Big Challenge For Second Language Learners

Published Date: 02 Nov 2017

CHAPTER I

INTRODUCTION

Background of the study

Learning English language as second language (L2) is a big challenge for second language learners (Darus & Subramaniam, 2009). It is because most of the learners will face problems with the lack of vocabulary, structure and syntactic rules. Learners make errors in learning L2 because they get interference by their L1 habits. They will use their L1 while learning L2 and this cause error in their learning. This could also explain why learners still have problems with grammatical functions most of the time, although they have eleven years of English language exposure.

In Malaysia, there are numerous learners who have Chinese language as their L1. Most of them have problems in learning English language especially the English grammar. Learners are more or less likely to be influenced either positively or negatively by their first language. According to Hassan (2002), learners L1 background knowledge will affect them in learning English language especially in speaking and writing. As a result, the interference of L1 has become the major problem for Chinese ESL learners in the process of learning English especially in writing.

Chinese ESL learners will transfer their L1’s habit when they write. It is because thinking in English and writing in English is very hard for learners to achieve. They will get influence by their L1 grammatical structure. Besides, the differences of syntactic rules between L1 and L2 also will affect them in writing. A few studies have reported that Chinese ESL learners will use their mother tongue to plan an outline before writing (Cumming, 1989; Jones & Tetroe, 1987), transfer the writing context to English language by using their mother tongue (Edelsky, 1982; Friedlander, 1990; Lay, 1982). Second language learners will use their mother tongue in such circumstances and the interferences from L1 to L2 can be negative.

Chinese ESL learners will get interference in learning English due to the differences of syntax, lexical usage and discourse patterns. First, Chinese syntax is different with English. There are not article (a/the /an) in Chinese language but in English language. For example:

Chinese Language: 星星很亮 (xing xing hen liang) / star is bright.

English Language: The star is bright.

Second, Chinese lexical translate to English cause errors. It is because learners will direct translate the word to English and it might turn to other meaning. For example:

Chinese Language: 我在宽中读书 (wo zai kuan zhong du shu) / I read in Foon Yew High School.

English Language: I study in Foon Yew High School.

Last but not least, the discourse rules between Chinese and English are difference. For example:

Chinese language: 我很爱我的家人 (wo hen ai wo de jia ren) / I so likes my family

English language: I like my family very much.

So, in this study, the researcher will examines interference of Chinese learner’s mother tongue in learning English as their second language.

1.2 Statement of Problem

To learn English as second language, learners at least have to master four basic skills which are listening, reading, speaking and writing. However, Chinese ESL learners seldom master the skills especially in writing (Darus & Subramaniam, 2009). It is because the L1 interference with English Language causes grammatical errors in the writing process. According to Darus & Subramaniam (2009), who cited a study by Nik Safiah (1978), this kind of grammatical error can be obviously found in Chinese ESL learner’s essay writing such as tenses, subject-verb agreement, and possessive noun. Leaners will made this kind of errors due to the inteference of their L1.

A few study have proved that learner’s L1 will inteference in their L2 writing process. Lim (1990) examine that how learner’s L1 influence in their writing process. He invite fifty Chinese ESL learner’s to participate. Lim compare the results by using free writing and guide writing task. He found out that most of the learner will make grammatical errors in tenses, subject-verb-agreement, pronoun and etc.

Another researcher, Chan (2004) also provides evidence in his article. He found out that Chinese learners will use their L1 syntactic rules related with their L2. 710 Hong Kong ESL learners were participant in the survey. After analyze the result, he found out Chinese learners will think in their L1 before they write. The direct transfer causes grammatical errors occur in their writing.

Chinese ESL learner will make grammatical errors in their writing process because they do not fully utilize the language even though they are able to use it. They will get interference by their L1most of the time. This is because it has became a habit for them and hard to change. As the saying goes, "practise makes perfect" if the learners do not polish their English language even with years of exposure to the language, it will make no difference.

1.3 Purpose of Study

The purpose of this study is to find out if L1 interference has a significant effect on Chinese ESL learners English essay writing. Besides, this study is also to identify types of errors that Chinese ESL learners commonly make with English grammatical functions in the English essay writing.

1.4 Research Questions

Based on the problems and purpose mentioned in the earlier sections, this study will focus on two research questions which are:

Does L1 interference have a significant effect on Chinese Learners English essay writing?

What types of errors do Chinese ESL learners commonly make with English grammatical functions in the English essay writing?

1.5 Significance of Study

This significance of study can help teachers understand the grammar problems caused by L1that learners face in their writing. Besides, this study would create awareness among teachers the importance of learning grammar as the fundamental of mastering English language. This will help teachers to find useful strategies to strengthen up Chinese ESL learners’ writing.

1.6 Scope of Study

The aims of this study is to identify the inteference of learner’s L1 in learning English language. 25 Chinese learner who study in S.M. PEI YUAN (P) KPR would be chosen as participate in the writing test. This study is using purposive sampling because only one class of Chinese ESL learners will be selected as participants.

1.7 Definition of key words

Inteference learner’s make an error in their L2 which influnced by their L1 (Lott,1983:256).

Grammar "a set of rules and example dealing with the syntax and word structure (morphology) of a language (Nordquist & Guide)".

ESL learner A person learn English language as second language or target lnguage and it is not their mother tongue.

CHAPTER II

LITERATURE REVIEW

2.0 Introduction

The first part of this chapter discusses three approaches which are used in this study. The second part of this chapter is to discuss the types of L1 interference in learning L2 and the last part of this chapter will be the research previously done by researchers.

2.1 Three approaches are used in this study.

Three approaches are used to describe L1 interference in this study. There are Contrastive Analysis (CA), Error Analysis (EA) and Interlanguage Analysis (IL).

2.1.1 Contrastive Analysis

CA, based on behaviorism, is an approach which used to compare the differences and similiarities of learner’s L1 and L2 (Richards and Schmidt, 2002). According to Raji (2012), CA can help to find the different between two languages and carry out how the different between learner’s L1 and L2 can cause them made errors while they learning L2. Thus, based on the differences and similiarities, it explains that why certain feature is hard for chinese learner’s to learn English as the L2.

CA was established in year 1957 by Lado. It was developed in 1960s to early 1970. It highlights that L1 is a main factor to influence learners in learning second language. According to the book linguistic across cultures which formulate by Lado, learner will feel easy to learn L2 if the elements of linguistic is similar to their L1 or vice versa. This shows that error occurs as a effect of inteference when the learners transfer their L1 habits into L2. Most learners which acquired English Language as their L1 usually feel it is easier to learn languages such as German Language compared to languages such as Mandarin Language. It is because as English and German have similiarities in their rules and sentence structures. According to Jamtawee, English and German language are similar in the element of lexical, morphology, and phonology. It means that this two language are similar in noun, adjective, adverb or etc. The only differences between this two language is the position of verb.

CA accentuates the influence of the L1 in learning L2 at phonological, morphological and syntactic levels. This emphasizes can help teachers to understand learner’s learning problems. However, according to Kim (2001), CA gradually lost its favor. It is because not all of the error will appear where CA predicted, but will occur when it is not predicted by CA. Due to more and more of the criticism occurs, CA slowly replaced by EA.

2.1.2 Error Analysis

According to Katherina, EA was established by Stephen Pit Corder and his teammate in year 1960. Unlike CA which compares the differences and similarities between learner’s L1 and L2, EA used to describe how learners’get inteference by their L1 which cause them to make errors when they are learning L2. It focuses more on how learners use their L2 to find out the errors and classified them into categories.

According to James (1998), EA was used to analyse the error that learner’s make while they learning L2. Most of them will make errors when they are writing. According to Abushihab, El-Omari, & Tobat (2011) who cited in Dictionary of Language Teaching and Applied Linguistics (1992), a student will make mistake and error while they write an essay and there is a differences between mistake and error.

Based on Brown (1993: 205), people will make mistake in their L1 and L2. But, they are able to self-correct it. Thus, in other word, mistake is a careless act and once an attention occur, it can be corrected by learners. Unlike mistake, errors cannot be self-corrected. It is because learners’ do not even know they making errors while learning L2. For example, learners might be able to recognise their mistake if they pay attention to the word such as "Students". The word with suffix "s" indicates many students. Hence, learners will know that, the verb to use in the sentence must be plural verb which is "are". It is the contrast with errors. Most of the errors can not be recognize by learners. For instance, learners who cannot differenciate the words such as "more" and "much" will use those words based on the subject in the sentence. "More people are waiting for food" and "Much people are waiting for food", means alot of people. But, learners who do not know how to use will overlook the words "more" and "much" in the same category. Teachers and parents think that errors should be avoided in learning because it represents failure and unsuccess. Thus, learners should avoided while learning.

2.1.3 Interlanguage

Interlanguage was developed by Selinker in year 1972. He defined IL as the other way of linguistic system that L2 learners will use when L2 learners are trying to convey their meaning in the current language that they are learning. According to Rustipa (2011), she stated that John Reinecke is the first person who used the term interlanguage in the year 1935. Reinecke refers interlanguage as a non-proper language of L1 and L2. It is because learners will produce a lot of errors in lexis, grammar, and pronunciation when they speak. For example, learnerswill write my family very love me instead of my family loves me very much.

Interlanguage occurs because learners will transfer their L1 to L2 and get inteference. It is because they are still not proficient in their L2. They might know how to use their L2, but they still will get inteference for the features of their L1 and this might influence the way they perform their L2.

IL can be fossilization. According to Brown (1980: 181), fossilization means learners’ L2 will permantly become an inaccurate linguistic form. It means that learners cannot improve in their IL, no matter how long they have learn the language. They will still continue to make certain errors. It is because learners will used their L1 linguistic knowledge to express in their L2. For example, "I so loves my family" is correct if you used Mandarin or Chinese linguistic knowledge to express this sentence which is wo hen ai wo de jia ting . However, it is an error if the sentence is used in English linguistic knowledge to explain. In English, the correct sentence should be, "I like my family so much". Thus, few researchers believe that SL learners cannot fully acquire L2’s grammar and it will becomes a feature in their IL enduring.

2.2 Three types of first language interference are used in this study:

They are three types of L1 interference in written English by Chinese students. There are L1 syntactic interference, L1 lexical interference, and L1 discourse interference.

2.2.1 L1 Syntactic Interference

L1 syntactic interference is actually related to the grammatical errors that students made. As we know, learners need to use the rules of grammar to form a phrase, clause or sentences. There is no denying that Chinese grammatical rules are totally different with English grammatical rules. Chinese learners will make errors when learning L2 especially in subject-verb-agreement (SVA), and noun phrase.

In English, there is a grammatical rules called subject-verb-agreement while Chinese does not. Many L2 learners will make errors while they form a sentence because they might ignore or do not notice the rules. In the study by Darus & Ching (2009), they pointed out that L2 learners will make errors in SVA. They found out that learners have a difficulties in distinguis singular or plural. It is because chinese grammar do not have s/es/ies. Besides, learners also have problems in the verb is or has and are or have.

For example:

My family have me, my brother, my father and my mother. (has)

My hobbies is playing badminton. (hobby)

They is so friendly. (are)

Chinese learners will get inteference by the noun phrase. According to Zhu (2010),she stated that English only accept noun, noun phrase and pronoun used in subject, while Chinese accept almost part of speech becomes subject such as adjective and adverb.

For example:

Too full is not good for us. (Adjective as subject)

Slowly, she will die. (Adverb as subject)

Different syntactic rules will cause errors while learners acquire their L2. It is because the rules of grammar between two languages are different. Learners will get interference and cause errors appear while learning L2.

L1 Lexical Interference

According to Zhu (2010), English and Chinese languages are dissimilar in word formation, morphology and in lexical usage. In English language, learners used an orthographic spelling to form a sentence while Chinese language is used ideographic character. Thus, this kind of interferences happened normally because of the learners’ are lack of lexical knowledge. It is because they think the word in their L1 and translate it to L2. The meaning of words has change.

Besides, vocabulary levels between these two languages are different. Chinese will direct translate the word into English when they are written. However, it might become other meaning due to the word choice. For example, form one learners will write I read in Pei Yuan High School instead of I study in Pei Yuan High School. It is because they direct translate the word read from Chinese. In Chinese read means du (study) 我在培元高中读书 (wo zhai Pei Yuan Gao Zhong du shu). Thus, learners direct translate the word to English and this caused the errors.

L1 Discourse Interference.

Chinese essay is different from English essay in the text format. No matter is in the essay pattern, organization and concept, both of them have a great access. L2 learners will make errors in discourse structures because they do not familiar with the characteristics of English discourse. According to Bennui (2008), characteristic of English discourse can be divided into three parts model which is introduction, body and conclusion. Then, each parts of model will be divided into few paragraph. It is because readers can easily understand the writer’s idea and what he wanted to express.

Besides, as we know that English essays provide a proper paragraph. According to Watcharapunyawong & Usaha (2013), each paragraph should include thesis statement or topic sentences in an English essay. It can be either in the beginning of paragraph or at the end, depends of the writer how to organize it. However, Chinese is totally different. According to Fagan & Cheong (1987), L2 learners will get influence by Chinese rhetorical styles when they write essay. Most of them do not follow the English essay’s format to write but follow chinese format which is "introduction-body-related or contrasting-sub-theme-conclusion." So, most of the L2 learners will get interference while they written essays.

Previous Study

Based on Malaysia education system, learners acquire English as their L2 since they first day enter the school. However they still make error in written essay. To investigate the problems, few researchers had done researches before. Phumklom cited a study which was done by Baljit Bhela from Flinders university Schools of Education. The study is related to L1 inteference. Bhela found out that the major problems for most of the L1 learners faced are, they will use their L1 syntactic structure. After that, they will change it to their L2 and cause errors occur.

Besides, another reseacher Chan (2004) also provides evidence in his article. He found out that Chinese learner will transfer their syntactic to English when they are writing. He examined and collected data through 710 Hong Kong Chinese L2 learners. The result shows that L2 learners will think in their L1 before they write and this cause errors appeare in their writing.

To find out what the errors that learners made in their writing, Darus & Ching (2009) investigate 70 form one Chinese learner in their study. The result shows that the errors that learners make can be categorized into 18 types which is subject-verb-agreement, preposition, pronoun, article and etc.

2.4 Conclusion

This first part of this chapter discussed the approaches which are used in this study, that are known as CA, EA and IL. The second part of this chapter discussed types of L1inteference in learners L2. Also, most of the previous researchers had summed up with one conclusion that L1 will influence learners in learning L2 and cause errors in their writing.

CHAPTER III

METHODOLOGY

3.0 Introduction

This chapter will introduce the methods used to carry out the research. This chapter has includes research design, participants, instrumentation, procedure and time frame, data analysis, and summary.

The aim of this study is to find out the problems that Chinese students faced in learning English as second language. Two research questions will be focus based on the problems.

Does L1 interference have a significant effect on Chinese ESL learners English essay writing?

What types of errors do Chinese ESL learners commonly make with English grammatical functions in the English essay writing?

3.1 Research Design

This study is to identify the problems faced by Chinese students in learning English. To investigate the problems, researcher will carry out the study by using qualitative method. Casebeer & Verhoef (1997) claimed that qualitative research is "the non-numerical examination and interpretation of observations, for the purpose of discovering underlying meanings and patterns of relationships". Using this method can help the researcher to accomplish the objectives of this research.

3.2 Participants

The target participants are selected through purposive sampling. It is because only one class of English Second Language (ESL) learners will be selected as participant. 25 Chinese junior one learners who study in S.M. PEI YUAN (P) KPR in Kampar, Perak will be selected as participants. They are selected due to their qualification because they have been exposed to seven years of English language in school and passed acceptable grades for English in UPSR. Besides, all of them are from non-English speaking background. They seldom used English to communicate outside of the school. Thus, it can help the result be more accurate.

3.3 Instrumentation

Two research questions were created to identify the problems faced by Chinese learners in learning English. Researcher will ask learners to write a 100-120 words English essay. After collecting the essay, researcher will use Markin software to identify the errors. According to Darus & Ching (2009), Markin is a software which developed by Martin Holmes in 1996. This software was chosen because it can help in categorization and statistical analysis of errors. The Markin software provides annotation buttons to classify the error.

3.3.1 Writing Test

The writing test is designed with two sections. Before answering the questions, there is a clear and brief introduction in the first page. It introduces the researcher who is conducting the survey and purpose of this study. A definition of grammar also included into first page. At the end of the introduction, researcher states that the information will be confidential.

This writing test has been divided into two sections which is section A and section B. Section A includes the general information such as gender, age, and year of study. After that, the survey also inquires how well the learners did in their Ujian Penilaian Sekolah Rendah (UPSR). Learners are required to rate their English proficiency from lowest to higher by the scale of 1 to 5.

In section B, a writing test is provided. Participants are required to write an essay based on the title provided. The word length is around 100-120. Learners have to answer on their own and discussions are not allowed.

3.4 Procedure and Time Frame

This study will take around one month. The time frame to collect data is from October 2012 to November 2012. S.M. PEI YUAN (P) KPR is the place where the researcher is going to carry out the study. The data collection will take 45 minutes to complete. In order to let junior one learner fully understand the importance of the study, researcher will explain the purpose of study by using simple English. Besides, researcher will explain the question and give simple instructions in the very beginning.

Learners will take few minutes to complete first section (section A) of the test. Then, they will use the remaining time to write a 100-120 word English essay. The topic of the essay is my family. The total time for researcher to conduct this questionnaire is 45 minutes. Essay will be collected and checked at the end of the class to avoid invalid data.

3.5 Data analysis

The researcher will analyze the data by using pie chart for section A. It is because pie chart can clearly represent the data. As for, section B an error categorization method will be used to identify the errors. The researcher will type the 25 essays into Markin software for categorization and statistical analysis of errors. The software will also convert it into a table.

This method was developed by Darus and Subramaniam (2007) and consists of 18 types of errors such as word choice, negative constructions and incomplete structures. However, this study will only focus on grammatical errors that students made in order to be consistent with the research questions and the purpose of the study.

3.6 Conclusion

The aim of this chapter is to give readers a clear picture of how the data was composed and examined in order to fulfil the research purpose and requirements. The details will be further discussed in chapter four and five.

CHAPTER IV

FINDINGS & ANALYSIS

4.0 Introduction

This chapter presents the overall findings of the research by using pie charts and tables. The objective of this part is to answer the two research questions which are "does L1 interference have a significant effect on Chinese Learners English essay writing" and "what types of errors do Chinese ESL learners commonly make with English grammatical functions in the English essay writing". Thus, the finding in this chapter will be related with the research question. This chapter has been divided into two parts which are questionnaire and conclusion.

4.1 Writing Test

The writing test has been divided into two sections. The first section is participant’s general information and the second section is an essay. The data will be collected and presented through pie charts and tables by using Microsoft Word. The statistics will be divided into percentages and mean.

4.1.1 General Information

The first section will present participants’ general information namely their gender, age, proficiency of English language, and their UPSR results and the frequency of using English language in their daily life. The questionnaire has completed by 25 learners, which is 16 males and 9 females. The researcher has chosen junior year one learners who are studying in S.M. Pei Yuan (P) KPR as participants.

Statement: Rate your English Language proficiency level.

Table 1

Learner’s proficiency in English Language

Scale

Number of learners

Percentage (%)

1

0

0

2

12

48

3

10

40

4

3

12

5

0

0

***Scale (Lowest) 1 – 2 – 3 – 4 – 5 (Highest) ***

Table 1 shows the learner’s proficiency in English Language. Learners rated their proficiency based on their understanding. The result shows that there are 12 learners (48%) who believe that they cannot master English Language well. This means that they may have problems in writing, reading, speaking or listening in English. 10 learners (40%) think that their English level is average. Another 3 learners (12%) consider their English proficiency is good which means that they can speak, write, read and listen well.

Statement: What is your score for the English subject in the Ujian Penilaian Sekolah Rendah (UPSR)?

Table 2

The score for the English subject in UPSR

Grade

Number of Learners

Percentages (%)

A

0

0

B

14

56

C

9

36

D

2

8

Figure 1: the score for the English subject in UPSR

Table 2 shows the number of learners, the percentages of grade that learners score in their UPSR. The chart shows that 14 learners (56%) scored B for English subject in their UPSR, and 9 learners (36%) scored C in their UPSR. Only 2 learners (8%) scored D for English subject in UPSR and none of them scored A in the UPSR.

Statement: Are you exposed to English or use English outside of English classes?

Table 3

Learner’s response towards the frequency of using English language outside of English classes.

Answer

Number of learners

Percentages (%)

Yes

13

52

No

12

48

Figure 2: Learner’s response towards the frequency of using in English language outside of English classes.

Table 3 shows the number of learners and the percentage of learners’ response towards the frequency of using English Language outside of English classes. The chart shows that 13 learners (52%) use English language outside of English classes. Most of them admit that they use English language to communicate with other people through social network such as facebook and google+. Another 12 learners (48%) disclosed that they do not use English Language outside of English classes. This shows that most of the time they will use their L1 instead of using L2.

4.1.2 Writing Test

This subdivision will show the findings of section B which are related to the research questions. Section B is provided an essay. Learners were required to write at least 100-120 word essay and the essays will be used to analyse through number of errors, percentage and mean.

After marking the writing test, researcher find out that Chinese ESL learners will get L1 interferences in: syntactic, lexical, and discourse patter. To be more clear, below is the list of example that learners’L1 make interference in their English writing.

Table 4:

L1 Interference in English Language

L1 Interference in:

Examples

Syntactic

I have three sister and two parents.

She hobby is cooking.

Finally, I likes my family.

Lexical

My father and mother very love our.

I read in Pei Yuan High School.

She every day gets up early to make breakfast to us.

Discourse Pattern

Wong Yi Wei hobby also is drawing, ambition also is painter.

I am very love my family.

I so like my family.

The table 4 shows that Chinese learners L1 will influence them in learning English Language. This result answers the first research question which is "does L1 interference have a significant effect on Chinese Learners English essay writing".

Table 5

Analysis of Errors

Short Annotation

Long Annotation

No. of Errors

Percentage (%)

Mean

Adj

Adjective

7

1.3

0.28

S/VAgreement

Subject verb Agreement

93

17.7

3.72

Art

Article

9

1.7

1.8

Aux

Auxiliary verb

48

9.2

1.92

Cap

Capitalization

23

4.4

0.92

Conj/Trans

Conjunction/Transition

12

2.3

0.48

Count/Non-count

Count/ Non-count

4

0.8

0.16

Det

Determiner

7

1.3

0.28

Irregular verbs

Irregular verbs

2

0.4

0.08

MissingW

Missing Word

20

3.8

0.8

Noun

Noun

1

0.2

0.04

Omit

Omit

28

5.3

1.12

Sing/Plu

Singular/Plural

19

3.6

0.76

PoN

Possessive Noun

68

13

2.72

Preposition

Preposition

14

2.7

0.56

Pro

Pronoun

36

6.9

1.44

Punctuation

Punctuation

33

6.3

1.32

Space

Space

3

0.6

0.12

Spl

Spelling

50

9.5

2

VForm

Verb Form

3

0.6

0.12

VTense

Verb Tense

1

0.2

0.04

WChoice

Word Choice

43

8.2

1.72

Total

524

100

Figure 3: Five Common Errors

Table 5 shows the number of errors that learners made, and converts the number of errors to percentage and mean. Short annotations are used to analyze the errors in the Markin software. The short annotations are a short form for long annotations. The result of the mean values show the most common errors that learners made are (3.72) Subject Verb Agreement, follow by (2.72) Possessive Noun, Auxiliary Verb, Pronoun and Article. The example of common errors will be shown in Table 6.

Table 6

Common Errors

Error Classification

Identification of errors

Correct Sentences

Subject Verb Agreement

My family haveS/VAgreement four people and I.

My hobbiesS/VAgreement is playing badminton

My father bringS/VAgreement us to swim.

My family has four people and I.

My hobby is playing badminton

My father brings us to swim.

Possessive Noun

My brotherPoN age is 10 years old.

Wong Yi WeiPoN hobby also is drawing.

He works in my auntPoN coffee shop.

My brother’s age is 10 years old.

Wong Yi Wei’s hobby also is drawing.

He works in my aunt’s coffee shop.

Auxiliary Verb

Another younger sister’s age Aux6 years old.

My father’s name Aux Chi Len Seong

Another younger sister’s age is 6 years old.

My father’s name is Chi Len Seong

Pronoun

I like shePro.

She lives with myPro.

So shePro ambition is to be a painter.

I like her.

She lives with me.

So her ambition is to be a painter.

Article

Her job is aArt officer.

Her ambition also is Art painter.

Her job is an officer.

Her ambition also is a painter.

The table 5 & 6 shows the most common errors that Chinese ESL learner make in their English writing. The results has answered the second research question that what types of errors do Chinese ESL learners commonly make with English grammatical functions in the English essay writing.

4.2 Conclusion

This chapter revealed the findings of the research collected using the questionnaire through the usage of tables and figures. The following chapter will present the discussions, limitation and conclusion of the study.