Radionuclide Transport above a Near‐Surface Water Table: II. Vertical Distribution of Gamma Activities within Soil Profiles in Relation to Wheat Rooting Density and Soil‐to‐Plant Transfers

AbstractUranium/Thorium (U/Th) and 226Ra dating has been applied to spring deposits in order to determine the timing of the drying up of springs in the Wādī al-Ajāl, Fazzān, Libya. These dates are compared with results of archaeological surveys of irrigation structures and archaeobotanical studies of plant remains to further our understanding of the factors that controlled the introduction of irrigated agriculture, its nature and timing.Though there are still important gaps in our understanding, the results suggest that by 3,100 ±125 BP surface water was either very scarce or nonexistent at the base of the escarpment, although the water table was probably very near the surface at the base of the Wādī in the vicinity of Jarma. Archaeobotanical evidence indicates that irrigated agriculture was introduced in the early part of the first millennium BC, soon after the desiccation of the springs and presumably in response to the fall in the water table and the increasingly scarce availability of surface water. No irrigation structures have been found that relate to this period, but the most likely scenario involves wells tapping the near surface water in the vicinity of Jarma. The earliest irrigation systems are foggaras which archaeological evidence suggests were probably introduced by the final few centuries BC, and definitely before the fourth century AD. The extensification of agriculture associated with extensive foggara development broadly corresponds with archaeobotanical evidence for an intensification and diversification of agriculture involving the introduction of a farming system utilising both winter and summer crops. There are likely to be strong connections between these two developments and that of the rise of the Garamantes.

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An evaluation of water quality at Sandhill Wetland: implications for reclaiming wetlands above soft tailings deposits in northern Alberta, Canada

Wetlands Ecology and Management ◽

10.1007/s11273-020-09771-8 ◽

2021 ◽

Author(s):

Jeremy A. Hartsock ◽

Jessica Piercey ◽

Melissa K. House ◽

Dale H. Vitt

Keyword(s):

Water Quality ◽

Electrical Conductivity ◽

Surface Water ◽

Water Chemistry ◽

Water Quality Monitoring ◽

Total Alkalinity ◽

Near Surface ◽

Water Quality Guidelines ◽

Quality Guidelines ◽

Annual Water

AbstractThe experimental Sandhill Wetland is the first permanent reclamation of a composite tailings deposit, and annual water quality monitoring is of specific interest for evaluating and predicting long-term reclamation performance. Here, we present water chemistry monitoring data obtained from Sandhill Wetland (years 2009–2019) and compare results to twelve natural reference wetlands and to environmental quality guidelines for Alberta surface waters. By comparing water quality at Sandhill Wetland and natural sites to established guidelines, we can begin to document the natural background water quality of wetlands in the region and examine if guideline exceedances are seen in natural undisturbed environments, or appear only at active reclamation sites. At Sandhill Wetland the dominant ions in near-surface water were bicarbonate, sulfate, chloride, sodium, calcium, and magnesium. Since the first growing season concentrations for these ions have increased annually, causing concurrent increases in electrical conductivity. In year 2019, water chemistry at Sandhill Wetland was most comparable to regional saline fens, systems that exhibit elevated electrical conductivity and high sodicity. Near-surface water at Sandhill Wetland exceeded water quality guidelines for three substances/properties (dissolved chloride, iron, and total alkalinity) in the most recent year of monitoring. The saline fen natural sites also exceeded water quality guidelines for the same chemical substances/properties, suggesting guideline exceedances are a norm for some natural wetland site types in the region. Of note, in each year of monitoring at Sandhill Wetland, dissolved organic compounds evaluated in sub- and near-surface water were below detection limits.

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Modeling Near‐Surface Water Redistribution in a Desert Soil

CSA News ◽

10.1002/csan.20360 ◽

2020 ◽

Keyword(s):

Surface Water ◽

Desert Soil ◽

Near Surface ◽

Water Redistribution

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Online Estimation of Near-Surface Water Current Fields Using Horizontally Mounted ADCPs on Inland Vessels

2020 European Navigation Conference (ENC) ◽

10.23919/enc48637.2020.9317463 ◽

2020 ◽

Author(s):

Martin Kosch ◽

Rene Zweigel ◽

Dirk Abel

Keyword(s):

Surface Water ◽

Water Current ◽

Near Surface ◽

Online Estimation

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Vertical Distribution and Controlling Factors of Soil Inorganic Carbon in Poplar Plantations of Coastal Eastern China

Forests ◽

10.3390/f13010083 ◽

2022 ◽

Vol 13 (1) ◽

pp. 83

Author(s):

Sihan Wang ◽

Weiwei Lu ◽

Fangchao Zhang

Keyword(s):

Vertical Distribution ◽

Soil Water ◽

Inorganic Carbon ◽

Eastern China ◽

Controlling Factors ◽

Water Soluble ◽

Soil Profiles ◽

Soil Inorganic Carbon ◽

Poplar Plantations ◽

Soil Inorganic

Afforestation is a strategy to protect croplands and to sequestrate carbon in coastal areas. In addition, inorganic carbon is a considerable constitute of the coastal soil carbon pool. However, the vertical distribution and controlling factors of soil inorganic carbon (SIC) in plantations of coastal areas have been rarely studied. We analyzed the SIC content as well as physiochemical properties along soil profiles (0–100 cm) in young (YP) and mature (MP) poplar plantations in coastal eastern China. The soil profile was divided into six layers (0–10, 11–20, 21–40, 41–60, 61–80 and 81–100 cm) and a total of 36 soil samples were formed. The SIC content first increased from 0–10 cm (0.74%) to 11–20 cm (0.92%) and then fluctuated in the YP. In contrast, the SIC content increased with increasing soil depth until 40 cm and then leveled off, and the minimum and maximum appeared at 0–10 cm (0.54%) and 81–100 cm (0.98%) respectively in the MP. The soil inorganic carbon density was 12.05 and 12.93 kg m−2 within 0–100 cm in the YP and MP, respectively. Contrary to SIC, soil organic carbon (SOC) first decreased then levelled off within the soil profiles. Compared with the YP, the SIC content decreased 27.8% at 0–10 cm but increased 13.2% at 21–40 cm, meanwhile the SOC content in MP decreased 70.6% and 46.7% at 21–40 cm and 61–80 cm, respectively. The water-soluble Ca2+ and Mg2+ gradually decreased and increased, respectively within the soil profiles. The soil water-soluble Ca2+ increased 18.3% within 41–100 cm; however, the soil water-soluble Mg2+ decreased 32.7% within 21–100 cm in the MP when compared to the YP. Correlation analysis showed that SIC was negatively correlated with SOC, but positively correlated with soil pH and water-soluble Mg2+. Furthermore, structural equation modeling (SEM) indicated that SOC was the most important factor influencing the SIC content in the studied poplar plantations, indicating SOC sequestration promoted the dissolution of SIC. Therefore, our study highlights the trade-off between SIC and SOC in poplar plantations of coastal Eastern China.

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