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参考答案：
海水中磷酸根离子含量的测定。
常用磷钼黄法。当水样中加入硫酸－钼酸铵－酒石酸氧锑钾－抗坏血酸混合试剂后，水样中的无机磷酸盐与酸性钼酸铵先形成黄色磷钼黄络合物，在酒石酸氧锑钾作用下，磷钼黄很快被抗坏血酸还原成蓝色磷钼蓝化合物，在880纳米波长(或近似此波长滤光片)进行光度测定。
可采用流液式(Technicon)自动分析器分析。其自动分析线见上图。
海水活性磷酸盐测定
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【单选题】Organic FoodOrganic farming was among the fastest growing segments of U.S. agriculture during the 1990s. The value of retail. sales of organic food was estimated to be $16 billion in 2004. According t...
A.
As you can imagine, organic agricultural practices are quite distinct from those of "conventional" fanning.
B.
Organic farmers:
C.
feed soil and build soil matter with natural fertilizer to grow their crops use insect predators, mating disruption, traps and barriers to protect crops from pests and disease make use of crop rotation, mechanical tillage and hand-weeding, as well as cover crops, mulches, flame weeding and other management methods to control weed growth.As a last resort, organic farmers may apply certain botanical or other non-synthetic pesticides. Conventional farmers:,
D.
apply chemical fertilizers to the soil to grow their crops spray with insecticides to protect crops from pests and disease use synthetic herbicides to control weed growth.
E.
How Do I Know if a Food is Organic
F.
Look for the word "organic" on vegetables or pieces of fruit, or on the sign above the organic produce display. The word "organic" may also appear on packages of meat, cartons of milk or eggs, cheese and other single-ingredient foods. Foods labeled "100 percent organic" must contain only organic ingredients. Products containing at least 70 percent organic content can be labeled "made with organic ingredients". Those foods labeled simply "organic" must have at least 95 percent organic ingredients, by weight or fluid volume, excluding water and salt. Anyone who knowingly sells or labels a product "organic" that is not produced and handled in accordance with these regulations can face a civil penalty of up to $10,000.
G.
Foods grown and processed according to the federal standards will in most cases bear the seal "USDA Organic". As its use is voluntary, companies may choose not to display the seal.
H.
Why Should I Care if a Food is Organic According to the USDA, organic food production allows farmers to lower input costs, decrease reliance on nonrenewable resources, capture high-value markets and premium prices, and boost farm income. Organic agriculture also has many important environmental, benefits:
I.
It promotes sustainability by establishing an ecological balance to prevent soil fertility or pest problems. In the long run, organic farms tend to conserve energy and protect the environment by maintaining ecological harmony.
J.
It enhances biodiversity, or the presence of multiple plant and animal species. Having a highly diverse genetic pool becomes useful in the future when beneficial characteristics can be tapped.
.
Because organic agriculture utilizes practices such as crop rotations, inter-cropping, symbiotic associations, cover crops and minimum tillage, the length of time that the soil is exposed to erosive forces is decreased, which minimizes nutrient losses and boosts soil productivity. By not using synthetic fertilizers and pesticides, organic agriculture-reduces pollution of groundwater.
K.
Organic agriculture helps to minimize the greenhouse effect and global warming through its ability to keep carbon in the soil.
L.
Why is Organic Food So Expensive
M.
Prices tend to be higher for organic titan conventional products. As stated on the Web site of the Food and Agriculture Organization (FAO) of the United Nations (UN), certified organic products are generally, more expensive than their conventional counterparts because:
N.
The organic food supply is limited as compared to demand. Production costs for organic foods are typically higher because of greater labor input and because farmers don’t produce enough of a single product to lower the overall cost.
.
Post-harvest handling of relatively small quantities of organic foods results in higher costs because organic and conventional 0roduce must be separated for processing and transportation.
.
Marketing and the distribution chain for organic products are relatively inefficient, and costs are higher because of relatively small volumes.
.
The FAO also notes that as the demand for organic food and products increases, technological innovations and economies of scale should reduce costs of production, processing, distribution and marketing for organic produce.
.
Is Organic Food Better than Conventional Food
.
Organic and conventional food must meet the same quality and safety standards. Organic food differs from conventionally produced food simply in the way it is grown, handled, and processed. There is no scientific evidence to suggest that it is more nutritious or safer than conventional food. A recently published report indicates that organic food is less likely to contain pesticide residues than conventional food. Yet, according to the National Research Council, the traces of pesticides left on conventionally grown products are unlikely to cause an increased cancer risk. Also, if fruits and vegetables are properly washed, most of the chemicals can be removed. As for taste, that’s up to you to decide what you like best. In general, people tend to find that the fresher a food is, the better it tastes, regardless of how it was produced.
【单选题】造成我国近海海域海水富营养化程度不断加重的主要原因是( )。
A.
大量生活污水和富含有机物的工业废水被直接排入大海
B.
渔业捕捞的失控
C.
近海的石油开采
D.
近大陆架消化污染的能力比较差
相关题目：
【单选题】Organic FoodOrganic farming was among the fastest growing segments of U.S. agriculture during the 1990s. The value of retail. sales of organic food was estimated to be $16 billion in 2004. According t...
A.
As you can imagine, organic agricultural practices are quite distinct from those of "conventional" fanning.
B.
Organic farmers:
C.
feed soil and build soil matter with natural fertilizer to grow their crops use insect predators, mating disruption, traps and barriers to protect crops from pests and disease make use of crop rotation, mechanical tillage and hand-weeding, as well as cover crops, mulches, flame weeding and other management methods to control weed growth.As a last resort, organic farmers may apply certain botanical or other non-synthetic pesticides. Conventional farmers:,
D.
apply chemical fertilizers to the soil to grow their crops spray with insecticides to protect crops from pests and disease use synthetic herbicides to control weed growth.
E.
How Do I Know if a Food is Organic
F.
Look for the word "organic" on vegetables or pieces of fruit, or on the sign above the organic produce display. The word "organic" may also appear on packages of meat, cartons of milk or eggs, cheese and other single-ingredient foods. Foods labeled "100 percent organic" must contain only organic ingredients. Products containing at least 70 percent organic content can be labeled "made with organic ingredients". Those foods labeled simply "organic" must have at least 95 percent organic ingredients, by weight or fluid volume, excluding water and salt. Anyone who knowingly sells or labels a product "organic" that is not produced and handled in accordance with these regulations can face a civil penalty of up to $10,000.
G.
Foods grown and processed according to the federal standards will in most cases bear the seal "USDA Organic". As its use is voluntary, companies may choose not to display the seal.
H.
Why Should I Care if a Food is Organic According to the USDA, organic food production allows farmers to lower input costs, decrease reliance on nonrenewable resources, capture high-value markets and premium prices, and boost farm income. Organic agriculture also has many important environmental, benefits:
I.
It promotes sustainability by establishing an ecological balance to prevent soil fertility or pest problems. In the long run, organic farms tend to conserve energy and protect the environment by maintaining ecological harmony.
J.
It enhances biodiversity, or the presence of multiple plant and animal species. Having a highly diverse genetic pool becomes useful in the future when beneficial characteristics can be tapped.
.
Because organic agriculture utilizes practices such as crop rotations, inter-cropping, symbiotic associations, cover crops and minimum tillage, the length of time that the soil is exposed to erosive forces is decreased, which minimizes nutrient losses and boosts soil productivity. By not using synthetic fertilizers and pesticides, organic agriculture-reduces pollution of groundwater.
K.
Organic agriculture helps to minimize the greenhouse effect and global warming through its ability to keep carbon in the soil.
L.
Why is Organic Food So Expensive
M.
Prices tend to be higher for organic titan conventional products. As stated on the Web site of the Food and Agriculture Organization (FAO) of the United Nations (UN), certified organic products are generally, more expensive than their conventional counterparts because:
N.
The organic food supply is limited as compared to demand. Production costs for organic foods are typically higher because of greater labor input and because farmers don’t produce enough of a single product to lower the overall cost.
.
Post-harvest handling of relatively small quantities of organic foods results in higher costs because organic and conventional 0roduce must be separated for processing and transportation.
.
Marketing and the distribution chain for organic products are relatively inefficient, and costs are higher because of relatively small volumes.
.
The FAO also notes that as the demand for organic food and products increases, technological innovations and economies of scale should reduce costs of production, processing, distribution and marketing for organic produce.
.
Is Organic Food Better than Conventional Food
.
Organic and conventional food must meet the same quality and safety standards. Organic food differs from conventionally produced food simply in the way it is grown, handled, and processed. There is no scientific evidence to suggest that it is more nutritious or safer than conventional food. A recently published report indicates that organic food is less likely to contain pesticide residues than conventional food. Yet, according to the National Research Council, the traces of pesticides left on conventionally grown products are unlikely to cause an increased cancer risk. Also, if fruits and vegetables are properly washed, most of the chemicals can be removed. As for taste, that’s up to you to decide what you like best. In general, people tend to find that the fresher a food is, the better it tastes, regardless of how it was produced.
【单选题】造成我国近海海域海水富营养化程度不断加重的主要原因是( )。
A.
大量生活污水和富含有机物的工业废水被直接排入大海
B.
渔业捕捞的失控
C.
近海的石油开采
D.
近大陆架消化污染的能力比较差
参考解析：
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