**2. Case study: the Arge**ș **River, Romania**

#### **2.1 Study area**

The water quality parameters were recorded within the Transnational Monitoring Network of the Danube River (TNMN) in Argeș River located in Southern Romania. Argeș River is a left tributary of the Danube being 350 km long and having a basin area of approximately 12,550 km<sup>2</sup> , which is 5.3% of Romania's total area (**Figure 1**). The source is located in the Făgăraș Mountains, and it flows into the Danube River at Oltenița.

#### **2.2 Methodology**

Corine Land Cover [26] database was used to perform the land use/land cover analysis using the ArcGIS Desktop functions (https://www.ecologic.eu/sites/ default/files/project/2021/Land%20Use%20Analysis%20final%20en.pdf).

The water quality was monitored on Argeș River near the confluence with the Danube River at Clătești village (**Figure 2**) within the TNMN, International Commission for the Protection of the Danube River (ICPDR)—https://www.icpdr. org/wq-db/. From the multitude of the parameters collected in the dataset between *Water Quality and Anthropogenic Pressures in a Changing Environment: The Arges River Basin… DOI: http://dx.doi.org/10.5772/intechopen.101790*

#### **Figure 1.**

*Argeș River hydrological basin (Code X.1) position in Romania (blue lines represent the delimitations of the subbasins).*

2007 and 2014, the following were considered for presentation in this work (n = 95 for each parameter): water temperature (°C), suspended solids—TSS (mg/L), pH, dissolved oxygen—DO (mg/L), biochemical oxygen demand—BOD5 (mg/L), nitrogen nutrients i.e., ammonium (NH4-N) (mg/L), nitrates (mg/L), and nitrites (mg/L) and heavy metals (μg/L) i.e., dissolved nickel, chromium, and lead. For these parameters, the sampling, storage, and handling of samples were performed with a monthly frequency being carried out according to the current standards [14]. The start of the time series was considered in the year 2007 because Romania became a member of the EU in that year, and consequently the water quality standards needed to be in agreement with EU legislation.

Statistical analysis was performed using descriptive and associative statistics using the SPSS software (SPSS Inc., Chicago, IL, 2011). Factor analysis considered principal component analysis (PCA) based on Varimax with Kaiser normalization to reduce the number of factors that explain the variability in the dataset.

#### **2.3 Results**

In order to have an image of the potential impact of land use within the surfaces existing in the basin of Arges river that drains the waters, the land use analysis was applied (**Figure 3**). The main cities supplied with water in the Arges river basin include the capital Bucharest, and other important cities e.g., Pitești, Curtea de Argeș, Câmpulung, Găești.

Oltenița. The category 112—discontinuous urban fabric occupies 4%. The 211—non-irrigated arable land category reaches 46% showing that the area is important for agriculture. Furthermore, the basin contains a key forest resource

#### **Figure 2.**

*Position of the monitoring point at Clătești village on Argeș River (arrow) (44.14500N, 26.59900E) https:// geoportal.ancpi.ro/portal/apps/webappviewer/index.html?id=5fca89129f2f466882bb7c64e6fd3d98#.*

(approximately 3283 km<sup>2</sup> ) which represents 26.2% of the river basin area and 5.2% of the national forest fund. Watercourses (511 class) represent 12% because the Argeș River gathers 178 codified watercourses with a length of 4579 km (5.8% of the total length of codified watercourses in Romania). The density of watercourses is 0.36 km/km<sup>2</sup> .

**Figure 4** shows the overall results of the land use analysis.

Land use may have a direct influence on the water quality in the watercourses because of direct discharge and runoff.

*Water Quality and Anthropogenic Pressures in a Changing Environment: The Arges River Basin… DOI: http://dx.doi.org/10.5772/intechopen.101790*

**Figure 3.** *Land use in the Argeș hydrological basin according to Corine Land Cover.*

#### **Figure 4.**

*Analysis of the land use in the Argeș hydrological basin (predominant classes: 112—discontinuous urban fabric 4%; 211—non-irrigated arable land 47%; 311—broad-leaved forest; 14%; 511—watercourses 12%)—details: https://land.copernicus.eu/user-corner/technical-library/corine-land-cover-nomenclature-guidelines/html.*

The time series recorded between 2007 and 2014 were plotted for the envisaged parameters to show the dynamics. **Figure 5** presents the fluctuations of pH values for the water samples collected each month. The associated trend line shows a pH value around 7.5, ranging from 6.53 to 8.26 (**Table 1**).

**Figure 6** shows the fluctuation of water quality parameters related to oxygen, nutrients, and heavy metals during the monitored period. BOD5 showed an increasing trend, while DO remained almost constant. Nitrogen parameters decreased from 2007 to 2014. The main statistics for each parameter are presented in **Table 1**.

Dissolved Ni and Pb showed the highest variations in the dataset and these indicators show the magnitude of the anthropogenic impact on the water quality due to the discharge of industrial wastewaters and atmospheric deposition. **Table 2** presents the correlation matrix resulting from applying the Pearson method. The strongest inverse correlations (p < 0.01) were found between BOD5 and dissolved lead, TSS and nitrites, temperature and nitrates, pH and temperature, temperature, and dissolved oxygen. Positive correlations (p < 0.01) were established between the dissolved heavy metals suggesting that their concentrations rise together.

The application of factor analysis to the dataset (a matrix of 95 objects by 11 variables) was made using the Varimax with Kaiser normalization [27] to reduce the number of factors that explains the variability. Five components were extracted and from the rotated matrix the factors were organized based on the relevant factor loadings (>0.6). The results showed that the first factor contains temperature and dissolved oxygen, the second has the heavy metals, the third groups the ammonium and pH, the fourth contains the TSS and nitrites, while the fifth is formed by BOD5 and nitrates. These factors accounted for a cumulative variance of 72.3% of the total variability in the dataset.

**Figure 7** summarizes the results of the factor analysis applied to the water quality dataset recorded at Clătești near the confluence of Argeș River with the Danube River.

When compared to the Romanian NTPA-013/2002 limit values (surface waters used for drinking source), the reported concentrations presented exceeding for dissolved Ni, Cr, and Pb. The presence of heavy metals at Clătești monitoring point on Argeș River is a clear indicator of the pressure on the water quality. Furthermore, ammonium exceeded the limit values for class A3 (lowest) and BOD5 for class A2, respectively. These suggest an increased pollutant load near the discharge of Argeș in the Danube River.

Within the hydrographic basin of the Argeș river, it is necessary to identify and quantify the significant pressures either from punctual sources, with discharges of treated waters or untreated in surface waters (sources of urban pollution/human

**Figure 5.** *pH time-series recorded between 2007 and 2014 (monthly concentrations).*


*Water Quality and Anthropogenic Pressures in a Changing Environment: The Arges River Basin… DOI: http://dx.doi.org/10.5772/intechopen.101790*

> **Table 1.**

*Descriptive statistics of the parameters recorded at Clătești monitoring point on Argeș River between 2007 and 2014.*

#### **Figure 6.**

*Dynamics of oxygen-related parameters, dissolved heavy metals, and nitrogen nutrients in the monitoring point on Argeș River.*

settlements and/or industrial sources with wastewaters discharged into streams due to non-compliance with the maximum permitted concentrations [28]), or diffuse pollution, from agriculture and other sources.

An investigative monitoring program is needed to identify the causes of exceeding the limits provided in quality standards and other regulations in the field of water management, to establish the causes for which a body of water in the Argeș basin cannot achieve the established environmental objectives, but also to quantify the impact on water quality, providing information on the programs of measures


*Water Quality and Anthropogenic Pressures in a Changing Environment: The Arges River Basin… DOI: http://dx.doi.org/10.5772/intechopen.101790*

*Correlation matrix of the parameters monitored on Argeș River at Clătești between 2007 and 2014.*

**Table 2.**

#### **Figure 7.**

*The component plot in rotated space for the water quality parameters (1st factor, temperature, and dissolved oxygen***,** *2nd factor***,** *the heavy metals***,** *the 3rd factor***,** *ammonium and pH***,** *4th factor***,** *TSS and nitrites; 5th factor: BOD5 and nitrates).*

needed to achieve the environmental objectives and the specific measures needed to remediate the effects of accidental pollution [28].

Such tools and measures lead to the completion of knowledge on water quality, to the achievement of an optimal qualitative assessment, to the testing of hypotheses on the assessment of pressures and impact [29].

The aim is also to conserve water-dependent habitats and species, to enable the sustainable use of resources and the efficient management of water resources. These measures are necessary to reduce the hydromorphological pressures, the effects of climate change, the phenomenon of eutrophication in water bodies as well as the protection of groundwaters. At the same time, a better understanding of the situation regarding the spatial distribution of habitats and species is needed in line with the trends in land-use change.
