Chapter 39 fourth quarter

After bidding farewell to Zheng Chunshu and Chen San, Yutong and Hu Shiyuan immediately returned to Guangdong by car.After returning to school, Yutong conducted a comprehensive compositional analysis of the collected samples non-stop. The test showed that the concentration of cadmium contained in the drinking water of Lengshuizhuang and the drinking water of Reshui Village were respectively 0.042 and 0.038 mg/L. Although the difference is not big, they both far exceed the national standard 0.01 mg/L. Based on this data analysis, the water quality of Reshui Village and Lengshuizhuang Village is also polluted by cadmium. Therefore, long-term drinking of this water quality will damage human health.But the facts show that only the villagers of Lengshuizhuang are affected, so where is the problem?

The drinking water of Lengshui Village and Hot Water Village come from the same Lengshui River upstream, but the Lengshui River diverges when it reaches the downstream.The branch entrance is located half a mile away from the mining area.Judging from the source, the water quality components of the two should be similar.However, from the various data detected, Yutong quickly noticed the difference in the concentration of zinc in the water quality of the two.The water quality of Lengshuizhuang has a zinc content of 0.6 mg/L, while the water quality of Rehui Village has a zinc content of as high as 1.5 mg/L.Through the analysis of the soil composition and the elements contained in the plants growing in the two places, Yutong quickly found the reason.It turns out that the soil properties of Reshui Village and Lengshui Village have different characteristics.

The soil contaminated by copper-zinc tailings can be divided into two types.The soil in the direction of Lengshuizhuang is slightly alkaline, and it is easy to grow wild plants that can enrich metal ions. For example, weeds can enrich zinc, manganese, copper, and iron ions, barnyardgrass can enrich zinc, manganese ions, wolfberry Grass (which can also grow in an acidic environment) is rich in zinc and manganese ions.The soil in the direction of Reshui Village is slightly acidic, and hardly any plants grow there.It is precisely because the plants growing in the polluted area of ​​Lengshuizhuang are enriched with inorganic zinc, which reduces the zinc content brought into the water from the soil.The hot water village is different.Most of the zinc in the soil entered the nearby river as non-growing plants held up the zinc.In this way, the concentration of zinc in the drinking water of villagers in the two regions differs greatly.

An idea suddenly jumped into Yutong's mind, could high concentration of zinc suppress the toxicity of cadmium? Yutong immediately consulted a large number of domestic and foreign materials on the Internet, and gradually came to a clear idea. Comprehensive data show that cadmium sneaks into the body, can inhibit the activity and growth of many enzymes, reduce protein and fat content, cause hypertension and vascular diseases, accumulate in the kidney, liver and reproductive organs, and cause damage to tissues and nerves.Usually there are two ways to prevent cadmium poisoning.First, to reduce the cadmium value, intake of a certain amount of iodine will combine with it to form a non-toxic compound, which is excreted from the body, thereby reducing the accumulation of cadmium in the human body.Second, increase the intake of zinc and choose foods containing zinc (of course, too much is not good, and it is difficult to find suitable high-zinc foods). As long as the proper ratio is controlled, the effect of preventing cadmium poisoning can also be achieved.Safety experiments show that the ratio of zinc to cadmium in the diet is greater than 40, which can basically ensure the health of humans and animals.In the case of the same concentration of cadmium pollution, the food with a higher ratio of zinc to cadmium tends to be less likely to be poisoned.

Undoubtedly, the presence of zinc can indeed eliminate the toxicity of cadmium to a certain extent.That is to say, drinking water with a certain concentration of cadmium also almost offsets the toxic effect of cadmium due to the higher zinc content in the drinking water in the hot water village.Therefore, the villagers in Reshui Village suffered much less damage from cadmium than those in Lengshui Village. From this, Yutong also thought about the problem of mentor poisoning. If someone drank cadmium-containing drinking water with him every day, and the other party secretly took these precautionary measures, he would be the ultimate victim, and the other party might not be affected.

In this way, Lin Jiemin became the biggest suspect again.However, how to prove that Lin Jiemin was poisoned with cadmium?Sampling and analysis of the water that the tutor and she drank together was something that the tutor had thought of earlier. The results of the inspection showed that the water in Lin Jiemin's house was safe and reliable, without any harmful substances exceeding the standard. In any case, for the safety of the tutor, we must try to prevent the tutor from interacting with Lin Jiemin. But he searched all over the department, but he didn't see the tutor, and he didn't see a call back when he called the tutor's mobile phone.A bad premonition welled up in Yutong's heart.

Yutong rushed to Professor Hu's house immediately, and it happened that Hu Lingxue was at home eavesdropping on the conversation between Hu Ping and Lin Jiemin. "Why is your face so red?" Yutong noticed that Hu Lingxue's expression was abnormal, so he asked. "Where is your father?" "Well... to..." Hu Lingxue hesitated and couldn't speak, so she lied, "I'm on a business trip." "Are you lying? The tutor has no plans to go out recently. If he really wants to go out, he will say hello in the department and make arrangements before going out. Did he go to Aunt Lin?"

Yutong sensed Hu Lingxue's abnormality, and hurriedly asked. "Yes, he went to Lin Jiemin's." Hu Lingxue felt that she could no longer hide it from Yutong. "The relationship between the old man and Aunt Lin is extremely abnormal." "Why do you have such an idea?" Yutong vaguely felt that Hu Lingxue was hiding something on her mind. "I suspect that my mother's sudden death has something to do with her." Yutong couldn't help being taken aback.