**2.2 Chemical analysis**

Standard NIST 1568a (Rice Flour) and about 500 mg material from each part of vetiver were placed into 100-ml digesting Teflon bottles. The materials were digested at 5 ml 16 M HNO3 and 1 ml 12 M HClO4 (5:1, v/v) during 1 day in hotplate 180°C.


### **Table 2.**

*Comparison of analytical results (mg/kg) for NIST 1568a (Rice flour).*

After evaporation, the solutions were added 0.03 ml 18 M H2SO4 and kept at 180°C during 24 hours. The digested samples were brought to a volume 30 ml 2% HNO3.

**Table 1** shows the results of concentrations of Al, Cu, Pb, Sn, and Zn in the digesting solutions, and the standard deviation (SD) is calculated from three times analysis (n = 3). It was determined by ICP MS in Korea Basic Science Institute (KBSI).

A standard reference material NIST 1568a (Rice Flour) was used to verify the accuracy of metal determination by ICP-MS, and the recovery rates of Cu, Zn, Cd, and Pb elements were very high within 90.7 ÷ 104.8% 5.0% (**Table 2**). The analytical results are acceptable.

*Chemical fingerprint:* By the author [19], to overcome the problems of variety of data over scale, we use the type of data interpretation in the form of chemical fingerprints with normalization to "reference plant" for discussion of heavy metals Al, Cu, Pb, Sn, and Zn (**Figure 3**). The "reference plant" was set to zero (normalization), and the data of trace metals Al, Cu, Pb, Sn, and Zn concentrations of parts of vetiver will be given as deviations from the value of "reference plant."

### **3. Results and discussion**

### **3.1 Aluminum (Al)**

Follow [20]: The Al in the plants is controlling colloidal properties in the cell, possible activation of some dehydrogenases and oxydases. But the high availability of Al in nutrient soil is one of the limiting factors in the production of most field crops [21– 23]. The physiological mechanisms of Al toxicity are still debate, but Al excess in plants is likely to interfere with cell division and with properties of protoplasm and cell walls [22]. The content of Al in plants varies greatly, depending on soil and plant factors.

*Chemical fingerprint:* In **Figure 4** is shown the relative deviation of Al from "reference plant." The concentration of Al in root materials is very high and much more than "reference plant" about 17- up to 30-folds (**Table 3**; **Figure 3**). The deviation in the lower parts (meristematic regions M and low parts of shoots S1) was less than zero, but upper parts of shoots S2 and S3 are higher and obtained at 120% (TB6-S2). It means that, in the shoots of vetiver, Al is concentrated in the leave top and the ratio of Al shoot: root is varied from 3 up to 8%.

The concentrations of Al in all parts of vetiver are increased by its increasing in contaminated water (**Tables 1** and **4**; **Figure 4**), and it was higher in the roots than in the shoots. The minimum concentrations are in the meristematic regions, because the amount of Al passively taken up by roots and then translocated to tops reflects the Al

*Perspective Chapter: Uptake Capacity of Metals (Al, Cu, Pb, Sn, Zn) in Contaminated Water… DOI: http://dx.doi.org/10.5772/intechopen.108931*

**Figure 3.** *Relative deviations of vetiver parts after normalization against "reference plant" [19].*

**Figure 4.**

*Relationships between the concentrations of metals (Al, Cu, Pb, Sn, and Zn) in several parts of vetiver and those in contaminated water.*

tolerance of plants, but the ability to accumulate Al in roots is not necessarily associated with Al tolerance [20].

### **3.2 Copper (Cu)**

Copper had the major functions in plants as component of some enzymes role as catalyst [24], involved in oxidation, photosynthesis, protein, and carbohydrate metabolism, possibly in symbiotic N2 fixation, and valence changes [20] (but it is toxic if concentration of Cu more than the plant needs). Cu is an essential element for the growth of most of aquatic organisms but is toxic at level as low as 10 mg/L [25]. In our experiment, vetiver plants were grown well in the solutions TB10 and TB6 with 27.821 and 46.369 mg/L Cu, respectively (**Table 1**).

In all parts of samples TB10 and TB6, copper concentration is higher in comparison with vetiver blank (BL1). In each vetiver sample, Cu is concentrate in root by the following order: R > M > S1 > S2, S3 (**Table 4**; **Figure 4b**) except blank BL1.

In the root tissue and the meristematic regions, Cu is almost entirely in complexed forms; it is most likely that the metal enters root cells in dissociated forms [20], and so it had strong capability to hold Cu, and Cu cannot be transported to shoots.

*Chemical fingerprint:* The Cu concentrations in "reference plant" are lower than in all vetiver parts, which were living in wastewater (except TB10-S2) (**Table 3**; **Figure 3**). The deviations with "reference plant" in the shoot oscillated from 16.7 (TB10-S3) to 361.5% (TB6-S1), in the meristematic region from 745 (TB10-M) to 1091% (TB6-M) and in the root from 3578 (TB10-R) up to 6507% (TB6-R). On contrary, in the root (�0.2%) and shoot (�52 ÷ �64%) of blank BL1, it is lower than zero (except meristematic region).

The trend of slope line is clearly in diagram "Cu concentration in Vetiver against Cu concentration in contaminated solution" (**Table 3**; **Figure 4b**): it is raised by increasing of Cu concentration in contaminated water. It seems that Cu concentration in vetiver is the function (in direct proportion) of its concentration in contaminated water. Cu concentrations in root (R), meristematic region, and shoots (S1, S2, S3) parts of vetiver are raised in proportion to its increasing in contaminated water. The Cu concentration increasing in root is faster than in meristematic region and in other parts M > S1 > S2, S3.

Cu has low mobility relative to other elements in vetiver, and most of this metal appears to remain in root and leaf tissues until it senesces [20].

*Perspective Chapter: Uptake Capacity of Metals (Al, Cu, Pb, Sn, Zn) in Contaminated Water… DOI: http://dx.doi.org/10.5772/intechopen.108931*


### **Table 3.**

*Relative deviation concentration in parts of vetiver from "reference plant" (mean standard deviation) in %.*

In the other plants, the excessive or toxic concentration of Cu is 20–100 mg/kg [20], but in vetiver plant it is much more, from 11 up to 660 mg/kg (**Table 4**).

The ratio of Cu in shoot: Root is low (4–7%) during living in the wastewater, and being higher (36–48%) in cleaning water that indicated the absorption capacity of vetiver root.

During the living in the difference concentrations of Cu in solution, the shoot of vetiver was uptake copper to the top. It seems to be raised by increasing of concentrations Cu in contaminated water (**Figure 4b**). For other plants, the level 10 mg/L of Cu in contaminated water is toxic, but vetiver can withstand and be alive at 46 mg/L.

The maximum Cu concentration in shoot of sample TB6 is 46.2, in meristematic region is 119.1, and in root is 660.7 mg/kg, which were much more than the previous results by the authors [3, 17, 26] (thresholds to shoot of Vetiver is 13–15, and root is 68 mg/kg).

In the contaminated water, there were both high Cu and Al contents, and its antagonism leads to reduction of Cu uptake by roots under high Al concentration [20].

### **3.3 Lead (Pb)**

Pb is necessary for plant at the level of 2–6 μg/kg [27]. Pb received much attention as a major chemical pollutant of the environment and as the toxic element to plants [20].


### **Table 4.**

*Concentrations of trace metals in vetiver parts, (mean standard deviation), mg/kg.*

*Chemical fingerprint:* Pb is concentrated in the roots of vetiver and deviation to compare with "reference plant" is 70.6 (BL1-R) up to 130% (TB6-R) (**Table 3**; **Figure 3**). But in the meristematic regions, the deviation is lower than zero and obtained 100% (TB10-R). Concentrate Pb in the shoots parts has the following order: (S2, S3) > S1, M, R, and it followed its concentrations in contaminated water and obtained fourfold more than "reference plant."

For other plants, the translocation of Pb from roots to tops is greatly limited, only 3% (Zimdahl R.L. 1975), but by our experiment for the vetiver, the translocation to shoot is obtained from 23 to 41%.

The trend of slope line is clearly in diagram "Pb concentration in Vetiver against Pb concentration in contaminated solution" (**Figure 4c**): It is raised very fast by increasing of concentration Pb in contaminated water.

The stimulating effect of Pb on Cd uptake by root may be an effect of the disturbance of the transmembrane transport of ions [20].

*Perspective Chapter: Uptake Capacity of Metals (Al, Cu, Pb, Sn, Zn) in Contaminated Water… DOI: http://dx.doi.org/10.5772/intechopen.108931*

### **3.4 Tin (Sn)**

Tin is very toxic to both higher plants and fungi [20].

*Chemical fingerprint:* The deviation of Sn to compare with "reference plant" in the low part of TB10 (R, M and S1) is lightly less than zero, but the upper parts (S2, S3) are higher and obtained 142%, and when the contaminated water raised (TB6), it is increased in all parts of vetiver and obtained to 207% (**Table 3**; **Figure 3**).

In the vetiver shoots TB10 and TB6: Concentrations of Sn are higher than in the root and meristematic region by the following order: S3, S2 > S1 > M, R (**Figure 4d**).

Not like to other plants, most of absorbed Sn remains in roots [28], the vetiver has the trend of uptake Sn, and it is accumulated in upper parts with ratio shoot: root varied from 82% (TB6-S1) to 277% (top of vetiver TB6-S3), and increased to the top by order S3/R > S2/R > S1/R.

### **3.5 Zinc (Zn)**

The major functions of Zn in plants are: activates enzymes, regulates sugar consumption [24], and is involved in carbohydrate and protein metabolism [20].

As Kabata-Pendias Alina and Pendias Henryk suggest, soluble forms of Zn are available to vetiver and the uptake of Zn from soil to be linear with concentration in the contaminated water (**Figure 4e**).

*Chemical fingerprint:* The deviation of Zn concentration in meristematic regions is always higher than zero in comparison with the "reference plant," and it is obtained of 508 ÷ 574%, and root and shoot parts are obtained only lightly more than zero (**Table 3**; **Figure 3**).

Zn is concentrate much more in meristematic regions than in the roots. Roots and meristematic regions contain much more Zn than shoots, the ratio shoot: root obtains 30 up to 46%. It means Zn may be translocated from roots and accumulate by the shoots of vetiver. Vetiver has higher tolerance to Zn and Pb than other species [18]. The Zn-Pb antagonism adversely affects the translocation of each element from root to shoot [20].

### **4. Conclusions**

In order to assess the uptake capacity of metals (Al, Cu, Pb, Sn, Zn) in contaminated water by *Vetiveria zizanioides* in laboratory condition, we have the conclusions as follows: Vetiver has higher tolerance to Al, Cu, Pb, Sn, and Zn than other species plants:


The results of this study show that vetiver had the high tolerance to trace metals Al, Cu, Pb, Sn, and Zn in upper parts of shoot, and it can be used for wastewater treatment from "metal production trade village Dong Xam" and in many other trade villages of Vietnam and other countries.
