Bioturbation, microbial activity and sediment properties in an estuarine ecosystem

1986 ◽  
Vol 90 ◽  
pp. 129-142 ◽  
Author(s):  
P. S. Meadows ◽  
A. Tufail
Keyword(s):  
Spatial Variation ◽  
Microbial Activity ◽  
Large Scale ◽  
Chemical Properties ◽  
Estuarine Sediments ◽  
Sediment Stability ◽  
Estuarine Ecosystem ◽  
Particle Sedimentation ◽  
Geochemical Properties ◽  
Sea Bed

SynopsisMacrobenthic bioturbation and microbial activity can have major ecological effects on present day marine sediments some of which are also seen in the fossil record. The coastal and estuarine sediments in the Clyde Estuary area are described. They contain very high densities of benthic macroorganisms and microorganisms. These organisms have dramatic effects on the physical and chemical properties of sediments, and field and laboratory studies have shown that many geotechnical and geochemical properties of sediments are dictated by them. The effects can be on a microscale of a few millimetres horizontally or vertically (micro-spatial variation), or can have large scale consequences over hundreds of metres (macro-spatial variation).Sediment stability (shear strength and critical erosion velocity), permeability and particle sedimentation are all altered by macro-invertebrate bioturbation or microbial activity, and many chemical properties such as Eh and pH may be influenced in a similar manner.Biological activity may therefore play a major role in modifying sediment geotechnics and early sediment diagenesis. It also has direct relevance to the siting of man-made structures on the sea-bed and to sediment stability and transport in estuaries.In situseeding experiments may lead to biological control and manipulation of these most important field phenomena.

scholarly journals Chemical Properties of Heavy Metal-Contaminated Soils from a Korean Military Shooting Range: Evaluation of Pb Sources Using Pb Isotope Ratios

2021 ◽  
Vol 11 (15) ◽  
pp. 7099
Author(s):  
Inkyeong Moon ◽  
Honghyun Kim ◽  
Sangjo Jeong ◽  
Hyungjin Choi ◽  
Jungtae Park ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Contaminated Soils ◽  
Management Strategies ◽  
Chemical Properties ◽  
Heavy Metal Concentration ◽  
Soil Samples ◽  
Shooting Range ◽  
Geochemical Properties ◽  
Mineral Phases

In this study, the geochemical properties of heavy metal-contaminated soils from a Korean military shooting range were analyzed. The chemical behavior of heavy metals was determined by analyzing the soil pH, heavy metal concentration, mineral composition, and Pb isotopes. In total, 24 soil samples were collected from a Korean military shooting range. The soil samples consist of quartz, albite, microcline, muscovite/illite, kaolinite, chlorite, and calcite. Lead minerals, such as hydrocerussite and anglesite, which are indicative of a transformation into secondary mineral phases, were not observed. All soils were strongly contaminated with Pb with minor concentrations of Cu, Ni, Cd, and Zn. Arsenic was rarely detected. The obtained results are indicated that the soils from the shooting range are contaminated with heavy metals and have evidences of different degree of anthropogenic Pb sources. This study is crucial for the evaluation of heavy metal-contaminated soils in shooting ranges and their environmental effect as well as for the establishment of management strategies for the mitigation of environmental risks.

scholarly journals Spatial variation and mechanisms of leaf water content in grassland plants at the biome scale: evidence from three comparative transects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruomeng Wang ◽  
Nianpeng He ◽  
Shenggong Li ◽  
Li Xu ◽  
Mingxu Li
Keyword(s):  
Spatial Variation ◽  
Water Content ◽  
Large Scale ◽  
Life Forms ◽  
Important Variable ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Desert Grassland ◽  
Large Spatial Scale ◽  
Grassland Plants

AbstractLeaf water content (LWC) has important physiological and ecological significance for plant growth. However, it is still unclear how LWC varies over large spatial scale and with plant adaptation strategies. Here, we measured the LWC of 1365 grassland plants, along three comparative precipitation transects from meadow to desert on the Mongolia Plateau (MP), Loess Plateau, and Tibetan Plateau, respectively, to explore its spatial variation and the underlying mechanisms that determine this variation. The LWC data were normally distributed with an average value of 0.66 g g−1. LWC was not significantly different among the three plateaus, but it differed significantly among different plant life forms. Spatially, LWC in the three plateaus all decreased and then increased from meadow to desert grassland along a precipitation gradient. Unexpectedly, climate and genetic evolution only explained a small proportion of the spatial variation of LWC in all plateaus, and LWC was only weakly correlated with precipitation in the water-limited MP. Overall, the lasso variation in LWC with precipitation in all plateaus represented an underlying trade-off between structural investment and water income in plants, for better survival in various environments. In brief, plants should invest less to thrive in a humid environment (meadow), increase more investment to keep a relatively stable LWC in a drying environment, and have high investment to hold higher LWC in a dry environment (desert). Combined, these results indicate that LWC should be an important variable in future studies of large-scale trait variations.

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

scholarly journals Separation of Fe from Mn in the Cryogenian Sedimentary Mn Deposit, South China: Insights from Ore Mineral Chemistry and S Isotopes from the Dawu Deposit

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 446
Author(s):  
Zhiming Xu ◽  
Chengquan Wu ◽  
Zhengwei Zhang ◽  
Jinhong Xu ◽  
Xiyao Li ◽  
...  
Keyword(s):  
South China ◽  
Large Scale ◽  
Early Stage ◽  
Sulfur Isotopes ◽  
Mineral Chemistry ◽  
Manganese Carbonate ◽  
Separation Mechanism ◽  
Geochemical Properties ◽  
Stage Separation ◽  
Fe Content

Manganese and Fe have similar geochemical properties in the supergene environment. Separation of Mn and Fe is an important process for the formation of high-grade sedimentary manganese deposits. Large-scale manganese carbonate deposits (total reserves of approximately 700 Mt) were formed during the interglacial of the Sturtian and Marinoan in South China. The orebodies are hosted in the black rock series at the basal Datangpo Formation of the Cryogenian period. The Fe contents in ores range from 1.15 to 7.18 wt.%, with an average of 2.80 wt.%, and the average Mn/Fe ratio is 8.9, indicating a complete separation of Mn and Fe during the formation of manganese ores. Here, we present element data of manganese carbonates and sulfur isotopes of pyrite from the Dawu deposit, Guizhou, China, aiming to investigate the separation mechanism of Mn and Fe and the ore genesis. The Fe in ores mainly occurs as carbonate (FeCO3) and pyrite (FeS2). The Mn, Ca, Mg and Fe exist in the form of isomorphic substitutions in manganese carbonate. The contents of FeCO3 in manganese carbonates are similar in different deposits, with averages of 2.6–2.8 wt.%. The whole-rock Fe and S contents have an obvious positive correlation (R = 0.69), indicating that the difference of whole-rock Fe content mainly comes from the pyrite content. The δ34SV-CDT of pyrite varies from 40.0 to 48.3‰, indicating that the pyrite formed in a restricted basin where sulfate supply was insufficient and the sulfate concentrations were extremely low. Additionally, the whole-rock Fe content is negatively correlated with the δ34S values of the whole-rock and pyrite, with correlation coefficients of −0.78 and −0.83, respectively. Two stages of separations of Mn and Fe might have occurred during the mineralization processes. The reduced seawater became oxidized gradually after the Sturtian glaciation, and Fe2+ was oxidized and precipitated before Mn2+, which resulted in the first-stage separation of Mn and Fe. The residual Mn-rich and Fe-poor seawater flowed into the restricted rift basin. Mn and Fe were then precipitated in sediments as oxyhydroxide as the seawater was oxidized. At the early stage of diagenesis, organic matter was oxidized, and manganese oxyhydroxide was reduced, forming the manganese carbonate. H2S was insufficient in the restricted basin due to the extremely low sulfate concentration. The Fe2+ was re-released due to the lack of H2S, resulting in the second-stage separation of Mn and Fe. Finally, the manganese carbonate deposit with low Fe and very high δ34S was formed in the restricted basin after the Sturtian glaciation.

scholarly journals Mapping the spatial variation of soil moisture at the large scale using GPR for pavement applications

2014 ◽  
Vol 13 (3) ◽  
pp. 269-278 ◽  
Author(s):  
Andrea Benedetto ◽  
Fabio Tosti ◽  
Bianca Ortuani ◽  
Mauro Giudici ◽  
Mauro Mele
Keyword(s):  
Soil Moisture ◽  
Spatial Variation ◽  
Large Scale

scholarly journals Physico-chemical properties and heavy metal contents of a tropical estuarine ecosystem, Nigeria

2018 ◽  
Vol 5 (11) ◽  
pp. 781-797
Author(s):  
Paul Chinedu Echi ◽  
Daberechi Ndudim Okpechi ◽  
Janet Azu Urum ◽  
Izuchukwu Samson Arukwe
Keyword(s):  
Heavy Metal ◽  
Chemical Properties ◽  
Oxygen Demand ◽  
International Standards ◽  
Anthropogenic Pressure ◽  
Estuarine Ecosystem ◽  
Metal Concentrations ◽  
Metal Contents ◽  
Zinc Cadmium ◽  
Lead Zinc

Ibaka Estuarine in Mbo, Nigeria, has little or no information on its basic properties, therefore its water samples were studied from March to June 2018 in three different stations and compared with International Standards to evaluate its physic-chemical properties as well as heavy metal contents. The physic-chemical properties studied include pH, salinity (g/L), EC (μs/cm), turbidity (NTU), total suspended solids (mg/L), total dissolved solids (mg/L), dissolved oxygen (mg/L), BOD5 (mg/L), and chemical oxygen demand (mg/L). In addition, some metal concentrations of manganese, iron, copper, lead, zinc, cadmium, chloride and magnesium were determined by atomic absorption spectroscopy (AAS). The range of metal concentrations manganese (0.08-0.12 mg/L), copper (0.05-0.09 mg/L), lead (0.01-0.03 mg/L), iron (1.86-4.66 mg/L), zinc (0.68-1.16 mg/L), cadmium (0.04-0.08 mg/L), chloride (675.0-791.25 mg/L), magnesium (10.66-14.30 mg/L). The study infers that anthropogenic pressure plays damaging role to its properties in addition to general health implication of high values for Fe, Zn, Cd, Cl and Mg which exceeded international standard.

scholarly journals Pratiques de production et caracteristiques physiques et chimiques du shô basi, un couscous de niebe (Vigna unguiculata) produit au Mali

2021 ◽  
Vol 21 (02) ◽  
pp. 17509-17528
Author(s):  
A Timitey ◽  
◽  
L Adinsi ◽  
YE Madodé ◽  
F Cissé ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Large Scale ◽  
Chemical Properties ◽  
Quality Criteria ◽  
Scale Production ◽  
Production Flow ◽  
Cowpea Seeds ◽  
Steam Cooking ◽  
End Products ◽  
Cowpea Varieties

In West Africa, cowpea is processed into several end-products among which the most consumed in Mali is a steamed granulated product known as cowpea couscous or Shô basi, in Bambara. Organoleptic properties ofShô basi are variable, probably as a consequence of the diversity of the practices of production. This study aims at determining these practices, their constraints and the physico-chemical characteristics of Shô basi as sold on Malian markets. A survey using focus group discussions, and involving eighteen (18) Shô basi production cooperatives, each gathering 8 to 32 members, was conducted in South Mali. The information collected was related to cowpea varieties used for production, flow diagrams, constraints of production, and quality criteria of the end-products. Eighteen (18) Shô basi samples were collected from the interviewed groups and used for the determination of the physical and chemical properties of Shô basi. Results showed that most of the processors were married, non or moderately literate and aged between 20 and 59 years women. The main cowpea varieties used for the production are sangaraka and wilibali, both from the species Vigna unguiculata. Both varieties of cowpea are characterized by a white or cream color. Shô basi is produced using a single process with two major technological variants. One involves a wet total dehulling (VDT), whereas the second involves a dry partial dehulling (VDP) of cowpea seeds. Regardless of the technological variant and cowpea variety used, interviewees indicated that a good qualityShô basi must have a light color, a soft mouthfeel texture, a homogeneous granule size and lacking beany flavor. Protein(25,0g/100g) and polyphenol (24,3mg/100g)contents as well as swelling level were similar for Shô basi from both variants. However, Shô basi from technology involving partial dehulling (VDP) was less bright, richer in fiber and minerals, and contained more fine granules thanShô basi involving whole dehulling(VDT). Cowpea dehulling, flour granulation, steam cooking and drying are the mean constraints for quality standardization and large-scale production of Shô basi in Mali.

scholarly journals Assessing the Effect of Different Agroforestry Practices on Soil Physico-chemical Properties and Microbial Activity

2020 ◽  
Vol 9 (9) ◽  
pp. 2802-2816
Author(s):  
Baswant Sushant Pralhad ◽  
P. Rajendran ◽  
M. P. Divya ◽  
R. Rajeswari ◽  
G. Thangamani ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Agroforestry Practices

scholarly journals Herbivory drives large‐scale spatial variation in reef fish trophic interactions

2014 ◽  
Vol 4 (23) ◽  
pp. 4553-4566 ◽  
Author(s):  
Guilherme O. Longo ◽  
Carlos Eduardo L. Ferreira ◽  
Sergio R. Floeter
Keyword(s):  
Spatial Variation ◽  
Reef Fish ◽  
Trophic Interactions ◽  
Large Scale
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