Floodplain Soils Research Articles

Soil contamination by plastic particles in the floodplain of the small Danilikha River in an urbanized area

The aim of the study. To assess the content, morphology and surface degradation degree of plastic particles in the Danilikha river floodplain soils in an urbanized area. Location and time of the study. The study was conducted in a recreational area in the projected “Kamensky Square”, located on the left bank of the low floodplain of the small Danilikha River (a left-bank tributary of the Kama River) in the city of Perm. Urban-alluvial gray-humus gley soils were identified in the area. Soil samples were taken from surface horizons in July 2023. Methods. To extract plastic particles from soil we used visual selection, sieving, and flotation in a saturated NaCl solution. The shape and type of plastic particles were determined visually by external features. Natural organic matter was removed with Fenton's reagent. Surface morphology of the of plastic particles and their number were determined using a stereomicroscope. Information-logical analysis was used to determine the relationship between the shape of plastic particles and their sizes. Results. In the combined soil sample from the surface horizons, the number of plastic particles reached 177 pieces/kg (excluding fibers). The mass of plastic particles, including fibers, was 0.7 g/kg. Films prevailed quantitatively among the forms of plastic particles (62%), whereas foam and foam balls made up 34% and 4%, respectively. By mass, particles predominated in the following sequence: foam balls ˃ film ˃ fiber ˃ foam. The size range was dominated by large plastic particles from 1.1 to 15 mm. Specific sizes of plastic particles for different shapes were established. Conclusions. For the first time, the content of plastic particles in the surface soil horizons of the Danilikha river floodplain in an urbanized territory was studied using the case of a recreational zone in the projected Kamensky Square. Plastic particles had different sizes and shapes, which indicated a variety of contamination sources. Contamination of the studied soils with plastic particles can be regarded as moderate. The surface degradation degree of plastic particles indicated their active weathering, which occurs in soil under neutral reaction. The surface degradation of the plastic particles was also actively influenced by external factors that act before plastics enter alluvial soils. To detect soil contamination with plastic particles, we recommend Perm municipal authorities to organize monitoring of plastics content in areas with high anthropogenic pressure.

Study and evaluation of varieties of non-traditional forage crops in the conditions of the cryolithozone

In the Republic of Sakha (Yakutia), where the main focus of agriculture is animal husbandry, there is a problem of providing cattle with high-quality feed. Currently, the productivity of natural hayfields in Yakutia, due to their irrational use, has decreased from 1.5-1.7 t/ha of hay in the 50s and 60s of the last century to 0.5-0.7 t/ha. Traditional annual and perennial forage crops do not provide the full amount of dry and juicy feed needed. In this regard, research has been conducted on the permafrost floodplain soils of Yakutia to study and search for varieties of non-traditional forage crops that would guarantee a high annual yield of forage mass. The varieties of mogara Altaysky 23, common millet Barnaulskoye 98, Barnaulskoye 18 and Africanskoye K-157 were studied. Experiments have shown that in the conditions of the cryolithozone, the development of mogara plants and common millet plants proceeds slowly and reaches the beginning of flowering phase at the end of the growing season, Africanskoye K-157 millet has more accelerated development and it stops at the beginning of seed maturation. The most leafy millet variety Africanskoye K-157 - (160.4 cm2/plant) provides the highest productivity of green mass (39.8 t/ha); the studied varieties of non-traditional forage crops are rich in protein content (12.5-14.3%), feed units (0.50-0.55 g per 1 kg), exchange energy for ruminants animals (7.1-7.4 MJ/kg).

Morphological Variations of Soils in Alluvial Floodplain of Sokoto Northwest Nigeria

Morphological Variations of Soils in Alluvial Floodplain of Sokoto Northwest Nigeria

Recognition of an extended record of euglenoid cysts: Implications for the end-Triassic mass extinction

The enigmatic non-pollen palynomorph Chomotriletes, occurs consistently within sediments associated with the end-Triassic mass-extinction. Based on a detailed palynological survey and other published records from Europe, Chomotriletes is prevalent within the uppermost Rhaetian Contorta and Triletes Beds and its equivalents elsewhere. Chomotriletes is now a senior synonym for Permian Circulisporites, Meso- to Cenozoic Pseudoschizaea, and Quaternary to Recent Concentricystes. Its widespread occurrence has significance for our understanding of the end-Triassic mass-extinction, but its biological affinity and ecological preference have remained contentious for almost a century. We undertook a TEM examination of a Holocene and a Pliocene example of Concentricystes and found their structure to be a close match to the wall of Jurassic Pseudoschizaea from Italy that has been interpreted to belong to cysts of the Euglenophyceae. Together with a nascent understanding of a deep time record of the euglenoid, Moyeria, Chomotriletes helps document a terrestrial signature of the Euglenophyceae in the fossil record. An extensive literature survey indicates that Chomotriletes is associated with wetlands and riverine floodplain soils, and that it inhabited mainly temperate to tropical latitudes and continues to do so to the present day. Its presence in ancient marine sediments therefore indicates transport via weathering and erosion. The association with wetlands is in line with the ecological preferences of species of the Euglenophyceae. The presence of euglenoid cysts in association with the end-Triassic extinction fits a scenario in which enhanced rainfall followed by strong soil erosion resulted in the release and redeposition of Chomotriletes into shallow marine settings.

Effects of slopes, rainfall intensity and grass cover on runoff loss of mercury from floodplain soil in Oak Ridge TN: A laboratory pilot study

Mercury is recognized as a global pollutant. A large amount of elemental mercury was used in the Manhattan Project in Oak Ridge, TN and Hg is still present in the water-shed surrounding the Y-12 facility and East Fork Poplar Creek. Soil erosion during rainfall-runoff events result in nonpoint source Hg transport from floodplain soils to aquatic ecosystems. This study investigated transport mechanisms of Hg through surface runoff processes from floodplain soils in Oak Ridge, TN into water with a simulated rainfall laboratory pilot scale experiment. The experiments simulated rainfall intensity (50–140 mm/h), the ground grass coverage (5 %-85 %), the soil moisture conditions and the slopes (7.5–16.32 degrees) producing soil runoff erosion processes. Results show that high grass coverage, decreased landscape slope and low rainfall resulted in the decreased Hg concentrations in sediments transported through runoff from the floodplain soil. Hg loss was strongly correlated with and controlled by soil loss. The order of environmental factors on Hg loss was the slope > rainfall intensity > grass cover. As grass cover increased from 5 % to 85 %, Hg in sediment decreased from 124 to 72.3 µg/kg and Hg in penetrating water decreased from 4.7 to 2.8 µg/kg on wet soil condition at the slope 12.560. Hg loss and soil loss significantly increased with the increase of the soil slope. As the slope increased from 7.550 to 12.560, Hg loss increased from 364 to 2905 mg/m2 in the dry soil condition with 5 % grass cover. Meanwhile Hg loss and soil loss significantly decreased with the increase of grass cover. The Hg concentration in sediment increased with increasing initial soil moisture from Dry Soil, to Wet Soil and Very Wet Soil. The roots of grasses stabilized soil Hg and the Hg content in soil rhizosphere were significantly higher than that in non-rhizosphere. This study indicates that rainfall intensity, ground grass coverages, landscape slopes and initial soil moisture content strongly controlled Hg transport from the floodplain ecosystem and its flux into stream water. Mercury associated with sediment was the major Hg input into stream waters from floodplain soils in Oak Ridge, TN. Proper onsite management, such as increasing ground coverages with local low lying grasses and decreasing landscape slopes may significantly reduce potential Hg transport into local stream water in Oak Ridge TN.

Holocene and late Pleistocene bioclimatic change inferred from δ13C of organic carbon in buried alluvial soils in the tallgrass prairie, northeastern Kansas

The tallgrass prairie of the Central Plains is one of the largest North American biomes, yet little is known about the history of late-Quaternary bioclimatic change in the region because settings that are favorable for the preservation of traditional paleoenvironmental proxies, such as pollen and plant macrofossils, are rare. However, the valleys of large streams contain thick soil-stratigraphic sequences that span the Holocene and terminal Pleistocene and are archives of other paleoenvironmental proxies. To better understand late-Quaternary bioclimatic change in the tallgrass prairie, we analyzed the stable carbon isotope (δ13C) composition of soil organic matter (SOM) preserved in buried soils in floodplain, terrace, and alluvial fan deposits in the Big Blue River valley of northeast Kansas. A combination of eight cores and three outcrops at six localities were investigated, and 27 radiocarbon ages provide a robust numerical chronology. Based on our analysis, the tallgrass prairie has experienced significant bioclimatic changes over the past 27,000 years. From the LGM to the beginning of the late Holocene (ca. 25,000–4500 cal yr BP), there is an overall increase in C4 plant contributions to SOM, suggesting general warming for that period. However, warming and C4 grass expansion occurred in a non-linear fashion, with minor variations in the abundance of C4 vs C3 plants reflecting either small fluctuations in temperatures during general warming trends or other environmental factors, such as landscape disturbance, periods of drought, or the seasonal distribution of precipitation. The δ13C record also suggests that a major warming event occurred in the region between ca. 3000–1300 cal yr BP, when the contribution of C4 biomass to SOM exceeded 95 %. This climatic event does not appear to be an anomaly, as multiple paleoenvironmental proxies indicate a brief but exceedingly warm and dry interval occurred from 3300 to 2800 cal yr BP.

A SUMMARY OF RADIOCARBON MEASUREMENTS OF FLUVIAL AND COLLUVIAL DEPOSITS IN CATCHMENTS OF SOUTH-CENTRAL ONTARIO, CANADA

ABSTRACTFluvial and colluvial deposits of Late Holocene age in South-Central Ontario catchments have provided few 14C dates, most by conventional methods registering century-old ages. Other young deposits, dated by conventional and accelerator mass spectrometry radiocarbon (AMS 14C), have yielded bomb-affected post-1950 ages over variable time limits. Attempts to date the base of Ah and lower-in-section soil horizons, in Early to Late Holocene stream terrace deposits, have yielded atomic bomb effects. Comparing bomb contamination in Late Holocene fluvial deposits, using both conventional and AMS methods, identifies a mix of bomb-affected beds juxtaposed with dated beds, the latter yielding ages with narrow standard deviations. Colluvial deposits overlying key glacial sections in the Rouge Catchment, while rare, yield bracketed AMS ages for an Ahbk horizon that refines weathering times relative to previously obtained conventional 14C dates. Bomb-affected sediment appears variably distributed within floodplain soils and in the ground soil of a colluvial section. Mass wasted deposits, with AMS 14C ages spread over the last few centuries, appear related to Little Ice Age (LIA) changes in climate, corroborated by pollen records. Further, these AMS-14C dated beds calibrate weathering of secondary Fe-Al oxihydroxides over the first half a millennium of weathering time.

Effects of Landscape Variables on Exchangeable Potassium Content in the Floodplain Soils of the Amur River

This article considers exchangeable potassium levels in the floodplain soils of the Amur River. The accumulation of exchangeable potassium in these soils was found to be largely determined by their age and weathering extent. In the young and highly weathered soils, the content of exchangeable potassium was lower than in the middle-aged soils. In the humus-accumulating horizon, it was 100–400 mg/kg and 200 mg/kg in the Upper and Middle Amur River, respectively. As for the mineral horizons, it ranged from 20 mg/kg in the young alluvial soils to 150 mg/kg in the residual-floodplain rusty soils. Interestingly, a significant increase in exchangeable potassium was observed for the coniferous-birch forests of the Upper Amur River (reaching an average of 400 mg/kg), but not for the oak forests in the Middle Amur River. Due to the asymmetry of the rate and ratio of zonal processes in the floodplain soils of the Upper and Middle Amur River, the residual-alluvial soils turned out to be sharply differentiated by the exchangeable potassium profiles. On average, the brown soils (Fluvic Cambisols) of the Upper Amur River contained up to 350 mg/kg of exchangeable potassium. The Fluvic Cambisols of the Middle Amur River had the lowest content of exchangeable potassium as compared to other studied soils.

Conservation agriculture's impact on total and labile organic carbon pools in calcareous and non-calcareous floodplain soils under a sub-tropical rice-based system.

To evaluate the effects of conservation agriculture (CA) on SOC pools and their lability, field experiments (2015-2020) were conducted on contrasting soils under subtropical climates. The experiment on non-calcareous soils, was comprised of tillage (minimum [MT] vs. conventional [CT]) in main plots, cropping systems (Wheat [Triticum aestivum]-Aus and Aman rice [Oryza sativa L.], WRR; Lentil [Lens culinaris]-Aus and Aman rice, LRR; and Mustard [Brassica nigra]- Boro and Aman rice, MRR) in the sub-plots, and crop residue (with or without 20% residue) in the sub-sub plots. The experiment on calcareous soils, was comprised of tillage (strip-till, ST; no-till, NT; and CT) and crop residue (high residue, HR at 50% by height vs. low residue, LR at 15%). Results showed that the MT had higher SOC contents by 18.8% than the CT in non-calcareous soils. Likewise, SOC was 12.5% and 6.7% higher in the NT and ST, respectively, than in the CT in calcareous soils. Significantly higher particulate organic (POC), permanganate oxidizable (POXC), and microbial biomass carbon (MBC) were observed in the MT, NT, and ST than in the CT at both locations. Reduced tillage with residue retention under LRR had a higher SOC, including labile C pools compared to WRR and MRR systems. Similarly, carbon management index (1.2-1.5 and 1.0-1.2) in both soils had significant positive correlations with SOC lability via POXC, POC, and MBC pools, indicating a SOC sequestration potential. In conclusion, our results showed positive effects of CA on SOC and its lability across soils.

Biogeochemical Assessment of Toxicity and Radioecological Danger of the Transboundary Kara-Balta River

The paper presents the results of researches of the concentration of chemical elements and natural radionuclide in the environmental objects of the Kara-Balta transboundary river basin (adjacent territories of Kyrgyzstan and Kazakhstan). The level of contamination of floodplain soils and bottom sediments of the Kara-Balta River with such chemical elements as U, Sb, As, Th, Pb, Sc, Co, Cu, Mo, Zn, V, Sr, Ba, Cs was established. Based on the calculated indicators of the contamination factor (CF), enrichment factor (EF), and index of geoaccumulation (Igeo), it was found that Sb, As and Br make the largest contribution to soil and bottom sediment pollution in the Kara-Balta water basin. At three checkpoints, an increased concentrations of U, B, Li, Sr, Mo were found in the water samples of the region’s reservoirs, which is related to the influence of the tailings of the Kara-Balta mining plant. The elevated concentrations of As, B, Ba, Co, Mn, Sb, V, and Zn were also established around the mouth of the Kara-Balta River, which flows into the Tasotkel reservoir (Kazakhstan). The results of the research can be explained by the fact that a significant part of the Kara-Balta transboundary river basin is located in the zone of a uranium natural–technogenic province.

Geomorphic evolution of the craton-derived Sone megafan in the southern Ganga plain, India: A tectono-climatic interplay

The Ganga plain neotectonics has been studied from surface and sub-surface faults, frequent geomorphic readjustment, changing sedimentation pattern, piedmont progradation, pedological variation, and frequent earthquake occurrences. However, being neotectonically stable, the peninsular region’s geomorphic changes are governed by climatic fluctuations, contributing to the Ganga plain’s sedimentation. Therefore, peripheral craton sourced marginal alluvial deposits in the Ganga basin are appropriate features to study the control of both the Himalayan tectonics and climate of core peninsular region away from their respective source areas. This study uses a process-response approach model to describe the geomorphic development of the Sone megafan, located at the marginal part of the Ganga plain to the south of the Ganga River, bordering the Indian craton.Geomorphological mapping, field investigation of the depositional features, soil profiles, and Optical Stimulated Luminescence (OSL) chronology suggest four phases of geomorphic evolution, i.e., in 22–8 Ka, 8.0 Ka–7.3 Ka, 7.3 Ka–2.4 Ka, and 2.4 Ka–0.5 Ka on the Sone megafan. The different evolutionary phases are marked by channel and floodplain abandonment and soil profile development. The megafan surface is divided into four distinct geomorphic units (OdSP – Oldest Sone Plain, OSP – Old Sone Plain, YSP – Young Sone Plain, and AFP – Active Floodplain) based on OSL ages and soil properties. Geomorphology and soil suggest a mixed climate in the source and sink area. The arid climate in the catchment contributed to the sediment production, and the humid climate promoted its transport, which resulted in the largest depositional unit of the megafan, even during the arid period in the Ganga basin. Contrast to the north of the Ganga River, no surface faults are found on the Sone megafan. However, the tectonic activity of the bounded basement faults, i.e., the East and the West Patna faults, are well pronounced in the sediment distribution and fluvial response. Tilting and twisting the fault-bounded block controls the sediment remobilization in space and time. Thus, the climatic fluctuation in the source, the sink, and the activity of the basement faults, propelled by the Himalayan tectonics, contributed to the Sone megafan’s geomorphic evolution. Two events of the Ganga River’s encroachment at the distal part of the Sone megafan were recorded (2.4 ± 0.14 and 1.3 ± 0.16 ka). The correlation between OSL ages of megafan units, climatic fluctuations in the Sone River’s catchment, and established time windows of tectonic episodes in the Ganga basin has also been investigated. As the Sone and the Gandak megafans rest on the same tectonic blocks, their tectono-geomorphic responses to the Himalayan neotectonics are similar.

Increase the Efficient Use of Phosphorus Fertilizer for Maize in the Calcareous Soils

ABSTRACT Phosphorus (P) is one of the 17 essential plant nutrients, and it is critical for plant metabolism, photosynthesis, and growth. P fertilizers are also critical for crop production and global food security. Type and application method of P fertilizer may lead to increased P accumulation and crop production in the Ganges delta soils. The aim of the present study is to increase the P use efficiency (PUE) by two different P application methods for maize cultivation. The experiment comprised a factorial combination of two methods (broadcasting and furrow placement) and three rates of P fertilizer (36, 48, and 60 kg P/ha). Considering P application methods, furrow placement gave 8.66–27.92% yield benefit over broadcasting method. Maize yield, PUE by crop plant, partial factor productivity, economic efficiency, and P concentration in leaf were remarkably higher in furrow placement than conventional broadcasting method of P application. The furrow placement exhibited higher yield at lower rate of P application (36 and 48 kg P/ha), while no significant changes were observed for grain yield between two methods for high P rate (60 kg/ha). Thus, it is concluded that furrow placement of P application at 36 and 48 kg/ha would give the best grain yield of maize in the Ganges delta floodplain soils.

Биологические показатели и их значение в диагностике аллювиально-луговых почв

The priority issue that is covered in the article is the expediency of using biological indicators in the diagnosis of alluvial-meadow soils. In Azerbaijan, floodplain soils, common on terraces and alluvial fans of large rivers, where there are groundwater recharge conditions and the influence of the flood floodplain regime, have been widely studied. Alluvial-meadow soils develop under the meadow soil with forb-cereal groups and shrub vegetation under the active influence of groundwater occurring at a depth of 1.0–3.5 and surface (flood) moisture. Rich herbaceous vegetation causes the development of the sod process; as a result, a large amount of organic matter accumulates. Considering that various subtypes of floodplain soils are formed, under characteristic bioclimatic conditions, our goal was to study some biological indicators of alluvial-meadow soils of natural and cultivated cenoses. On the selected biotopes (virgin cenosis, near-terrass biotope, alluvial deposits of Shin-chai, as well as agrocenoses of cereals and tobacco), the group composition and amount of microbiota, complexes of invertebrates, phytomass and humus content were comparatively studied. The accounting of phytomass on the virgin cenosis showed that plant products amount to 363 g/m2 of raw and 26 g/m2 of dry mass. Possible relationships between individual biological and some physico-chemical parameters are considered. The results obtained can be used as biotests in the diagnosis of alluvial-meadow soils. Plants are the primary source of organic residues in the soil, their main function of which as a soil-forming plant is to create primary bioproducts and participate in the global biological cycle.

Природные закономерности почвенно-растительного покрова юго-западных отрогов Баджальского хребта

Expert assessment has been performed using the cartographic method in a key area of the Badjal Rige southwestern spurs. The basic natural regularities of the soil and vegetation cover have been identified, including heterogeneity and contrasting change of soil and vegetation complexes within the limits of vertical zoning; belt-zone differentiation (alpine, subalpine, and taiga); wide distribution of corroms; maximum diversity and high dynamism of floodplain soil and plant complexes. The article presents a 1 : 40,000-scale vegetation map; it is based on the ecological and phytocenotic classification of vegetation. The main mapped units are association groups and their combinations. The legend reflects 13 divisions of the vegetation cover. Corroms occupy the largest areas (24.9 %). The subalpine zone vegetation makes 20.9 % of the total area. Mountain taiga forests take 32.9 % of the total mapped territory, including spruce forests (7.3 %), larch forests (21.9 %), and birch-larch forests (3.7 %). Larch woodlands are responsible for slightly less than 3 % of the territory; sphagnum oligotrophic bogs, for 0.5 %. Floodplain forests are spread over the area of 12.5 %; that includes spruce forests (4.8 %), chosenia-poplar-larch forests (4.5 %), and poplarlarch forests (3.2 %). 4.4 % of the area is pebbled. There are 5 types and 13 subtypes of soils represented in the soil cover. Dystric histosols and leptic folic histosols form the soil background. Soils are characterized by the presence of organogenic-coarse humus or dry peaty horizons. Organic matter content is high or very high. The reaction of the soil solution varies from very acidic to acidic. Based on the vegetation map, soil areas are roughly quantified. In terms of the set of soil and plant complexes as well as their regular change in vertical zoning, the area under discussion is the reference territory. Represented here is the Okhotsk type of land cover zoning, which is typical for the Far East with its monsoonal climate.

Selected Enzyme Activities Under Different Land Use Management in Lower Missouri River Floodplain Soils

ABSTRACT Floodplains are vital and productive ecosystems that provide essential biological, and hydrologic functions. However, human modifications to floodplains, such as urbanization, and agriculture have increased the need to assess the impacts of land use changes on the sustainability of their functions. Riparian forest (RF), agroforestry (AF), and row-crop agriculture (AG) are among common land-use systems in the lower Missouri River Floodplain (MRF) region in New Franklin, MO. This study tested the hypothesis that variations in soil physicochemical and biological parameters in relation to land management could affect soil enzyme activities. Soil samples were collected from three land use systems, and enzyme activities were measured in three seasons fall 2019, summer 2020, and spring 2021. Soil properties such as soil C and N, bulk density, organic matter, and water-holding capacity were measured. The results revealed significantly higher levels of β-glucosidase, β-glucosaminidase, and dehydrogenase activity in agroforestry (AF) and riparian forest (RF) treatments relative to agriculture (AG) management in all three studied seasons. No substantial differences in total PLFA were detected among land use systems. This research demonstrated that tree-based systems can substantially enhance soil bulk density and organic matter concentration, leading to increased activity of the selected enzymes. Efforts to incorporate agroforestry systems help to create a more diverse and complex ecosystem compared to monoculture cropping systems. This, in turn, stimulates connections among diverse plant species, microorganisms, and soil fauna, leading to improved nutrient cycling, organic matter decomposition, and overall soil health.

Bacterial community diversity for three selected land use systems as affected by soil moisture regime

Despite their important role in soil nutrient cycling, soil bacterial communities' response to land management practices and soil hydrologic fluctuations are not sufficiently studied. The effects of land use and soil moisture regime on soil bacterial community structure and diversity in the Missouri River Floodplain have been investigated in this study. Three land use systems represented riparian forest (RF), pecan (Carya illinoinensis) orchard/hay agroforestry system (AF), and row crop corn [Zea mays L.]/soybean [Glycine max (L.) Merr.] agriculture system (AG). Microbial diversity indices and the abundance of selected bacterial phyla were investigated in bulk soil samples by performing 16 s rRNA amplicon sequencing. Soil samples were collected from three selected land use systems in September 2020 and May 2021. To simulate the hydrological dynamics of the riparian systems, intact soil cores were subjected to two different soil moisture regimes: saturated (FD) and alternately saturated and field capacity (FL) for 8 weeks of incubation. A control sample was maintained at field capacity for the entire duration of the experiment. Soil physicochemical properties substantially differed among land use. Soil organic matter (OM%) was significantly greater in AF and RF than in AG. Proteobacteria, Actinobacteriota, and Acidobacteriota were found to be the most dominant bacterial phyla across all samples. The bacterial richness and Shannon indices were not considerably different among land use systems. Soil FD conditions considerably increased the abundance of Actinobacteriota in AF soils. The abundance of these phyla was strikingly higher in AF with the greatest organic matter relative to AG and RF under all three water regimes. Further work may be needed to assess the effects of hydrological events on floodplain soils' microbial community indices.

Urban stream restorations increase floodplain soil carbon and nutrient retention along a chronosequence

Stream restoration is a common management practice to meet regulatory or voluntary efforts to improve water quality via nutrient and carbon (C) retention, including in the Chesapeake Bay watershed. However, most restoration projects have few quantifiable measures of project success, no standard metrics, and rarely collect pre-restoration data. Storage of nutrients, such as phosphorus (P) and nitrogen (N), in floodplain soils of restored streams can act as an easily quantifiable indicator of restoration success, particularly when the project goals include improved water quality. To determine how floodplains of restored streams change in their P and C storage as time since restoration increases, floodplain surficial soil samples (10 cm depth) were collected from 18 streams in the urbanized Piedmont region of northern Virginia, representing a chronosequence of time (1–10+ yrs.) since restoration as well as unrestored streams with high impervious surface cover (ISC) and unrestored streams with low ISC. The samples were analyzed for total carbon (TC), total nitrogen (TN) and total phosphorus (TP) storage, whereas C turnover rate and equilibrium phosphorus concentration (EPC0) were measured as metrics of C and P loss. These metrics were compared to time since restoration and potential environmental drivers, including soil moisture, pH, median particle size (D50), organic matter content (OM), and bioavailable P, iron (Fe), and aluminum (Al). These stream restorations demonstrated increasing nutrient storage for TC, TN, and TP along the chronosequence to values greater than both unrestored or reference streams, as well as decreasing C turnover and no significant changes in EPC0. Soil wetness and OM, key drivers in nutrient retention, also increased as restoration projects aged increasing C, N, and P storage. Overall, stream restoration did improve soil C, N, and P retention in floodplains as compared to unrestored sites and exceeded those of low ISC ‘reference’ sites.

Loading of zinc and iron in grains of different wheat genotypes in the calcareous and floodplain soils of Bangladesh

Major malnutrition in Bangladesh is zinc (Zn) and iron (Fe) deficiency as most people commonly depend on cereals, chiefly rice and wheat. The main objectives are to enhance Zn and Fe concentrations through the use of selected varieties and the application of respective fertilizers. Field experiments were conducted at Bangladesh Agricultural University (BAU) farm, Mymensingh (AEZ 9, non-calcareous soil) and at Bangladesh Institute of Nuclear Agriculture (BINA) substation, Ishwardi (AEZ 11, calcareous soil) for two consecutive wheat seasons (2014–15 and 2015–16) with 10 varieties and 15 advanced lines. Varieties BARI Gom 25, 27, 28 & 29 and breeding lines Vijay, HPYT-5, 15 & 21 and BL-1883 have been recognized as Zn-enriched wheat varieties (24–30 μg g−1). Among the genotypes, Zn further increased by 4–8 μg g−1 due to Zn fertilization. Concerning Fe-enriched wheat genotypes (24–30 μg g−1), five varieties viz. Shatabdi, Prodip, BARI Gom 25 & 28 and Sufi, and four lines such as HPYT-12, BL-1883, BL-1040 and Fery-60 have been identified. The grain Fe concentration of wheat genotypes increased when Fe was added, the increment being 6–12 μg g−1. A positive relationship between Zn and N is observed with increased protein content. The grain yield of wheat was increased by 3.8–25.7% due to Zn application over the varieties and locations but Fe addition had no effect. The result of the current study showed that a potential breeding line with appropriate fertilization can improve Zn and Fe levels in wheat grain, without incurring loss to wheat yield.

Characteristics of Humic Acids in Drained Floodplain Soils in Temperate Climates: A Spectroscopic Study

This study aims to assess the characteristics of humic acids (HAs) in floodplain soils. HAs were isolated from the Fluvisols located out of the embankment in the riparian forest (unflooded riparian forest) and within the embankment (inter-embankment), in the area periodically flooded. HAs from these soils were examined for quantity, structure, and humification degree using extraction methods as well as elemental analysis, UV-Vis, FTIR, EPR, and 1HNMR spectroscopies. In the soils after drainage, a significant decrease in HAs has been observed compared to the periodically flooded areas. Obtained results showed that organic matter from periodically flooded soils is more humified and contains HAs with a more aromatic, lignin-like structure compared to the humus matter from unflooded Fluvisols. Humic acids from periodically flooded soil contained a lower amount of C and H compared to those isolated from unflooded soils located out of the embankment, which resulted in a less aliphatic or more aromatic character of their molecules. A higher H/C ratio of HAs from the Fluvisols after drainage exhibits more condensed aromatic ring or substituted ring structures in the molecules. Soils with organic matter with a higher humification index contained HAs with lower radical concentration values in comparison to soils with less humified organic matter. Results obtained show that in flooded areas with periodically reductive conditions, humic acids do not lose as many -OCH3 groups as in better oxidized soils and therefore exhibit a lignin-like aromatic structure. It has been proven that the formation and dynamics of HA transformation may vary due to the water regime in soils.

Impact of different industrial activities on heavy metals in floodplain soil and ecological risk assessment based on bioavailability: A case study from the Middle Yellow River Basin, northern China

Understanding the impact of different industrial activities on heavy metals and conducting scientific ecological risk assessments are critical to the management of heavy metal pollution. The present study compared soils affected by different industrial activities in three types of industrial cities (coal city, oil-gas city, and economic city) to control samples and examined the ecological risk based on bioavailability in the Middle Yellow River Basin. The findings revealed that the impact characteristics of different industrial activities on soil heavy metals in the research area were different. Both coal-based and oil-gas industry activities had a minor impact on soil heavy metals, whereas economic industry activities in the southern part had a major impact, as evidenced by significant enrichment of Cd, Hg, Cu, Pb, and Zn. In principal component analysis, the soil heavy metals affected by economic industry activities designated a distinct source from the control samples, particularly the anthropogenic sources represented by Hg and Cd. In the context of heavy metals in chemical form, three types of industrial activities all had an effect on bioavailability (0.72–24.27%) and could increase migratory activity in the environment. Furthermore, both traditional and improved assessments, based on total content and bioavailability, showed a low ecological risk near coal cities and oil-gas cities in the middle and northern parts, while there was a medium-high ecological risk near economically developed cities in the south, particularly Tianshui, Baoji, Qishan, Xianyang, Xi'an, and Tongchuan. In comparison, improved risk assessment based on bioavailability tends to not only compensate for an overestimation in traditional risk assessment from the perspective of total content, but additionally achieve a more reasonable, effective, and advanced assessment of heavy metal risks in scientific research. The outcome of this study has significance for the ecological conservation and high-quality development of the Yellow River Basin.