Impacts of the urbannization on water quality of cau river in bac ninh city

- This study focused on clarifying some main sources of pollution from urban activities for water quality of Cau River in Bac Ninh city.. Hypothesis The urbanization process in Bac Nin

I INTRODUCTION

Water resource is an essential component of the living environment It contributes to the success of economic and social development, planning, and national security Nowadays, our national resource is facing the risk of pollution and depletion The rapid development and the high population density are causing severe pollution in many rivers With economic development, people often have ignored the direct or indirect adverse impacts on the environment The risk of lacking clean water is a major threat to the survival of human and all living organisms Therefore, we are in need of having appropriate measures to protect and use water resources rationally

Cau River (Nhu Nguyet River) is an important tributary of Thai Binh river system The watershed area of the Cau River is about 6,030km2, and the river is about 290 km long It provides water to agricultural and industrial activities in six provinces including: Bac Kan, Thai Nguyen, Bac Giang, Ban Ninh, Vinh Phuc, and Hai Duong

In Bac Ninh province, Cau river is about 70 km long, flowing through Yen Phong district, Bac Ninh city, and Que Vo district The river through Bac Ninh city is approximately 30 km long The river’s water quality is affected by pollutants from Dai Lam alcohol-making village (Tam Da- Yen Phong), Ngu Huyen Khe River – which receives waste water from the iron and steel – producing villages in Chau Khe, Van Mon aluminum recycled village, Phong Khe paper-making village, and many households living

on both sides of the river

However, for a long time, the extent and level of water pollution caused by urbanization

in Bac Ninh city have been unclear Therefore, implementing a study on the effects of urbanization on water quanlity of Cau River in Bac Ninh city is urgent and necessary to provide a more scientific basis for the river water protection and improvement

II SCOPE, GOAL, OBJECTIVES, AND HYPOTHESIS OF THE STUDY

2.1 Scope of the study

- This study just focused on analyzing some parameters to compare water quality in upstream and downstream of Cau River in Bac Ninh city

- This study focused on clarifying some main sources of pollution from urban activities

for water quality of Cau River in Bac Ninh city

2.2 Goal

This study aims to contribute to provide scientific bases for water resources protection and improvement in order to meet the need of society in a sustainable way

2.3 Objectives

- To assess the present water quality of Cau River in Bac Ninh city

- To assess the impacts of the urbanization on Cau River’s water quality

- To propose the most suitable measures to prevent impacts of the urbanization on water resources of Cau River in Bac Ninh city

2.4 Hypothesis

The urbanization process in Bac Ninh city has resulted in negative impacts on the water quality of Cau river in Bac Ninh city

III METHODS

3.1 Literature reviews

Urbanization is one of the most detrimental forces affecting river health and one of the biggest challenges facing watershed managements However, methods to determine how large-scale changes in watersheds affect local habitats are still producing varied results

(Kearns et al 2005) Hydrologic impacts due to urbanization are reported to cause water

quality problems such as sedimentation, habitat changes Several of the changes wrought

by urbanization can affect the natural stream temperature regimen The effect of reduced shade upon maximum stream temperatures has been well documented (Brown, 1969; Brown and Krygier, 1970; O’Dell, 1971; Ringler and Hall, 1975; and Hartley, 1975) Urban runoff can affect water chemistry by changing levels of nutrients and heavy metals

(Porcella and Sorenson 1980, Morse et al 2002) The impacts from urbanization can cause changes in the biological communities of the stream ecosystems (Morse et al 2002, Chadwick et al 2006, Voelz et al 2005, Walsh 2006) In addition, urban areas contain

many people in relatively small area, and the activities of these people produce pollutants and cause pollution Fortunately, most urban area pollutants are of a point source nature and are controlled by discharge regulation So urban impacts are especially concerning

because they can be seen throughout watersheds, and not just on a local level (Kearns et al

2005) Impacts can be seen on multiple scales, and it is important to look at how watershed impacts of increasing urban development and land use affect habitats on a local scale

3.2 Study area

This study will focus on the area of Bac Ninh city as shown in the following map:

3.3 Sampling

Collecting samples at 2 cross-sections in 3 times:

 Cross-section 1 of Cau river (length: 100m) where water flow enters Bac Ninh city (red

star on the left of the map)

 Cross-section 2 of Cau river (length: 150m) where water flow leaves Bac Ninh city (red

star on the right of the map)

3.3.1 On-site

 Using a meter to measure pH and temperature at 3 points per cross-section ( points

on the surface water)

o At cross-section 1: - First time (11/07/2014): 7.45-8.00 am

- Second time (11/08/2014): 7.30-7.45 am

- Last time (20/09/2014): 7.32-7.46am

o At cross-section 2: - First time (11/07/2014): 8.55-9.10 am

- Second time (11/08/2014): 8.40-8.55 am

- Last time (20/09/2014): 8.50-9.10 am

 In each time for sampling, at each cross-section, dividing into 3 blocks crossing the river At each block, taking 10 grab samples (500ml/grab sample) at 10 equidistant points

(figure 3.1), then labeling and saving them in a dark cool box Totally, we had 60 grab

samples from 2 cross-sections for a sampling time

50cm

pH, t 0 point 1

pH, t 0

0 point 3

A grab sample

A grab sample Surface water

Block 3 Block 2

Block 1

Figure 3.1: The way to sampling at a cross-section in Cau River

o At cross-section 1: - First time (11/07/2014): 8.00-8.30 am

 Ten grab samples from the same block were mixed thoroughly to form a composite sample

Figure 3.2: The way to create a composite sample

 Taking an aliquot sample from each composite sample for analyzing, including:

 DO, EC, Turbidity: 500ml water aliquot sample for analyzing (using the meter)

 As, Cd, Hg, Pb: 200ml water aliquot sample for analyzing (using the meter)

 Total suspended solid (TSS): 100ml water aliquot sample for analyzing

- Dry filter-paper in a 104oC oven for 1-2 hours Cool the filter Then weight and write the mass of filter-paper, we have m1 (g)

- Filter 100 mL of a water sample through the filter-paper above (Note: Shaken well water sample before filtering)

- Dry the filter with deposition in a 1050C for 2-3 hours Cool the filter Then weight and write the mass of filter-paper, we have m2 (g)

- Calculation is:

TSS(mg/L) =

⁄Where, m1 is the mass of filter-paper before filtering in gram

m2 is the mass of filter-paper after filtering with water sample in gram

V is volume of water sample (100mL)

 Chemical Oxygen Demand (COD): 2ml water aliquot sample for analyzing (using Closed Reflux, Titrimetric method)

The principle of this method is that the sample is refluxed with potassium dichromate K2Cr2O7 in concentrated sulfuric acid (H2SO4) solution After digestion, the remaining unreduced K2Cr2O7is titrated with ferrous ammonium sulfate to determine the amount of K2Cr2O7 consumed and the oxidizable organic matter is calculated in term of oxygen equivalent

- Wash culture tubes and caps with 20% H2SO4before first use to prevent contamination

- Make volumetric measurements as accurate as practical; use Class A volumetric ware The most critical volumes are of the sample and digestion solution Use a microburet for

titrations Measure H2SO4to ±0.1 mL The use of hand-held pipettors with non-wetting

pipet tips is practical and adequate Place sample in culture tube or ampule and add digestion solution Carefully run sulfuric acid reagent down inside of vessel so an acid

layer is formed under the sample-digestion solution layer Tightly cap tubes or seal

ampules, and invert each several times to mix completely

- Place tubes or ampules in block digester preheated to 150°C and reflux for 2h behind a protective shield Cool room temperature and place vessels in test tube rack Some

mercuric sulfate may precipitate out but this will not affect the analysis Remove culture

tube caps and add small TFE-coveredagnetic stirring bar If ampules are used, transfer

contents to a larger container for titrating

- Add 0.05 to 0.10 mL (1 to 2 drops) ferro in indicator and stir rapidly on magnetic

stirrer while titrating with standardized 0.10MFAS (Standard ferrous ammonium sulfate

titrant) The end point is a sharp color change from blue-green to reddish brown, although

the blue-green may reappear within minutes In the same manner reflux and titrate a blank

containing the reagents and a volume of distilled water equal to that of the sample

Calculation:

COD mg/L =

where:

a = mL FAS used for blank,

b = mL FAS used for sample,

M = molarity of FAS = * 0.1000

8000 = milli equivalent weight of oxygen × 1000 mL/L

V = volume of water sample (mg/L)

 The 5-day Biochemical Oxygen Demand (BOD5): 15ml water aliquot sample for

analyzing

- Estimate the BOD5 of the sample and select suitable dilutions from the following table

(Standard Methods provides additional guidance as follows: use less than 3 mL for strong industrial wastes, 3-15 mL for raw and settled wastewater, and 15-75 mL for biologically treated effluent)

Estimated

BOD 5 (mg/L)

Suggested Sample Volumes (mL)

Estimated BOD 5

(mg/L)

Suggested Sample Volumes (mL)

The diluted sample used to determine BOD must have a pH between 6.5 and 7.5 For municipal sewage or effluent, the pH range is generally between 5 - 9, but the buffering capacity of the phosphate buffer will often bring the pH of the diluted sample between 6.5 and 7.5

- Determine the DO of the two dilution water blanks and all sample bottles and record

on data sheet as Initial DO

- Place the samples and the 2 dilution water blanks in a 20  1C incubator for 5 days Fill water seals with dilution water and cap to reduce evaporation from seals Check and add water to seals if necessary Due to the 5 day testing period, certain samples require that set-ups and run-outs of results be performed by different individuals

- Before removing the caps, pour off the water above the cap

- After 5 days determine the DO of the two dilution water blanks and the sample bottles

- Calculation formula:

The general equation for the determination of a BOD5 value is:

BOD5 blank sample (mg/L) = DO0 blank sample - DO5 blank sample

BOD5 sample (mg/L) = (DO0 sample - DO5 sample)*f

 BOD5 = BOD5 sample – BOD5 blank sample

Where, DO0 = initial DO of the sample,

DO5 = final DO of the sample after 5 days, and

f = Dilution Factor =

Notes: a Blank BOD5 If the DO depletion in the dilution water blanks exceeds 0.2 mg/l, the results of the test are questionable The results of samples which used the same

dilution water the "high" blank should be qualified on the DMR Do not subtract blank values from sample results

b Dissolved oxygen values of the samples Only dilutions with DO depletions of at least 2 mg/L, and DO5 of at least 1 mg/L may be used to calculate the sample's BOD

15 votes for farmer After that, I collected, synthesized, processed, and analyzed the data

- Interview some producer in craft villages, local people, and local cadres

IV RESULTS AND DISCUSSION

4.1 The present water quality of Cau River in Bac Ninh city

Figure 4.1: The average temperature of

surface water at 2 cross sections

in Cau River ( 0 C)

Figure 4.2: The mean pH of surface water

at 2 cross sections in Cau River

Temperature and pH are two in many parameters which are used to assess the level of water pollution However, these norms are unsubstantial and depend on the time of sampling From data collected, in three times sampling, temperature ranged between 29.60C to 32.00C There was no big difference in temperature in Cau River in Bac Ninh city The greatest temperature was in point 2 at ending cross-section (320C – 11/08/2014) The lowest temperature was in point 1 and point 2 at beginning cross-section (29.60C in

20/09/2014) It’s demonstrated that pollution level in 2 cross-sections did not differ a lots Moreover, in cross section 2 temperature seemed larger a litter bit than in cross section 1

So after flowing through Bac Ninh city, temperature of surface water in Cau River raised slightly We know that the higher temperature is, the higher pollution level is also So based on temperature data, I can evaluate provisionally that if surface water in Cau River is polluted, the pollution level in cross section 2 will be higher than in cross section 1 (figure 4.1)

Besides, surface water had pH values ranging from 7.0 to 7.5 According to VNR 08 in column B1, the permissible pH value is between 5.5 and 9, so all measuring points were within the standard pH in cross section 2 also larger than that of in cross section 1 However, pH of samples did not differ much and it also did not exceed the regulation (figure 4.2)

In conclusion, although pH and temperature are within permissible level, they were changed when Cau River flows through Bac Ninh city So the urbanization process affects

pH and temperature in surface water of Cau River

Table 4.2: Concentration of lab-measured indicators of water sample in Cau River,

Bac Ninh city in the first time (11/07/2014)

Table 4.3: Concentration of lab-measured indicators of water sample in Cau River,

Bac Ninh city in the second time (11/08/2014)

(mg/L) (mg/L) (mg/L) (mg/L) (NTU) (µS) (µg/L) (µg/L) (µg/L) (µg/L)

detected

Not detected

Not detected 0,112

detected

Not detected

Not detected 0,127

detected

Not detected

Not detected 0,123

detected

Not detected

Not detected 0,131

detected

Not detected

Not detected 0,124

detected

Not detected

Not detected 0,132

(mg/L) (mg/L) (mg/L) (mg/L) (NTU) (µS) (µg/L) (µg/L) (µg/L) (µg/L)

detected

Not detected

Not detected 0,108

detected

Not detected

Not detected 0,125

detected

Not detected

Not detected 0,121

detected

Not detected

Not detected 0,128

detected

Not detected

Not detected 0,121

detected

Not detected

Not detected 0,128

Table 4.4: Concentration of lab-measured indicators of water sample in Cau River,

Bac Ninh city in the last time (20/09/2014)

(mg/L) (mg/L) (mg/L) (mg/L) (NTU) (µS) (µg/L) (µg/L) (µg/L) (µg/L)

detected

Not detected

Not detected 0,102

detected

Not detected

Not detected 0,102

detected

Not detected

Not detected 0,105

detected

Not detected

Not detected 0,108

detected

Not detected

Not detected 0,106

detected

Not detected

Not detected 0,110

4.1.2 Conductivity

Figure 4.3: Conductivity of aliquots samples in

three sampling times in Cau River (µS)

Figure 4.4: The average conductivity at two cross sections in Cau River (µS)

Conductivity is a measure of the ability of water to pass an electrical current In general, samples which were from cross section 2 had greater conductivity than that of from cross section 1

From figure 4.3, a sample with the highest conductivity was E2 sample (184.2 µS – 11/07/2014) while that of the lowest conductivity was in E1 sample (104.2 µS - 11/08/2014) There is a sewer discharge near the place where taking sample E1 Because of the presence of organic compounds like oil, phenol, alcohol, and sugar (from domestic waste), they do not conduct electrical current very well and therefore E1 sample aliquots have a low conductivity when in water

The figure 4.4 shows the mean result of conductivity in cross section 1 and cross section 2 It can be clear that, after flowing through Bac Ninh city, conductivity level in water increased slightly Since inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge) were presented in water due

to the urbanization activities Moreover, conductivity is also affected by temperature; the

warmer the water, the higher conductivity We can see in part 4.1.1, temperature in ending cross section was greater than temperature in beginning section

So the urbanization process in Bac Ninh city affected conductivity in Cau River

4.1.3 Surface concentration of Dissolved oxygen (DO)

Figure 4.5: The concentration of DO in aliquot

samples in three sampling times

in Cau River (mg/L)

Figure 4.6: The average concentration

of DO at 2 cross-sections in Cau River

(mg/L)

Dissolved oxygen is a molecule of O2 that is dissolved into the water The amount of

oxygen water can hold depends upon temperature (more oxygen can be dissolved in colder water), pressure (more oxygen can be dissolved in water at greater pressure), and salinity (more oxygen can be dissolved in water of lower salinity)

It can be seen from figure 4.5 that, concentration of DO in samples B1, B2, B3 was higher than in samples E1, E2, and E3 The highest DO was in B2 aliquot sample (6.55 mg/L – 11/07/2014) and the lowest DO was in E1 aliquot sample (3.72 mg/L – 11/07/2014) Moreover, DO level of samples taken in 11/08/2014 was also lower than that

of in other days In my opinion, temperature was one of factors causing this result The higher temperature, the lower DO Because the weather was very hot in that day (it was hottest in three sampling times) Besides, there was a wharf in cross section 1 area, more boat and sailing moving, so it could create more oxygen dissolved in water

In addition, figure 4.6 indicates that the concentration of DO in water went down after water flew though Bac Ninh city Although DO level of water decreased, it exceeded the

2.00 4.00 6.00

in Cau River (mg/L)

DO(begin )

DO(end) VNR 08

DO level in VNR 08 column B1 It could be conclude provisionally that the urbanization

activities caused the decrease in DO level of water and surface water of Cau River in Bac

Ninh city is quite pollution with DO concentration is greater approximately than a half of

the permissible level

4.1.4 Turbidity

Figure 4.7: The amount of Turbidity in

aliquot samples in three sampling times

in Cau River (NTU).

Figure 4.8: The average amount of Turbidity

at 2 cross sections in Cau River (NTU).

From figure 4.7, turbidity of all samples was quite high There were fewer changes

between samples in a same cross section However, turbidity of samples in different

sections showed more changes, it was greater in beginning section than that of in ending

section The highest turbidity was sample B2 (44.38 NTU – 11/07, taken in middle of river

where has more sailings and boats went through) While E1 sample was the lowest

turbidity (28.07 NTU – 11/08/2014)

Besides, turbidity of water decreased when Cau River went out Bac Ninh city (figure

4.8) So concentration of suspended solids, organic matter decomposition, and the other

factors causing turbidity in water were highly variable from cross section 1 to cross section

2 It depended on the source of discharge from factories near the beginning section And

11/07/2014 11/08/2014 20/09/2014

based on self-cleaned ability of water, turbidity in cross section 2 was less than in cross section 1

Although turbidity does not appear in the standard (VNR 08), we can see that the amount of turbidity in water was very high It also causes more impacts to water quality of Cau River

4.1.5 The 5-day Biochemical Oxygen Demand (BOD 5 )

Biochemical Oxygen Demand (B.O.D.) is the amount of dissolved oxygen needed by aerobic biological organism in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period

Figure 4.9: The concentration of BOD 5 in

aliquot samples in three sampling times

There was a different trend in 11/07/2014 all samples from cross section 1 were greater than samples from cross section 2 in concentration of BOD5 This time was a day on which

0.00 10.00 20.00 30.00 40.00 50.00

BOD5(begin) BOD5(end) VNR 08

the beginning area was most affected and directly by sewage from paper-making factories (one day after it discharged)

Figure 4.10 shows that the BOD5 level went up when Cau River flew pass Bac Ninh city The concentration of BOD5 in ending cross-section was greater approximately 1.5 times as many as that of in beginning cross-section

In conclusion, the urbanization process in Bac Ninh city has resulted on concentration of BOD in Cau River’s water It caused the raise of BOD in water The concentration of BOD here was very high and exceeded significantly the regulation in VNR 08 (column B1) It made surface water here pollute and the decrease of oxygen dissolved amount in water, so it affected the life and development of aquatic species

4.1.6 Chemical Oxygen Demand (COD)

Figure 4.11: The concentration of COD in

aliquot samples in three sampling times

in Cau River (mg/L).

Figure 4.12: The mean concentration of COD at 2 cross sections in Cau River

(mg/L)

Mostly, the amounts of COD in aliquot samples were very high and ranged from 20 to

320 (mg/L) The highest amount of COD was in sample B1 in 11/07/2014 (320 mg/L - it was approximately 11 times higher than the regulation in VNR 08) The lowest amount of COD was in sample in 11/08/2014 (20 mg/L - greater one and a half as much as the regulation) Concentration of COD was quite different in samples and in time For example, the difference between B1 and E2 was 200 (mg/L) in 11/07/2014, whilst that of between B3 and E2 was 220 (mg/L) Temperature is also a factor affecting COD

0.00 50.00 100.00 150.00 200.00

COD(begin) COD(end) VNR 08

concentration In 11/08/2014, it was the hottest day in three times sampling, the amount of COD in that day was also lower than on other days

Moreover, the concentration of COD in ending area was lower than that of in beginning cross section (it was lower 1.8 times) It a good sign for water quality in Cau River Although, the amount of COD in Cau River was decreased, it still exceeded drastically the regulation in VNR 08 column B1 (figure 4.12)

All analysis data above concluded that surface water in Cau River contaminated by organic maters and chemicals Although the amount of COD went down after Cau River flows through Bac Ninh city, it exceeded many times the criteria proving pollution level in Cau River is very high and serious

4.1.7 Total Suspended Solids (TSS)

Figure 4.13: The concentration of TSS in

aliquot samples in three sampling times

0 100 200 300 400 500 600

In addition, the amount of TSS exceeded remarkably the permissible level in column B1 - VNR 08 (figure 4.14) Cau River is also a place where concentrates waste sources from houses and production activities It also has more boat and sailing go through, so it is often disturbed in the bottom layer and unstable Moreover, there are more craft villages locating in Bac Ninh province so the amount of suspended solids in wastewater is very large This is also the causes for the high level of TSS in Cau River The large TSS concentration in water causes high turbidity, affects surface water quality as well as the life

Pb, and Hg was very small, almost they were not detected I just found the concentration of

Cd in all water samples

Figure 4.15: The concentration of Cd in

aliquot samples in three sampling times

in Cau River (µg/L).

Figure 4.16: The mean concentration of Cd

at 2 cross sections in Cau River (µg/L)

As can be seen from figure 4.15, concentration of Cd in all water samples was very large It was in alarm level For example, E1 and E3 were 2 samples having high concentration of Cd (the highest of Cd level were 0.131µg/L and 0.132µg/L

0.00 0.05 0.10 0.15

(µg/L)

Cd (begin)

Cd (end) VNR 08

correspondingly in 11/07/2014) It may be affected by fields and waste from fields which are very close to E1 and E3 position The lowest concentration of Cd was in B1 aliquots sample (0.102µg/L – taken in 20/09/2014)

The Cd concentration of samples in cross section 2 was greater than that of in cross section 1 Cadmium is also affected by DO Cadmium stays in a solid form in the presence

of oxygen and sinks to the bottom of the water If the water goes anoxic (without oxygen) cadmium may dissolve into the water This is a problem because cadmium (as with other hard metals) is poisonous to animals So, the less oxygen dissolved in water, the more Cd dissolved We can see in part 4.1.3, the concentration of DO was declined after Cau River flows through Bac Ninh city So the Cd level increased also Besides, the Cd level in two cross-sections exceeded significantly the standard in VNR 08 column B1 (it was approximately greater 12 times as many as the regulation) (figure 4.16)

From the data above, I can conclude that the urbanization process in Bac Ninh city has caused an increase in the concentration of Cd in Cau River Surface water is polluted with very great amount of Cd It exceeded dramatically the permissive level in VNR 08

4.2 Impacts of the urbanization on Cau River’s water quality

Through survey processes, I found that most of local people were aware of the degradation of Cau River There were some situations: landslides, erosion, flow changes, irregular water regime: it was flood in the rainy season, while in the dry season, water level was low These facts have significantly impacted on their production activities Previously, local people still used water in Cau River for daily demands The social and traditional culture activities also took place on the river Now, due to the degradation of Cau River, most of these activities are disappearing All local people use wells for daily demand Wells are deep from 15-20m; especially some are deep up to 30-40m According

to local people, groundwater still guarantees for their daily demand However water quality

is not good because all interviewed households agreed their well was contaminated with lime and they had to eliminate lime several times per year

Table 4.5: Summarizing local people’s opinions about water quality

Water for daily life Water for agriculture

Source Clear Not

clear

Polluted with lime Source Clear

Not clear

Opaque color

Based on interviewing data in table 4.5, 100% interviewed household showed that water river was polluted And it could be clear in changing color and smell

After researching process, I found that there were many factors causing pollution in Cau River However, due to poor condition in researching and in time, I just figured out some main sources of pollution which affected directly on water quality, including: Daily life activities of residents, construction activities, agriculture activities, and production activities in craft villages in Bac Ninh city

4.2.1 Daily life activities of residents in Bac Ninh city

The population of Bac Ninh city is growing rapidly in recent years with the speed of urbanization and industrialization, however the drainage system has not developed correspondingly causing pollution increase by waste water The population growth of Bac Ninh city in recent years shown in the following table:

Table 4.6: The population growth and density of Bac Ninh city from 2010 to 2013

No Year Population (people) Density (people/km2)

(Source: People’s committee of Bac Ninh city, 2014)

From table 4.6, Bac Ninh city’s population has been increasing rapidly in recent years From 2010 to 2013, population density grew up drastically by 1.312people/km2 while the

land area was not expanded (82.60km2) So it increased the pressure on land resources, influencing directly to ecological environment

Household waste water of local people is the main reason affecting water quality in Cau River Household waste water contains waste products, organic matter, nutrients and bacteria So if it is not treated, it can lead to pollution of surface water and ground water Through interview process, environmental issues were interested Local people took part in clean street activities The households paid environmental fees to collect and treat waste On the city there are about 125 garbage collection points to ensure handing in time Most waste water from households was treated by drainage system Estimating waste water from households in the city was about more than 2,000,000m3/day However, in some houses around Cau River, people collected garbage, dead animals and then threw in the river They also directly discharged waste water into the river without treatment

4.2.2 Construction activities in Bac Ninh city

Construction activities are also one of these factors which impact on water quality

in Cau River, Bac Ninh city In the urbanization process, trees and vegetation were removed; houses, some with sewers and some with septic tanks were also built Besides, wells were drilled Then they bulldozed of land for houses, roads and filled in of farm ponds More roads, bridges and houses were built, more wastewater is discharged into local streams So more storm runoff and erosion because there is less vegetation to slow water as it runs down hills Moreover more sediment land erosion is washed into streams This increases the chance of flooding and harms the water quality of the Cau River Besides, the water that used to soak into the ground now runs off into streams The runoff can also be collected by storm sewers and sent to the river So sewage in river was increased causing pollution – it can change some parameters in water quality of Cau River

4.2.3 Agriculture activities in Bac Ninh city

Although Bac Ninh city is a city of industrialization and modernization, some people’s life still depend on agriculture Moreover, if the population increases, agriculture will be raised too So the urbanization activity affects greatly on agricultural activities And then agricultural activities impact directly on water quality of Cau River in Bac Ninh city

Table 4.7: Some main agricultural species in Bac Ninh city

Major pests

January-May Jun-November

-Cattle manure: 8,100-10,800 -Supe phosphate: 405-540

- Nitrogenous fertilizer:190-215

-Potassium: 135-160 -Lime powder: 675-810

-Insects -brown planthopper

- bedbug

Peanut 2

January-Jun August-December

-Cattle manure: 8100 -Supe phosphate: 405-540

- Nitrogenous fertilizer: 80-110

-Potassium: 110-135 -Lime powder: 810

Insects

-Cattle manure: 8,100 -Supe phosphate: 405-540

- Nitrogenous fertilizer: 80-110

-Potassium: 110-135 -Lime powder: 810

- Insects

- bedbug

January-April Jun-September

-Cattle manure: 10,800 -Supe phosphate: 540

- Nitrogenous fertilizer: 405-485

-Potassium: 135 -Lime powder: 540

-Insects -mouses

(Source: People’s committee of Bac Ninh city, 2014)

With land area of production for crops, we have a summary of the volume of fertilizers used in the study area:

Table 4.8: The volume of fertilizers used in Bac Ninh city

Species Area (ha)

Mass of fertilizer Cattle

Total 43,728,876 2,208,044 846,729 1,478,964 3,268,866

(Source: People’s Committee of Bac Ninh city, 2014)

As can be seen from the table 4.8 the amount of fertilizers used in Bac Ninh city was very huge The using rate of manure N : P : K = 1 : 2.6 : 1.8 This index showed that the percentages of using Phosphate fertilizer in Bac Ninh city were quite high It was 2.61

times as many as the mass of Nitrogenous fertilizer and 1.5 times as many as the mass of

Potassium fertilizer using in study area In fact, the volume of fertilizer used in some places is more than the standard above, so these given numbers are relative

The amount of fertilizer that trees absorb is only one third, the others are dispersed into some sources such as soils, surface water, or ground water This is the source which causes soil pollution, surface water pollution, and affects water quality Moreover, chemical fertilizers also have a large amount of heavy metals These heavy metals will accumulate on soil and water The concentration of heavy metals in some common fertilizers is shown in table 4.9:

Table 4.9: The amount of heavy metals in some common fertilizers (mg/kg)

Element Cattle manure Phosphate

(Source: Le Van Khoa, 2000)

In addition, pesticides (plant protection products) are also a cause of water pollution Pesticides are toxic chemicals designed to be deliberately released into the environment Although each pesticide is meant to kill a certain pest, a very large percentage of pesticides reach a destination other than their target Instead, they enter the air, water, sediments, and even end up in our food Pesticides easily contaminate the air, ground and water when they run off from fields, escape storage tanks, are not discarded properly and especially when they are sprayed aerially It is a potential factor causing many diseases for local people and ecological environment

Table 4.10: Some common pesticides are used in Bac Ninh city

1 Monifos 250EC Abamectin 9g/l + Chlorpyrifos Ethyl 241g/l 0.06-0.07 ml/ m2/season

2 Virtako 40WG Chlorantraniliprole 20% + Thiamethoxam

2/season

3 Dogent 800WG Fipronil 780g/kg + Acetamiprid 20g/kg 0.0003-0.00125g/

m2/season

4 Dogent 3G Acetamiprid 0.1g/kg + Fipronil 2.9g/kg 0.004-0.006 g/ m2/season

5 Dogent 50SC Acetamiprid 0.2g/kg + Fipronil 49.8g/kg 0.006-0.008 g/ m2/season

6 Vilusa 5.5SC Hexaconazone 4.8% + Carbendazim 0.7% 2.1-2.5 ml/ m2/season

7 Wofatac 350EC Profenofos + Lambda Cyhalothrin 0.08-0.153 mm/ m2/season

8 Actatin 150SC Indocacarb 0.03-0.06 g/ m2/season

10 Abenix 10FL Albendazole (min 98.8%) 0.06-0.07 ml/ m2/season

11 Goldnil 250EC Difenoconazole (min 96%) 0.06-0.07 ml/ m2/season

12 Acvipas 50EC Acetochlor (min 93.3%) 0.01-0.02 g/ m2/season

14 Acenidax 17WP Acetochlor 14.6% + Bensufuron Methyl

2/season

15 Natos 15WP Acetochlor 14.0% + Bensulfuron Methyl

0.8% + Metsulfuron Methyl 0.2% 0.15-0.21 g/ m

2/season

16 Butanix 60EC Butachlor (min 93%) 0.14-0.18 ml/ m2/season

17 Butavi 60EC Butachlor (min 93%) 0.04-0.07 ml/ m2/season

19 Caria 5EC Quizalofop – P – Ethyl 5% + 95%

2/season

20 Metrimex 80WP Ametryn 40% + Atryzin 40% 0.15-0.21 g/sao/season

25 Racumin 0.75

(Source: People’s Committee of Bac Ninh city, 2014)

According to the results in table 4.10, there were 25 types of common chemical plant protection used in Bac Ninh city All of them are on the list of permissive pesticides for using in Vietnam (stipulated in Circular 09/2009/TT-BNN on March 3rd, 2009 of the Ministry of Agriculture and Rural Development) However, in the study area, local people used these pesticides without exactly dose as the package instruction Most of people agreed that if spraying a large amount of pesticides, it would increase its ability to use A few interviewed people (about 20%) said that they paid attention to the excess of pesticides After using, bottles and packages were not collected for treating, they were scattered around the fields and along Cau river’s sides

From there, we can see that, agriculture is the main factor that causing Cd

4.2.4 Production activities in craft villages in Bac Ninh city

There are many craft villages scattered in Bac Ninh province They are located around Bac Ninh city Because of the limitation of time and study condition, I just focused

on two craft villages, which are located in Bac Ninh city, are said to be the main sources of pollution for Cau River: Phong Khe paper-making village and Khac Niem noodle making

village

4.2.4.1 Phong Khe paper making village

Phong Khe paper making village is located in Phong Khe commune, Bac Ninh city Total natural area of Phong Khe commune is 548.67 ha It is high population density with 1600people/km2 It is a commune with developing making-paper craft Most of working-age people in the commune are working in the paper industry Now these factories are producing some main kinds of paper, including: carton, toilet paper, kitchen paper, and votive paper Each type has a different production process and input materials

Paper production is one of technologies which used much water In paper production facilities, the amount of used water after discharging took with impurities, chemicals, pulp, organic and inorganic form of pollutants Because there is not the circulatory system for treating waste water and chemicals The characteristic of paper-making wastewater results

in high concentrations of BOD5, COD, TSS

The main raw materials for paper production in Phong Khe village are the bank of

Rhamnoneuron balansae and all kinds of scrap paper with a mass about 30,000 ton/year

Based on estimating, the amount of garbage from factories was approximately 1,200kg/day, including all kinds of plastic packages, nails, lanyards The amount of solid waste discharged into the environment increased drastically, including both waste from the production process and daily life Besides, coal slag is also one kind of solid waste with large amount Coal is used to provide steam in paper lick-up process With more than 200 paper production chains in Phong Khe commune consumed about 8,000 tons of coal per