scholarly journals The Sediment Selectivity of Perinereis aibuhitensis Larvae: Active or Passive?

2021 ◽  
Vol 8 ◽  
Author(s):  
Jinghui Fang ◽  
Wei He ◽  
Shan Meng ◽  
Zengjie Jiang ◽  
Jianguang Fang ◽  
...  

The selectivity of Perinereis aibuhitensis larvae on different sediment types was studied using an experimental behavioral device in the lab. There were six types of sediment with different organic matter content: 2.19, 2.30, 2.86, 3.25, 3.51, and 5.52%. The results indicated significant differences in the six treatments’ organic matter content (p < 0.05). When the P. aibuhitensis larvae initially attached to the sediment, the larvae’s density showed no significant difference among the six treatments. The density of larvae decreased gradually during the experimental period. It increased with the increasing organic matter content in sediment at every sampling time, but there was no significant difference (p > 0.05). The larvae’s specific growth rate in the first month was significantly higher than those in the second and third months (p < 0.05). The mortality showed no significance at different sediments in equal sampling times, but the mortality was lower in high organic matter content sediments. This study showed that the P. aibuhitensis larvae did not make an active selection; random selection happened when initially attached to the sediment with different organic matter contents. Higher organic matter content in the sediment was more conducive to larvae survival, and the organic matter content is the limitation factor on the mortality and the density. The different densities in the natural habitat of P. aibuhitensis might occur due to the passive selection by the environment.

2020 ◽  
Author(s):  
Jessica Potts ◽  
David Jones ◽  
Richard Pywell ◽  
Andy Macdonald ◽  
Paul Cross

<p>Over the last half century, society’s dependence on insect-assisted pollination of crops has risen by over 300% globally, while recent findings have estimated a 76% decline in flying insect biomass over the last 27 years. These losses in invertebrate numbers are thought to be due to a possible combination of various factors including parasites and diseases, agricultural intensification, climate change and possible chemical exposure including pesticides such as neonicotinoids.</p><p>Neonicotinoids are one of the most widely used insecticides on the global market. Their systemic mechanisms allow for ease of application and relatively successful outcomes in controlling biting and sucking invertebrates, however neonicotinoids have been strongly associated with recent declines in non-target organisms. Many neonicotinoids come directly in contact with the soil, either through application as a seed coating or soil drench, or through spray drift and drip from foliar applications. Relatively little research has focussed on the movement, fate and interactions of these chemicals in UK soils under general field management strategies, although evidence suggests that the addition of soil bio-amendments, such as fertilisers, can influence the mechanisms behind pesticide mobility.</p><p>My study aims to quantify the effects of Acetamiprid-based pesticide mixtures on below-ground soil functions, through the analysis of their movement and behaviour in soils of contrasting organic matter contents. A secondary aim is to assess the impact of neonicotinoids on select non-target organisms.</p><p>We used <sup>14</sup>C labelled Acetamiprid to track the behaviour of the mixtures compared to the pure active ingredient. Previous research has only used the pure active ingredient, however this isn’t representative of true field scenarios. These spiked pesticides were added to soils of contrasting organic matter content collected from a long-term experiment at Woburn Experimental Farm, Rothamsted Research. We assessed the behaviour of these mixtures across a range of leaching, sorption and mineralisation experiments.</p><p>The mineralisation of all mixtures was found to be comparatively slow, with <23% of any given chemical/SOM combination being mineralised over the 60 day experimental period. The highest mineralisation rates were in samples with the highest SOM levels. The preliminary leaching data found that >80% of each chemical was recovered from the soil during the experiment. This, combined with low sorption and mineralisation rates, suggests that neonicotinoids are highly persistent within the environment.</p><p>Ongoing work is being conducted to investigate the knock-on impacts and biological implications of acetamiprid use under true field conditions.</p>


2020 ◽  
Vol 3 (1) ◽  
pp. 49-59
Author(s):  
Benni ◽  
Sofyan Husein Siregar ◽  
Irvina Nurachmi

The aim of this study is to determine the water quality, the particle size (mm) and the organic matter content sediment, the type and abundance of epipelic diatoms, and  the effect of particle size and organic matter content of the sediment on the abundance of epipelic diatoms at Bayur Bay Waters. This study was conducted in June - July 2019. The survey method was applied in this study and sampling location determine by purposive sampling. The resullt of measurement of water quality parameter ranged salinity 29 ‰ - 34 ‰, pH 7-8, current speed of 0,10 m/s – 0,53 m/s, temperature 30,330C - 31,670C. The sediment types are grouped into four types, namely gravel, sandy gravel, gravelly sand, and sand. The average of particle size (Mz) ranged -1,37 Ø - 0,80 Ø. The organic matter on sediment ranged 2,46% -6,36%. Eleven species of epipelic diatoms was recorded namely Amphora sp, Cocconeis sp, Diploineis sp, Halamphora sp, Melosira sp, Navicula sp, Nitzschia sp, Pinnularia sp, Stephanodiscus sp, Isthmia sp and Synedra sp. The average value of abundance range 2.836 – 10.812 ind/cm2. Epipelik diatom abundance was not significantly different between the stations. The effect of sediment particle size on the abundance of epipelic diatoms by 34,37%. The effect of content of organic matter sediment on abundance of epipelic diatoms in Bayur Bay Waters by 51,78%.


Author(s):  
Florent Biduaya Mukeba ◽  
Myriam Mukadi Ngondo ◽  
Nazaire Kabemba Kadima ◽  
Prince Bofati Ilonga ◽  
Patrick Kayembe Bibasuya ◽  
...  

Aim: The aim of this study was to compare the texture, mineral element and heavy metal content of the soil under the litter of different selected species in relation to the plan of their pedogenesis. Methods: The granulometric analysis of the various samples based on laser diffraction, measurements of Total Nitrogen and Total Organic Carbon were performed using the Elemental Analyzer, the Organic Matter content is estimated by the loss of ignition method using a Salvis furnace, In order to estimate the CaCO3 content. The same samples were heated in the oven at 1000°C for 60 minutes and reweighed. The carbonate content is estimated by the loss in mass during this second firing, multiplied by 2.274 which is the molecular weight ratio between CaCO3 and CO2. The heavy metal and mineral composition was evaluated by ICP-AES and AAS. Results: The granulometric analyses show a sandy texture, according to the FAO classification. The organic matter content thus observed in the soils under the litter of these four species did not show any significant difference. The concentration of major mineral elements recorded in soils under the litter of Blighia welwitchii, Oncoba welwitschii, Zanthoxylum gilletii and Harungana madagascariensis did not show any significant difference. However, potassium, phosphorus, and magnesium have a high concentration compared to calcium and sodium. This study showed that the levels of cadmium, lead, arsenic and aluminum in the various samples of litter soils of all plant species including nickel for B. welwitschii are above the standards set by the Canadian Council of Ministers of the Environment for soil quality. Pollution factors for aluminum are the highest. This indicates that aluminum is the most polluting metal. The low pollution factors for lead and nickel are due to the low fixation of these metals by soils. Conclusions: Our study took place in the Luki Biosphere reserve and showed that the different soils under litter are polluted by very toxic and persistent heavy metals such as cadmium, lead, aluminum, arsenic and nickel. This study has revealed new aspects of heavy metal pollution. This pollution represents a serious threat to the environment in general and to humans in particular through the food chain.


2020 ◽  
Vol 32 ◽  
Author(s):  
Gustavo Ruschel Lopes ◽  
Hugo Mendes de Oliveira ◽  
Gabriel Fernandes Alves de Jesus ◽  
Maurício Laterça Martins ◽  
Carlos Henrique Araújo de Miranda Gomes ◽  
...  

Abstract: Aim The increment of decomposition of organic matter in sediment samples from Nile tilapia farms was evaluated with the introduction of Bacillus subtilis and B. licheniformis bacteria. Methods Sediment samples placed in 18L plastic boxes received single dose inoculum with the following concentrations: 1.21 x 106 CFU g-1 (equivalent to 75 g ha-1), 2.41 x 106 CFU g-1 (equivalent to 150 g ha-1), 4.82 x 106 CFU g-1 (equivalent to 300 g ha-1) and 1.61 x 107 CFU g-1 (equivalent to 1000 g ha-1), in addition to a control treatment with saline solution only. Organic matter content, total organic carbon (TOC) and oxidizable (OOC), total nitrogen (TN), ratios (TOC: N and OOC: N), clay content, pH in water, Shoemaker, McLean, Pratt index (SMP Index), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) contents, potential acidity (H + Al), cation exchange capacity (CEC) at pH 7.0, base saturation (V) and sum of bases (S). Results The values of OM showed significant difference, between the lowest values (treatments 75, 150 and 300 g ha-1) and the highest value, (control treatment). TOC, OOC, NT and their relationships (TOC: N and OOC: N) showed significant differences between the mean values of the control treatment and the other treatments. Conclusions The addition of Bacillus subtilis and B. licheniformis bacteria increased the decomposition rate of organic matter in sediments samples from Nile tilapia farms.


KIMIKA ◽  
2016 ◽  
Vol 27 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Amstrong Calinawan ◽  
Concepcion S. Mendoza ◽  
Leonila Adarna

Pesticides pose a threat to the environment and eventually human health. Extent of contamination of pesticides can be determined and monitored by analysis of pesticide residue in surface water, sediments, soil, and biota. Samples were collected from Manlapay, Barangay Mantalongon in Dalaguete, reportedly the vegetable basket of Cebu, from October to November 2013. Concentration of the pesticide deltamethrin was determined by Gas Chromatography-Electron Capture Detector along with organic matter content (OM), potassium (K) and cation exchange capacity (CEC) using standard methods of analysis. Data showed that deltamethrin was found to be present in soil and cabbage and beyond detection limit in water. Inverse relationship was found between residue in cabbage and in soil confirming pesticide leaching as supported by rainfall data. Organic matter and cation exchange capacity in soil showed significant correlation to detected deltamethrin residue confirming that pyrethroids are strongly bound to organic matter and free exchangeable potassium ions. Deltamethrin residue in water does not show any correlation to any other parameters as it is beyond detection limit, probably due to volatilization and photodegradation of deltamethrin in water. Temperature variation does not show significant difference to deltamethrin residue in all three matrices. The detected deltamethrin residue concentrations in the cabbage (<0.001-0.029 ppm), soil samples (0.007-0.008 ppm) and water samples (<0.0005 ppm) were all below international guideline limits (ASEAN maximum level of 0.5 ppm deltamethrin in cabbage, EC ecologically accepted concentration of 1290 mg deltamethrin/kg soil, and a maximum limit of 0.0025 ppm deltamethrin according to Canadian water quality, respectively). Inspite of the low concentrations detected in cabbage, soil and water samples, an extensive pesticide monitoring on environmental samples within the area is advisable.  This will help the adoption of an efficient risk assessment strategy to inform appropriate interventions.


Agriculture ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 58 ◽  
Author(s):  
Hanieh Eghdami ◽  
Ghanimat Azhdari ◽  
Philippe Lebailly ◽  
Hossein Azadi

To understand and manage ecosystem complexity, it is important to determine the relationships between soil characteristics, human activities, and biodiversity. This study analyzes the relationships between vegetation, soil, and man-made damage with regards to land use change in the Fereydan region, Iran. Soil physical properties such as sand and silt content, clay, saturated soil’s moisture content, and gravel percentage as well as chemical properties such as lime content, pH, electro conductivity (EC), and organic matter content were measured. In order to trace these variables, the principle component analysis (PCA) was applied. The study area was divided into three states of conditions; i.e., good condition rangelands, poor condition rangelands, and abandoned rain-fed area. Based on the results there was a significant difference between species diversity in good condition rangelands compared with two other sites. The results further revealed that among soil chemical and physical characteristics, only soil organic matter had a significant difference between different rangeland sites. According to the results, the rangelands with good conditions had the highest amount of organic matter (1.43–1.50%) compared with two other studied rangelands (poor conditions: 1.02–1.09%; abandoned rain-fed: 1.2–1.46%). The most influential factor on the species diversity index was the distance to village parameter that revealed the important role of humans in degrading rangelands and reducing species diversity.


Author(s):  
O. A. Lipatnikova

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.


Author(s):  
Amita M Watkar ◽  

Soil, itself means Soul of Infinite Life. Soil is the naturally occurring unconsolidated or loose covering on the earth’s surface. Physical properties depend upon the amount, size, shape, arrangement, and mineral composition of soil particles. It also depends on the organic matter content and pore spaces. Chemical properties depend on the Inorganic and organic matter present in the soil. Soils are the essential components of the environment and foundation resources for nearly all types of land use, besides being the most important component of sustainable agriculture. Therefore, assessment of soil quality and its direction of change with time is an ideal and primary indicator of sustainable agricultural land management. Soil quality indicators refer to measurable soil attributes that influence the capacity of a soil to function, within the limits imposed by the ecosystem, to preserve biological productivity and environmental quality and promote plant, animal and human health. The present study is to assess these soil attributes such as physical and chemical properties season-wise.


2020 ◽  
Vol 117 (3) ◽  
pp. 351-365
Author(s):  
J. Pijlman ◽  
G. Holshof ◽  
W. van den Berg ◽  
G. H. Ros ◽  
J. W. Erisman ◽  
...  

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