They are called
a. sunspots
Answer:
An oil spill, fertilizer run off, and another thing i could think of is a flood hope this helped :)
Explanation:
Ductus Arteriosus is a blood vessel normally present in fetuses during development. The blood vessel is designed to bypass the pulmonary artery and brings blood to the Descending Aorta, as the fetus cannot breath through the lung (being as they are fluid filled). This is normally not a problem because oxygenated blood comes from the mother's blood supply.
Patent Ductus Arteriosus, is what happens when that vessel does not close. While not as dangerous as other congenital defects. However, because there is still a bypass, blood that normally need to be oxygenated by going through the pulmonary arteries to the lungs, can be diverted and placed into the blood stream without vital oxygen. This condition may eventually lead to CHF (congestive Heart Failure) and Pulmonary Hypertension if not treated.
Hello!
The amount of water in a river varies for each particular area. Whether the area has been receiving rainfall or a drought.
Seasons also play a role; if it's Spring, you may receive more rainfall and have a higher water levels. If it's Summer, you may experience a drought, causing lower water levels.
Although that was not very much information, I thought I'd provide a small bit of information. Hope it helps. :)
