Tag: stackable planters

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An additional experiment was carried out in an airtight container without aeration

Briefly, 400 mg sub-samples of the dried, ground plant matter were freeze-dried for 12 h, weighed, and extracted in polypropylene tubes by sequential sonication and centrifugation with 20 mL methyl tert-butyl ether and then again with 20 mL acetonitrile. The combined extracts were evaporated under nitrogen to less than 1 mL, and mixed with 5 mL methanol and 20 mL water. A 6 mL aliquot of the extract was taken for analysis by LSC to determine the fraction of activity as extractable residue. Selected 150 mg sub-samples of the solventextracted plant matter were combusted on the Biological Oxidizer as described above to determine the fraction of 14C present as non-extractable residue. When nutrient solution and jars were exchanged, the volume of remaining nutrient solution in each jar was gravimetrically determined. A 9 mL aliquot of the solution was mixed with 13 mL Ultima Gold scintillation cocktail and the 14C was quantified by LSC. Water loss from evaporation during each 3 d period was found to be negligible in the no-plant control containers. It is likely that microbial activity in the nutrient solution may have resulted in transformation of the spiked 14C-compounds and that plants may have accumulated both parent PPCP/EDCs and transformation products. To discern the contribution of transformation products to plant accumulation, the used nutrient solution from day 21 was preserved with 2 g sodium azide and 100 mg ascorbic acid, extracted, and fractionated using high performance liquid chromatography . Solutions from 14C-BPA, DCL, or NPX treatments were first filtered through a What man #4 filter paper and then passed through a HLB solid phase extraction cartridge . Before use, the cartridges were sequentially conditioned with 5 mL each of MTBE, methanol , and water. The filtered solution was drawn through the conditioned HLB cartridges under vacuum and followed by 50 mL deionized water. A sub-sample of the filtrate that passed through the cartridge was collected for analysis by LSC to quantify 14C that was not retained by the cartridge.

The cartridges were dried with nitrogen gas,hydroponic bucket and then sequentially eluted with 5 mL of MeOH:MTBE and 5 mL MeOH. The collected eluent was dried under nitrogen to 100 μL. The concentrated eluent was transferred to an HPLC vial equipped with a 250 μL insert. The condensing vial was rinsed with 130 μL of methanol, and the rinsate and 20 μL of non-labeled parent standard were added to the HPLC vial. Preliminary experiments showed that the recovery of this extraction procedure from the initial solution to HPLC analysis was 81.5 ± 7.1% for BPA, 85.8 ± 2.5% for DCL, and 74.0 ± 1.9% for NPX. Nutrient solutions from the 14C-NP treatment were extracted by a simple liquid-liquid extraction method. Each nutrient solution sample was shaken with 50 mL hexane for 30 min, and then the upper layer of the sample was transferred to a centrifuge tube and centrifuged at 3500 rpm for 30 min to reduce emulsification. The hexane phase was transferred to a 15 mL glass tube, concentrated under nitrogen to 300 μL, and transferred to an HPLC vial. The condensing vial was rinsed with 180 μL of methanol, and the rinsate and 20 μL of non-labeled NP standard were added to the HPLC vial. The recovery of this extraction method from the initial solution to HPLC analysis for NP was determined to be 66.8 ± 12.0%. Young plants of lettuce and collards were grown for 21 d in nutrient solution containing one of the four 14C-labeled PPCP/EDCs. No significant differences in plant mass were observed between treatments at the end of the experiment. During the experiment, three plants died . Figure 2 shows the mean mass balance for the systems at the end of the experiment, depicting the fractions of the spiked 14C present in plant tissues, in the used nutrient solution, and as unaccounted activity. The unaccounted activity reflected the 14C that was not found in the nutrient solution at the time of solution renewal or in the plant tissues after harvest and may include losses via unidentified processes, such as volatilization, microbial mineralization in the nutrient solution , or stomatal release. Activity in each fraction varied across compounds and to a lesser degree across plant species, suggesting specificity to uptake. Figure 3 shows the cumulative 14C dissipation from the nutrient solution as calculated from the difference in activity in the solution at the beginning and end of each 3 d interval of solution renewal, representing 14C loss from plant uptake and other processes. Dissipation followed the decreasing order of BPA > NP > DCL > NPX for all treatments and occurred at a similar rate throughout the 21 d cultivation. The presence of plants significantly increased the dissipation of PPCP/EDCs from the nutrient solution, except for NP.

For example, the initial concentration of 14C-DCL in the nutrient solution was 105.3 ± 0.3 dpm/ mL, but it decreased to only 32.8 ± 1.9 dpm/mL after 3 d in the presence of lettuce, while 91.2 ± 3.2 dpm/mL remained in the no-plant control. Lettuce and collards treatments had different levels of chemical dissipation in the nutrient solution. For example, the overall dissipation of BPA in the lettuce treatment was 69.1 ± 8.7%, as compared to 88.4 ± 5.3% in the collards treatment . Different compounds also dissipated at different rates. For instance, in the presence of collards, the cumulative loss was 88.4 ± 5% for BPA, 55.6 ± 11.8% for DCL, and 45.5 ± 4.3% for NPX.The dissipation of NP in the solutions with plants was found to be similar to that in the noplant control, especially for the lettuce treatment . The loss of NP from the noplant control was likely associated with volatilization, as continuous aeration was used to maintain the oxygen level in the nutrient solution throughout the experiment. The Henry’s Law constant for NP is 1.09 ×10−4 atm m3 mol−1 , suggesting a tendency for volatilization. The loss of NP in the solution was found to be insignificant, as all of the spiked 14C was found in the solution , and a solvent rinse of the system showed little sorption of 14C-NP on the container wall . Doucette et al. found that in a hydroponic set up, about 13% of the spiked NP was lost to volatilization in the absence of plants. The increased volatilization losses in the current study were likely due to specific aeration and temperature conditions used. Despite volatilization losses, significant amounts of 14C were detected in plant tissues, suggesting that both collards and lettuce accumulated NP . Noureddin et al. studied the uptake of 5 mg/L BPA from hydroponic solution by water convolvulus and found that approximately 75% of the spiked BPA was removed after 3 d. This removal was comparable to that observed for BPA with lettuce in this study, but was smaller than that with collards . Calderón-Preciado et al. evaluated hydroponic uptake of triclosan, hydrocinnamic acid, tonalide, ibuprofen, naproxen, and clofibric acid by lettuce and spath and showed that the removal of NPX from solution was about 70% for lettuce and 10% for spath after 3 d. In comparison, Matamoros et al. observed less than 10% removal of NPX after 3 d of hydroponic growth with wetland plants , while 46% removal of NPX was measured in the collards treatment in the present study.

Matamoros et al. also showed that DCL did not dissipate appreciably in treatments with wetland plants, which was in contrast to the high removal of DCL by leafy vegetables observed in this study . It is likely that the smaller plant mass and the use of non-aerated nutrient solution in the earlier study contributed to the limited plant uptake. The range of variation suggests that plant species,stackable planters along with other factors such as plant mass and environmental conditions, affect the actual accumulation of PPCP/ EDCs into plant tissues. Plant tissues were collected after 21 d of cultivation, rinsed with deionized water, and separated into roots, stems, new leaves, and original leaves for analysis of both extractable and non-extractable 14C. Table 1 shows concentrations of 14C in plant tissues, expressed as parent-equivalents. In agreement with the dissipation trends in solution, plant accumulation followed the decreasing order of BPA > NP > DCL > NPX. Concentrations based on dry plant mass ranged from 0.22 ± 0.03 to 12.12 ± 1.91 ng/g in leaves and stems. Statistical analysis showed that the accumulation in leaves and stems was not significantly different between lettuce and collards, or among the different compounds. In contrast, roots accumulated significantly more 14C than all the other plant tissues, with concentrations that ranged from 71.08 ± 12.12 to 926.89 ±212.89 ng/g. Accumulation of 14C in plant tissues exhibited several apparent trends. In whole collards plants, significantly greater accumulation was found for the neutral compounds BPA and NP than the anionic compounds DCL and NPX , suggesting that the charge state of PPCP/EDCs may greatly influence plant uptake . Similar effects have been frequently observed for anionic herbicides, and are attributed to exclusion of negatively charged molecules by cell membranes . Between lettuce and collards, lettuce significantly accumulated less PPCP/EDC when all test compounds were pooled , although the interaction effect for individual compounds was not significant . Accumulation of BPA or NP in plant roots was significantly higher for collards than lettuce , while portion of DCL accumulated into lettuce and collards roots was not significantly different. Analysis of tissue extracted with solvent showed that essentially all of the 14C was non-extractable; only the root samples from NP-collards treatment contained a detectable fraction of 14C in extracts .

Combustion of extracted plant tissues confirmed that almost all 14C remained as non-extractable residue, one possible endpoint for xenobiotics taken up by plants . Only a few studies have examined the plant uptake of some of the same PPCP/EDCs considered in this study. Wu et al. grew iceberg lettuce and spinach for 21 d in hydroponic solution initially spiked with a suite of 19 PPCPs, including DCL and NPX, each at 500 ng/L and found no detectable residues of DCL or NPX, except for NPX in spinach at 0.04 ng/g. Calderón-Preciado et al. analyzed apple tree leaves and alfalfa from fields irrigated with water containing BPA, DCL, and NPX. DCL was detected at 0.354 ng/g in apple leaves and 0.198 ng/g in alfalfa; NPX was detected at 0.043 ng/g and 0.04 ng/g, respectively. The low concentrations found in these studies generally agree with the findings of this study, but there is some variation in the tendency for specific compounds to accumulate. This variation may be partly attributed to the different analytical approaches. In other studies, uptake of PPCP/EDCs by plants was evaluated using non-labeled compounds, and accumulation was measured by targeted chromatographic analysis for the extractable parent compound. The use of 14C-labeled compounds in the current study should have provided “worst-case” estimates of human exposure, as the concentrations included non-extractable residue and likely also included transformation products. Transformation products may be an important component of potential risk since the metabolites of some PPCP/EDCs have higher biological activity than their parents and studies have shown that a large portion of PPCP/EDCs that are taken up by plants may be transformed in vivo . A translocation factor , which was the total 14C in stems, new leaves, and original leaves divided by the 14C in roots, was calculated . The derived TFs were consistently very small, demonstrating the poor translocation of these PPCP/EDCs from roots to upper tissues after uptake. The TF values followed the decreasing order of NPX > DCL > NP > BPA, the opposite observed for plant accumulation. Lettuce displayed lower TFs than collards for the same PPCP/EDCs. For example, the mean TF for BPA was only 0.010 ± 0.003 for lettuce, but was 0.051 ± 0.008 for collards. The much greater accumulation of PPCP/EDCs in roots, as compared to leaves, has been observed in previous studies. For instance, Herklotz et al. found that the levels in leaves were 0.00952 – 0.00503 of those in roots for cabbage grown in nutrient solution spiked with carbamazepine, salbutamol, sulfamethoxazole, and trimethoprim. Doucette et al. reported that the accumulation of NP in leaves was 0.0233 – 0.0167 of that in the roots of crested wheatgrass grown in solution.

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Each enclosure contained an array of six rectangular PIT antennas arranged in the same orientation

Given that the proposed California threshold is 0%, a scenario in which both GM and non-GM products are offered side-by-side in the market seems unlikely. Some non-GM products may remain unlabeled if food companies are able to find substituting ingredients that are not at any risk of containing GM. But certified non-GM products will mostly disappear. As U.S. corn, canola, and soybean production uses primarily GM varieties, Prop 37 labeling standards will force change in the composition of retail products offered. As the initiative applies only to California, it may not be profitable to undergo a reduction of GM inputs for one state. If this is the case, then the vast majority of food products that are not completely GM-free will bear the new label. As a consequence, a fraction of consumers now wary of the label may shift their consumption towards organic. Such a transition implies potential gains for organic growers but potential losses for conventional growers. Today, a move towards “non-GM” or “naturally grown” labels is underway, especially with natural grocers. Some organic corn and soybean growers in the U.S. have converted back to conventional with non-GM seeds, thereby saving labor and other costs, while still getting similar price premia. The “non-GM” or “natural” products are the closest competition for organic products now; but they will be reduced or eliminated with Prop 37 due to forced relabeling and the prohibition of terms such as “naturally grown” on food labels . Table 4 outlines the likely impacts of Prop 37 on various categories of food and beverages.conducted a series of field studies during 2012-2017. To test fish and food web responses within different land-management scenarios, we conducted our project on standard rice and winter wheat fields, adjacent fallow lands,stackable planters and rice fields with different harvest practices or other experimental modifications. This work yielded several publications that provided insight into habitat conditions in flooded rice fields for fish and invertebrates . The focus of our effort was on rearing habitat for young Chinook Salmon, but this work may also be relevant to other native fishes.

The goal of this paper is to summarize the key lessons learned from 6 years of research on the feasibility of using farm fields as rearing habitat for juvenile Chinook Salmon in the Yolo Bypass and other Central Valley locations. Our hope is that our summary will provide guidance to future researchers, as well as inform managers as they evaluate potential management approaches. An important caveat is that our studies were not intended as a proof of concept for any specific management actions. Rather, our research was intended to examine some of the attributes that could reduce limitations to rearing conditions identified in early research, and gain insight into some of the key considerations for potential future agricultural floodplain management. A second major caveat is that we had to rely on juvenile hatchery Chinook Salmon as a surrogate for wild Chinook Salmon, our ultimate target for habitat restoration. We recognize that there are several potential differences in the behavior of hatchery and wild Chinook Salmon . However, hatchery salmon were the only feasible alternative in this case since downstream migrating wild juvenile Chinook Salmon were mostly cut off from the Yolo Bypass because of extreme drought conditions. Nonetheless, hatchery salmon have been used successfully as a research tool in many types of ecological studies, so many of the lessons learned here should have at least some relevance to wild Sacramento River Chinook Salmon. Finally, our project was separate from a number of other fish management research projects in agricultural parcels, such as current efforts to investigate whether invertebrates grown on flooded rice fields can be used as a food subsidy for adjacent river channels . The Yolo Bypass is a 24,000-ha, partially leveed flood basin that is used to safely convey floodwaters away from Sacramento Valley communities . The Yolo Bypass contains a suite of habitats including agricultural lands, managed wetlands, upland habitat, and perennial ponds and channels, with broad open-water tidal wetlands at its downstream end where it joins the Sacramento-San Joaquin Delta .

The basin receives seasonal inflow from the Sacramento River, Colusa Basin , Cache Creek, and Putah Creek, as well as substantial perennial tidal flow from the San Francisco Estuary via the lower Sacramento River at the downstream end of the floodplain . The Yolo Bypass floods to various degrees in approximately 80% of water years, but inundation events are often relatively short and sometimes driven entirely by inflow from the west-side tributaries. The most substantial flow events come from the Sacramento River, which enters the Yolo Bypass via Fremont Weir and Sacramento Weir. However, in drought periods, such as during 2012-2015, there is little or no flooding.For each year, we evaluated water quality , food web responses , and fish growth and condition . Water temperature in fields was recorded continuously at 10- to 15-minute intervals with Onset HOBO® loggers, and a suite of other water-quality parameters was measured and recorded using handheld and continuously installed multi-parameter sondes. We included plankton sampling with the broad goal of characterizing the communities and densities of phytoplankton and zooplankton in the study fields. Because long-term monitoring of the Yolo Bypass includes weekly plankton sampling in both the perennial Yolo Bypass channel of the Toe Drain and the Sacramento River, we could compare our experimental fields to productivity across habitats. Because the study fields were shallow compared to canal and riverine channel environments, sampling methods had to be slightly modified compared to the Toe Drain and Sacramento River. As a result, we used hand-tosses of a smaller 30-cm zooplankton net , recording the length of the toss, and the relative percent of the net mouth that was submerged during net retrieval. Detailed methods for zooplankton sampling are described in Corline et al. . Fish used in the experiments were primarily fall-run Chinook Salmon parr obtained from Feather River Fish Hatchery; however, small numbers of wild Sacramento River Chinook Salmon were also studied in 2013 and 2013, 2015, and 2016 . The majority of the study fish were free swimming throughout the flooded fields, but mesh cages were also used as a tool to compare hatchery salmon growth and survival across substrates in 2012 or habitats in 2016 and 2017. The initial study year was a pilot effort to evaluate whether managed flooding of a rice field could provide suitable habitat for juvenile salmon rearing, and to assess associated growth and survival. A single 2-ha field contained a patchwork of four agricultural substrate types, including disced , short rice stubble , high rice stubble , and fallow vegetation. Approximately 10,200 juvenile salmon were released in the field, with a subset implanted with passive integrated transponder tags, so individuals could be identified, and individual growth rates could be measured. Twenty PIT-tagged fish were also released in each of eight enclosures placed over patches of the different substrate types, to determine if growth rates differed .Substrates in flooded rice fields differ from those that juvenile salmon may encounter in natural floodplains or riverine systems. Thus, the goal of the second study year was to investigate whether juvenile salmon had differential growth and survival rates across agricultural substrates,stacking pots and whether they would preferentially use a specific substrate type when given a choice. Our logic was that understanding these responses could provide insight into whether some agricultural practices provide more suitable salmon rearing conditions than others.

To compare growth and survival rates across rice stubble, disced, and fallow substrates, we created a series of nine 0.8-ha experimental fields with individual inlets and outlets, with three replicates of each substrate . We placed approximately 4,600 hatchery origin juvenile Chinook Salmon in each field for 40 days and measured weekly during the study period to estimate average growth rates. To examine substrate preference, we used PIT-tag technology to track individual fish in two large circular enclosures . In addition to examining the potential for preference among agricultural substrates, this study also investigated whether newer and smaller PIT tags were viable for detecting juvenile salmon movements in these habitats. One enclosure included three habitat treatments , and the other served as a comparison with only the disced treatment.Fish remained in the enclosures for 14 days, during which occupancy data were collected. Detailed methods can be found in Conrad et al. .As an engineered floodplain, the Yolo Bypass is designed to drain efficiently. During moderate inundation events, availability of floodplain habitat can be brief—persisting for a week or less. In 2016, our focus was to test the feasibility of using agricultural infrastructure to extend the duration of a small to moderate flood event, increasing the length of time flooded habitat was available to fish. We called this idea “flood extension.” We planned similar studies in other study years, but extreme weather events prevented implementation . Landowner partners in the Yolo Bypass at Knaggs Ranch, Conaway Ranch, and Swanston Ranch agreed to maintain shallow inundation for 3 to 4 weeks in a designated experimental field after a natural flood event. At Knaggs Ranch, the landowner made modest to extensive modifications to the drainage infrastructure to allow more control over the drainage rate from the inundated field to the Toe Drain. At Swanston and Conaway ranches, inundation was maintained with flash boards, which could be removed once it was time to drain the field. During the first week of flood extension, we held stocked hatchery salmon and any entrained natural-origin salmon, allowing us to estimate growth and survival rates upon drainage. Thereafter, we allowed salmon to leave fields if they chose to do so. We outfitted field drains with a plastic mesh live-car trap, where we captured and measured emigrating individuals before they proceeded downstream. In 2016, the attempt to test a “flood extension” concept was unsuccessful because inundation occurred late in the season, resulting in unsuitably warm water temperatures for juvenile salmon in our experimental fields. We therefore made a second attempt to conduct a flood extension pilot in 2017 at Knaggs Ranch, Conaway Ranch, and Swanston Ranch, and at a new site in the Yolo Bypass Wildlife Area located south of Interstate 80 between the cities of Davis and Sacramento . Field infrastructure was identical to 2016, with the YBWA utilizing flash boards to hold water in similar fashion to Conaway and Swanston ranches. As we describe below, high flows made it infeasible to complete the flood extension work, although we were still able to conduct water-quality and food-web sampling, along with the use of experimental cages to evaluate salmon growth comparatively across experimental sites.Previous research has shown that inundated Yolo Bypass floodplain habitat typically has substantially higher densities of phytoplankton, zooplankton, and drift invertebrates than the adjacent Sacramento River across a suite of water year types . Our studies consistently showed that managed inundation of agricultural fields supported statistically higher levels of phytoplankton and invertebrates than the Sacramento River . Also notable was that phytoplankton and zooplankton densities in our flooded experimental fields in Yolo Bypass were higher than those measured during river inundated flood events and in the Toe Drain, a perennial tidal channel . In addition, the invertebrate community in flooded rice fields was completely dominated by zooplankton , particularly Cladocera, whereas drift invertebrates such as Diptera were found in higher concentrations in study sites at Conaway Ranch and Dos Rios. Drift invertebrates are often a more substantial part of the food web in natural flood events in Yolo Bypass . Nonetheless, zooplankton densities can be relatively high in Yolo Bypass during dry seasons and drought years . The specific reasons for these differences include longer residence time and shallower depths in the Yolo Bypass than in adjacent perennial river channels . Water source also may have been important for quantity and composition of invertebrates, including zooplankton, since all the managed flooding work was conducted using water from Knights Landing Ridge Cut, not the Sacramento River.Given the high densities of prey in the flooded fields, along with the low metabolic costs of maintaining position in a relatively low-velocity environment, it is not surprising that growth rates of juvenile salmon were comparatively high . This result was consistent across approaches used: cages, enclosures open to the substrate, and free-swimming fish.