Review of 'Biogeochemistry of a tropical river affected by human activities in its catchment: Brantas River estuary and coastal waters of Madura Strait, Java, Indonesia'

Post publication peer review report

Title: Biogeochemistry of a tropical river affected by human activities in its catchment: Brantas River estuary and coastal waters of Madura Strait, Java, Indonesia

Authors: T.C Jennerjahn, V Ittekkot, S Klöpper, Seno Adi, Sutopo Purwo Nugroho, Nana Sudiana, Anyuta Yusmal, Prihartanto,  B Gaye-Haake

DOI: 10.1016/j.ecss.2004.02.008

Introduction
I am interested to read this paper and eventually send out some comments, because I was born and had lived in Surabaya until I was 18 years old. The Brantas river flows through Surabaya. In the past this river had been used to support conventional transportation, until it was stopped, may be in early 1980’s. This river has been used as one of the water source for Surabaya. Therefore any studies about water quality and how it’s influenced by human/man-made activities had drawn many public attention.    

General comments

This paper has a very good introduction and defining the main goal. The authors had also shared the method in a detail manner. They also had mentioned the fertilizer and domestic waste as the main controlling factors to the biogeochemical composition of the samples. 

With the LUSI mud volcano started to erupt in 2006, this paper could be used as the baseline to see the change of biogeochemical values in the water and sediment along the riverbank. LUSI mud had been directed to flow in to the Porong river. This mitigation program, directed by LUSI Mitigation Board, should contribute to the new geochemical balance in the river ecosystem. Future researcher could re-sample the same sites and several more sampling sites in between to see the changing environment.    

Specific comments

There are no specific comments. 

Closing

River water and riverbank sediment could be used as signature of the change of land use in a river basin. In this case, this paper would be a good baseline data for more research to unravel the changes that could be induced by LUSI mud volcano hazard.