ES5602 – Environmental Pollution and Monitoring (EPM) Coursework – Topic 10
Environmental Monitoring of Chemical Pollutants in River Systems
Background:
Copper (Cu) is a metal which is malleable, ductile, and an extremely good conductor of both heat and electricity. Copper has low chemical reactivity. In moist air it slowly forms a greenish surface film called patina; this coating protects the metal from further attack. Most copper is used for electrical equipment (60%); construction, such as roofing and plumbing (20%); industrial machinery, such as heat exchangers (15%) and alloys (5%). The main copper alloys are bronze and brass. Copper can be released into the environment by both natural sources and human activities. Examples of natural sources are wind-blown dust, decaying vegetation, forest fires and sea spray. A few examples of human activities that contribute to copper release are mining, metal production, wood production and phosphate fertilizer production. Because copper is released both naturally and through human activity it is very widespread in the environment. Copper is often found near mines, industrial settings, landfills and waste disposals.
Scenario and Tasks: Data analysis
An electroplating plant located on a river is releasing a wastewater stream containing copper into the river. The table below contains copper concentrations (mg/L) found in river water samples collected from three sampling sites located near the metal plating facility. Sampling sites 1 and 2 denote upgradient sites while sampling site 3 is a single downgradient site suspected of being contaminated with copper. Use an appropriate statistical test to confirm that the river is being contaminated with copper.
Month
Upgradient
Downgradient
Site 1
Site 2
Site 3
1
4.2
5.2
9.4
2
5.8
6.4
10.1
3
11.3
11.3
14.5
4
7.0
11.5
16.1
5
7.0
10.1
21.5
6
8.2
9.7
17.6
The decision makers have set the type I error rate () at the 5% level, if the difference between the mean concentrations is 0.0 mg/L, and the type II error rate () at the 20% level, if the difference between the mean concentrations is 4.0 mg/L. Is there any evidence from the data that the concentration of copper is increasing at the confidence level of 95%?
• Devise and execute a monitoring strategy to analyse river water samples containing copper.
• Explain which analytical techniques can be used for the analysis of copper present in river water samples.
• Highlight the environmental and human health effects of copper.
• Suggest some treatment systems that can be used to remove copper from wastewater originating from a point source.
• Use descriptive statistics to describe the basic features of the data.
• Use a goodness-of-fit (GOF) test to evaluate if the data follow a normal distribution.
• Use an appropriate homogeneity of variances (HOV) test to determine if the variances of the sites are equal at the 95% confidence level.
Further Information: Environmental monitoring and modelling
Suppose you select independent random samples of size n1=n2 from a downgradient site (DG) and a upgradient site (UG) with known standard deviations (sdS = 2.2 & sdR = 3.6; pooled sd = 2.9). You want to test the null hypothesis that
µDG µUG against the alternative hypothesis that µDG < µUG. Find the required number of samples if = 0.05 and = 0.20.
A metal plating plant located on a river has an accident in which 120 kg of copper plating solution is released. The river drops an average of 2.5 m over a distance of 1 km. From the data given below, calculate the concentration of copper at a distance of 8 km after 2 hours from the time of the spill. Depth = 1.97 m; Width = 20 m; Velocity = 1.1 m/sec; Half-life = 3,000 years.
Tips：EDA; GOF; HOV test; parametric or nonparametric test; sample size; modelling