Human intervention on fluvial systems : dams and barrages
Answers
Answer:
The environmental impact ca nbe split up in 3 categories:
Human damage
Eco system damage
Consumption of natural sources
The pollution degree depends on the amount and concentration of emissions, so the disperion from the chimney or stack.
More data is needed to know the pollution impact of a stack. The background pollution (highways, cars, houses, ...), hourly metreological data, detailed geographical data and other pollution sources. Afther all this data is collected the simulation can be done. Air pollution simulation software developed by universities is available for free:
AUSTAL2000
CALPUFF
Incinerators have a continious emission monitoring system and calculate the half hourly average value and the daily average value.
Here we discuss:
how the chemical formation is, and at which temperature,
what is the most popular pollution source,
what are the health effects,
the adviced values for secure levels, if they exist.
Generation, source and heath effects
Chemical formation
Dioxines are formed between 2 benzene rings, with one or two O-atoms and a Cl-atom. The connection between the 2 benzene rings are with the O-atom.
Connection with 1 O-atom: PCDF (polychloredibenzofurane)
Connection with 2 O-atoms: PCDD (polychloredibenzodioxines)
If the temperature is high enough, min. 850 C, the the dioxines are “broken”-burned. But dioxines may again be generated in the stack when the flue gasses have again 200-400 C.
Pollution source
Dioxines and furanes are mainly generated by heat systems and open fires. Dioxines are also created by waste incineration, the non-ferro industry and by domestic heat systems (espacially wood furnace). The dioxines arrive in the human body mainly by the food chain. Mosly: fat fish, milk, fat of meat, product with animal fat like sauses, cakes and desserts.
Most important health effects
Dioxines are causing cancer, may have an effect on the gown and development of the human body. The may disturb the functioning of hormones and the immunity system of the human body.
Human biomonitoring results (table 1) in different geographical area’s of environmental assessment (in Belgium) shows people have always a certain level of dioxines and furanes in there body. There is no significant different level in different area’s of environmental assessment.
table 1 : Dioxines and furanes (pg Calux TEQ/g fat) in human bodies
City aglomeration Agricultural zone Fruit tree zone Domestic waste incinerator zone
21,2 21,0 21,6 20,7
table 1 : Dioxines and furanes (pg Calux TEQ/g fat) in human bodies
Some adviced values for secure levels
There is no adviced value for secure levels. If the concentration of dioxines in the human body is low, the lower the change on cancer and the better.
Chemical formation
Formation PCB’s are formed by the chemical reaction of a free Cl-atom with benzeen rings. The temperature need to be between 250 °C and 400 °C.
Pollution sources
PCB's have 209 chemical derivations. PCB138, PCB153, PCB180 are the most frequent. PCB's where produced and used by the industry, due to there thermical excellent character. For example in transfo's of refrigerators. Today they may not be produced and used anymore. But they are still in our environment due to leakages and incineration of those PCB containing machines. PCB's are accumulating in fat of fish, fat of meat, milk, etc.
Most important health effects
PCB's may cause a lower weight of natal babies, disturb the functioning of the thyroid gland and may cause a slow development of intelligents. PCB's may disturb the functioning of hormones and the immunity system of the human body.
Pollution sources
One of the most important pollution sources of cadmium is cigarette smoke. In the past mostly non-ferro industry and incinerators where emissioning cadmium. Also some construction materials where containing cadmium. Today cadmium is present in salads, spinage and seldom. Also in meat of animals which are living in polluted area's.
Food and cigarette smoke are the largest potential sources of cadmium exposure for members of the general population. The average person ingests about 30 micrograms (u
Most important health effects
Exposure of lead before the birth or to young children may have a negative influence on the inteligent development, control of small movements or concentrati that the health is not in danger when the values are l
Most important health effects
The smaller the size of the particles, the more dangero
Explanation:
some adviced values of secure levels the would world Health:dams and barrages