Threats to the integrity of urban streams in the southwest amazon

Catâneo, Dayana Tamiris Brito dos Santos; Oliveira, Marcela Alvares; Matos, Najla Benevides; Costa, Anna Cristyna Tavares da; Pereira, Fabrícia Simões; Santos, Tauanne Alves Putumujú; Silveira, Maria Áurea Pinheiro de Almeida; Doria, Carolina Rodrigues da Costa

doi:10.4136/ambi-agua.2988

Abstract

This study characterized the physical integrity, hydromorphology, and limnology of ten urban streams in the Southwestern Amazon. The objective was to investigate how these characteristics covary and identify threats to the health of these ecosystems. The physical integrity of the streams was assessed using a Habitat Integrity Index (HII), hydromorphology based on width, depth, flow, and substrate type, and limnological characterization through 14 physico-chemical parameters during dry and rainy seasons. Three streams were classified as preserved, two as intermediate, and five as degraded. Anthropogenic alterations were observed in hydromorphological characteristics, especially in width, depth, and substrate type across different integrity categories. Limnological analysis revealed that chemical and biochemical oxygen demands, ammoniacal nitrogen, nitrate, dissolved iron, and sulfides exceeded the limits established by Brazilian water quality regulations (CONAMA 357/2005). The alteration of these parameters reveals that the primary threat to the integrity of these ecosystems is sewage collection and treatment issues, reflecting the absence of basic sanitation. Redundancy Analysis (RDA) indicated the influence of specific substrate types on parameters in degraded streams, while preserved streams showed a correlation between dissolved oxygen with riparian forest conditions and the absence of anthropogenic influence. Cluster analysis emphasized the importance of integrating environmental, hydromorphological, and limnological metrics for a comprehensive assessment of ecosystem health. Given the heterogeneity of Amazonian aquatic ecosystems, this study may contribute to the establishment of criteria based on regional characteristics for accurate assessment and guidance of public policies aimed at protecting and ensuring the integrity of these ecosystems.

Keywords:
limnological characteristics; microbiological analysis; Porto Velho; urbanization

[1] ^*Corresponding author: Dayana Tamiris Brito dos Santos Catâneo, e-mail: daybrito65@gmail.com

Stream code	Micro-basin	Area	Latitude	Longitude	Characteristics of the studied excerpt
Ig01	Bate Estaca Stream	Urban	-8,804731	-63,907608	Left bank of the stream: few residences; domestic sewage disposal; garbage in the surrounding area and in the stream. Right bank: belongs to an Army Protection Area, absence of residences, medium-sized vegetation with an average height of 10m, strong presence of pioneer species. Close to an area of rural properties with small and medium size farms.
Ig02	Grande Stream	Urban	-8,777872	-63,900783	Many residences on both banks; garbage in the surrounding area and in the stream; dumping of domestic sewage, nearby gas stations and car washes; vegetation marked by large open areas where tree vegetation is discontinuous. Presence of individuals of exotic species and extensive graminoid stratum. Low floristic diversity.
Ig03	Belmont Stream	Periurban	-8,687056	-63,864361	Located inside a municipal conservation unit. Absence of residences, sewage, and garbage discharges. Huge area with well-preserved vegetation and high specific diversity.
Ig04	Bate estaca Stream	Urban	-8,808041	-63,890761	Many residences on both banks; domestic sewage disposal; garbage in and around the stream. Presence of extensive graminoid stratum. Low floristic diversity.
Ig05	Belmont Stream	Urban	-8,755018	-63,870291	Many residences on both banks, being larger on the right bank; the arboreal vegetation is discontinuous. Presence of individuals of exotic species. Presence of extensive graminoid stratum.
Ig06	Belmont Stream	Urban	-8,756044	-63,859701	Located within an environmental protection area; many residences in the surrounding area but absent on the banks; evidence of domestic and industrial sewage; presence of individuals of exotic species and extensive graminoid stratum. Low floristic diversity.
Ig07	Tancredo Neves Stream	Urban	-8,764679	-63,834249	Many residences on both banks; excess discharge of domestic and commercial sewage. Presence of extensive graminoid stratum. Low floristic diversity.
Ig08	Grande Stream	Urban	-8,769907	-63,901383	Right bank with many residences; left bank a Municipal park. Discharge of domestic sewage on both banks; presence of a gas station and car wash nearby. Presence of extensive graminoid stratum. Low floristic diversity.
Ig09	Garças River	Periurban	-8,810971	-63,839371	Located in a little altered permanent preservation area. Absence of residences on both banks and sewage discharges; presence of waste in low quantities. Vegetation with an average height of 12m, important presence of pioneer species.
Ig10	Bate estaca Stream	Periurban	-8,833167	-63,943667	Permanent preservation area present, but altered, rural property area - small and medium size farms, receives effluents from the municipal landfill upstream of the sampled section, vegetation with an average height of 13m and high specific richness.

Limnological parameters	Abbreviation	Unit
Hidrogenionic potential	pH	-
Electrical Conductivity	EC	mS/cm^-1
Temperature	TP	°C
Dissolved oxygen	DO	mg/L
Turbidity	TB	NTU
Total ammonia nitrogen	NH₄⁺	mg/L N
Chloridae	Cl	mg/L Cl
Dissolved iron	FeD	mg/L Fe
Chemical oxygen demand	COD	mg/L O²
Biochemical oxygen demand	BOD	mg/L O³
Nitrate	NO₃^-	mg/L N
Nitrite	NO₂^-	mg/L N
Sulfate	SO₄^2-	mg/L SO₄
Sulfide	H₂S	mg/L S

Limnological parameters	Seasonal period	Stream
		Preserved				Intermediate			Degraded
		Ig03	Ig09	Ig10	Mean	Ig01	Ig02	Mean	Ig04	Ig05	Ig06	Ig07	Ig08	Mean
Ph	Wet	6.10	7.54	7.10	6.91	7.00	7.76	7.38	7.83	6.58	6.72	7.46	7.12	7.14
Ph	Dry	6.74	6.68	6.60	6.67	7.14	7.48	7.31	8.12	7.18	7.64	8.02	6.82	7.56
EC	Wet	0.01	0.02	0.17	0.07	0.15	0.17	0.16	0.29	0.16	0.25	0.34	0.19	0.25
EC	Dry	0.02	0.01	0.35	0.13	0.34	0.28	0.31	0.65	0.23	0.46	0.53	0.22	0.42
TP	Wet	25.04	23.58	26.18	24.93	26.90	27.72	27.31	34.00	29.04	29.60	30.20	27.40	30.05
TP	Dry	24.20	25.40	25.18	24.93	28.20	27.54	27.87	26.78	24.86	29.50	30.54	28.70	28.08
TB	Wet	0.00	3.91	1.93	1.95	7.13	61.69	34.41	39.40	11.40	16.80	62.30	65.60	39.10
TB	Dry	0.00	9.90	3.90	4.60	10.30	14.80	12.55	25.70	8.10	17.30	36.40	4.09	18.32
DO	Wet	5.65	6.20	5.70	5.85	4.30*	4.90*	4.60	5.43	6.72	5.38	5.18	5.06	5.55
DO	Dry	5.36	6.66	5.60	5.87	5.70	5.50	5.60	4.80*	5.20	4.66*	4.47*	2.90*	4.41
COD	Wet	72.00*	56.00*	88.00*	72.00	284.00*	68.00*	176.00	118.20*	609.00*	780.00*	800.00*	66.00*	474.64
COD	Dry	284.99*	232.40*	184.48*	233.96	331.26*	88.22	209.74	1990.00*	20.70	3.68	77.41*	3.89	419.14
BOD	Wet	19.00*	14.80*	11.00*	14.93	120.00*	20.00*	70.00	82.80*	460.00*	516.00*	510.00*	33.00*	320.36
BOD	Dry	131.14*	38.66*	29.14*	66.31	132.64*	42.84*	87.74	461.50*	19.50*	414.40*	35.03*	804.80*	347.05
Cl	Wet	0.40	0.30	0.60	0.43	0.40	0.50	0.45	0.40	0.40	0.40	0.30	0.40	0.38
Cl	Dry	28.40	21.30	56.80	35.50	56.80	49.70	53.25	48.90	35.50	35.50	49.70	42.60	42.44
FeD	Wet	0.39*	0.66*	0.65*	0.57	1.90*	2.81*	2.36	1.55*	0.57*	0.81*	1.63*	1.17*	1.15
FeD	Dry	0.37*	5.52*	0.74*	2.21	1.00*	0.38*	0.69	2.61*	0.23	0.10	0.89*	0.38*	0.84
NH₄⁺	Wet	0.50	0.21	1.57	0.76	0.56	1.87	1.22	1.96	0.07	1.78	1.11	0.81	1.15
NH₄⁺	Dry	0.12	0.02	1.70	0.61	2.43	0.12	1.28	6.00*	0.02	0.12	2.04*	0.88	1.81
NO₃^-	Wet	0.21	0.01	0.26	0.16	0.16	0.20	0.18	0.13	0.30	0.43	0.19	0.19	0.25
NO₃^-	Dry	0.12	1.94	22.90*	8.32	11.60*	1.12	6.36	0.86	13.80*	9.50	35.03*	2.08	12.25
NO₂^-	Wet	0.16	0.03	0.08	0.09	0.08	0.12	0.10	0.12	0.01	0.48	0.21	0.09	0.18
NO₂^-	Dry	0.02	0.02	0.02	0.02	0.20	0.07	0.14	0.01	0.01	0.06	0.02	0.06	0.03
SO₄^2-	Wet	23.10	11.66	26.12	20.29	32.97	37.30	35.14	0.30	33.70	27.37	13.94	22.51	19.56
SO₄^2-	Dry	0.12	4.75	6.94	3.94	3.48	11.54	7.51	12.14	2.23	8.57	9.72	9.15	8.36
H₂S	Wet	0.10*	0.02*	0.09*	0.07	0.05*	0.35*	0.20	0.10*	0.02*	0.09*	0.13*	0.10*	0.09
H₂S	Dry	0.03*	0.12*	0.00	0.05	0.00	0.01*	0.01	0.01*	0.04*	0.01*	0.03*	0.00	0.02

Brasil

Brasil

Threats to the integrity of urban streams in the southwest amazon

Ameaças à integridade dos córregos urbanos na Amazônia Sul-Ocidental

Abstract