If the PCB concentration in Lake Michigan averaged 0.47 ppt in 1991, what will it be in 2005? *3 part question*

182. The PCB concentration in Lake Michigan is declining according to a first-order rate law having a rate constant of 0.079 per year. If the PCB concentration in Lake Michigan averaged 0.47 ppt in 1991, what will it be in 2005? In what year will the concentration fall to 0.10 ppt? What is the half-life period of PCBs in this lake? (Answer first with PCB concentration of the year 2005, then the year the concentration will be 0.10 ppt, and lastly the half-life). ***I will be out of town from Friday until Sunday night (with no computer access). If I don't pick up the response during that time, don't think I'm not planning to pay!! I will!!

Not for OTA 102922 - Equil. ratios; pH; pE values, etc.

Deduce the equilibrium ratio of NH4+ to NO3- at a pH of 4.0 for aerobic water having a pE value of +9.0 and for anaerobic water for which the pE value is -7.0. (Provide the aerobic answer the anaerobic answer.) This is not for OTA 102922 as he has already tried this question once.

Leachate from landfills- example and health effects

I am trying to understand the effects of leachate from landfills and its effects on groundwater, and since I am in environmental health- its effects on the human health. Can anyone help explain these concepts to me? Also, does anyone know of any examples where leachate became a problem? Why is it important to study?

Landfill Leachate- Groundwater- Proof read

I am just trying to summarize what Landfill Leachate does to groundwater, and am hoping you can read this over to see if it makes sense and flows. Also, am I missing anything extremely important? I appreciate your expertise in reading this over.. It is extremely important to me. The parts I am most concerned with are the highlighted areas. I am not sure if they make sense. I'd apprecitae if you could alter it to make sense. Plus can anyone think of a good title on a paper that discusses: "This paper will outline the importance of landfill leachate by defining what leachate is and its effects on groundwater and its concern on public health through an example of a leachate landfill (... click for more

Problem involving dissolving of limestone

In a location in Florida, water seeping into the ground contains 50 times as much carbon dioxide as rainwater. This ground water passes through a limestone deposit and ultimately into an underground spring. The spring has a flow rate of 2500 liters per second. How much limestone (CaCO3) in metric tons will be dissolved in this system in 1000 years?