LIST OF IMAGES
Figure 1.1: pH values at some monitoring points 21
Figure 1.2: pH values of some coastal seawater samples 21
Figure 1.3: TSS content in wastewater of some production facilities 22
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Figure 1.4: TSS content in some coastal seawater samples of Cua Luc Bay 23
Figure 1.5: COD content in some seawater samples along the coast of Cua Luc Bay 24
Figure 1.6: Cd content in some coastal seawater samples of Cua Luc Bay in 2012 26
Figure 1.7: Mn content in some seawater samples along the coast of Cua Luc Bay 28
Figure 1.8: Mn content in some seawater samples along the coast of Cua Luc Bay 29
Figure 1.9: Coliform content in some coastal seawater samples 32
Figure 1.10: Oil and grease content in some coastal seawater samples 33
Figure 2.1: Geographical location of Cua Luc Bay and vicinity on remote sensing image 36
Figure 2.2: Viet Hung Industrial Park (2013) 46
Figure 3.1: pH changes in Cua Luc Bay - Bai Chay Bridge in the period 2009 - 2013 64
Figure 3.2: Coliform content changes in Cua Luc bay - Bai Chay bridge in the period 2009 - 2013 65
Figure 3.3: Oil content evolution in Cua Luc bay - Bai Chay bridge in 2009
– 2013 ..............................................................................................................................66
Figure 3.4: Fluctuations in Coliform content over the quarters of 2011 67
Figure 3.5: Fluctuations in oil and grease content over the quarters of 2011 67
Figure 3.6: Fluctuations in oil and grease content over the quarters of 2012 68
Figure 3.7: CLN zoning diagram of Cua Luc bay area in 2011 77
Figure 3.8: Water quality zoning diagram of Cua Luc Bay area in 2012 77
INTRODUCTION
1. Urgency of the research topic
The Cua Luc Bay basin is a territory consisting of three main basins: Dien Vong River, Troi River and Man River flowing into Cua Luc Bay (the area of the bay is about 56 km 2 ). Cua Luc Bay has a direct relationship with Ha Long Bay. Most of the pollutants discharged into the bay that are not completely decomposed are transferred to Ha Long Bay through Cua Luc Strait. The research territory extends from Cua Luc Strait to the northern watershed of the basin, including Cua Luc Bay and the communes along the bay of Ha Long City, Hoanh Bo District located in the basin. The terrain is mainly mountainous, forming a water collection basin of about 610 km 2 .
Currently, in the Northeast of the bay, coal production continues to develop. However, according to the socio-economic development plan of Quang Ninh province to 2020, with a vision to 2030, coal production within the scope of Ha Long city, in which coal companies in the East and Northeast of the bay will gradually decrease and cease. In the East, sea encroachment activities have formed urban residential areas (Cao Xanh Ha Khanh urban area, Vung Dang...). In the West and Southwest, Cai Lan area, Northwest - Viet Hung Industrial Park, North Bay - Hoanh Bo Industrial Park are operating and will be supplemented with new enterprises according to the socio-economic development plan of Quang Ninh province. In the bay, economic activities are taking place quite vigorously such as deep-water port activities, waterway transportation, sand mining, coal wharfs, aquaculture...
The water environment quality of Cua Luc Bay depends mainly on the pollution load of socio-economic activities taking place in the area flowing into the bay and the economic activities taking place in the bay.
The above analysis is the initial basis for the author to choose the thesis topic with the title " Assessing the current status and changes in the water environment of Cua Luc Bay and proposing solutions to reduce pollution " to serve sustainable development is really necessary .
2. Objectives of the topic
- Assess the current state of the water environment in Cua Luc Bay.
- Analyze the evolution of water pollution and propose solutions to reduce water pollution.
3. Research scope:
- Regarding space: Cua Luc Bay and the area surrounding the bay are limited by the belt roads from Bai Chay Bridge - Gieng Day (to the southwest) - Le Loi along the northern belt - Bang Bridge - Cao Xanh Road (to the east), and also extended to the watershed divide to the north of the bay, because all activities in this space affect the quality of the water environment in the bay.
- In terms of science: review the main activities causing water pollution in the bay, assess the current situation, analyze changes in the water environment, and propose solutions to reduce pollution.
4. Research content
- Analyze characteristics and evaluate the impact of natural and socio-economic conditions (resource exploitation and use activities, industrial development activities, deep-water port activities, urban development, etc.) on water pollution in Cua Luc Bay.
- Assessment of the current state of water environment in Cua Luc Bay.
- Analyze the evolution and trends of water environment change in Cua Luc Bay related to economic development, climate change and sea level rise.
- Zoning of water pollution sources and zoning of water quality.
- Propose appropriate solutions (Scientific, management) to minimize water pollution in each environmental area.
5. Databases used in the thesis
- Summary reports of projects and published works related to water environment research in general and Cua Luc Bay in particular.
- Water environment monitoring documents of the Provincial Department of Natural Resources and Environment.
rescue
- The results of the author's field survey during the thesis period.
5. Thesis content
Chapter 1: Overview of research problem
Chapter 2: Location, time, methodology and research methods Chapter 3: Research results
CHAPTER 1. OVERVIEW OF THE RESEARCH PROBLEM
1.1. Overview of some research works related to water pollution in Cua Luc Bay
Water environment is considered the most important research object, because it is the place that receives most of the environmental pollutants (JICA, 1999). In this section, only the results of some typical studies directly related to the thesis are briefly mentioned.
- Research works on water pollution in Cua Luc Bay : Water pollution in Cua Luc Bay basin was first systematically studied in 1997, in the project " Research on environmental pollution in Ha Long Bay " (ESSA - Canada 1997) [4, 5] . In this study, the load of water pollutants discharged from human activities was calculated on each small basin ( basin perspective approach ), including BOD, DO, Coliform and suspended solids (TSS) washed away by surface water. The study forecasts the fluctuations in suspended solids causing water pollution up to 2015 as follows: Suspended solids ( TSS) washed away from the basin are an important factor determining water environmental conditions but are not the main source of water pollution in Ha Long Bay. The suspended solids content in coastal seawater at Cua Luc and Bai Chay is very low, at 1 - 2 mg/l; In coastal areas of Hon Gai town, it is about 4 - 8 mg/l; In Cai Lan area, it is about 10 mg/l. Thus, in general, the suspended solids content is still very low compared to the suspended solids content standard in seawater used for recreation purposes (25 mg/l) and for aquaculture (50 mg/l) according to Vietnamese Standard TCVN 5945 - 1995 (ESSA, 1998. P. 93 - 101). However, in 1998, research by Hoang Viet and others showed that the hydro-chemical parameters of the water environment in Cua Luc Bay had strong fluctuations, especially the suspended solids content TSS increased very high, from 45.7 to 98.2 mg/l, far exceeding the permitted standard.
Metals such as Zn, Cu, Pb, Cd, Ni, Cu, Mn, Fe, As, Hg have average contents lower than the permissible limit according to TCVN 5943-1995 for aquaculture purposes from several times to several dozen times (Nguyen Xuan Tuyen et al., 1999.
VI. pp. 27 - 37; Luu Quang Dieu et al., 1999. IV. pp. 19 - 24).
In the research works in the past 10 years on the sedimentation and erosion of Cua Luc Bay bottom (Nguyen Cao Huan et al., 2004), the environment of Ha Long Bay (Jica, 1999) also clearly reflected the current status and changes in the water environment of Cua Luc Bay associated with the period of accelerating coal mining and development of industrial zones and urban areas around the bay [13].
- Regarding sources of water pollution : Most research works reflect the sources of water pollution in the bay. Based on the composition, properties and origin of the agents causing water pollution, there are some main sources as follows: sources of waste soil and rock and wastewater from coal production, sources of industrial waste, sources of urban waste, sources of waste from ships in the bay (ESSA, 1997; JICA, 1999). Since 1999, the leveling of land for the construction of infrastructure for industrial parks and urban areas has been considered one of the main sources of water pollution in Cua Luc Bay (Nguyen Cao Huan et al., 2004) along with the rapid increase in coal production activities in the East of Cua Luc Bay and in the Dien Vong River basin) [50] .
- Regarding the mechanism of dispersion of pollutants in the aquatic environment: Mainly due to tidal currents in the bay and coastal areas combined with the hydrological regime of rivers from the North flowing into Cua Luc Bay (ESSA, 1998) and (JICA, 1999 ). Applying the method of dividing the bay basin into small basins to calculate the load of pollutants flowing into Cua Luc Bay and modeling the hydrological regime in Cua Luc Bay and Ha Long Bay, the research results show that the materials washed away in the basin and coastal areas, including coal dust from coal production activities, are carried quite far, to the outer boundary of the World Natural Heritage Ha Long Bay. However, the above studies have not yet set out urgent requirements for impact research.
of materials washed away in the basin to the sustainability, including the aquatic environment of Cua Luc Bay .
1.2 Theoretical basis
Some related concepts
1. Concept of bay
"A bay is a large body of water that extends deep into the mainland, where the coastline has a large curve. A lagoon is a body of water with similar characteristics but smaller than a bay." (Petroleum Dictionary, published by the Vietnam Geological Society, 2004).
"A bay is a part of the sea that penetrates deep into the continent, with an opening to the sea with a considerable width. A cove is a part of the sea that penetrates deep into the continent, connected to the sea, usually only by small channels or creeks... A cove is also called a small bay" (Geological Dictionary explains).
To better distinguish the concepts of "large bay", "bay" and "cove" and cove, one can refer to the American Geological Dictionary published in 1987, reprinted in 2001. Accordingly, "A bay is a large, open body of sea or lake located between two coastal headlands or small islands and islets. A bay is larger than a cove (small bay) but smaller and shallower than large bodies of sea and ocean water embraced by long arcs of coastline connecting to the ocean is called a gulf".
A bay from a geographical point of view is a body of water that is surrounded by land on at least three sides (Wikipedia.com). A typical example and similar to Cua Luc Bay in this aspect is San Francisco Bay.
The Cua Luc Bay basin includes the basin and the bay. There are many small river and stream basins in the basin; Each small basin is considered a natural system.
- The territory has its own unique characteristics. Cua Luc Bay both functions as a bay receiving small flows in the basin and as a typical funnel-shaped estuary, receiving most of the wastewater and solid waste from the mining activities of industrial sub-zones, from sand and clay mining activities, and domestic wastewater from residential areas around the bay.
2. Concept of environment and environmental pollution
Environment is a very broad concept, defined in many different ways, especially after the Stockholm Conference on the Environment in 1972. In addition to the concept of environment set forth in Vietnam's Law on Environmental Protection, another notable concept can be considered below.
From a geographical perspective, “The environment is a part of the earth surrounding humans, with which at a certain point in time human society has a direct mutual relationship, meaning that the environment has the closest relationship to human life and production activities” (SVKalesnik: General geographical laws of the earth. M.1970, pp.209-212).
In the Global Report 2000 , published in 1982, the definition of environment was given: “In its literal sense, the environment is the physical and biological objects that surround humanity... The relationship between humanity and its environment is so close that the distinction between individual humans and the environment is blurred.”
In the UNESCO Declaration of 1981 , the environment is understood as "The whole of natural systems and systems created by humans around us, in which humans live and through their labor exploit natural or artificial resources to satisfy human needs".
The concept of environment is stated in the Law on Environmental Protection of the Socialist Republic of Vietnam (2005) and is specified as follows: "The environment includes natural and artificial material factors surrounding humans, affecting the life, production, existence and development of humans and living organisms".
According to origin and nature, the environment is divided into two main groups: natural environment and social environment.
A polluted environment is an environment containing one or more pollutants with concentrations exceeding the maximum allowable limits specified in environmental standards/regulations. The level of pollution, high or low, is determined by the ratio between the actual pollutant concentration and the allowable concentration value.