North Wales Dee Estuary Field and Laboratory Activity

Determination of Metal Concentrations in Sediment and Plant Samples from Dee Estuary, in Order to Assess the Level of Environmental Risk Related to Environmental Pollution.
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Date of Submission
Table of Contents TOC \o "1-3" \h \z \u List of Tables PAGEREF _Toc419057104 \h 3List of Figures PAGEREF _Toc419057105 \h 4Introduction PAGEREF _Toc419057106 \h 5Objectives PAGEREF _Toc419057107 \h 6The Dee Estuary PAGEREF _Toc419057108 \h 7Field and Laboratory Methods PAGEREF _Toc419057109 \h 8Laboratory Session 1 PAGEREF _Toc419057110 \h 9Laboratory Session 2 PAGEREF _Toc419057111 \h 10Results PAGEREF _Toc419057112 \h 11Discussion PAGEREF _Toc419057113 \h 14Conclusion PAGEREF _Toc419057114 \h 17References PAGEREF _Toc419057115 \h 19
List of Tables
TOC \h \z \c "Table" Table 1: An Anova table for differences between sites and metal concentrations PAGEREF _Toc419056942 \h 9
Table 2: An Anova table for differences between Sample types and metal concentrations PAGEREF _Toc419056943 \h 10
Table 3: Descriptive Analysis for the clusters obtained from clustering metal concentrations based on site names PAGEREF _Toc419056944 \h 12
Table 4: Results from a two-sample t-test showing the difference in metal concentrations between sediment cores PAGEREF _Toc419056945 \h 12
Table 5: An Anova table for the difference between sediment cores and metal concentrations PAGEREF _Toc419056946 \h 13
List of Figures
TOC \h \z \c "Figure" Figure 1: The Dee Estuary: Retrieved from Sefton (2013). PAGEREF _Toc419056966 \h 7
Figure 2: Results obtained from the correlational analysis between different metal concentrations PAGEREF _Toc419056967 \h 12
Introduction
Industrialization, globalization, social, and agricultural activities, are known to cause environmental pollution. Such activities always lead to corruption of the ecosystem, which is likely to cost the lives of future generations because pollution has an effect on human health. It is also critical that pollution not only affects humans, but also other organisms because they end up producing food from intoxicated raw materials, or ingest food that has been produced from intoxicated raw materials (Acquavita et al., 2012). It follows that pollution affects the entire food chain of an ecosystem because organisms of an ecosystem depend on each other for existence. Consequently, it is important for scholars and practitioners in ecology to understand how human activities contribute to pollution because such an understanding will help them control the rate of pollution in the topical society (Modoi et al., 2014). This will in turn reduce pollution and safeguard the environment for the benefit of future generations.
It is critical that the current society is polluting the environment at a higher rate than previous generations because of industrialization. As evidence, the contemporary society is full of industries that emit chemicals into the air and water bodies. It is notable that chemicals emitted into the air by the same industries are often washed down into water bodies by rain. Simply put, water bodies such as rivers, lakes, seas, and oceans are at the receiving end of pollution (Njagi, 2009). It is also vital to highlight that modern agricultural activities contribute to pollution because of the use of chemicals such as fertilizers, pesticides, and insecticides to increase production. The chemicals contain heavy metal compounds, which are also washed into rivers when it rains. This implies that ecological researchers should focus on the effect of pollution on water bodies in order to limit the amount of toxic substances into the food chain (Nordberg, 2014).
It is evident that large fractions of heavy metal compounds from the environment always end up in water bodies. Crucial to the discussion is the fact that the chemicals arrive in large water bodies after being transported from human settlements through rivers. This implies that ecologists can examine the amount of heavy chemicals in most water bodies by studying estuaries, distributaries, and deltas (U.S. Environmental Protection Agency, 2012). However, this paper will focus on only one estuary in order to increase the rigor of the study. This owes to the reality that estuaries are not only entry points of rivers into large water bodies, but are also focal points for several human activities. Additionally, estuaries are key areas for sediment transfer between marine and fluvial systems. Therefore, they are perfect sites for data collection (SHARMA, 2015). This paper focuses on the determination of metal concentrations in sediment and plant samples from Dee estuary, in order to assess the level of environmental risk related to environmental pollution.
Objectives
It is notable that the researcher had a main objective of determining metal concentrations in sediment and plant samples from Dee estuary, in order to assess the level of environmental risk related to environmental pollution. In order to achieve the main objective, the researcher relied on six objectives, which acted as a guideline for the entire research. Additionally, each objective was accompanied by a null and an alternative hypothesis as listed below.
1 To identify if there is a statistically significant difference in metal concentrations between sampling sites
H0: There is no statistically significant difference in metal concentrations between sampling sites.
H1: There is a statistically significant difference in metal concentrations between sampling sites.
2 To determine if there is a statistically significant difference in metal concentrations between sample types.
H0: There is no statistically significant difference in metal concentrations between sample types.
H1: There is a statistically significant difference in metal concentrations between sample types.
3 To identify whether certain metals behave in a similar way to other metals
H0: Certain metals do not behave in similar ways to other metals
H1: Certain metals behave in similar ways to other metals
4 To identify whether certain metals and sampling sites cluster together
H0: Certain metals and sampling sites do not cluster together
H1: Certain metals and sampling sites do not cluster together
5 To establish if there is any statistically significant difference within sediment cores
H0: There is no statistically significant difference within sediment cores
H1: There is no statistically significant difference within sediment cores
6 To identify whether there is a statistically significant difference between sediment cores
H0: There is no statistically significant difference between sediment cores
H1: There is a statistically significant difference between sediment cores
The Dee Estuary
The Dee Estuary extends from its mouth, which is defined by a line between Hilbre Point and Point of Ayr Spit to the usual tidal limit of Chester Weir (Sefton 2013). It is a glacially over-deepened valley, which developed as a result of geological structural controls. It is thirty Km long and has maximum width of 8.5 Km at the mouth. The western side of the estuary has a small spit called the Point of Ayr while the eastern has a spit called Hilbre Point. It is critical that Dee is an important estuary in Europe because it has a high population of wildfowl and waders. The estuary also supports an array of human activity such as fishing and trade. Human activities on the estuary are industrialized, which is evidenced by the presence of industries such paper mills, Tata steel, and a power station. Therefore, there is a need to determine the concentration of metal elements on the estuary, not only because it drains material into the sea, but also because of the human activities supported by the estuary.
Figure 1: The Dee Estuary: Retrieved from Sefton (2013).
Field and Laboratory Methods
The estuary was divided into four field sites, which include Prestatyn on the eastern end, Talacre on the Point of Ayr, Holywell next to the recycling centre, and Flint next to the castle. Groups of five individuals were formed to collect samples from four sites. The first sample was the surface sediment, which was collected after considering that different grain sizes and organic content influence the metal content of sediments. This owes to the reality that such elements affect the absorption rate or chemical bonding, which in turn influences the amount of metal concentration. Another sample collected comprised of seaweeds, which include Fucus Vesiculosus and the Cladophora spp. Samples of salt marsh vegetation were also collected. Specifically, the vegetation included Holywell and Flint. Ultimately, samples of sediment cores, which comprised of Flint and Holywell, were also collected from sediments that were cohesive enough to support coring.
Laboratory Session 1
The following materials were used for the first laboratory method.
* Pestle and mortar
* Plastic spatula
* Dried samples collected from the Dee estuary
* Tube racks and 50ml centrifuge tubes
* Concentrated nitric acid
* White paper towel
* Deionized water
* Ultrasonic bath
* Access to an analytical balance
* A small beaker for balancing 50 ml centrifuge tubes on the analytical balance
One 50 ml centrifuge tube for each vegetation and sediment sample collected from the field trip were labeled. The pestle and mortar was washed thoroughly using deionized water and dried with a white paper towel. The vegetation samples and dried sediment were then homogenized and ground using a pestle and mortar.0.5 grams of the grounded material was weighed into separate 5 ml tubes using a plastic spatula and an analytical balance. The tubes were then taken to one of the two fume cupboards before concentrated nitric acid was added to each of the samples using a bottle dispensing pipette. Every group also prepared a one procedural blank by adding 5 ml of concentrated nitric acid to an empty 50 ml centrifuge tube and labeled appropriately. The same tubes were placed on ultrasonic bath for ten minutes to agitate the samples such that all of the particles are in contact with concentrated nitric acid. The 50 ml centrifuge tubes containing the concentrated nitric acid were placed in identified location and left for seven days for cold nitric acid extraction of metals.
Laboratory Session 2
The following materials were used for the second laboratory session.
* 50 ml centrifuge tubes containing homogenized and ground samples and 5 ml of concentrated nitric acid
* Buchner filtration apparatus
* ICP-OES auto sampler tubes
* 50 ml volumetric flasks
* Deionized water and dispensing bottles
ICP-OES auto sampler tubes were labeled with labels that were matching the Dee estuary samples. 50 ml centrifuge tubes containing the samples and 5 ml of concentrated nitric acid were taken to the fume chamber where deionized water was added into the tubes up to the 20 ml mark. The sample tubes now containing 25ml of diluted nitric acid were taken back to the bench area where a Buchner filtration funnel was used to filter the sample. The filtrate was then poured into a 50 ml volumetric flask using a funnel. Deionized water was added to the 50 ml volumetric flask to ensure the solution reached the 50 ml mark. The cap was held tightly in order to mix the contents of the flask thoroughly. The labeled ICP-OES sample tubes were filled with diluted nitric acid extract solutions, placed on the rack, and submitted for metal determination. The data was recorded on a master Excel file and analyzed using the Statistical Package for Social Sciences (SPSS).
Results
Are there statistically significant differences between sites? In order to identify whether there is a statistically significant difference between the sites and mental concentration, a one way ANOVA was used for analysis (Polit et al., 2014), (Guasch et al., 2012), and (Miller et al., 2007). It is critical that metal concentrations were treated as the independent variable while sites were treated as dependent variables. Table 1 below shows the results obtained from the analysis (for some of the metals).
ANOVA

 

F

Sig.

Aluminium

62.477

0.001

Arsenic

22.731

0.001

Cadmium

38.639

0.001

Cobalt

41.726

0.001

Chromium

91.945

0.001

Table SEQ Table \* ARABIC 1: An Anova table displaying the results for differences between sites and metal concentrations
Are there statistically significant differences between sample types? The same test and conditions used above were used to check whether there is a statistically significant difference between sample types and metal concentrations. Table 2 below displays the results obtained after running a one way Anova in SPSS.
ANOVA

 

F

Sig.

Aluminium

57.912

0.001

Arsenic

23.433

0.001

Cadmium

26.447

0.001

Mercury

17.546

0.001

Nickel

50.105

...