Analysis of Soil Salinization Characteristics in Coastal Area of Panjin City, Liaoning Province

Abstract

Soil salinization is one of the major geological environmental issues in the coastal area of Panjin City, Liaoning Province. By collecting soil samples from the upper 0–40 cm and conducting total salt content tests, this study summarizes the statistical characteristics of soil salinity content, analyzes the correlations between soil salinity ions and total salt content, explores the spatial distribution characteristics of soil salinization in the study area, evaluates soil salinization, and identifies the driving factors of soil salinization in the region. The results show that the total salt content in the study area ranges from 1.3 to 9.0 g kg⁻¹, with Na⁺, Cl⁻, and SO₄²⁻ being the dominant ions. Total salt content is positively correlated with Mg²⁺, Na⁺, Cl⁻, and SO₄²⁻, indicating that the main forms of salinity are sulfates and chlorides. The degree of soil salinization is classified as mild to moderate. The types of soil salinization change from the center to the sides in the following order: sulfate type → chloride–sulfate type → sulfate–chloride type. The degree of soil salinization shows distinct zonality, gradually decreasing from the coastal area to the inland. The main driving factor of soil salinization is the groundwater level, while the evapotranspiration ratio and groundwater salinity are secondary factors that jointly control the process.

1. Introduction

Soil salinization is a common environmental geological issue in coastal areas, characterized by the continuous accumulation of soluble salts in the soil surface, forming salt crusts and salt patches [1]. Soil salinization is a global ecological problem that directly leads to a reduction in arable land area, soil erosion, and soil desertification, thereby triggering a series of vicious cycles. It severely affects human life and hinders economic development, potentially leading to food security issues. Globally, 932 million hm² of land is affected by salinization, accounting for about one-third of the world’s usable land [2,3]. In China, saline soils account for about 5% of the country’s usable land area [4]. Chinese saline soils are characterized by their diversity, large area, and wide distribution, mainly found in the arid and semi-arid regions of the northwest, such as Xinjiang, Qinghai, Inner Mongolia, and Ningxia [5,6,7,8], the inland areas of the northeast, including Jilin, Inner Mongolia, and Heilongjiang [9,10], and the eastern coastal regions, such as Shandong, Jiangsu, and Hebei [11]. The trend of salinization is still expanding nationwide [12].

With the development of society and the increasing population, the importance of arable land resources is becoming more significant, and the issue of soil salinization is gradually attracting global attention. Since President Xi Jinping emphasized the comprehensive transformation and utilization of saline-alkali land, several hot topics related to soil salinization have been intensively studied. In recent years, research on soil salinization has mainly focused on the following aspects: (1) monitoring methods for salinization; (2) factors influencing salinization; and (3) spatial distribution characteristics of salinization. Yuan et al. [13,14,15] conducted in-depth research on the methods for accurately extracting soil salinization information. The results showed that although determining soil salinity by measuring soluble salt content is accurate, it is costly and difficult to implement on a large scale. In contrast, using hyperspectral remote sensing to extract salinization information is relatively accurate and has advantages such as wide monitoring range, strong continuous monitoring capability, and fast information updates. In recent years, some domestic scholars have also used isotopic techniques to reflect the degree of soil salinization, but this method is still immature and not yet widely applied. Fu et al. [16,17,18,19] studied the factors causing soil salinization and their distribution characteristics. The results indicated that climatic conditions, groundwater depth, and topography are closely related to the spatial distribution of soil salinization in the study area, and human activities also influence the formation of soil salinization to a certain extent. Li et al. [20,21,22] investigated the spatial distribution characteristics of soil salinization. The results showed that the influence of various factors on soil salinity at different soil depths is complex, and the interaction between any two factors has a more significant impact on the spatial distribution of soil salinity.

The southeastern coastal area of Liaoning Province is a concentrated distribution area of coastal saline soils. Due to the long-term influence of seawater infiltration [23], the groundwater level is shallow, and the groundwater salinity is high. Coupled with unreasonable land use by humans, soil salinization is widespread in this region. The spatial distribution of salinization is uneven, and the variation of water and salt in space is complex, severely restricting local agricultural development. The southeastern coastal area of Liaoning Province, as an important reserve land resource in the northeast, has great potential for development and utilization [24]. Correctly and effectively analyzing the spatial differentiation characteristics of soil salinity and its driving factors is of practical significance for the scientific use of saline land resources.

This study, supported by the China Geological Survey project, focuses on the southern coastal area of Panjin City, a core region of the southeastern coastal area of Liaoning Province. It aims to reveal the distribution characteristics and patterns of soil salinity ions, analyze the correlations between soil salinity ions and total salt content, explore the spatial distribution characteristics of soil salinization in the study area, evaluate soil salinization, and identify the driving factors of soil salinization. This study is intended to actively respond to national strategic needs, clarify the development direction of comprehensive utilization of saline-alkali land, provide theoretical basis and technical support for formulating precise comprehensive improvement measures and management systems for coastal saline land agriculture, offer geological basis for national land space planning in coastal areas and soil improvement in coastal areas, promoting zero growth of land degradation in coastal zones [25], and constructing a regional integrated monitoring network for resources and environment.

2. Materials and Methods

2.1. Study the General Situation of the Region

The study area is located in the coastal area of Panjin City, Liaoning Province, situated in the southwest of Liaoning Province, on the east coast of the Bohai Sea, downstream of the Liao River. It includes Dawang District, Panshan County, and Xinglongtai District, covering a total area of 1757.21 km². It is an important convergence area between land and sea in the Bohai Rim region of Northeast China. The terrain of the study area slopes from north to south, gradually tilting towards the south with relatively low-lying areas. The main geomorphological type is the Holocene alluvial–marine plain. The study area has a warm temperate continental semi-humid monsoon climate, with distinct seasons and concurrent heat and rainfall. The average annual high temperature is 17 °C, the average annual low temperature is 6 °C, and the average annual precipitation is over 700 mm, mainly concentrated in July and August, accounting for more than 50% of the annual precipitation. The average annual evapotranspiration ranges from 1000 to 1400 mm. The main soil types are Fluvisols, Paddy soils, and Coastal Saline soils. The dominant lithology in the area is silt loam and silt. The groundwater level is high, and the salinity is strong, which easily leads to soil salinization.

2.2. Sample Collection

The sampling period was chosen during the non-fertilization period of agricultural land to avoid the influence of fertilizers on soil test indicators. The sampling locations were in the southern coastal area of Panjin City, south of the Jingha and Danshen Expressways. Nine sampling profiles were set up in the study area, perpendicular to the southern coastline of Panjin City, with five sampling points along each profile, resulting in a total of 45 soil samples collected. Soil samples were collected from the surface layer of plots with obvious salinization, with a sampling depth of 0–40 cm. The double diagonal method was used to collect cubic mixed samples with a sampling shovel. During the sampling process, the sampling amount was kept consistent vertically, and efforts were made to keep the soil samples fresh.

2.3. Sample Testing

The sample tests included the analysis of 10 water-soluble salts in the soil: fluoride (F⁻), bicarbonate (HCO₃⁻), chloride (Cl⁻), calcium (Ca²⁺), magnesium (Mg²⁺), sulfate (SO₄²⁻), potassium (K⁺), sodium (Na⁺), nitrate (NO₃⁻), and phosphate (PO₄³⁻). Potassium and sodium ions were determined by flame photometry (The equipment used in the flame photometry is FP6410 produced by Shanghai INESA, Shanghai, China), calcium and magnesium ions by EDTA complexometric titration, bicarbonate ions by double indicator neutralization method, sulfate ions by EDTA indirect complexometric titration, chloride ions by standard silver nitrate direct titration, fluoride, nitrate and phosphate by ion chromatography, and total salt content by the electrical conductivity method. The sample tests were completed by the Shenyang Geological Survey Center of the China Geological Survey.

2.4. Data Sources and Processing

The data on soil water-soluble salt analysis in this study were obtained from laboratory tests of soil samples. The data on groundwater depth and salinity in the study area were sourced from the Liaoning Provincial Geological Environment Monitoring Station, and the evapotranspiration ratio data were obtained from the China Meteorological Data Center.

SPSS 27 was used to perform statistical analysis, correlation analysis, and principal component analysis on the soil salinity test data. ArcGIS 10.6 was employed for interpolation to draw isopleths and create maps.

3. Results

3.1. Statistical Characteristics of Soil Salinity Content

The study area has diverse ion types (

Table 1. Characteristic values of soil salt composition in the monitoring area.

Feature Value	pH	Total Salt/(g kg−1)	Ion Concentration/(mg kg−1)
			Mg2+	Ca2+	Na+	K+	F−	Cl−	SO42−	NO3−	HCO3−	PO43−
Maximum Value	8.97	9.0	225.00	921.00	1760.0	134.00	67.40	3043	2155	473.00	755	317
Minimum Value	5.93	1.3	14.30	31.20	113.00	10.30	0.00	13.10	27.00	0.00	0.00	0.06
Average Value	7.89	3.9	61.78	173.79	486.22	43.96	14.70	533.30	619.99	84.60	304.62	8.60
Standard Deviation	0.71	1.8	49.09	173.57	347.09	28.97	10.89	581.35	540.25	116.23	163.00	46.57
CV	-	46.15	79.46	99.87	71.39	65.90	74.08	109.01	87.14	137.39	53.51	541.51
Ion Proportion (%)	-	-	2.65	7.45	20.85	1.89	0.63	22.87	26.59	3.63	13.07	0.37

), and the content of each ion shows significant spatial variation, reflecting the diversity of salinity sources and influencing factors in the study area. The pH value in the study area ranges from 5.93 to 8.97, with a relatively small variation and an average value of 7.89, indicating slight alkalization of the soil. The total salt content ranges from 1.3 to 9.0 g/kg, with significant variation. Among the 10 measured ions, Ca²⁺, Na⁺, SO₄²⁻ Cl⁻, and HCO₃⁻ account for 90.84% of the total ion sum. The cation concentration shows the order Na⁺ > Ca²⁺ > Mg²⁺ > K⁺, with Na⁺ and Ca²⁺ being the dominant cations in the saline soils of the study area. Na⁺ has a strong toxic effect on plants, and the hydrolysis of exchangeable sodium ions can make the soil alkaline, further deteriorating soil quality and becoming a key environmental factor limiting vegetation survival and growth. The anion concentration shows the order SO₄²⁻ > Cl⁻ > HCO₃⁻ > NO₃⁻ > F⁻ > PO₄³⁻, with the sum of sulfate and chloride ions accounting for 46.44%. Cl⁻ and SO₄²⁻ are the dominant anions in the study area. Excessive Cl⁻ and SO₄²⁻ can affect plants by inhibiting dehydrogenase [26], influencing plant metabolism, impacting microbial community development, disrupting soil nutrient cycling, and causing soil pollution.

3.2. Correlation Analysis of Soil Salinity Ions and Total Salt Content

By analyzing the correlations between the contents of various ions in the soil, we can infer the sources of soil salinity and reflect the movement trends of salts. As shown in

Table 2. Correlation matrix of soil salinity parameters.

	Total Salt Content	Mg2+	Ca2+	Na+	K+	F−	Cl−	SO42−	NO3−	HCO3−	PO43−
Total Salt Content	1
Mg2+	0.627 **	1
Ca2+	0.291	0.555 **	1
Na+	0.687 **	0.711 **	0.206	1
K+	0.282	0.568 **	0.205	0.544 **	1
F−	0.230	−0.229	−0.180	−0.118	−0.199	1
Cl−	0.536 **	0.681 **	0.474 **	0.868 **	0.458 **	−0.186	1
SO42−	0.510 **	0.863 **	0.562 **	0.590 **	0.637 **	−0.220	0.454 **	1
NO3−	0.296 *	0.672 **	0.590 **	0.236	0.243	−0.257	0.239	0.657 **	1
HCO3−	0.326 *	−0.260	−0.237	0.041	−0.115	0.485 **	−0.107	−0.266	−0.187	1
PO43−	−0.016	0.058	−0.047	0.142	0.143	0.044	0.071	0.077	−0.124	−0.263	1

Note: **. Significant correlation at the 0.01 level (double tail); *. Significant correlation at the 0.05 level (single tail).

, total salt content is positively correlated with Mg²⁺, Na⁺, Cl⁻, and SO₄²⁻, indicating that the total salt content increases with the increase in these ions. Cl⁻ and SO₄²⁻ are positively correlated with Mg²⁺, Ca²⁺, Na⁺, and K⁺, suggesting that the salts in the soil may exist in the forms of MgCl₂, CaCl₂, NaCl, KCl, MgSO₄, CaSO₄, Na₂SO₄, and K₂SO₄. The correlation between Cl⁻ and Na⁺ and between SO₄²⁻ and Mg²⁺ is greater than 0.85, indicating that the salts in the soil are most likely in the forms of NaCl and MgSO₄. The presence of NaCl also suggests that soil salinity ions may be influenced by shallow brackish water and seawater.

Principal component analysis was applied to the soil salinity ions using the dimensionality reduction approach. The data were condensed to obtain representative soil salinization factors and to quantitatively describe the main characteristics of soil salinity ions based on the comprehensive evaluation of principal component analysis. The soil data were standardized to unify the units of multiple indicators and subjected to the Kaiser–Meyer–Olkin (KMO) test and Bartlett’s test of sphericity. The total variance was interpreted, and the orthogonal rotation method was used to derive the final component matrix.

Based on the total salt content and major salinity ions in the study area, three principal components were extracted. The cumulative contribution rate of the first, second, and third principal components is 72.09%, which exceeds 70% and can basically represent the main information of the original variable factors (

Table 3. Explanation of total variance by principal component analysis.

Initial Eigenvalue					Extracted Sum of Squared Loadings
Component	Initial Eigenvalue	Initial Eigenvalue Variance Percentage	Cumulative%	Total	Extracted Variance Percentage	Cumulative%
1	4.387	43.868	43.868	4.387	43.868	43.868
2	1.157	15.165	59.034	1.157	15.165	59.034
3	1.305	13.055	72.089	1.305	13.055	72.089
4	0.906	9.058	81.147
5	0.733	7.328	88.475
6	0.454	4.539	93.014
7	0.404	4.036	97.050
8	0.197	1.968	99.018
9	0.089	0.893	99.911
10	0.009	0.089	100.000

).

The factor loadings of the salinity ion indicators are shown in

Table 4. Factor load coefficient after rotation.

Indicator	Factor Load Coefficient
	1	2	3
Mg2+	0.940	0.043	0.080
Na+	0.754	0.541	−0.146
Ca2+	0.651	−0.292	0.333
K+	0.672	0.245	−0.221
F−	−0.359	0.580	0.251
Cl−	0.762	0.367	−0.094
SO42−	0.888	−0.049	0.083
NO3−	0.668	−0.361	0.436
HCO3−	−0.321	0.683	0.497
PO43−	0.099	0.081	−0.776

Notes: Extraction method: principal component analysis. Three components were extracted.

. In the first principal component, Mg²⁺, SO₄²⁻, Cl⁻, and Na⁺ have the highest loadings, indicating that these four indicators contain the most comprehensive original variable information and have the greatest impact on soil salinization. The high loadings of Mg²⁺, SO₄²⁻, Cl⁻, and Na⁺ (all greater than 0.7) suggest that these ions are closely related to soil salinization. They also reflect that the main components of soil salinity are sulfates and chlorides, which corroborates the results of the ion correlation analysis. The salts in the soil are most likely in the forms of NaCl and MgSO₄. The second and third principal components contain fewer factors with lower loadings, indicating less reference value and a smaller impact on soil salinization.

3.3. Spatial Distribution Characteristics of Soil Salinization

According to the Coastal Soil Salinization Monitoring and Evaluation Technical Regulations, the total salt content in the southern coastal area of Panjin City ranges from 1.3 to 9.0. Based on the frequency distribution histogram of soil total salt content, the degree of soil salinization in the study area is classified as mild to moderate salinization (Figure 1).

According to the standard of the Chinese Soil Science Society for soil classification [27], the type of soil salinization in the area is determined based on the ratio of chloride ion content to sulfate ion content. The area of chloride-sulfate type soil salinization in the study area is 765.74 km², accounting for 43.06% of the total area, mainly distributed in the central part of the study area, the Liaohe Estuary Wetland. The area of sulfate–chloride type soil salinization is 895.40 km², accounting for 50.35% of the total area, mainly distributed on both sides of the study area. The area of sulfate type soil salinization is 6.42 km², accounting for 3.61% of the total area, distributed sporadically in the southern part of Dawang District. The area of chloride type soil salinization is 3.28 km², accounting for 1.84% of the total area, distributed sporadically in the southeastern part of the study area (Figure 2). The ratio of chloride ions to sulfate ions in the study area ranges from 0.17 to 4.60. The types of soil salinization in the southern coastal area of Panjin City have a distinct zonal distribution. The overall trend of salinization type change from the center to the sides is: sulfate type → chloride-sulfate type → sulfate-chloride type. The degree and intensity of salinization gradually decrease, and the area gradually increases. The most widely distributed types of soil salinization are chloride–sulfate type and sulfate–chloride type.

3.4. Evaluation of Soil Salinization and Analysis of Driving Factors

Referring to the “Technical Guidelines for Environmental Impact Assessment—Soil Environment,” the soil salinization in the study area was evaluated using the soil salinity comprehensive scoring method. According to the evaluation results, the soil salinization in the southern coastal area of Panjin City has a distinct zonal distribution, with concentrated distribution ranges for each grade of salinization. The degree of soil salinization generally decreases from the coastal area to the inland (Figure 3). The area of mild salinization is 116.69 km², accounting for 6.64% of the study area, mainly distributed in the western part of the study area (Dongguo Town–Fule Village–Changtun Village–Miaogou–Shixin Town) and the southwestern part (Yuanzhiyi–Xiaohe Branch Farm). The area of moderate salinization is 1377.23 km², accounting for 78.38% of the study area, mainly concentrated in the central part (Yueyaz–Lujiatou–Xinxing Town–Zhaoquanhe Town–Yanchang Village–Nandianzi–Gunlonggang–Sunjialiuzi–Luojiapu–Xinsheng Farm Third Brigade Third Squadron). The area of severe salinization is 263.23 km², accounting for 14.98% of the study area, mainly distributed in the eastern part (Dawang District–Xudong Village–Qingnian Village–Shuangjingzi Village) and the area around Dougouzi Village–Liaobin Township.

The main factors affecting soil salinization, such as groundwater salinity, groundwater level, and evapotranspiration ratio were selected for the evaluation. The soil texture was not included in the analysis because the soil types in the study area are mainly silt loam and silt, which have consistent soil texture attributes. The relationship between these factors and soil salinization was further revealed using SPSS 27 for stepwise regression analysis.

As shown in

Table 5. Correlation coefficient of influencing factors of soil total salinity.

	Soil Total Salinity	Evapotranspiration Ratio	Groundwater Salinity	Groundwater Level
Soil Total Salinity	1	0.195	−0.127	0.399 **
Evapotranspiration Ratio	0.195	1	−0.521 **	0.757 **
Groundwater Salinity	−0.127	−0.521 **	1	−0.536 **
Groundwater Level	0.399 **	0.757 **	−0.536 **	1

Note: **. Significant at the 0.01 level.

, all regression coefficients are less than 0.05 and pass the significance test. The factor most strongly correlated with soil total salt content is groundwater level (0.399). The factor most strongly correlated with groundwater level is the evapotranspiration ratio (0.757), followed by groundwater salinity (0.536). The most significant correlation with groundwater salinity is the evapotranspiration ratio (−0.521). This indicates that the groundwater level has the most direct impact on soil salinization in the area. The significant vertical migration and exchange between soil and groundwater suggest that the groundwater level affects the movement and accumulation of salts, which is the main way of salt migration in the area. The significant correlation between groundwater level and groundwater salinity and evapotranspiration ratio indicates that these two factors also indirectly affect the soil total salt content. In summary, soil salinization in the area is mainly controlled by the groundwater level, with evapotranspiration ratio and groundwater salinity as secondary factors.

Based on the evaluation results and regression analysis, the driving factors of soil salinization in the study area are as follows: (1) the shallow groundwater level in the study area ranges from 1.38 to 10.31 m. The groundwater level shows a distinct zonal decrease from northwest to southeast. The spatial distribution of soil salinization is highly similar to the spatial distribution of the groundwater level. As the groundwater level decreases, the soil salt content increases. The shallower the groundwater level, the more convenient the conditions for capillary water to rise to the surface, leading to soil salinization. (2) The average annual evaporation in the study area is generally high, with an evaporation–precipitation ratio of 1.68 to 2.32. The highest annual evaporation is 1669.6 mm, which is 2.3 times the annual precipitation. Strong evaporation leads to significant water loss from the soil, with the salinization process exceeding the leaching process, resulting in soil salinization. (3) The total dissolved solids in groundwater directly affect the formation and distribution of saline soils. The concentration of total dissolved solids in the study area ranges from 344 to 7504 mg/L. The higher the concentration of total dissolved solids in groundwater, the more salts are carried by capillary water, leading to higher salt accumulation in the soil and increased likelihood of soil salinization. (4) The lithology in the study area is mainly silt loam and silt. These soil characteristics include fine particles, high homogeneity, tight structure, small pores, weak permeability, and strong adsorption capacity. These characteristics cause soluble ions to adhere to the soil surface, making it difficult to remove salts and leading to soil salinization.

4. Discussion

This study comprehensively analyzes the characteristics, spatial distribution, and driving factors of soil salinity in the southern coastal area of Panjin City, Liaoning Province, revealing the formation mechanism and dominant factors of soil salinization in the region. The discussion is as follows.

4.1. Causes of Soil Salinization and Dominant Driving Factors

The results indicate that soil salinization in the study area results from the combined effects of natural factors and intrinsic mechanisms. Groundwater depth is the most direct and critical factor controlling the spatial variation of soil salinity. Shallower groundwater depth enhances capillary action, facilitating the migration and accumulation of salts from highly mineralized groundwater into the topsoil. The evaporation–concentration effect, characterized by a high evapotranspiration ratio, serves as the core driving force for salt accumulation in the surface layer. Its intensity far exceeds that of precipitation leaching, leading to a strong salt accumulation process. Groundwater mineralization provides the direct source of salts, and its concentration determines the flux of upward salt migration. Furthermore, the widespread distribution of silty loam and silt textures in the study area, due to their poor permeability, strong capillary action, and good adsorption properties, significantly promotes salt ascent and retention while inhibiting the desalination process. These four factors—groundwater level, evaporation, water quality, and soil texture—constitute a complete “source–pathway–sink–dynamics” causation system for salinization.

4.2. Soil Ion Composition and Source Indicators

Both soil ion correlation and principal component analysis show that Na⁺, Mg²⁺, Cl⁻, and SO₄²⁻ are the dominant ions in the study area, and these ions exhibit strong homology, suggesting that salts primarily exist in the form of chlorides and sulfates such as NaCl and MgSO₄. This ion combination strongly indicates a marine origin, confirming the continuous influence of seawater immersion, marine sedimentation, and saline groundwater on modern soil salt accumulation. This is highly consistent with the coastal geographical location and geological background of the area. It is worth noting that the relative increase in Ca²⁺ and HCO₃⁻ content in some areas may reflect the influence of terrestrial salt sources, possibly related to activities such as groundwater extraction and agricultural irrigation. In summary, the characteristics of soil salt ion composition fully demonstrate that the salts in the study area mainly originate from seawater immersion, marine sedimentary parent material, and saline groundwater recharge. This understanding provides important guidance for formulating targeted salinization prevention and control measures. During the treatment process, special attention should be paid to blocking seawater intrusion pathways and controlling groundwater levels to prevent salts from rising to the topsoil through capillary action.

4.3. Spatial Distribution Patterns and Their Significance

The degree and type of soil salinization exhibit a clear zonal distribution pattern, decreasing from the coast to the inland areas. The salinization types transition from chloride or sulfate–chloride types in the coastal areas to chloride–sulfate and sulfate types in the inland areas. This pattern is consistent with the spatial trends of groundwater depth and mineralization, further confirming the controlling role of groundwater on salt distribution. It provides a scientific basis for zonal management with significant economic benefits. In severely salinized coastal areas, the construction of drainage engineering and the cultivation of salt-tolerant pioneer crops (e.g., Suaeda salsa) can effectively reduce soil salinity, creating conditions for subsequent agricultural use. In moderately salinized areas, the promotion of integrated rice-reed-fishery ecological models can improve soil quality while increasing comprehensive income per mu. In lightly salinized inland areas, the development of salt-tolerant economic crops (e.g., salt-tolerant rice and wolfberry) and facility agriculture can significantly enhance land output efficiency. The zonal management model not only reduces treatment costs but also enables efficient utilization of saline-alkali land resources, which is of great significance for expanding cultivated land area, ensuring food security, and promoting agricultural income growth.

4.4. Practical Value and Limitations of the Study

This study combines traditional geoscientific surveys with modern statistical and spatial analysis techniques to identify the dominant factors influencing salinization in the Panjin coastal area and their weights, providing a specific scientific basis and geoscientific support for local land spatial planning, precise improvement of saline-alkali land, and sustainable agricultural development. The management measures proposed based on the research results offer important scientific guidance for the local government to formulate effective measures to alleviate groundwater salinization, improve saline-alkali land, and expand cultivated land area. Through saline-alkali land improvement and the cultivation of suitable crops, the scale of rice and salt-tolerant special economic crops can be effectively expanded, driving the development of agricultural product processing and eco-tourism, thereby forming new economic growth points.

However, this study is primarily based on sampling data from a specific period, and the understanding of dynamic salinization processes (e.g., seasonal fluctuations and long-term evolution trends) remains insufficient. Future research could incorporate time-series remote sensing monitoring and long-term positioning observations, and further quantify the impact of human activities (e.g., irrigation methods and land use changes) on water-salt migration to construct more comprehensive prediction and evaluation models.

5. Conclusions

(1) The soil salt composition characteristics in the area are significant and indicative of typical marine origins. The total salt content in the soil varies widely (1.3–9.0 g/kg), and the ion composition is dominated by Na⁺, Cl⁻, and SO₄²⁻. Their combination fully reflects the compound effects of seawater immersion, marine sedimentation, and saline groundwater recharge. Principal component analysis further shows that Mg²⁺, Na⁺, Cl⁻, and SO₄²⁻ are key indicators characterizing the degree of salinization, confirming that chlorides and sulfates are the main salt forms.

(2) Soil salinization exhibits significant spatial heterogeneity and zonal patterns. Spatial analysis shows that from the coast to the inland, salinization types transition in a zonal sequence from sulfate → chloride–sulfate → sulfate–chloride types, with salinization intensity gradually decreasing. Moderately salinized soil dominates (78.38%), overall consistent with the water-salt migration of coastal alluvial–marine plains.

(3) Groundwater depth is the dominant driving factor of salinization, with significant multivariate synergistic effects. Through stepwise regression and mechanistic analysis, groundwater depth is identified as the most important factor affecting the spatial differentiation of soil salinity. Together with the evapotranspiration ratio and groundwater mineralization, it constitutes a “source–pathway–sink–dynamics” coupling mechanism. Shallow groundwater levels, strong evaporation, high mineralization, and silt texture synergistically promote salt surface accumulation and inhibit natural desalination processes.

(4) The research results provide a theoretical and technical basis for the precise management of coastal saline-alkali land. This study integrates geoscientific surveys, statistical analysis, and GIS spatial modeling to systematically identify key driving factors and their weights. The constructed zonal management strategy can provide theoretical and technical support for land ecological restoration, improvement of saline-alkali farmland, and agricultural adaptation planning in the southeastern coastal areas of Liaoning Province. It is recommended to strengthen dynamic monitoring and quantitative assessment of human activity interference in the future and develop a multi-scenario salinization risk warning system to achieve sustainable use of regional land resources.