post-reseeding. We conclude that while inversion tillage and reseeding are essential agricultural practices, environmental trade-offs exist through potential nutrient and sediment losses. LiDAR-based image differencing was found to be a useful tool in helping to quantify these risks. Quantifying sediment and nutrient losses as a result of inversion tillage and reseeding induced soil erosion aids in understanding potential trends in water quality statuses.

Changes of Plant Growth and Nutrient Concentrations of the Drainage According to Drainage Reuse and Substrate Type in Sweet Pepper Hydroponics

Changes of Plant Growth and Nutrient Concentrations of the Drainage According to Drainage Reuse and Substrate Type in Sweet Pepper Hydroponics

Biochar application ameliorated the nutrient content and fungal community structure in different yellow soil depths in the karst area of Southwest China.

The influence of biochar on the change of nutrient content and fungal community structure is still not clear, especially in different yellow soil depths in karst areas. A soil column leaching simulation experiment was conducted to investigate the influence of biochar on soil content, enzymatic activity, and fungal community diversity and structural composition. Three biochar amounts were studied, namely, 0%(NB, no biochar), 1.0%(LB, low-application-rate biochar), and 4.0% (HB, high-application-rate biochar). The results showed that biochar increased the pH value and the contents of soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) but reduced the microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN). Furthermore, this effect was enhanced with increasing biochar amount. Biochar was conducive to improving the nutrient availability in topsoil (0-20 cm), especially TN, AK, and MBN. Meanwhile, biochar affected the enzymatic activity, especially the sucrase activity. Biochar affected the diversity and structure of the fungal community, of which HB treatment had the most obvious effect. Among these treatments, Aspergillus, unclassified_Chaetomiaceae, Mortierella, Spizellomyces, Penicillium, Fusarium, and unclassified_Chromista fungal genera were the highest. Moreover, biochar inhibited the growth of harmful pathogens and increased the abundance of beneficial fungi in soil, and the effect was enhanced with increasing biochar amount and soil depth. Redundancy analysis (RDA) showed that AK was an important factor in yellow soil, although the main environmental factors affecting the fungal community structure were different in different soil depths. Overall, biochar had a positive effect on improving the land productivity and micro-ecological environment of yellow soil in the karst area.

Impacts of a nutrient trading plan on stream water quality in Sugar Creek, Ohio

AbstractIn the early 2000s, a phosphorus nutrient trading plan (NTP) requiring best management practices (BMPs) to be installed as pollution abatement strategies to offset phosphorus waste from the Alpine Cheese Company was implemented in four subwatersheds of Sugar Creek in northeast Ohio. To assess the impacts of the Alpine NTP, 49 sites were sampled approximately biweekly from 2010 to 2018 for phosphate, total phosphorus, nitrate, ammonia, and total nitrogen. In addition, the Ohio Environmental Protection Agency conducted stream health surveys at 21 sites before and after the BMPs were implemented. This study evaluated the potential impact of 68 BMPs implemented under the NTP on the observed changes in nutrient concentrations and stream health indicators. Most nutrient concentrations observed during high discharge conditions showed significant declines from 2010 to 2018 for all subwatersheds, which was most likely due to BMPs that reduced erosion and surface runoff. However, there were fewer significant declines and some significant increases in nutrient levels during low discharge conditions, suggesting a possible contribution from legacy nutrient sources. Most sites reported increases in stream health indicators, but many streams are still below recommended levels. Collectively, the installation of BMPs and decreases in nutrient concentrations observed during high discharge conditions can be attributed to the NTP and likely contributed to improved stream health.

A Model Nutrition Control System in Potato Tissue Culture and Its Influence on Plant Elemental Composition.

Low or excessive soil fertility is a major constraint to potato production. The influence of each individual nutrient element on potato plants under field studies remains ambiguous due to the influence of environmental variations. Creating an in vitro model plant with deficient or excessive nutrient content will provide a more controlled study and allow for a better understanding of how the concentration of one element can affect the uptake of other elements. Here we designed a tissue culture-based nutrition control system to systematically analyze the effects of essential nutrients on potato plants. Insufficient or excessive nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) contents were created by modifying the Murashige and Skoog (MS) medium. Deficient to toxic plant nutrient statuses were successfully defined by the evaluation of dry biomass and morphological symptoms. The results showed that plant shoot growth, nutrient uptake and content, and nutrient interactions were all significantly impacted by the changes in the MS media nutrient concentrations. These tissue culture systems can be successfully used for further investigations of nutrient effects on potato production in response to biotic and abiotic stresses in vitro.

Identifying nutrient sources and sinks to the South Platte River and Cherry Creek, Denver, CO, during low‐flow conditions in 2019–2020

AbstractElevated concentrations and loads of nutrients in the South Platte River and Cherry Creek in Denver, Colorado, may have adverse effects on those streams and downstream water bodies, including increased production of algae, eutrophication, and decreased recreational opportunities. This article describes streamflow and concentrations and loads of nutrients for the South Platte River and Cherry Creek in Denver based on data collected during two longitudinal Lagrangian sampling campaigns in low‐flow conditions in fall of 2019 and 2020. The results are used to assess sources and sinks of nutrients in the study area and help to establish baseline conditions against which future changes in nutrient concentrations and loads can be assessed. Discharges from Chatfield and Cherry Creek Reservoirs, storm drains, and most tributaries to the South Platte River, and Cherry Creek were generally small sources of streamflow and nutrient loads in both years. The Marcy Gulch, South Platte Water Renewal, and Robert W. Hite wastewater treatment plants were larger sources of streamflow and nutrient loads. The Burlington Ditch was a sink for streamflow and nutrient loads, diverting more than 95% of the South Platte River during the two sampling campaigns. Most other sinks were associated with decreases in streamflow between sampling sites. Golf courses were a potential source of nutrients for Cherry Creek but not for the South Platte River.